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.

What bacteria does not grow on MacConkey agar?

Gram-positive bacteria will not form any colonies on MacConkey medium.

What type of bacteria grows on MacConkey agar?

MacConkey agar is used for the isolation of gram-negative enteric bacteria. It is used in the differentiation of lactose fermenting from lactose non-fermenting gram-negative bacteria. It is used for the isolation of coliforms and intestinal pathogens in water, dairy products and biological specimens.

Is Serratia marcescens a lactose fermenter?

Now, Serratia marcescens and also Citrobacter are slow lactose fermenters, so they are a bit lazy, but eventually ferment lactose.

Does Serratia grow on MacConkey agar?

Growth on Macconkey's agar.

Since the gram stain of Serratia marcescens revealed that the organism was a gram negative bacteria, MacConkey's agar served as a selective media. The organism grew as dark red colonies against the light pink background of the media.

Staphylococcus grow on MacConkey Agar Possible ??? ( Microbiology Q

What does Serratia marcescens look like on agar?

Serratia marcescens. Medium-sized colonies that appear buff in colour on Blood Agar. The bacteria produce a red pigment which is easily seen when grown on blood-free media such as nutrient agar or Kings agar B. This culture has been incubated at 30°C.

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.

Does Serratia marcescens ferment glucose?

Its colonies are smooth and moist on non-selective media. The bacterium reduces nitrates, is oxidase negative, and uses acid production to ferment glucose. S. marcescens is the most frequently occurring of the Serratia genus and is found in soil, water, and sometimes on starchy foods such as bread.

What types of bacteria are inhibited on MacConkey agar what ingredient s in MacConkey agar selects against those bacteria?

This medium is both selective and differential. The selective ingredients are the bile salts and the dye, crystal violet which inhibit the growth of Gram-positive bacteria. The differential ingredient is lactose.

What does the pink in MacConkey agar mean?

MacConkey Agar is a solid, selective and differential agar that only cultivates gram-negative bacterial species, it can further differentiate Gram-negative organisms based on their lactose metabolism: Lactose fermenters, colonies, turn red or pink on MacConkey agar. Non-fermenters do not change color.

Does Staphylococcus grow on MacConkey agar?

MacConkey agar selects for organisms like Escherichia coli (Gram negative bacilli) while inhibiting the growth of organisms like Staphylococcus aureus (Gram positive cocci).

Which of the following will form pink colonies on MacConkey agar?

- Lactose-fermenting Gram negative bacilli will form pink-purple colonies on MacConkey agar.

What does MacConkey agar test for?

MacConkey agar is a selective and differential culture medium for bacteria. It is designed to selectively isolate Gram-negative and enteric (normally found in the intestinal tract) bacteria and differentiate them based on lactose fermentation.

What is the texture of Serratia marcescens?

For comparison purposes, after 3 days of incubation at 30°C, the S. marcescens MG1 parental wild-type colonies were ∼4 mm in diameter, had a “non-sticky-to-touch” colony texture, and had a rough or grainy appearance (Fig.

Is Serratia marcescens Gram-positive or negative?

Serratia species are gram-negative bacilli of the Enterobacteriaceae group of bacteria, although they are not a common component of healthy human fecal flora.

What makes Serratia marcescens unique?

Serratia marcescens has a unique ability to produce extracellular enzymes (28). Several such enzymes have been shown to have the ability to degrade chitin, a substance which mainly comprises fungal cell walls (28).

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.

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.

Is Serratia marcescens oxidative or fermentative?

marcescens is its capability to produce lactic acid by oxidative and fermentative metabolism. Therefore, S. marcescens is lactic acid O/F+.

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].

Is Serratia catalase positive or negative?

Catalase-positive. DNase-positive. Voges-Proskauer-positive, except S. fonticola .