The attachment of Listeria monocytogenes isolates Scott A and Jalisco Cheese to stainless steel surfaces at 35", 21", and 10°C was investigated using scanning electron microscopy (SEM). Cells were found to adhere at all three temperatures, but cells with fibrils were observed only at 21°C. When grown at pH 8, the attachment matrix was more prevalent at 21°C than at 35°C and may also be related to the length of incubation time at 21°C. It appears that adherence may be related to the flagella and any exopolymer surrounding the cells.

The objective of this study was to determine the antibacterial effectiveness of selected hydroxycinnamic acids (caffeic, ferulic, pcoumaric) against Escherichia coli and Staphylococcus aureus at pH 5.0, 6.0 and 7.0 and Bacillus cereus at pH 6.0, 6.5 and 7.0. p-Coumaric acid was generally the most effective,inhibitor tested causing >99.9% inhibition of E. colt' at 1000 pg/ml (pH 5.0,48 hr), S. aureus at 500 pg/ml (pH 5.0, 48 hr), and B. cereus at 500 pg/ml (pH 7.0, 9 hr). inhibition increased as pH decreased with E. coli and S. aureus but not B. cereus. Bacillus cereus appeared to be the most susceptible strain with 1000 pg/ml of the compounds tested causing >99% inhibition at all three pH's.

Attachment of Yersinia enterocolitica to stainless steel surfaces at 35, 21, and 10°C was investigated using scanning electron microscopy (SEM). Cells adhered at all three temperatures, but, in general, the greatest number of adhered cells were observed at pH 8 and 21°C. Multi-flagellated cells were noted under these growth conditions. When grown at pH 9.5 and 21°C, fibrils were observed between cells and extending to the stainless steel surface. Fewer cells with flagella were seen at this pH. Adherence may be related to the flagella and any exopolymer surrounding the cells.

Epifluorescent microscopy was used to assay for the effect of selected chemicals and enzymes upon physical attachment of Pseudomonas @u@ to stainless steel. The assays were conducted after the pretreatment of cells with the agents, in the presence of agents, and in the removal of attached cells with test agents. Compared to the controls, sodium periodate, cetyltrimethylammonium bromide (Cetavlon), NaOH, and Concanavalin A inhibited the attachment process in the pretreatment and presence assays. Trypsin, sodium dodecyl sulfate (SDS), NaOH and sodium periodate were effective in removing attached cells, while Cetavlon and Triton X-100 stabilized the attachment of cells to the stainless steel surface and prevented their removal. Neither EDTA nor mechanical removal of flagella had a significant effect upon attachment. These results suggested that attachment of P. fiagi to stainless steel involved a polysaccharide and protein matrix surrounding the cells.

Kluyveromyces fragilis was more suitable than Candida pseudotropicalis or Kluyveromyces lactis for production of ethanol from whey. Direct-acid-set cottage cheese whey and the supernatant fluid resulting from heat treatment of the whey at 95 C for 20 min showed similar rates of fermentation when inoculated with K. fragilis. Inoculation rates of 10, 12 and 14 ml of active K. fragilis culture per 100 ml of media were not significantly different in rate of ethanol production. Samples incubated with K. fragilis at 35, 37, 40 and 42 C showed more rapid reduction in specific gravity than samples incubated at room temperature or 30 C. Lactose conversion in whey was 83% complete and in whey supernatant fluid, 77%.