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.

URS1 is known to be a repressor binding site in Saccharomyces cerevisiae that negatively regulates expression of many genes including CAR1 (arginase), several required for sporulation, mating type switching, inositol metabolism, and oxidative carbon metabolism. In addition to the proteins previously shown to directly bind to the URS1 site, we show here that the UME6 gene product is required for URS1 to mediate repression of gene expression in the absence of inducer. We also show that mutations in the CAR80 (CARGRI) gene are allelic to those in UME6.

A phosphatase related to the vaccinia virus VH1 phosphatase has been cloned from Saccharomyces cerevisiae. The yeast phosphatase is related to the Schizosaccharomyces pombe cdc25 gene product and to a protein encoded by a mammalian open reading frame known as 3CH134, which is an immediate early gene responding to serum stimulation. The phosphatase activity of the yeast gene product appears to be restricted to the hydrolysis of phosphotyrosine-containing substrates, whereas the vaccinia phosphatase hydrolyzes both phosphoserine-and phosphotyrosine-containing substrates.The mRNA encoding the yeast phosphatase is dramaticaily induced by nitrogen starvation. Inactivation of the yeast phosphatase gene results in a decrease in growth rate.The cell appears to regulate tyrosine phosphorylation via the activities of protein-tyrosine kinases and protein-tyrosinephosphatases (PTPases) (1, 2). PTPases are a family of enzymes that have features either of receptor-like proteins or of a group of catalysts which are located intracellularly (3). The PTPases catalyze phosphate hydrolysis via a phosphoenzyme intermediate where phosphate is transferred from substrate to enzyme (4). An essential cysteine residue has been implicated in the catalytic mechanism of the PTPases (4-6). The cysteine residue appears to form a thiol-phosphate enzyme intermediate (4). The PTPase family showed an absolute specificity for hydrolysis of phosphotyrosine and did not hydrolyze substrates containing phosphoserine or phosphothreonine (7,8). A vaccinia virus protein with structural identity to the PTPases (VH1, encoded by the open reading frame in the HindIII restriction fragment H of the virus genome) was able to hydrolyze phosphoserine-and phosphotyrosine-containing substrates (9). Site-directed mutagenesis of the viral phosphatase suggested that it also employed a catalytic mechanism similar to that of the other PTPases (4-6, 9). Sequence identity between VH1 and the cell cycle gene product p80cdc25 suggested that the latter protein would have phosphatase activity and predicted that the catalytic cysteine residue was involved in phosphate ester hydrolysis. Subsequent experiments showed the cdc25 gene product was indeed a phosphatase, and mutagenesis of the predicted critical cysteine resulted in a loss of phosphatase activity (10-12).We have been particularly interested in exploring the possibility that there may be cellular counterparts to the viral phosphatase VH1. We report here that a gene from Saccharomyces cerevisiae, YVH1 (yeast VH1) ¶, exhibits protein sequence homology to VH1 and a protein encoded by a mammalian cDNA, 3CH14. We have completed the previously reported partial YVH1 sequence (13), expressed the gene in Escherichia coli, and demonstrated that the recombinant protein possesses phosphatase activity. While the VH1 phosphatase readily hydrolyzes phosphoserine-containing substrates, the recombinant YVH1 protein will not hydrolyze serine-phosphorylated casein or histone under similar conditions. The low levels of phosphatase ...

Grape must was fermented by a mixed culture of Saccharomyces cerevisiae W-3 (a wine yeast) and Issatchenkia orientalis KMBL 5774 (a malic acid-degrading yeast). Co-fermentation with 1:1 (v/v) inoculum ratio of W-3 and KMBL 5774 decreased malic acid to 0.33 mg/ml from 1.1 mg ml with W-3 alone. Ethanol production was the same in both cases (7.8%, v/v). Acetaldehyde, 1-propanol, 2-butanol and isoamyl alcohol all decreased, with an increase in methanol, in the co-fermented wine. Sensory evaluation showed a higher score in the wine fermented with 1:1 (v/v) inoculum ratio than those obtained by 4:1 (v/v) inoculum ratio or W-3 alone.