Hi everyone,
I have been researching a pink pigmented bacterial isolate this semester found in a serial dilution from local cow feces. After running a series of different experiments including Sanger sequencing of the 16S region and a BLAST search, I am still not entirely confident in the results as most of the bases were low quality. I was wondering if anyone has seen this bacterial colony before and what it may be? I am not required to be 100% confident in the identification beyond what BLAST has provided, however I have taken a lot of interest to this project and was curious to find answers outside of what was necessary and decided to ask if anyone has seen colonies like this before. The photos provided are on an LB Nutrient agar. If it is any help, the results of some of my experiments showed there was also growth on a Mannitol salt agar, the Kirby Bauer showed it was resistant to Penicillin, susceptible to Gentamicin, and borderline Intermediate for Polymyxin B. The BLAST results suggested it May be Lysinibacillus Sphaericus, however the colonies appear to have different morphology than those and this does not explain the results of the Kirby Bauer assay.
Thanks for your help.
If resistant to penicillin it must be a Gram negative bacterium. What are other closest bacterial genera matches it's giving? Check for Pseudumonas sp also.
Gram-staining; cell shape; cell size; arrangement of cells; motility; spore formation; oxygen requirement; growth temperature (range & optimum); growth pH (range & optimum); salts requirement (concentration range & optimum); relationship to oxygen; catalase; oxidase; urease; other enzymes; growth substrates; fatty-acid profile; cell-wall type; DNA G+C content.
If you think it Lysinibacillus Sphaericus share the microscopy. Looks like species from the B. cereus group: B. cereus, B. thuringiensis, B. anthracis,B. mycoides, and B. weihenstephanensis.
Ruman microbial flora includes Gram negative,facultatively anaerobic bacteria also.Cows are ruminants and usually you find rumen bacteria in cow feces.Therefore,better to focus on literature about rumen bacteria for identifying this bacterium. By the way,Cowan and Steel's Manual for the Identification of Medical Bacteria will be a good guide for you to identify this microorganism because it provides a set of tests that you can perform to get an idea about its identification.
If you are not satisfied with the sequence analysis from a particular laboratory, repeat it somewhere else. If you did it by yourself, repeat it and get another expert eye to look at it. If the results are the same, then return to the old biochemical characterizations. You cannot miss its identity using current edition of Bergey's Manual of Determinative Bacteriology.
I think the best approach of identifying a microorganism is to carryout biochemical & morphological characterization first and get to know what might be the genera the particular organism is included and then confirm it through molecular biological techniques.However,in order to confirm the identity doing both is important.
Ensure that the isolate is a pure culture. Then repeat with other cutting-edge technique(s) in different laboratory.
Hi, Emily Bromberg, it looks like a bacillus sp. but better test for its spore formation, and oxyge sensitivity (aerobic or anaerobic) . If your specimen (cow feces) is fresh, it may be an anerobic, or facultative or microaerophilic for growth.
It is also good approach to repeat the sequencing for confirmation, better by an expert, as advised by Maurice Ekpenyong. Good luck.
I think the basis for bacteria identification is gram staining. The most important thing for u to do is to run a gram reaction on the isolates then, carry out biochemical tests on them also before going into molecular level of identification.
Hi,
I think, the isolate is Bacillus cereus or B. subtilis.
In bergy's manual 2009 was found some pictures seem your picture.
Hi, Emily Bromberg,
Be sure that a bacterium can not be identified by only appearance of colony on a agar plate. It needs laborious biochemical & fermentation tests or shortcut 500 bps readings. 16rDNA. Good luck.
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