Potential application of LASER/microbe bioassay technology for determining water-soluble vitamins in foods.

A microbiological technique was developed for quantitating niacin by determining microbial growth rates in response to the amount of vitamin available. Unlike the current official AOAC method, the new procedure for niacin measured the growth rates during the early exponential growth phase rather than during the stationary phase. Lactobacillus plantarum was used to determine niacin to a lower limit of 100 pg/mL.

Quantitative bioassay using laser-monitored bacteria to assess toxicology and metabolism of bioactive Group IV compounds.

A new approach has been developed for assessing the toxicity and the metabolism of Group IV compounds and for other toxic substances that may interact with them at the molecular level. The approach is based upon the selective responses of sensitive biodetectors whose molecular interactions with a wide variety of toxic substances have been previously described and reported. Detection and quantitation of carbon, silicon, and tin-containing compounds has been accomplished using a laser-monitored bacterial bioassay.

Metabolic activation of DMH by colonic microsomes: a process influenced by type of dietary fat.

A study was conducted to determine whether 1,2-dimethylhydrazine (DMH), a potent colon carcinogen, is activated to a more potent mutagen by the drug-metabolizing system of the colonic mucosa and to determine the extent to which this metabolism is modified by lipids in the diet. DMH-treated rats fed a diet enriched with 10% corn oil exhibited markedly elevated colonic enzyme levels for mutagen production. This diet also produced the greatest number of animals with colon tumors, when compared with diets containing other levels and sources of lipid.

Parameters for detection of mutagenesis of 1,2-dimethylhydrazine using an in vitro Bacillus subtilis system.

Parameters for detection of mutagenesis of 1,2-dimethylhydrazine (DMH) using a Bacillus subtilis microbial assay are defined. His+ and his met mutations were induced in B. subtilis TKJ6321 in the absence of rat liver S-9 Mix.