How quickly can coliform bacteria ferment lactose to produce gas in appropriate conditions?

Coliform bacteria are a group of bacteria commonly used as indicators of water quality and the possible presence of pathogens. In microbiological testing, the fermentation of lactose to produce gas is a key characteristic used to identify these bacteria.

Under appropriate laboratory conditions, coliform bacteria can typically ferment lactose and produce gas within 24 to 48 hours. This fermentation process is monitored in tests like the MPN (Most Probable Number) and the standard coliform test, where the presence of gas indicates the metabolism of lactose.

While some specific strains of coliforms might show rapid fermentation, the general consensus in water quality testing is that the fermentation and gas production related to coliform identification is reliably observed within a timeframe of 24 to 48 hours. Thus, the correct answer aligns with the established understanding of coliform behavior in these tests, making it a well-accepted timeframe in water quality assessments.