Biocheminsider

By Prof Walter Jaoko Introduction What Is XLD Agar? Xylose Lysine Deoxycholate agar (XLD agar) is a selective growth medium used for the isolation and differentiation of Enterobacter, especially Salmonella and Shigella species from food, environmental samples and clinical specimens.The agar was developed by Welton Taylor in 1965. It has a pH of approximately 7.4, leaving it with a bright pink or red appearance due to the indicator phenol red. Sugar fermentation lowers … Read more

By Prof Jeremiah Seni Introduction Pour plate method is usually the method of choice for counting the number of colony-forming bacteria present in a liquid specimen. In this method, fixed amount of inoculum (generally 1 ml) from a broth/sample is placed in the center of sterile Petri dish using a sterile pipette. Molten cooled agar … Read more

By Prof Mariam M Mirambo Introduction In microbiology, streaking is a technique used to isolate a pure strain from a single species of microorganism, often bacteria. Samples can then be taken from the resulting colonies and a microbiological culture can be grown on a new plate so that the organism can be identified, studied, or tested.The Aim of this method is to obtain … Read more

By Prof Mariam M Mirambo Introduction Endospore Staining is a technique used in bacteriology to identify the presence of endospores in a bacterial sample, which can be useful for classifying bacteria.Within bacteria, endospores are protective structures used to survive extreme conditions, but this protective nature makes them difficult to stain using normal techniques such as simple staining and Gram staining. Special techniques for endospore … Read more

By Prof Walter Jaoko Introduction Motility is one characteristic used in the identification of bacteria.The mobility in bacteria is largely credited to presence of large hair-like appendages over the body called as “flagella.” These are the locomotor organ of bacteria, though some move using axial filaments.Bacteria are classified into two: motile and non-motile. A motile … Read more

By Prof Walter Jaoko Basic Characteristics Properties (Yersinia pestis) Capsule Positive (+ve) Catalase Positive (+ve) Citrate Negative (-ve) Flagella Non-Flagellated Gas Negative (-ve) Gelatin Hydrolysis Negative (-ve) Gram Staining Negative (-ve) Growth in KCN Negative (-ve) H2S Negative (-ve) Hemolysis Negative (-ve) Indole Negative (-ve) Motility Non-Motile MR (Methyl Red) Positive (+ve) Nitrate Reduction Positive … Read more

By Prof Walter Jaoko Basic Characteristics Properties (Streptococcus canis) CAMP Negative (-ve) Catalase Negative (-ve) Gram Staining Positive (+ve) OF (Oxidative-Fermentative) Facultative anaerobes Shape Cocci Urease Negative (-ve) VP (Voges Proskauer) Negative (-ve) Fermentation of Adonitol Negative (-ve) Arabinose Negative (-ve) Arabitol Negative (-ve) Arbutin Positive (+ve) Dulcitol Negative (-ve) Erythritol Negative (-ve) Fructose Positive … Read more

Reviewed By Prof Walter Jaoko Shigella flexneri is a species of gram-negative, non-spore-forming bacterium belonging to the genus Shigella. Shigella flexneri is primarily associated with bacillary dysentery, a form of gastroenteritis characterized by severe diarrhea with blood and mucus. Symptoms of shigellosis can include abdominal cramps, fever, and dehydration. The infection is typically transmitted via … Read more

By Prof Walter Jaoko Basic Characteristics Properties (Providencia stuartii) Capsule Non-Capsulated Catalase Positive (+ve) Citrate Positive (+ve) Flagella Flagellated Gas from glucose Negative (-ve) Gelatin Hydrolysis Negative (-ve) Gram Staining Negative (-ve) Growth in KCN Positive (+ve) H2S Negative (-ve) Indole Positive (+ve) Motility Positive (+ve) MR (Methyl Red) Positive (+ve) Nitrate Reduction Positive (+ve) … Read more