Best Answer Charles.C, 02 August 2016 - 07:51 PM
Thank you for your response. I will have a look at the link you suggested. I would have enough background knowledge to understand text, in my degree I covered modules such as microbiology, food science and biochemistry. I asked the question as we had an abnormal micro result on a sample we sent to the lab, which came back with a high yeast count and presumptive entro. All samples since have came back fine, but it has made me realise that I need to learn more about micro as I don't feel well enough equipped if another sample came back with unacceptable results . I can't find practical information i.e.. what is the optimum temperatures for the oganisms to grow, what temperature can they be killed at, what is the main cause etc.
Thanks!
Hi walsh,
Thks reply.
Some comments –
Relevant temperature answers may relate to the type of food/species/matrix involved (unspecified).
Relevant micro answers may relate to the specific procedure/data involved (unspecified).
“Presumptive” is not a very meaningful term unless “negative”. Needs to be “Confirmed” if “Positive”.
“High Count” depends on the number/context.
Will need to give more details if further comments are of interest.
The typical initial approach to an unusual result if considered significant is to investigate production record / repeat (anon.) analysis same/similar lot if possible.
I have attached various refs below which should help to explain a lot of yr general queries. Hopefully fairly understandable but please query if otherwise. The microbial kingdom is highly diverse, don't be too surprised if info. in different refs is not always in total mutual agreement.
Enterobacteriaceae
Members of the Enterobacteriaceae are small Gram negative, non-sporing straight rods. Some genera are motile by means of peritrichous flagella except Tatumella, Shigella and Klebsiella species which are non-motile. They are facultatively anaerobic and most species grow well at 37°C, although some species grow better at 25-30°C. They grow well on peptone and meat extract media. Some strains grow on D- glucose as the sole source of carbon and energy, but other strains require vitamins and or amino acids. Acid is produced during the fermentation of D- glucose and other carbohydrates.
(mic5)
Yeast/Mould
The large and diverse group of microscopic foodborne yeasts and molds (fungi) includes several hundred species. The ability of these organisms to attack many foods is due in large part to their relatively versatile environmental requirements. Although the majority of yeasts and molds are obligate aerobes (require free oxygen for growth), their acid/alkaline requirement for growth is quite broad, ranging from pH 2 to above pH 9. Their temperature range (10-35°C) is also broad, with a few species capable of growth below or above this range. Moisture requirements of foodborne molds are relatively low; most species can grow at a water activity (aw) of 0.85 or less, although yeasts generally require a higher water activity.
(mic2)
PS - Please note that mic6 has some interesting comments on Enterobacteriaceae but data directly relates only to RTE foods.
Interesting to note what yr own situation is ?
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