Lauryl tryptose broth

Lauryl tryptose broth (for total coliforms) 35°C 7°C 0.5°C for 24 8 h Gas production (shades of yellow color) or acid reaction with the addition of bromocresol purple to the medium [2,67]... 

For the presumptive test for total coliforms, lauryl tryptose broth (LTB) growth medium is used alor g with fermentation tubes with inverted vials (Durham tubes) for gas production. As an alternative to the use of Durham tubes, 0.01 g/L of bromcresol purple is added to the medium and used as an indicator. Serial dilutions of the water sample to be tested are made and inoculated into LTB growth media. Samples are then incubated at 35°C for 24 h and for an additional 24 h if no growth was observed at the end of the first 24 h. If coliform bacteria are present in the samples, growth (turbidity), gas bubbles, or acid will be produced in the tubes as a result of fermentation of lactose. The number of gas positive tubes or tubes in which acid reaction occurred is used to calculate the MPN of bacteria in the samples [2]. A 10-tube MPN is used to test bottled water samples whereas the 5-tube MPN is used to test freshwater, marine waters, and shellfish. 

Lauryl tryptose mannitol broth with tryptophan (presumptive for E. coli) Completed (Optional) Tests 44 C. 5°C for 24r-48 h Gas production in Durham tube and formation of a red ring after addition of Kovacs reagent [67]... 

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