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Culture Collection


C_Sagan_Returns
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Currently enrolled in Applied Microbiology, I'm responsible for developing a culture collection of > 10 different species. Having only a simple general microbiology background, I don't know many microbes by name. It's been suggested that we bring in samples from outside the classroom and try to isolate and culture several specimens. Fungi can be included, but bacteria should be the focus of this collection.

I'm looking for any ideas so feel free to namedrop. Here are some ideas I've got so far:

 

Fungi:

Geotrichum fici -- While looking up various genera for an assignment, I discovered G. fici produces a pungent odor reminiscent of pineapple. How would I select an organism ubiquitous to the environment like this fungus (It's found everywhere right??)?

 

Bacteria:

Other than the model organisms one is first introduced to (e.g., M. luteus, S. marcescen, B. subtilis, E. coli, etc.) I don’t have many ideas. Characteristics of interest include (!! = Required):

--○ The ability to be cultured!!

--○ GRAS status (No Y. pestis)!!

--○ Possessing unique metabolic processes

--○ Having a pleasant scent or beautiful colour

--○ Holding historical significance

--○ Being interesting in some other fashion

 

Ecological Niches:

Aside from hunting specific beasts, one can investigate a plethora of microenvironments. One niche of interest that peaks my interest is the flora inhabiting the human navel and produce that nasty (some have referred to it as "cheese"-like) smell.

 

What are your favorite microbes?

 

Any thoughts?

 

Thanks,

CSR

Edited by C_Sagan_Returns
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I have a fondness for Trypanosoma cruzi - but only because when I first heard the name of the disease it causes I was in a lecture and the guy sitting next to me thought it was so funny that he couldn't control his giggles - and when someone next to you is laughing like mad, it's kind of infectious and soon the whole hall was in tears - apart from our lecturer, who was quite an eminent scientist and really wasn't amused. I am now more mature - the disease it causes is really unpleasant but the name is Chagas disease

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I like any beta haemolytic streps - especially the ones that smell like caramel :D eg S. constellatus.

 

I also like Pseudomonas sp. - P. aeruginosa which has a lovely green pigment to it and it can also produce a shiny metallic pigment too. It smells like grape soda!!

 

There are other Pseuomonads that are pretty colours.

 

Not sure on the GRAS status of those ones though :/

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I like any beta haemolytic streps - especially the ones that smell like caramel :D eg S. constellatus.

 

I also like Pseudomonas sp. - P. aeruginosa which has a lovely green pigment to it and it can also produce a shiny metallic pigment too. It smells like grape soda!!

 

There are other Pseuomonads that are pretty colours.

 

Not sure on the GRAS status of those ones though :/

 

Oh wow, kewl!! I never knew that, thanks so much for the ideas. This was the kind of reply I was looking for. Please, keep em' comin' guys and gals.

 

Also, I understand that most of these species are found almost everywhere but, any suggestions as to how I should isolate these beasts would be much appreciated.

 

CSR

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P. aeruginosa is an opportunistic pathogen, so be careful. Also I have to add the caveat that if you isolate bacteria from environmental samples you cannot assume GRAS status, as there may be infectious in between them and there is always the chance to increase their titer to dangerous numbers. This is especially true for bacteria isolated from humans, even if it is only the skin.

It depends on countries and then even on the respective local biosafety regulations, but often if you cannot state with certainty what you got in your raw sample, you will have to treat everything as potentially infectious (with all safety measures that have to be taken etc.).

 

That being said, there are number of interesting soil bacteria. For example rhizobia (e.g. Sinorhozobium meliloti, Rhizobium legumniosarum, Mesorhizobium loti they induce nitrogen fixing root nodules in their respective legume hosts. A simple class experiment would be infecting the respective legumes with the given bacteria and see their growth increase compared to non-infected plants.

Corynebacterium glutamicum an industrially relevant amino acid producer,

Synechocystis photosynthetic bacterium.

Shewanella oneidensis it is known to dissimilatory reduce about anything.

Myxobacteria, e.g. Myxococcus xanthus it forms fruiting bodies and hunts other bacteria.

 

Just to name a few.

Make no mistake though, creating a pure sample out of an environmental one is quite a pain in the lower back. Even if you see a nice uniform colony upon microscopic investigation one can find that it is not that pure after all. I remember a grad students whose job was to isolate bacteria with a specific metabolic ability out of anaerobic samples. Took ages until he realized that the co-contaminant was there because it was smaller than the sterile filter he used....

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Pseudomonas aeruginosa is fairly unique in producing a pleasant green pigment which may diffuse throughout the entire media, and a pleasant smell (supposedly like grapes, but I thought it was just vaguely fruity). This makes it easy to identify (or at least guess, since this combination of color and smell is quite rare).

 

However, P aeruginosa is also famous for having strains resistant to nearly every antibiotic. Don't try to acquire it from a hospital floor, or you will likely get a nasty strain.

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Uhm you do not need to acquire a P. aeruginosa strain from hospital to have them AB resistant. Basically all are. The reason is likely the high abundance of exporters found in them that throw everything out before it can harm the cell. One should keep onself clear from this bugger if one has a compromised immune system or have specific conditions that may allow infection (e.g. cystic fibrosis).

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