Is Serratia lactose positive or negative?

Is Serratia lactose positive or negative?

Biochemical Test and Identification of Serratia marcescens

How do you test for Serratia?

marcescens to produce pyruvic acid, thus it can rely on citrate as a carbon source and test positive for citrate utilization. In identifying the organism, one may also perform a methyl red test, which determines if a microorganism performs mixed-acid fermentation. S. marcescens results in a negative test.

What is a litmus milk test?

Litmus milk is a milk-based medium used to distinguish between different species of bacteria. The litmus in the medium acts as both a pH indicator and a redox (oxidation-reduction) indicator. The test itself tells whether the bacterium can ferment lactose, reduce litmus, form clots, form gas, or start peptonization.

Which enzymes are being tested in a litmus milk medium?

Some bacteria possess proteolytic enzyme caseinase and hydrolyze casein. Casein hydrolysis results in the release of large quantities of ammonia that makes the medium alkaline with foul smell, the litmus turns into a purplish blue.

Is Serratia a lactose fermenter?

Serratia strains are motile, rarely ferment lactose, and produce an extracellular DNase. The organism is widespread in the environment but not a common component of the human fecal flora.

Is Escherichia coli Gram-negative bacilli?

E coli is a gram-negative bacillus that grows well on commonly used media. It is lactose-fermenting and beta-hemolytic on blood agar. Most E coli strains are nonpigmented. The image below shows Escherichia coli on Gram staining.

Is staph gram-positive?

Staphylococcus aureus is a gram-positive bacteria that cause a wide variety of clinical diseases. Infections caused by this pathogen are common both in community-acquired and hospital-acquired settings.

What color is Serratia marcescens?

red
Serratia marcescens is a gram-negative, facultatively-anaerobic bacterium and opportunistic pathogen which produces the red pigment prodigiosin.

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