The utilization of constituents of an apple fruit as a growth substrate, the production of polysaccharide-hydrolases, and the degradation of fruit tissue by the enzymes were examined with three strains of Penicillium expansum (O-385-10, MR-213-3, and IFO8800) P. expansum grew well on an agar plate containing xylan or pectin as a carbon source, and abundantly produced conidiospores. On the other hand, the organism showed poor growth on glucose, fructose or sucrose, and the production of spores was repressed by these saccharides. Cellulose and starch did not support the growth of the organisms. Crude enzymes (xylanase and pectinase) were prepared from the culture broths of the organism grown in the xylan and pectin liquid media, respectively. When the small cubes of an apple fruit were incubated with the crude enzymes, these enzymes released a large amount of reducing sugars from the cubes. It was observed that the xylanase degraded cell walls of the fruit and the pectinase separated cells from the fruit cubes .
Small round structured virus (SRSV) genes were detected from 14 of 1, 366 fecal samples which were collected from healthy food handlers working at school lunch facilitiesusing reverse transcription-polymerase chain reaction (RT-PCR) during one year between June 1997 and May 1998. The SRSV genes were detected from two persons after twoweeks but not after four weeks; thus, the excretion of SRSV genes was believed to continue for at least two weeks at least. Analysis of the SRSV gene sequences confirmed that these strains belonged to two different types in genogroup II of Norwalk-like viruses.
A PCR method was developed for the simultaneous detection of Escherichia coli O157 and H7 antigens. Two PCR primer pairs for amplification of both E. coli O157 rfbE and H7 fliC genes, which are necessary for the expression of the O157 and H7 antigen respectively, were performed for the detection of E. coli O157: H7. All Shiga toxin-producing E. coli (STEC) O157: H7 and STEC O157: NM strains were positive for both E. coli O157 rfbE and H7 fliC genes. Non-STEC O157 strains were positive only for E. coli O157 rfbE genes and H7 strains except O157 were positive only for H7 fliC genes . Some of the nonmotile strains were positive for H7 fliC genes. No cross-reaction was observed with other E. coli serotypes (except O157 and H7) and other bacterial species, like Salmonella O30 and Citrobacter freundii which react with E. coli O157 antiserum. It is recommended that PCR amplification of both E. coli O157 rfbE and H7 fliC genes is one of the most specific methods for E. coli O157: H7 identification.
ATP levels of bacteria in Tryptic Soy Broth with 0.5 to 8.7% (w/w) NaCl (water activity, aw 0.997-0.945) were studied during 3-day incubation period at 25°C by the luciferin-luciferase bioluminescence reaction method. The amount of intracellular ATP per cell of Staphylococcus epidermidis, Escherichia coli and Vibrio parahaemolyticus ranged from 1.3 to 6.1×10-18 mol/cell in the stationary phase. ATP content of bacterial cells varied greatly with age. The changes in aw had little effect upon the amount of ATP.