Table of Contents
How do you identify B. subtilis?
Bacillus subtilis is a typical germ, which is rod-shaped and Gram-positive. When cultured on ordinary nutrient agar, the morphology circular colony of this bacteria is rough, opaque, fuzzy white or slightly yellow with jagged edges [1, 7].
Is B. subtilis VP positive?
The VP test for this bacteria was positive, while indole and methyl red tests were negative. Further analysis showed that these bacteria shared a homology up to 99.4% with Bacillus subtilis DQ198162. 1. Thus, this newly identified bacterium was classified as Bacillus subtilis.
Is catalase present in Bacillus subtilis?
Strong catalase activity was secreted by Bacillus subtilis cells during stationary growth phase in rich medium but not in sporulation-inducing medium. N-terminal sequencing indicated that the secreted activity was due to the vegetative catalase KatA, previously considered an endocellular enzyme.
Is Bacillus subtilis beta hemolytic?
Typical Bacillus spp. exhibit large, flat colonies on non-selective media. They are often beta-hemolytic.
Is B cereus catalase-positive?
Characteristics of Bacillus cereus Bacillus cereus is a gram-positive, catalase-positive, endospore-forming, rod-shaped bacterium.
Is Bacillus megaterium catalase-positive or negative?
Organisms like B. megaterium yield yellow coloured colonies. The cultures isolated were characterized through a number of microbiological and biochemical tests. The colonies identified as catalase-positive, Gram-positive, endospore-forming rods.
What type of hemolysis is B. subtilis?
Bacillus subtilis is a facultative anaerobic Gram-positive non-pathogenic bacterium that includes members displaying hemolytic activity.
Is B. subtilis gamma hemolytic?
No digestion of blood is termed gamma hemolysis. A CNA-blood plate is both selective and differential….Materials:
| Bacteria | Cell Wall | Hemolysis |
|---|---|---|
| Bacillus subtilis (Bs) | Gram(+) | Grayish colonies |
| Enterococcus faecalis (Ef) | Gram(+) | Gamma |
| Haemophilus haemolyticus | Gram(-) | Can’t tell; won’t grow on blood plates |
Is Bacillus beta-hemolytic?
Bacillus cereus is an endemic, soil-dwelling, Gram-positive, rod-shaped, beta hemolytic bacterium. Some strains are harmful to humans and cause foodborne illness, while other strains can be beneficial as probiotics for animals. It is the cause of “Fried Rice Syndrome”.
What does a negative decarboxylase test look like?
Result Interpretation of Decarboxylase Test. A positive test is a turbid purple to faded-out yellow-purple color (alkaline). A negative test is a bright clear yellow color (acid) or no change (nonfermenting rods). The control tube must retain its original color or turn yellow.
What does a positive lysine decarboxylase test result mean?
Change back to purple from yellow indicates a positive test for lysine decarboxylase . Failure to turn yellow at 24 hours or to revert back to purple at 48 hours indicates a negative result. What reagents are added?
How long does it take for lysine decarboxylase to turn yellow?
Change back to purple from yellow indicates a positive test for lysine decarboxylase . Failure to turn yellow at 24 hours or to revert back to purple at 48 hours indicates a negative result.
What color should the control tube be for decarboxylase test?
The control tube must retain its original color or turn yellow. The turbidity and alkaline or purple color in the control tube invalidate the test. The questionable results are compared to the control tube. Figure: Decarboxylase tests (Moeller’s method) – Positive, Negative, and Uninoculated tube.