Microwave radiation in Escherichia coli and Bacillus subtilis cell suspensions resulted in a dramatic reduction of the viable counts as well as increases in the amounts of DNA and protein released from the cells according to the increase of the final temperature of the cell suspensions. However, no significant reduction of cell density was observed in either cell suspension. It is believed that this is due to the fact that most of the bacterial cells inactivated by microwave radiation remained unlysed. Scanning electron microscopy of the microwave-heated cells revealed severe damage on the surface of most E. coli cells, yet there was no significant change observed in the B. subtilis cells. Microwave-injured E. coli cells were easily lysed in the presence of sodium dodecyl sulfate (SDS), yet B. subtilis cells were resistant to SDS.

Antimutagenic substances were purified from a culture supernatant of Lactobacillus plantarum KLAB21 cells isolated from kimchi, a Korean traditional fermented vegetable, and their characteristics were investigated. The antimutagenic substances were separated into two fractions by DEAE-cellulose ion-exchange column chromatography, which were designated the R1 and R2 fractions. The R1 fraction was then divided into two fractions again by Sephadex G200 gel filtration chromatography, and the fractions were designated R1-1 and R1-2. All three fractions were further purified using a Sepharose CL-6B gel filtration column. All the purified fractions were successfully stained with fuchsin as well as Coomassie brilliant blue, suggesting that they are glycoproteins. The purified fractions were confirmed to possess antimutagenic activity against N -methyl- N ′-nitro- N -nitrosoguanidine on Salmonella enterica serovar Typhimurium TA100 cells. Their molecular masses were determined to be 16 (R1-1), 11 (R1-2), and 14 (R2) kDa on the Sepharose CL-6B column. Total sugar contents were 8.4% (R1-1), 7.3% (R1-2), and 9.4% (R2). The amino acid compositions of the fractions were different from each other; the major amino acids were glutamic acid (21.5%) and phenylalanine (17.1%) in the R1-1 fraction and glycine (41.3%) in the R1-2 fraction, but valine (31%) and phenylalanine (22.6%) were the major amino acids in the R2 fraction.

The Muscat Bailey A (MBA) grape, one of the most prominent grape cultivars in Korea, contains considerable amounts of monoterpene alcohols that have very low odor thresholds and significantly affect the perception of wine aroma. To develop a potential wine starter for Korean MBA wine, nine types of non-Saccharomyces yeasts were isolated from various Korean food materials, including nuruk, Sémillon grapes, persimmons, and Muscat Bailey A grapes, and their physiological, biochemical, and enzymatic properties were investigated and compared to the conventional wine fermentation strain, Saccharomyces cerevisiae W-3. Through API ZYM analysis, Wickerhamomyces anomalus JK04, Hanseniaspora vineae S7, Hanseniaspora uvarum S8, Candida railenensis S18, and Metschnikowia pulcherrima S36 were revealed to have β-glucosidase activity. Their activities were quantified by culturing in growth medium composed of different carbon sources: 2% glucose, 1% glucose + 1% cellobiose, and 2% cellobiose. W. anomalus JK04 and M. pulcherrima S36 showed the highest β-glucosidase activities in all growth media; thus, they were selected and utilized for MBA wine fermentation. MBA wines co-fermented with non-Saccharomyces yeasts (W. anomalus JK04 or M. pulcherrima S36) and S. cerevisiae W-3 showed significantly increased levels of linalool, citronellol, and geraniol compared to MBA wine fermented with S. cerevisiae W-3 (control). In a sensory evaluation, the flavor, taste, and overall preference scores of the co-fermented wines were higher than those for the control wine, suggesting that W. anomalus JK04 and M. pulcherrima S36 are favorable wine starters for improving Korean MBA wine quality.