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Natural Science Forum / Biology / Microbiology / March 2005LSD agar
I've just completed a fermentation experiment and am writing up the report. We used LSD plates for cell counts. Can anyone tell me the visible difference this plate induces between the genera? I had small pink colonies and I'm hoping that they were Lactobacillus. I've found the recipe and a lot of places that will sell me the media but no one will give me the details about its differentiation. > I've just completed a fermentation experiment and am writing up the > report. We used LSD plates for cell counts. Can anyone tell me the > visible difference this plate induces between the genera? I had small > pink colonies and I'm hoping that they were Lactobacillus. I've found > the recipe and a lot of places that will sell me the media but no one > will give me the details about its differentiation. Hi What is the full name of LSD media ? Also I doubt that your pink isolate is a Lactobacillus, as far as I know all Lactobacilli are not pigmented. Could be wild yeast ? N10 Lactobacillus-Streptococcus differential media. We were making sauerkraut and pickles so the main genus present should have been either LactoB. or StreptoC. not any yeast. > Lactobacillus-Streptococcus differential media. > > We were making sauerkraut and pickles so the main genus present should > have been either LactoB. or StreptoC. not any yeast. Have you tried a Gram stain that should separate Lactobacilli from Streptococci quite easily. Best N10 The samples are gone, and this was a guided expirament, the LSD agar was provided to tell us which genus we had. I just can't find any information on what each chould have looked like on the plate > The samples are gone, and this was a guided expirament, the LSD agar > was provided to tell us which genus we had. I just can't find any > information on what each chould have looked like on the plate Sounds like you werent guided very well if detailsof differential characteristics were not provided. Who manufactures the agar ? N10 The details are not in the lab manual the description says to 'see seperate handout', I think that was forgotten. I get hits from this site www.sigmaaldrich.com and from www.multilab.biz there is says: L.S. Differential Medium Base (Lactobacillus Streptococcus Differential Medium Base) - for differentiation of Lactobacilli and Streptococci on the basis of colonial morphology, TTC reduction and casein reaction. But it does not tell me what to look for or how they are different. okay here is what I've found out. on LSD agar Lactobacillus will appear red, large >1mm, w/ irregular margin, circular Streptococcus will appear read, .2-.5 mm, smooth margin, circular > okay here is what I've found out. > on LSD agar > Lactobacillus will appear red, large >1mm, w/ irregular margin, > circular > Streptococcus will appear read, .2-.5 mm, smooth margin, circular Well guess if you know how big the colonies were you have your answer. If you dont you will have write up the exact truth of the matter Hope you sort it out best N10 >> Lactobacillus-Streptococcus differential media. >> [quoted text clipped - 3 lines] >Have you tried a Gram stain that should separate Lactobacilli from >Streptococci quite easily. Why? Both are G+. Is there some interesting difference in how they behave? But if the OP had the samples, simple observation of cell morphology should distinguish them. After reading thru the thread, seems that what this medium is got resolved. But... one good source of media info online is the Oxoid manual, at www.oxoid.com bob >>> Lactobacillus-Streptococcus differential media. >>> [quoted text clipped - 15 lines] > > bob Hi Bob Yes gram staining does show morphology more clearly then a straight wet prep and ofcourse per text book both genera are gram positive . Lactobacilli however can be frequently gram variable, a factor which is occasionally useful as a component of identification. Streptococci are consistently gram positive as you indicate. Best N10 |
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