report in pdf - Graduate School VLAG

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PhD trip to
South Africa
Food Microbiology
Final Report
Wageningen
University
5 – 15 March 2005
PhD trip to
South Africa
Food Microbiology
Final Report
Wageningen University
5 – 15 March 2005
Food Microbiology, Wageningen University
1
PhD trip South Africa
Preface
Every two years a study trip is organized for PhD students of the
Laboratory of Food Microbiology of Wageningen University. All
participating PhD students are affiliated with the Graduate School
VLAG. The aim of the study trip is to exchange knowledge and
ideas between two countries, while at the same time it should make
us aware of different cultures and societies and how these
differences influence education and research.
After visits to countries in Europe and America in the past years,
this year we chose to visit South Africa. South Africa has a solid
history of engagement with research related to practical applications.
Since the democratic elections took place in April 1994 South
Africa has had to deal with a number of challenges and
opportunities. They have undertaken the transformation from an
industrial society to one that is knowledge-based and they have
opened their economy to global competition. Research is focused on
new technologies and implementations and this has resulted in the
extension of the global trade in specific South African products. The
theme of our study trip was therefore:
“International differences in implementation of research into
practical applications”
Organizing this trip has cost us a lot of time but also was a lot fun.
Our weekly Friday morning meetings quickly gave us the nickname
of “theemutsen” and “het kippenhok”, indicating that we always had
a lot to discuss. Most of the time about the PhD trip, but also on our
little frustrations during the organization, pregnancies and other
women talk.
This report contains the reports of both the visits we paid to the
universities and industries in South Africa, and the social program
that was incorporated in the PhD study trip. We would like to thank
all sponsors and everyone who has helped in the organization for
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making this study trip possible. And of course, all participants for
making the trip very enjoyable and fun! We believe our visit has
been a great and valuable experience for all PhD students, both from
an academic and a social point of view.
The organizing committee,
Heidy den Besten, MSc.
Janneke Wijman, MSc.
Ineke van Boeijen, MSc.
Melanie Kuiper, MSc.
Website: http://www.ftns.wau.nl/lmm/content/phdtrip/
From left to right: Heidy, Janneke, Ineke and Melanie
3
Contents
Preface
2
Summary
5
Study tour program & List of participants
Study tour program overview
List of participants
7
8
9
Travel reports
Saturday March 5th: Amsterdam-Cape Town
Sunday March 6th: Cape Town
Monday March 7th: PPECB and Winery “The Bergkelder”
Tuesday March 8th: Stellenbosch University
Wednesday March 9th: SABS
Wednesday March 9th: Nestlé
Wednesday March 9th: SAAFoST meeting
Thursday March 10th: CSIR
Thursday March 10th: ARC
Friday March 11th: Symposium at University of Pretoria
Saturday March 12th: Pilanesberg
Sunday March 13th: Pilanesberg
Monday March 14th : Pilanesberg
10
11
12
14
16
19
22
24
26
28
30
34
36
38
List of sponsors
Sponsors
39
40
4
Summary
Last March 14 PhD fellows and Professor Marcel Zwietering of the
Laboratory of Food Microbiology visited South Africa because of
their biannual study trip. The program of 10 days was well
organized and very diverse. As stated very often by Marcel: "All
three climates were good, the social, scientific and weather climate."
Mainly the weather because we left The Netherlands at -15 oC and
landed in South Africa at 30 oC. We were guided around the Cape of
Good Hope making photos of baboons, penguins and seals. We also
saw "townships": near highways the black townships, on swamplike areas the colored townships and in the city the white people,
which shocked all of us.
During the week, we visited several companies which check the
quality of food products: PPECB (texture of exported fruits), SABS
(bacterial growth in canned fish), CSIR (spoilage of moulds in
packed products) and ARC (quality of milk and meat). All
companies were very pleased with our visit and several questions
were asked after the presentations presented by our PhD fellows.
Several companies were located near Cape Town and others near
Johannesburg. Therefore, we took a plane in the middle of the week
from the South to the North-East.
Furthermore, we visited the Department of Microbiology at the
University of Stellenbosch and organized a one-day symposium at
the University of Pretoria. The research of the microbiology group
in Stellenbosch was similar to microbiological research performed
in Wageningen, although not as much focused on Food
Microbiology as in our group. A lot of research was linked to AIDS,
which is a major problem in South Africa. The symposium in
Pretoria attracted many different researchers. The research of the
MSc and PhD students in Pretoria was focused on food
fermentation, pre- and probiotics and one talk about low bacterial
diets for cancer patients. Again, several PhD fellows of Wageningen
presented their work, which led to interesting discussions. During
the lunch, Maarten Mols, Mark de Been and myself visited the
Bioinformatics group. A building with large letters
"BIOINFORMATICS" on the outside (like WCFS). Mark was
impressed by the building and all of us by their computer capacity
and the work they performed.
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Finally, also a meeting together with SAAFoST (the South African
Assocation for Food Science and Technology) was organized. Our
group gave presentations and these were discussed during a dinner
with around forty members of SAAFoST. Of course we also visited
a South African winery, The Bergkelder, for some smelling and
tasting and we were guided through a Pet Food producing factory of
Nestlé and a fruit packaging factory of Colors.
Our last weekend we stayed in a safari park called Pilanesberg. Each
day at 05.00 and 18.00 o’clock, we were game driving. We spotted
rhinos, zebras, elephants, hippopotamus, crocodile, giraffes, elands,
waterbucks, impalas, springboks, warthogs, brown hyaenas, African
wild dogs etc.
We could conclude that: only few people work in large buildings
where guns are not allowed, the only vegetarian in our group got ill
and the others not due to loads of antibiotics in the large portions of
meat, we gained a lot of knowledge about research and culture of
South Africa and the local Windhoek-ies (beer) and shooters
(springbokkie and pancake) tasted good.
For more information , check www.foodmicrobiology.wur.nl.
Armand Hermans
6
Study tour program
&
List of participants
7
Study tour program overview
Cape Town and Stellenbosch
Sat 5 March
Sun 6 March
Mon 7 March
Tue 8 March
Flight from Amsterdam to Cape Town
Social program in the area of Cape Town
PPECB (visit to farm + packhouse)
Winery Bergkelder
University Stellenbosch
Flight to Johannesburg
Johannesburg and Pretoria
Wed 9 March
Thu 10 March
Fri 11 March
12 -14 March
Mon 14 March
Tue 15 March
Nestlé
SABS
SAAFoST
CSIR
ARC - meattechnology
University Pretoria
Symposium
Social program at Pilanesberg National Park
Flight from Johannesburg to Amsterdam
Arrival in Amsterdam
8
List of participants:
List of participating PhD students:
1.
2.
3.
4.
Armand Hermans
Ineke van Boeijen
Janneke Wijman
Jianfen Liang
5.
6.
Judith Straver
Loveness Nyanga
7.
8.
9.
10.
11.
12.
13.
Maarten Mols
Melanie Kuiper
Mark de Been
Mohammad Aminul Islam
Petra Berk
Petra Roubos - van den Hil
Polycarpe Kayodé
14. Stijn van der Veen
Armand.Hermans@wur.nl
Ineke.vanBoeijen@wur.nl
Janneke.Wijman@wur.nl
Jianfen.Liang@wur.nl
Jfliang1970@yahoo.com.cn
Judith.Straver@wur.nl
Loveness.Nyanga@wur.nl
Nyangael@science.uz.ac.zw
Maarten.Mols@wur.nl
Melanie.Kuiper@wur.nl
MdeBeen@cmbi.kun.nl
Tupurislam@yahoo.com
Petra.Berk@rivm.nl
Petra.Roubos@wur.nl
Polycarpe.Kayode@wur.nl
Polykap@yahoo.fr
Stijn.van.der.Veen@nizo.nl
Participating Professor:
15. Marcel Zwietering
Marcel.Zwietering@wur.nl
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Travel reports
10
Saturday March 5th: Amsterdam-Cape Town
On the Saturday morning (some still say the middle of the night) the
5th of March we went with most of the PhD students of our
department on a study trip to South Africa. Thinking everything was
well organised for a
smooth journey Down
South,
suddenly
getting to Schiphol
airport was a bigger
challenge as expected.
Because
of
bad
weather and heavy
snowfall the trains
were not to be trusted.
So, a small van was
hired to bring us to the airport. Our airplane arrived on time and
boarding went smooth when we received the message that we had to
wait for passengers from a connecting flight. After an hour waiting,
the passengers from the connecting flight were already on board, we
got another message; one of the monitors from the cockpit did not
work. After a delay of over 2 hours (and after removal of the ice
from the airplane) we finally left Schiphol on our great journey
Down South. After all of these delays of course our arrival was
delayed as well. At approximately one o’clock at night we arrived at
the airport of Cape Town over where we were picked up to travel to
the nice university town of Stellenbosch. At half past two we finally
arrived at the hostel in Stellenbosch. We had the pin-code of the
front gate so we thought: no problems. However, that is where the
fun started. Finding our rooms turned out to be a big challenge. All
rooms where locked and the few people that were awake never
heard of our room numbers. After some searching and waking up
some people we found a couple of beds that were still empty. After
filling up these beds a couple of us were checking out the block to
see whether we missed something. It turned out that a house 50
metres down the road was part of the hostel as well and of course
our rooms were in this house.
Stijn van der Veen
11
Sunday March 6th: Cape Town
After a good night rest (a couple of hours max.) our social program
started at nine o’clock Sunday morning. We were going to see the
Table Mountain and the cape peninsula. However, Sunday morning
it was raining and the Table Mountain was covered with clouds. So,
the Table Mountain was off. Luckily, our two guides still made the
best of it. First, we drove to Cape Town and past some Townships
along the freeway. Our guides explained us that half of the 4 million
residents in the Cape area were living in these primitive Townships.
After passing the harbour of Cape Town and the Green Point
Stadium at which Nelson Mandela organised its first aid concerts we
entered the wealthy area of Cape Town. We were surrounded by big
villas with fabulous views over the bays (Clifton Bay, Camps Bay).
These bays were excellent places for swimming, but it was bad
weather in the morning. Entering Hout Bay we had great views over
the mountains covered with clouds and the Harbour. At the harbour
we had some time to wander around and look at the boats or buy
some African crafts in the little shops. Afterwards, we drove over
the Chapman’s Peak Drive, which is a road along the coast going
over Chapman’s Peak. This Road is supposed to be very beautiful
with great views.
Unfortunately,
half of the Drive
was covered by
fog. Coming out
of
Chapman’s
Peak Drive we
passed the Town
of
Noordhoek
and drove on to
the Cape of Good
Hope
Nature
Reserve. This is a beautiful robust area at the bottom of the Cape
Peninsula. In this nature reserve we saw some baboons (bobians).
Close to Cape Point we had an excellent lunch (some still claim the
meet was so tender because of the use of antibiotics in the feeding)
before we had a walk to the lighthouse on top of Cape Point.
Needless to say that the views from this lighthouse were fantastic.
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After our visit at the Cape of Good Hope Nature Reserve we drove
on to the picturesque village Simon’s Town over where we went to
see a penguin colony. The Red Eyed penguins of Simon’s Town are
permanently located at these surroundings and this species is only
found at the coasts of South Africa. Unfortunately by now the day
was already coming
to an end. Heading
back to our hostel in
Stellenbosch we had
a very beautiful
scenic drive along
the coast of False
Bay. Our view over
the Buffelstalberg on
the other side of the
False Bay was really
great. Back at our hostel we had our first Braai (barbeque), of which
many would follow. Ending the days with some (alcoholic)
beverages we were ready to face the scientific program, which
started early Monday morning.
Stijn van der Veen
13
Monday March 7th: PPECB and Winery The Bergkelder
In the morning the group met a representative from the Perishable
Products export Control Board (PPECB) who gave a lecture on what
PPECB is and how it operates. PPECB currently acts as an
independent
service
provider of quality
certification and cold
chain
management
services for producers
and
exporters
of
perishable
food
products exported from
South Africa. It is a
statutory organization
and it conducts its
business in terms of the
Perishable Products Export Control ACT 9 of 1983 and it also
operates as an assignee for the National Department of Agriculture
under the requirements of the Agricultural Product Standards Act
119 of 1990.
PPECB ensures product quality and food safety of South Africa
fresh products from farm to fork. Its national industry partners and
customer base include producers of citrus, deciduous and
subtropical fruits, exporters, vegetables, grain and marine products.
PPECB has also international industry partners and customer base
such as USDA/APHIS, EU Commission, ICCT (International Cold
Chain Technology), EUREPGAP and BRC.
After the lecture from PPECB the group visited one of the
companies (Colors Fruits), which exports fruits from South Africa
and is serviced by PPECB. Colors Fruits Company is the largest
producer-exporter of fruits from South Africa. It focuses on adding
value to fruits through packaging. Colors exports fruits to different
markets worldwide, United Kingdom being the largest market and it
is EUREPGAP certified. Fruits exported include apples, pears,
citrus, grapes, stone- fruits and exotics. At this company the group
went through the whole packaging process. During the packaging
process the different fruits are graded according to size/weight and
then put into three grades which have different packaging colour for
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different markets. Colors Fruits Company has also a laboratory for
quality control of the different batches of fruits where parameters
like sugar content are determined.
In the afternoon a visit to the winery “The Bergkelder” was made.
At the Bergkelder an audiovisual presentation was done which
showed
the
whole
process of wine making
including information
on growing the grape
trees. The group also
viewed the bottling
plant, maturation cellars
and made a stroll
through the cellar in the
mountain tunnel. At the
end of the tour the
group was given an opportunity to taste different types of wine and
also taught how drinking wine blend well with cheese -eating.
Loveness Nyanga
15
Tuesday March 8th: Department of Microbiology, Stellenbosch
University
Stellenbosch is a university
town 50 kilometers away
from Cape Town. The town
is set on the banks of a river
in the wine-growing region
and is encircled by majestic
mountains. Teaching at
Stellenbosch University is
provided in 10 faculties
situated on four campuses:
Stellenbosch,
Tygerberg,
Bellville Park and Saldanha.
On 7th of March at 8:30 in
the morning we left our
guesthouse so called "Back
packers" to visit the
university by walk. It was a 15 minute walk to the department of
Microbiology where we were received by one of the faculties who
introduced us briefly the activities of the department. The
Department has eight academic staff, each of them has a research
laboratory with sufficient space for the comfortable accommodation
of eight researchers. Although the numbers vary from year to year,
approximately 10-12 BSc Honours, 25-30 MSc and 15-20 PhD
students are registered in the Department. In addition, there are
approximately 10 post-doctoral and other research workers, making
a total complement of 60-70 researchers.
After a short introduction, we were taken to the auditorium of the
department where Prof DE (Doug) Rawlings gave a short
presentation on his current research activities and introduced two of
his students one of whom has been working as a post doc fellow
named Marla Tuffin and another was an MSc named Lonnie van
Zyl. They carried on a presentation afterwards. Prof Rawlings and
his students work on the molecular biology of biomining
microorganisms and their plasmids. They also use these iron and
sulfur-oxidizing, autotrophic, acidophiles for the commercial
extraction of minerals from ores. Current research is focused on
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metal resistance mechanisms and their acquisition as well as other
genes present on plasmids and transposons that participate in the
horizontal gene pool. After the presentation of Prof. Rawlings and
his group, Prof Marcel Zwietering gave a short introduction about
Wageningen University and the Laboratory of Food Microbiology
and described briefly the mission of our trip. Afterwards, he
introduced Petra Roubosvan den Hil, Polycarpe
Kayode and Petra Berk
respectively
who
presented their current
research activities. After
the
end
of
the
presentations we went to
the botanical garden of
the university guided by
Nikki (one of the
administrative staff) to have some coffee and snacks. We stayed
there about an hour and enjoyed the beauty of nature. Then we
visited all the laboratories individually and got to know in details the
current research activities carried out by each laboratory. Each
laboratory is headed by one professor. In the following, the name of
the professors and their ongoing research projects are described
sequentially according to our visit:
•
•
•
Prof. LMT (Leon) DICKS has been working mainly on
three different projects: 1)Taxonomy of lactic acid bacteria
2) Characterization of antimicrobial peptides (incl.
Bacteriocins) produced by lactic acid bacteria and 3)The
developing of probiotic lactic acid bacteria for animal feed.
Prof. BA (Bernard) PRIOR has been working on two
research projects 1) Lignocellulose bioconversion using
microorganisms and their enzymes 2) Regulation of
glycerol metabolism by osmotic stress in yeasts
DR A (Alf) BOTHA has been working on the association
between fungi and other micro-organisms in soil. He is also
working on the saprophytic fungi, those have potential
biotechnological importance. He has been studying the
biology of these fungi. Attention is especially focused on
17
•
the impact of human activities, including pollution and on
the numbers of these organisms in their natural habitats. In
addition, the chemotaxonomy of the Mucorales, as well as
the biotechnological applications of these fungi, is also
studied.
PROF WH (Emile) VAN ZYL has been working on four
different projects including 1)The genetic manipulation of
the yeast Saccharomycs cerevisiae for polysaccharide
utilization 2) Cloning and expression of genes encoding
animal and human viral proteins in yeasts and fungi 3)
Conversion of pentose sugars to ethanol with the aid of
recombinant yeasts and 4) Lignocellulose bioconversion
using microorganisms and their enzymes.
It was really a fascinating experience to get know about the
Stellenbosch university particularly the department of microbiology.
We stayed there almost for 6 hours and within this short period of
time we shared many things of common interest. After the end of
this nice expedition we went back to the guesthouse to pack up our
luggage and headed for Cape Town airport where we checked in for
the flight to Johannesburg.
Mohammad Aminul Islam
18
Wednesday March 9th: SABS
On Wednesday afternoon, we visited the South African Bureau of
Standards (SABS) in Pretoria. The entrance control at SABS was
quite strict (checking of bags and bodies for weapons) compared to
the Dutch situation, but after that we received a warm welcome by
Roy Roos, the Microbiology manager of SABS (e-mail:
roy@sabs.co.za).
A video presentation made clear that SABS is present in all areas of
life from drinking water to wedding rings. The activities of SABS
are divided in three business areas: standards, certification and the
test house (for more information is referred to www.sabs.co.za). The
test house contains the scientific services division, of which we
visited the Microbiology department.
The work carried out at the Microbiology department covers the
following areas:
• Testing of the sterility of pharmaceutical products.
SABS mostly carries out validation testing, where SABS’
clients supply the products and the test protocols to be used.
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•
•
•
The tests are performed in a room equipped with HEPA filter
and pressure differences to prevent contamination from the
outside. Depending on the product involved, the sample is first
filtered over a micro filter or brought on the medium directly.
Normally, a 7 to 14 day incubation period at 25-30°C is
employed to ensure that sub-lethally damaged cells have the
ability to recover.
Testing of antibiotic activity.
The vast majority of antibiotic assays are performed on
pharmaceutical samples (tablets) and a small part on feed
samples. One of the methods employed is the agar diffusion
two-point assay. Here an international standard like penicillin or
streptomycin is compared with the sample under consideration,
both at high and low concentration. The antibiotic activity is
measured by diameters of inhibition zones. Multiple repetitions
are made to ensure
that deviations in
diameter caused by
slant or thick media
are detected. In case
of feed samples,
multiple levels of
spiking are applied to
circumvent the effect
of
intervening
chemicals present in
the feed.
Testing of vitamin activity.
Vitamin activity is tested in a liquid medium, using a two-point
assay (analog to antibiotic testing). A separate laboratory is
used to prevent glassware becoming contaminated with
nutrients, which intervene with the vitamin assay.
Testing of disinfectant activity.
The effect of surface disinfectants is tested by bringing a
disinfectant solution into contact with suspensions of indicator
organisms (E. coli, Pseudomonas, Staphylococcus, Aspergillus
niger, Candida albicans) for 5 min and evaluating the
percentage killed. Tests are performed also with yeasts or
bovine serum added to the suspension to simulate the effect of
20
•
•
•
other flora or residual nutrients respectively. Noteworthy is that
food industry often makes the mistake to apply a disinfectant
concentration above the optimum concentration, resulting in
reduced effectiveness.
The effects of hand disinfectants is tested by bringing the hands
of 15 volunteers into contact with suspensions of indicator
organisms, washing hands using a standardized protocol and
evaluating the residual contamination level using touch plates.
These results are difficult to reproduce and to correlate, for
instance due to different skin types of volunteers.
Testing of water quality.
Water quality is tested using membranes. The tests are carried
out on total count, coliforms and E. coli. Tests for other
microorganisms (such as Legionella, Glardia and
Cryptosporidium) are carried out by CSIR.
Testing of food quality.
SABS perform mainly absence tests on regulated products (e.g.
absence of Salmonella on perishable products or absence of
sporeformers after canning)
Hygiene surveys.
Finally, SABS surveys hygiene in pharmaceutical and food
industries. First, the contamination with different groups of
microorganisms (e.g. funghi, aerobes) is determined. This
results in recommendations for improvement, of which
monitoring of the process checks the results.
Judith Straver
21
Wednesday March 9th: Nestlé
Nestle Purina is located at Johannesburg. It is a pet food factory
built in 2003 in South Africa. Main products of the factory are dried
pet foods for dogs and
cats.
The factory has a strict
system for the safety of
the final products. The
system is named NQS
(Nestlé Quality system).
NQS is constituted with
several quality elements,
such as QMS, NGMP,
HACCP and GMP.
The whole plant can be separated into a raw material area and a
processing area. The airflow in the processing area is from the final
products to the processing area.
In order to assure the quality, especially safety, of the final products,
the factory has been divided into several zones according to their
functions. Zones and their functions are presented as follows:
Receiving area: This area is at one of the gates of the factory. It is
the CCP for the whole system. The manager told us this area is
extremely important because all materials will be received here.
Raw materials might be contaminated with mycotoxin. And no steps
can eliminate this kind of hazard. The transporting truck has to wait
here for about two hours for the quality check. Small quantities of
materials will be sampled at different parts of the whole tank. 25 kg
samples will be taken for 30 tons of material, and 1 kg of the
collection will be sent to the lab for quality analysis. Results will be
obtained by rapid analysis. The final product will be safe if the
materials are safe since all materials will be used in two days and
almost nothing is stored in the factory.
22
Storage and mix area: This area is a dry area for the temporary
storage of materials. In this area the bags with materials are opened
and a mixture of the materials is according the different recipes.
Control area: This area is the center for machines controlling.
Operators will control the quality of mid-products by adjusting the
processing temperature and time. Machines will go automatically.
Wet processing area: This area is just next to the control area. They
are separated from each other with glass. The procedures in this area
include adjusting of water content and extrusion of material.
Dry area: Drying, coating and packaging of the final products will
be fulfilled here.
Storage area: This is the area for the short-time (only one day)
storage of the final products.
To sum up, the first priority of the plant is preparing safe products.
Jianfen Liang
23
Wednesday March 9th: SAAFoST meeting
Now being back home for almost a week. I realized I had to do
something. I recently changed rooms; luckily I’m sitting next to
Janneke now. Since she was one of the organizers who made the trip
possible, she knows what I was forgetting. She told me kindly I had
to write a little story about the SAAFoST meeting. How much space
do I have, I asked Janneke, a little bit annoyed by my questions (she
thinks I should remember everything she once said), responded: half
a page up to one page. This should be enough to write a story about
the meeting that lasted for just over an hour. I remembered I wrote
some notes in my booklet about this meeting. So I should start to
write before my page ends.
Ready for at least an hour drive, we went from Nestlé Purina’s pet
food plant to DSM. To our great astonishment the drive lasted for
five minutes. Entering the premises through the gates wasn’t a real
problem and Jaci Barnett rushed out to welcome us. We all got a
badge with our names, like we were special. Actually we were
special! The entire meeting was dedicated to our three speakers
Armand, Janneke and Loveness.
Marcel Zwietering gave a short introduction about Wageningen
University and our group (ATV-FHM). He mentioned the good
scientific, personal and meteorological climate of South Africa and
introduced the first
victim of this
audience hungry
for
information:
Armand Hermans.
Armand
is
working at the
RIKILT (Institute
of food safety) and
he talked about his
project. In the last
decade
certain
Salmonella strains
became emerging. Armand examined why this Salmonella
Typhimurium DT104 is emerging by two approaches: comparative
genomics and with the use of micro arrays. The genomics part
24
showed that inserted phages could be responsible for the elevated
levels of DT104 found. The micro array works the other way
around, this is not a emerging strain what does it lack. The array
displayed that the non-emerging strains miss some virulence genes.
Armand will focus more into the expression of genes in DT104 and
the characterization of Salmonella by PCR.
The second victim, Janneke Wijman, presented her work on biofilm
formation within a WCFS project. To quote my notes in my little
booklet: Janneke talked about WCFS bla bla!, however writing this I
forgot what I meant with it. Ongoing with the more scientific part of
her performance, she explained what Bacillus cereus can do and
what biofilms are and how they grow. Biofilms are important in
dental plaque and in the lungs of CF patients. Especially strain
diversity is a hot topic in biofilm research. Janneke investigated
several strains in different media and at different temperatures. She
found that most strains form more biofilm when grown in defined
medium with 0.5% glucose. Strikingly, some strains were only able
to form biofilms when grown at a specific temperature.
Loveness Nyanga was the third and final victim. With her
experiments she tries to prevent the loss of and upgrade the
traditional process of fermenting massau fruits. She wants to
establish a suitable starter culture to produce alcoholic beverages
from indigenous fruits of Zimbabwe. The massau fruits are
indigenous in Zimbabwe however these are only cultivated in
Mozambique, concluding that there could be a market Zimbabwe.
After these presentations the audience was saturated with
information and became hungry. We enjoyed the typical South
African meal: Cottage Pie, which was a dish with potato and minced
meat. I ‘d love to write more, however my page, promised by
Janneke, is about to become full. Therefore, I ‘d like to thank Jaci
Barnett and the organizing committee for this opportunity to meet
some of our South African colleagues.
Maarten Mols
25
Thursday March 10th: CSIR
Today we visited the Council for Scientific and Industrial Research
(CSIR), the division of Food, Biological and Chemical technologies
(Bio-Chemtek). The aim of this division is to create economic and
social benefits through innovation in food and life-sciences. The
total staff of CSIR consists of 2500 scientist of whom 320 are
working in the
five areas of
Bio-Chemtek:
Bioprospecting,
Biotechnology,
Specialty
and
Fine Chemicals,
Food
Science
and Technology,
Analytical
Science
and
Technology and
Technology for
Development.
The work performed within the group of Microbiology is: initiate
new projects, participate in research projects, solve problems for
local food industry and perform routine analysis on spoilage,
vitamins and monitor air quality.
Here we report a summary of work performed on spoilage at the
microbiology group. Spoilage can appear in high acid food stuff,
soft drink, alcoholic beverages, condiments and sauces. Spoilage of
fruits and fruit products by heat resistant moulds is a major problem.
These heat resistant moulds include Byssochlamys fulva/nivea,
Taloramyces
species
and
Neosartorya fischeri. These
moulds can produce harmful or
unwanted substances, like
production of an awful
chemical-like taint (kerosene
smell). Another group of
Trichoderma
strains
can
produce styrene, which has a
26
plastic-like taint. This taint was thought to be from the packaging
material but after research, this taint was produced by these
Trichoderma strains.
After the presentation of the Bio-Chemtek members, Jianfen Liang,
Maarten Mols and Polycarpe Kayodé of our group gave
presentations to share their research findings with the Bio-Chemtek
members. Several questions arose after each presentation. After a
coffee break our group was guided through the microbiology
department, which harbors a large culture collection on bacteria,
fungi and yeast/moulds. Furthermore we also visited the process
building which harbored extruders, spray-dryers, milling machines
and other sophisticated apparatus.
Armand Hermans
27
Thursday March 10th: ARC
The Agricultural Research Council (ARC) has the largest
agricultural research capacity and pool of expertise in South Africa
to serve the food and nutrition fraternities, both locally and in the
region. They regularly interact with fellow scientists regionally and
internationally to ensure the quality of the services they offer. The
vision of ARC is:
"To be an internationally recognized centre of excellence in
agricultural science and innovation"
We visited the animal nutrition and animal products institute. It is
one of the institutes of the ARC, the objective of this institute is to
develop environment-friendly technologies, promote animal
production and improve the quality of animal products. Research
and development are undertaken to provide for the nutritional needs
of animals and to improve the quality of meat and dairy products.
This information is made available to farmers, producers, feed
manufacturers and organizations that utilize, process and market
animals and animal products.
The Department of Animal Products and Food Security conducts
research on waste and effluent management, probiotics and culture
management, product technology and sensory analysis services to
the food and beverage
industries, food safety and
hygiene, and projects to
address food security in rural
communities.
We arrived at the institute at
1.00
pm.
We
were
welcomed with a great
lunch. There were a lot of
South African sausages and
other meat with bread and drinks. After lunch the director Dr. Heinz
Meissner told us about the institute. He told about the research they
are doing on probiotics, food safety and sensory analyses.
Then Prof. Marcel Zwietering gave a short introduction about the
Wageningen University and the research we are doing on the Food
28
Microbiology department. Thereafter Judith Straver gave a
presentation about her PhD project “modeling of micro-organisms, a
food chain perspective”. The next speaker was Mohammad Aminul
Islam about “prevalence of Shiga toxin producing E. coli in
Bangladesh”.
They were also very interested in the work Janneke Wijman does, so
she gave a short presentation about her work of Biofilm formation
by Bacillus cereus.
After this presentation Louise Maré, a PhD student who worked at
this institute in collaboration with the university of Stellenbosch,
told something about her work. She almost finished her project:
“the effect of probiotics on the milk production of cows”. She looks
to effects of this
probiotics in the
gastro-intestinal
tract.
Furthermore, Dr.
Heinz Meissner
told us that in
South Africa the
meat might still
contain
some
antibiotics in it.
We visited the
microbiolo-gical
laboratory, an abattoir and the sensory analyses rooms. We drank a
cup of coffee and went back to the hostel.
In the evening we had a “braai” at the hostel, with again a lot of
meat (with antibiotics!!), salads, beer and shooters.
Petra Roubos
29
Friday March 11th: Symposium at University of Pretoria
On the 11th of March we had a symposium at the University of
Pretoria. Since it was not far from the hostel we went there by foot.
When we arrived in the food science building we could enjoy a nice
cup of tea or coffee. The Symposium on Food Microbiology started
at nine sharp and was kicked off by prof. André Oelofse of the
Centre for Nutrition from the University of Pretoria. He told us
about the motto of the centre for nutrition, “wellbeing through
nutrition” and their mission to facilitate education and research in
nutrition. The centre of nutrition consists of 6 departments;
consumer science, chemical pathology, animal science, food
science, veterinary science and human nutrition. The research of the
food science department is focused on food security, nutrition and
infection, nutrigenomics and food composition. The research covers
the whole lifespan
from children to
elderly. After that
there was a short
introduction
by
prof.
Marcel
Zwietering about
the
Wageningen
University
(WU)
and related research
centres. The first
PhD student to give
a presentation was Melanie Kuiper from WU. The title of her
presentation was “Legionella in biofilms”. She told us about the fact
that Legionella needs other micro-organisms for growth in biofilms
and how she conducted her research to investigate what organisms
were needed for growth of Legionella. The conclusion was that
Legionella needs protozoa for growth in aquatic biofilms and that
Hartmannella vermiformis was present as the only dominant
protozoa. Also she concluded that Legionella is able to proliferate in
the presence of one bacterium and H. vermiformis. The next speaker
was Renza Vermeulen from the University of North West. She
talked about the microbe count of Low Bacterial Diets (LBD) served
to neutropenic patients. Neutropenic patients are patients with a
30
decrease of circulation neutrophils, which are white blood cells. This
LBD diet is used for patients after a bone marrow transplant. LBD
evolved from a sterile diet which was first used in 1960, when all
food was irradiated to kill all microbes. Patients in need of LBD are
very limited in what they can eat, and how this heavily processed
food tastes, which has a great impact on their quality of life. Also no
study had proven that LBD decreased the risk of bacterial and fungal
infections. So the question is, if it is necessary to limit these patients
in their food consumption at such high level. The next speaker was
Mark de Been from Radboud Univerity of Nijmegen and the WU.
His subject was signal transduction in Bacillus cereus. The goal of
his research was to identify molecular targets for preservation
stresses in B. cereus. He searched for two-component systems in the
genome of B. cereus, B. anthracis and B. thuringiensis. He found
50-60 two-component systems in different strains. The twocomponent systems consist of a histidine kinase and a response
regulator. He found a group of histidine kinases that resembles
sporulation genes of B. subtilis. Since all speakers finished in time
we had half an hour of coffee break with delicious South African
cookies. After the break there was a change in schedule and Elbie
Beukes told us about the enhancement of the probiotic potential of
South African kefir. She wants to incorporate selected probiotic
strains into kefir grains, in which already moulds and bacteria are
present. From kefir, milk is made which has a long shelf-life, is
suitable for lactose intolerant people, can be mass produced and can
be enriched. The aim of the project is to identify which probiotic
strains are best suitable and how much probiotic bacteria should be
added. She wants to investigate this by studying in vitro adhesion,
molecular techniques, a consumer panel and gas chromatography.
The next speaker was from WU again from the product design and
quality management group, Judith Straver. Judith had a great talk
about modeling hazards in food chains with Salmonella. She used
the broiler meat chain as a case study and showed us that it is
important to consider the whole food chain in quality issues and that
simple scenarios can give already a good insight in what happens.
Richard Nyanzi from the Tswane University of Technology talked
about enhancing the nutritional and probiotic quality of mahewu.
Mahewu or Mague is a fermented maize meal beverage. It has been
used by mine workers for decades, widely consumed by the general
31
public and a part of established food habits. The aim of this project
is to develop a synbiotic protein enriched maize beverage. In the
first part of the study the quality characteristics of commercial and
traditional Mague will be analysed. A synbiotic version will be
developed and the protein quality will be enhanced. In his
preliminary conclusions he showed that Lactobacilli readily adapt to
growth in maize gruel, but need an additional carbon source. The
last speaker before lunch was Loveness Nyanga from Wageningen
University. She is from Zimbabwe and studied the microbiological
and biochemical properties of masau fruit fermentation and
prospects for the development of starter cultures to produce masau
wine and or beverage. The masau fruits are highly nutritious,
drought resistant, eaten fresh, dried or as masau jam, it is a
traditional medicine and widely cultivated in middle and east India,
Mozambique and on trial in Zimbabwe. The aim of the study is to
isolate and identify yeasts on masau fruits and from the fermented
product using classical and molecular techniques. Till now 81 yeasts
has been isolated of which 8 has been identified on ribosomal RNA.
We finished exactly in time for lunch, which we enjoyed outside.
Prof. André Oelofse took some guys on a tour to the bio-informatics
department of the University of Pretoria.
Petra Berk
32
In the afternoon, six communications were given. Four of them were
presented by Wageningen Students and two by Students of
University of Pretoria (UP). Stijn van der Veen, Armand Hermans,
Ineke van Boeijen and Jianfen Liang presented the communications
from Wageningen. The first communication from UP by Shadrack
Phophi deals with the food safety in fresh produce market. The
communication highlights that fungi and bacteria are the
predominant microorganisms in fresh fruits and vegetables sold in
local markets of Johannesburg and Pretoria. However products
stored in cool room showed lower level of contamination. Possible
sources of contamination of products could be the soil, irrigation
water, faeces and handling. The second communication by Mathoto
Lefyedi concerns the effect of alkaline treatment on the microflora
and quality of sorghum malt. A major problem in malt production in
South Africa is the presence in the product of aflatoxin, a toxin
secreted by Aspergillus flavus. The study showed that application of
0.2% of NaOH results in lower microbial count and improves the
Diastatic power of the malt.
Polycarpe Kayodé
After the symposium there was a possibility to drink some sodas,
wine and beers and eat some real South-African treats. One of the
master students joined us for dinner and showed us her room, which
we thought was very luxury. Prof. André Oelofse had arranged
dinner in a restaurant where we could try some South-African
specialties; potjies, ostrich steak, kingklip (fish), bobotie and other
delicious foods. The only problem was that is was way too much for
us to eat, so some people took something back to the hostel in a
doggy-bag. After dinner some of us joined the South African student
to a local disco in which we had lot of fun, listening to the South
African anthem and other South African sing along songs of which
we could understand only few words which made it even more fun.
Petra Berk
33
Saturday March 12th: Pilanesberg
After a night of going out in the city of Pretoria where we learned
some great South African hits like “Lekker Bejaard” and “Oud
geleerd is dronk gedaan”, we left for Pilanesberg National Park in
the morning, where we were to stay for the next three days to
conclude our trip. On the way from Pretoria to Pilanesberg we made
a short stop at a local market and there it appeared that some people
are very skilled in bargaining and beating down the prices. After
greatly stimulating the South African economy (i.e. all our bags
were stuffed with African souvenirs), we continued our way to
Pilanesberg where we arrived early in the afternoon.
Pilanesberg is a beautiful park. It is one of the largest national parks
in southern Africa, covering an area of 50000 hectares. It is
encircled by a ring of hills, which was produced by volcanic action
some 1200 million years ago.
In the evening we already did our first safari and we had a good
start, since we immediately spotted a group of baboons (bobbejaan),
including baby-baboons, on the side of the road. Furthermore, we
spotted
some
elephants
(Afrikaolifant) and some
white
rhino
(witrenoster) and lots
of prey animals,
which we were to see
even more during the
following days (and
which all looked
more or less the
same). Just to give an
Pilanesberg National Park
impression,
that
evening or the following days, we spotted: blue wildebeest
(blouwildebees),
red
hartebeest
(rooihartbees),
tsessebe
(basterhartbees), kudu (koedoe), eland, waterbuck (waterbok),
reedbuck (rietbok) and impala (rooibok). And lots of birds, such as:
white egret (witreiger), marabou, sacred ibis (shoorsteenveër),
glossy ibis (glansibis), hadeda ibis (hadeda), helmeted guinea fowl
34
(gewone tarentaal), secretary bird (sekretarisvoël), spotted eagle owl
(gevlekte ooruil), grey lourie (kwêvoël), red billed hornbill
(rooibekneushoningvoël) and ostrich (volstruis). And that evening
we saw a lot of zebras (vlakte kwagga) with many baby-zebras.
They were really everywhere (“vlakte kwagga hier en vlakte kwagga
daar”) and we soon started to wonder where all the lions were to eat
them …
… and the lions could certainly have learned something of us,
because that same evening we had a huge “braai” with lots of
(zebra?) meat.
35
Sunday 13th March: Pilanesberg
Next morning (actually in the middle of the night) we did a second
safari. Again there were lots of prey animals, but remarkably
enough, hardly any zebras. Late in the morning we spotted warthogs
(vlakvark) with baby-warthogs, three enormous white rhinos that
crossed the road, a group of giraffes (kameelperd) with babygiraffes and a lone hippo (seekoei). But again no lions …
The rest of the day we spent in Sun City, a village/city located
within Pilanesberg Park
and which can best be
described as South
Africa’s Las Vegas. Sun
City contains many
facilities, including a
huge
entertainment
centre with a casino,
bird aviaries, an Indiana
Jones-like
palace,
palace gardens, the
Bridge of Time (where
you can experience a real earthquake with a magnitude of 1 on the
Richter scale) and the Valley of Waves, which is a huge swimming
paradise. This subtropical swimming paradise proved to be a good
place to relax after a busy week. Some people just couldn’t get
enough of the thrilling slides and the artificial waves. And these
waves really appeared to be dangerous since certain people were
actually smitten against the rocks and were left on the shore with
some nasty injuries.
Sun
City
really
turned out to be an
Indiana
Jones-like
place when some
people discovered a
secret passage that
lead to the swimming
paradise. This was
especially nice for
them, since they
36
didn’t have to pay the entrance fee for this facility. So if you are
ever planning to go to Sun City and want to take a dive in the
Valley, just contact Stijn van der Veen, Petra Roubos or Armand
Hermans and they can describe this secret passage to you.
In the evening, we again did a safari and again did not see any big
cats. This time we woke some rhinos, which were sleeping
alongside the road (and the rhinos woke some of us). Furthermore,
we followed a brown hyena (bruinhiëna), which was walking in a
slow pace on the road and which didn’t care about us at all. And we
spotted a large family of elephants after which I really have the
impression that elephants like trashing the forest, since they break
down large parts of trees, but still only eat the leaves. Back at the
camping site we had a nice “braai” and since it was our last evening
in South Africa, we also had lots of beers.
37
Monday March 14th : Pilanesberg
This was our last day in South Africa and we started again with a
safari early in the morning. A Dutch family joined us on our safari
and we had the impression that they had paid an additional sum of
money, because we really saw a lot of animals. We actually saw all
the animals we had already seen the days before. In addition, our
safari-guide even took us on a detour to show us a place where they
kept African wild dogs (wildehond), which were soon to be released
in the park. He also took us alongside the small lake that is in the
middle of the park, where we spotted a genuine Nile crocodile
(Nylkrokodil). Finally, we saw the big family of elephants again,
which we had seen the previous evening, and we could now see that
besides baby-elephants, there were even baby-baby-elephants
among them. But again no lions …
After the safari, we packed our luggage and still had some time to
go for a beautiful walk alongside the borders of the park. Of course
we desperately hoped to see some lions on the other side of the
fences, but alas. The only thing we saw were enormous ostriches,
which walked on the camping site, kudus, termite hills and lots of
giant ticks that attacked us from all sides.
And then, after the walk, we left Pilanesberg and headed for
Johannesburg International airport. At the airport, we said goodbye
to Loveness and Polycarpe and at about 24.00 hrs took our plane to
Amsterdam.
Mark de Been
38
List of sponsors
39
VLAG
Wageningen University (ATV-PDQ)
WCFS
Wageningen Centre for Food Sciences
RIKILT
KNAW
Koninklijke Nederlandse Akademie van Wetenschappen
40
A&F
NIZO
CMBI
Sonnema
Stichting LEB Fonds
Stichting Landbouw Export Bureau 1916/1918
41
Sonnema Berenburg, In sûpke op syn frysk.
PUUR OP KARAKTER
42

report in pdf - Graduate School VLAG

Transcription

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