Question

Can you help me identify this unknown bacteria?

-colonies are red, dark red in the middle then slowly fades out

-gram negative

-rod shaped that associates in groups

-does not form spores

-has motility

-catalase positive

-gelatinase positive

-lactose negative

-mannitol positive

-butanediol negative (possibly positive, results were unclear)

-oxidase negative

-nitrate reduction positive

-starch hydrolysis negative

-caesin hydrolysis positive

-fat hydrolysis positive

-indole production positive

-urea hydrolysis negative

-thioglycolate: microaerophilic

-citrate utilization positive

Answer 1

The dark red , rod shape colonies and gram negative indicates that the bacteria is Serratia marcescens.

”marcescens” Comes from the latin word which means fading away and fading of the colour is a characteristic of the species.

the bacteria has a flagella indicating its motility, it doesn’t form spores. The other characteristics also match well with Serratia.

Therefore, Given the above characteristics, the bacteria is Serratia marcescens.

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