Is Serratia citrate positive?

Serratia species can be distinguished from other genera by its production of three enzymes DNAase, lipase, and gelatinase. Members of this genus give positive reactions for citrate, Vogues–Proskuer, ortho-nitrophenyl-β-d-galactoside (ONPG) and can ferment mannitol and trehalose.

Is S. marcescens citrate positive?

Citrate is used by S. marcescens to produce pyruvic acid, thus it can rely on citrate as a carbon source and test positive for citrate utilization.

Is Serratia marcescens positive for oxidase?

While all the organisms are gram negative rods, S. marcescens is the only lactose nonfermenter that is motile, oxidase negative and indole negative.

Is Serratia marcescens glucose positive or negative?

Serratia marcescens was able to metabolize mannitol to produce acid, but gas was not produced. Glucose – Positive for the fermentation of glucose to produce acid, but negative for the production of gas.

Is Salmonella citrate positive or negative?

When Simmons Citrate agar is inoculated with Salmonella typhimurium , the medium turns royal blue. This is a positive result for the citrate test. When Simmons Citrate agar is inoculated with Escherichia coli , the medium remains green. This is a negative result for the citrate test.

Osmosis | Serratia Marcescens

Is Serratia marcescens indole positive?

The Biochemical identification of Serratia marcescens showed that bacteria were Gram –ve, Rod, Catalase positive, oxidase negative, lactose non- fermenter, motile, Indole negative, citrate utilization positive, TSI y/y, DNase positive and Urease negative as shown in table (1) as [27].

Does Serratia marcescens grow on MacConkey Agar?

Culture: S. marcescens grows well on blood agar and MacConkey agar. It is non-lactose fermenting. Some strains produce a red pigment in nutrient agar, tryptic soy agar, MacConkey agar at room temperature.

Is Serratia marcescens Lipase positive?

Most strains of Serratia marcescens produced both enzymes while most strains of Serratia liquefaciens exhibited strong lipase but only a minor phospholipase activity.

Is Serratia marcescens a Mesophile?

The mesophile Serratia marcescens grows normally in the temperature range of 20" to 37" C; its lower limit of growth is 10". Recently, a red-pigmented organism, which grows only in the temperature range 0" t6 19" C, was isolated froin flounder's eggs (1).

Is Serratia a lactose fermenter?

Serratia Species

Of the many species in the genusSerratia, Serratia marcescens is the one most commonly isolated from human infections, andSerratia liquefaciens is occasionally grown. Serratia strains are motile, rarely ferment lactose, and produce an extracellular DNase.

Does Serratia marcescens hydrolyze casein?

S. marcescens is differentiated from other Gram-negative bacteria, as it is able to perform casein hydrolysis.

Is Serratia marcescens beta hemolytic?

Background: Serratia marcescens is a gram-negative bacterium and often causes nosocomial infections. There have been few studies of the virulence factors of this bacterium. The only S. marcescens hemolytic and cytotoxic factor reported, thus far, is the hemolysin ShlA.

Why is E. coli negative for citrate test?

Only bacteria that can utilize citrate as the sole carbon and energy source will be able to grow on the Simmons citrate medium, thus a citrate-negative test culture will be virtually indistinguishable from an uninoculated slant. E. coli is citrate negative.

What is the arrangement of Serratia marcescens?

Serratia marcescens is a gram-negative rod-shaped facultatively anaerobic bacterium that is extremely motile. An S. marcescens gram stain shows short, pink-colored dots, as seen below. Rod-shaped bacteria, bacilliform bacteria or bacilli describe the typical shape of Serratia marcescens.

Will Serratia marcescens grow in mannitol salt agar?

Most non-pathogenic staphylococci will not ferment mannitol. The Staphylococcus aureus ferments mannitol and turns the medium yellow. The Serratia marcescens does not grow because of the high salt content.

Does Serratia marcescens grow on EMB agar?

Eosin methylene blue agar (EMB) is a differential and selective media that supports the growth of gram-negative bacteria, including Escherichia coli and S. marcescens.

What is the colony morphology of Serratia marcescens?

Gram stain of Serratia marcescens shows typical "short rod" morphology. Due to limits of resolution using a light microscope, single rods often resemble pairs of cocci or coccoidal cells.

How do you test for citrate?

Are Enterobacteriaceae catalase positive?

The Enterobacteriaceae are a large and diverse group of gram-negative, nonspore-forming bacilli that ferment glucose with the production of acid and usually gas, are oxidase-negative, reduce nitrate to nitrite, and are usually catalase- positive.

Is Shigella citrate positive or negative?

Escherichia coli and Shigella dysenteriae are citrate negative.

Why does Serratia marcescens produce a red pigment?

The bacterium has a protein that causes a reaction that is particularly fast at high temperature. This reaction probably prevents a gene from being expressed, a gene that makes the red pigment.