Abstract: A rapid method for measuring heterotrophic bacteria (or total viable organisms—TVO) in samples of drinking water. The water samples are diluted to reduce the masking effect of fast-growing bacteria over slow-growing bacteria. Subsamples are mixed with a growth medium, incubated, and analyzed for fluorescence whereby a semi-quantitative or pass-fail determination of heterotrophic bacteria in the water sample can be made.

Abstract: A rapid method for detecting the presence or absence of coliform bacteria in a liquid or liquified dairy sample, for example, skimmed milk, lowfat milk, or whole milk. A growth medium containing a fluorogenic substrate is combined with the dairy sample and is incubated for a brief period of time, for example for about 4 hours, after which a first fluorescence value of 4-methylumbelliferone is measured. The dairy sample is incubated again for about 2-8 hours after which a second fluorescence value of 4-methylumbelliferone is measured. Total, fecal, or thermotolerant coliform bacteria are determined to be present in the sample if the second fluorescent value exceeds the first fluorescent value by a predetermined 4-methylumbelliferone concentration threshold.

Abstract: A rapid method for detecting the presence or absence of coliform bacteria in a liquid or liquified dairy sample, for example, skimmed milk, lowfat milk, or whole milk. A growth medium containing a fluorogenic substrate is combined with the dairy sample and is incubated for a brief period of time, for example for about 4 hours, after which a first fluorescence value of 4-methylumbelliferone is measured. The dairy sample is incubated again for about 2-8 hours after which a second fluorescence value of 4-methylumbelliferone is measured. Total, fecal, or thermotolerant coliform bacteria are determined to be present in the sample if the second fluorescent value exceeds the first fluorescent value by a predetermined 4-methylumbelliferone concentration threshold.