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exp 5.pdf - TITLE Isolation of Spore-Forming Bacteria from...

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TITLEIsolation of Spore-Forming Bacteria from Dried FoodOBJECTIVEBecome familiar with isolation and identification techniques of spore-formingbacteria for dried food sample.INTRODUCTIONBacterial spores are much more resistant than their vegetative counterparts. Themost dangerous spore-former isClostridium botulinumwhich produces a potentneurotoxinthatcanprovefatal.Themostcommonfoodpoisoningfromaspore-former is caused byC. perfringens. Other food poisoning spore-formers includeBacilluscereus,B.subtilisandB.licheniformis.Thereareanumberofnon-pathogenic spore-formers including butyric and thermophilic anaerobes thatcause significant economic losses to food producers.ClostridiumandBacillusareGram-positive spore forming rods that cause bacterial food poisoning.Clostridiumspecies are strictly aerobic to aerotolerant bacteria found in soil as well as in normalintestinal flora of man and animals. The genera contain many species, some of whichcause disease in humans and some are important in thermal canning of food.Bacillusspecies are aerobic or facultatively anaerobic bacteria; in some species cultures mayturn Gram-negative with age. These organisms can survive in low acid foods and maycause spoilage when heat processing fails to meet accepted standards. Control ofspore formers requires an understanding of both the resistance and outgrowthcharacteristics of the spores. The main food poisoning spore-formers areClostridiumbotulinum, C. perfringensandBacillus cereus. OccasionallyB. subtilisandB.licheniformishave been implicated in food poisoning incidents. Non-food poisoningspore-formers can also produce spoilage in food products resulting in commercial loss,which can be substantial. Spoilage should be carefully investigated because it may bean indication that there is a fault in the processing or that hygiene standards areinsufficient. Today's spoilage outbreak may be tomorrow's food poisoning incident.Because spore-formers are inherently more resistant than vegetative cells, methods ofcontrol need to be chosen carefully. Information on control of spore-formers bydisinfectants is best obtained from the manufacturers of these chemicals. Formulation
of disinfectants is constantly evolving to meet the demands of the food industry and tomeet international disinfectant tests. The most widely used disinfectant is probablychlorine, but it is only slowly sporicidal and is readily inactivated by organic matter,although there are organic chlorine release agents which are more effective in thepresence of soiling.UV light is finding increased use in the food industry for the destruction ofmicro-organisms on surfaces and in water and air. UV lamp technology has improvedconsiderably in the last 8-10 years and it is now possible to obtain very powerfullamps, which can produce significant reduction of spore-formers. Multi-lamp arraysare also being developed to fit around conveyor systems so that the surfaces of

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Term
Fall
Professor
DR. Fadhilah
Tags
Microbiology, Bacteria, Safranin, Endospore, mesophilic temperature

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