Biosurfactant-producing yeasts widely inhabit various vegetables and fruits.

The isolation of biosurfactant-producing yeasts from food materials was accomplished. By a combination of a new drop collapse method and thin-layer chromatography, 48 strains were selected as glycolipid biosurfactant producers from 347 strains, which were randomly isolated from various vegetables and fruits. Of the producers, 69% were obtained from vegetables of the Brassica family.

Respiration-deficient mutants of Zymomonas mobilis show improved growth and ethanol fermentation under aerobic and high temperature conditions.

Respiration-deficient mutant (RDM) strains of Zymomonas mobilis were isolated from antibiotic-resistant mutants. These RDM strains showed various degrees of respiratory deficiency. All RDM strains exhibited much higher ethanol fermentation capacity than the wild-type strain under aerobic conditions.

Utilization of fermented barley extract obtained from a by-product of barley shochu for nisin production.

Fermented barley extract (FBE) obtained from a barley shochu by-product (shochu kasu) and its ethanol fractions were evaluated as a medium and supplement, respectively, for nisin A production by Lactococcus lactis subsp. lactis ATCC 11454. A Brix 2.