Tuesday 31 January 2017

Bacteriological analysis of drinking water by MPN method.

INTRODUCTION  Most probable number (MPN) analysis is a statistical method based on the random dispersion of microorganism...




 From the number and distribution of positive and negative reactions, the MPN of indicator organisms in the sample may be...PRESUMPTIVE TEST  It is used for detection and estimation of coliform in water sample. For estimation of coliforms, lacto...CONFIRMED TEST  Some spore forming bacteria give false positive test in presumptive test.  Confirmed test is done to det...COMPLETED TEST  Subculture typical colonies in lactose containing medium and incubated at 37° C and 44.5 °C.  Presence o...
REQUIREMENTS :  Petridishes  Test tubes  Sampling bottle ( sterile)  MacConkey or Lactose broth  EMB agar, Nurtient a...PROCEDURES : FOR PRESUMPTIVE TEST  Prepare MacConkey purple media of single and double strength in test tubes with Durham... Incubate the tubes at 37°C for 24 hours.  After incubation , observe the gas production in Durham’s tube and color chan...FOR CONFIRMED TEST  Take the positive tube from the presumptive test and using EMB in duplicate.  Incubate one plate at ...COMPLETED TEST  Inoculate the colony in a tube of Lactose broth with Durham’s tube .  Subculture the colony on Nutrient ...














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