Food poisoning bacteria - Food poisoning bacteria (Nov/23/2008 )

Hi all,

I have a question relating to food poisoning which im hoping someone can help me with.

Im trying to answer the following question:

Describe, with reference to journal literature, how food poisoning bacteria are able to survive and/or proliferate in foods.

The answer must convey a recognition and understanding of:
* the influential factors within foods which influence the growth and survival of microorganisms
* relate these factors to the growth of specific food borne bacterial pathogens
* use information from journals (at least five references published within four years) to effectively explain the relationship of environmental factors and the growth of specific food borne bacterial pathogens

Now i have been able to identify the environmental factors which are oxygen, water, temperature, PH and time, but im confused what the influential factors are and how i am supposed to relate these factors to the growth of specific food borne pathogens. So if anyone can explain this to me or point me in the right direction i will be gratefull for any help i receive.

I have been researching on the internet but cant seem to find any information, i am going wrong somewhere but any one with knowledge of this area please help me out.

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if you know the environmental factors, then relate them to food:

eg. Bacillus cereus likes to live in cooked rice in chinese buffets. why? look up bacillus' oxygen requirements (ie. it's an aerobic organism, and rice in a buffet is kept in an aerobic atmosphere); water (bacillus requires certain water level, which is present in rice), temperature (bacillus can survive in high temperatures (up to 60oC), so rice that is kept at 50-60oC as is often in a buffet situation can grow bacillus because it likes hot conditions, and can form spores to survive such conditions too), PH (as for water) and time (rice on a buffet can be left for hours - bacillus can live in these conditions for hours, not get killed and will proliferate in such conditions).

choose a couple fo bacteria as examples and say how the environment they're commonly found in (ie. food) helps them grow.

choose something like salmonella, campylobacter, e coli etc.

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Hi,

I understand the environmental factors, but what does it mean by the influential factors within foods? thats where my problem lies. If you have tried to explain it in your post im sorry but like i said im confused i cant seem to understand it. Do you mean how the environmental factors are influenced by certain pathogens to survive and proliferate in foods?

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I think prea is talking about the food environment i.e. a pot of rice. This pot of rice is like an environment (like my lab is an environment to me) to the bacteria. If it favors them, then they'll grow and proliferate. Prea mentioned about the oxygen requirements.

Now, microbes do change their environment too. Making it more suitable for them (reduced pH). Then that'd lead to conditions favoring other microbes. Often, you'd get more than one type of microbes in spoilt food.

Another factor may be water acitivty. In honey, water activity is very low (60+ % sugar) and thus you don't meet spoilt honey so often. Salted fish (and other pickled stuff) on the other hand supports halophiles. Some still eat them though its spoilt (in microbiological point of view).

Now, back to inedible food, there you have it. Factors like oxygen, pH, osmotic pressure etc. are able to promote growth of food-borne pathogens.

Hope it helps. Anymore to add anyone?

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Hi junior25,

I think that the prea's post contain the answer you are looking for. The influential factors within foods are the factors that allow certain bacteria to proliferate and survive in those environments, meaning influential TO bacteria (and not the other way around).

This makes a big difference for certain pathogens that wouldn't be able to thrive in plain soil, surfaces, waste water or inorganic garbage.

Now you need to correlate this factors (nutrients, pH, etc) with the ability of certain pathogen to survive and colonize the host after it has eaten contaminated food. Prea's example are very good.

For good references, try using pubmed. Search a food borne pathogen name, or even "food pathogen" and will retrieve several papers you can use (or at least the abstracts).

Good luck!

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Hi,

Ok thanks everyone for replying.

Ok i kind of have an idea now of what i need to do, but im still confused on the influential factors. Iv been told the the influential factors within foods which influence the growth and survival of microorganisms include nutrion.....so would protein and carbohydrates be included??? if anyone can comment on this and give me a few more influential factors i should be looking at the would be great.

Ok once i have the influential factors how can i relate these to the environmental factors which include ph and temperature etc....? im still pretty confused on how to do this so can someone help me out. I took into account what prea said and i did produce an answer but i was told by my lecturer that it was too basic and i was not addressing the influential factors. My assignment was more focused on the environmental factors such as ph and temp, oxygen etc so i need to focus more on the influential factors.

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