gelatin hydrolysis test selective or differential

subterminal endospores (resistant to boiling without pressure).seven subtypes (A-G) produces different botulinum toxin (types C and D are not pathogenic).typical gram-positive, may stain gram-negative or gram-variable, especially in older cells.terminal spore (resistant to heat and most antiseptics).obligate anaerobe (sensitive to oxygen).toxin: tetanospasmin (causative tetanus).formation of p-cresol as the main fermentation product of tyrosin.enzymes: hydrolytic enzymes, p-hydroxyphenylacetate decarboxylase, ferments mannitol.produces two enterotoxins toxin A and toxin B (lethal cytopathic toxin).found in improperly sterilized canned foods (germination of endospores) and water.enzymes: hemolysins (ß-hemolysis), lecithinase, extracellular proteases, lipases (phospholipase-C), collagenase, hyaluronidase, saccharolytic enzymes and is able to reduce sulphite to sulphide.produces a huge range of invasins and exotoxins.botulinum, which causes botulism.īelow are the most well-known pathogenic Clostridia species with their typical properties and occurrence: Clostridium Perfringens tetani, which is responsible for deadly tetanus infections, and C. perfringens, which is responsible for cooked meat-associated food poisoning and wound and surgical infections that lead to gas gangrene, and C. Three particularly bad actors in this group are C. Although there are non-pathogenic Clostridia, this genus produces some of the most potent biological toxins. Clostridia also have an extended range of extracellular enzymes that degrade large biological molecules in the environment into fermentable compounds. Metabolism of substrates like amino acids and fatty acids results in foul-smelling degradation products.

Their fermentation of organic compounds, like sugars, produces large amounts of CO 2 and H 2 as well as volatile organic compounds like acetic and butyric acid, acetone and butanol.

The natural sources of Clostridia are anaerobic habitats with organic nutrients, particularly soils, aquatic sediments and the intestinal tracts of animals. Most Clostridia cannot grow under aerobic conditions and even can be killed by exposure to O 2, but they form endospores that are able to survive long periods of exposure to air and other adverse environmental conditions. Reaction : Zone of opalescent around colony indicated lecithinase activity against lecithovitellin in egg yolk and precipitation around colony indicated lipase activity.Detection, Identification and Differentiation of Clostridia SpeciesĬlostridia are relatively large, gram-positive, rod-shaped bacteria that can undergo only anaerobic metabolism. Media & Reagents : Two egg yolk agar plates.ġ4 LV REACTION Lecithinase & Lipase activities Method : Spot inoculate 1, 2 & 3 on each of L-V agar plate Incubate at 370C for 24 hrs. LV REACTION Lecithinase & Lipase activities Materials : 1. The enzymes are demonstrated by cultivation on egg yolk agar. LECITHOVITELLIN REACTION (LV) Lecithinase & Lipase activities Purpose : To determine the ability of the organisms to produce lecithinase or/and lipase. Incubate at 370C for 24 hrs.ġ1 CASEIN DIGESTION TEST Interpretation :ġ2 Lecithinase & Lipase activities Purpose : Spot inoculation of 1 & 2 on each of casein agar plates. Escherichia coli on BA.ġ0 CASEIN DIGESTION TEST Media & Reagents : Method : To determine the ability of organisms to produce caseinase (proteinase) enzyme which digest casein. Negative : no clear zone around colonies.ĩ CASEIN DIGESTION TEST Purpose : Materials : Remark : Some orgamisms, produce weak reaction, clear zone present under colonies. Negative : no clear zone around colonies. Incubate at 370C for 24 hrs.ħ STARCH HYDROLYSIS TEST Interpretation :įlood the cultures with Lugol’s solution, and remain for 5-10 minutes. Inoculate 1 & 2 on each of starch agar plate.

To determine the ability of the organism to produce amylase enzyme which digests or hydrolyses starch. Incubate at 370C for 24 hrs.ģ GELATIN HYDROLYSIS TEST Interpretation :īefore reading, flood the cultures with acid mercuric chloride, leaving for 5-10 minutes. Inoculate by cross streaking of 1 & on each of gelatin plates. Acid mercuric chloride solution Method : 1. Escherichia coli on BA.Ģ GELATIN HYDROLYSIS TEST Media & Reagents :ġ. Determination of the ability of the organisms to digest (hydrolyse) gelatin, as a sole source of protein by activity of the gelatinase enzyme.

Gelatin hydrolysis test selective or differential