A plating procedure simulating conditions in ripening Cheddar cheese was used to isolate microorganisms in young cheese that grow at ordinary ripening temperatures. Forty-one commercial cheese samples, most 7 days old, were obtained from ten Iowa manufacturing plants. Samples were plated in special Trypticase-soy agar, covered with 50 ml of 1.5% (w/v) agar, and incubated at 7.2 C for 3 months. Following incubation, 967 microorganisms were isolated, purified, and characterized. Numbers and percentages of microorganisms were: 475 enterococci, 49.5%; 148 micrococci, 15%; 126 lactic streptococci, 13%, 108 miscellancous gram-positive rods, 11%; 48 associate bacteria (resembling species of Leuconostoc), 5%; 33 miscellaneous gram-negative rods, 3.5%; 24 lactobacilli, 2.5%; and 5 other miscellaneous microorganisms, 0.5%. Forty-five commercial lactic starter cultures were examined by the same plating procedure. Duplicate plates of each culture were incubated at 7.2 and 21 C. Although agar plate counts were slightly higher at 21 C, they were within the same range, at both incubation temperatures, for most samples. No enterococci were recovered from commercial lactic starter cultures.

There is a rich potential source of food in the sea to help supply protein to the world's needs. The problems associated with the fishing industry are many and complex. Problems of preservation of the fisherman's catch are directly connected to proper sanitation practices and the control of microorganisms. To solve these problems for the trawl fisherman, several projects are underway at the Gloucester Technological Laboratory which consider industrial sanitation type improvements and steps to govern microbial outgrowth by use of antimicrobial agents. These projects are concerned with the application of gamma irradiation by different types of colbalt-60 irradiators, the improvement of vessel and shore handling procedures, the use of antimicrobial agents, and even by special innovations in shipping containers and principles. These projects are discussed with their special aspects of sanitation and microbial control. The fishing industry is learning from the experience of other food industries and hopes to greatly extend the shelf-life of fishery products by application of improved industrial sanitary practices and by the control of microorganisms.

Starter bacteria play very important roles in the cheese vat including major contributions to flavor development and control of harmful microorganisms; hence, starter production is the single most important operation in Cheddar cheese production. Thus, the proper selection, blending, preservation, and packaging of starter strains by the culture suppliers and the adoption of strict sanitation, temperature control, and standardized procedures in cheese plants for bulk starter production would contribute toward ensuring a sound and unfailing starter program in the cheese industry.

Exposure of soil to volatile substances from alfalfa (Medicago sativa L.) hay, corn (Zea mays L.) leaves, and other plant residues induces an immediate rise in the respiration rate of the soil microflora. This if followed by an increase in bacteria numbers and by vegetative growth of fungus mycelia over the soil surface. These volatiles, active at a distance from the plant residue, may function as respiratory and growth stimulants for soil microorganisms in the initial stages of colonization of residue.

A technical review discusses the characteristics and uses of preservatives and antioxidants in food processing and production. Topics include chemical preservatives allowed in foods or used to treat foods during processing, and their effects on microorganisms; applications of specific food preservatives; historical and current uses of antioxidants in preventing the oxidation of fats, oils, and fatty acids to rancid products; the mechanisms involved in fat oxidation and factors that affect fat oxidation rates; and some of the properties, solubilities, and specific uses of phenolic and non-phenolic antioxidants, synergists, and sequesterants. Several detailed structural and data tables are included. (wz)

In the absence of other microorganisms the virus of feline infectious enteritis produced a mild, non-fatal clinical disease in germfree cats. A biphasic temperature rise occurred on post inoculation day (PID) 2 and 4. All of the germfree cats began to recover by PID 7. Absolute lymphopenia occurred on the first day followed by absolute neutropenia on PID 4. The leucocyte counts were within the normal range by PID 10. Severe atrophy of the thymus was the only macroscopic lesion produced. Depletion of mature lymphocytes and reticuloendothelial cell hyperplasia occurred in all other lymphocytic tissue. No inclusion body considered to be of diagnostic significance could be demonstrated. There was no evidence of enteritis grossly or microscopically in germfree cats.

Flocculation of clay minerals by microbial metabolites was determined by measuring changes in particle-size distribution. No floculation occurred when clay and metabolite mixtures were analyzed in sodium metaphosphate as the suspending electrolyte. When the mixtures were analyzed in electrolytes containing the chloride salt of the cation to which montmorillonite was made homoionic, all metabolites caused flocculation in the presence of trivalent cations, some with divalent cations, but none with monovalent cations. Similar results were obtained with purified rhizobial polysaccharides, which, however, also flocculated kaolinite homoionic to Na. The degree of flocculation of the clays differed with the source of the metabolites. A nonionic polyacrylamide (Separan) flocculated both montmorillonite and kaolinite, regardless of the type of cation present. The possible implications of these results in the aggregation of soil by microorganisms are discussed.

Technical details concerning techniques, materials, and equipment for the application of ionizing radiation to the destruction of microorganisms in food and drug processing operations are reviewed, summarized, and discussed. Topics include the types of radiation used (beta particles, cathode-, gamma-, and x-rays, and neutrons); calculating the power equivalents of accelerators and isotopes; radiation sources; radiation efficiency in a given process for cathode and gamma rays; isotopic and machine source types; comparison of radiation sources; dosimetry measurements; the effects of dose rate and radiation type; chemical, physical, biological, and enzymatic effects of ionizing radiation; and the prevention of undesirable side-reactions. The wholesomeness aspects of food preservation by ionizing radiation are discussed with respect to nutrient aspects, toxicity, carcinogenicity, and induced radioactivity. A brief discussion of radiological safety is included. (wz)