1. Scanning electron microscopy was used to examine microorganisms in situ on chicken skin. They developed in a layer of material on the surface of the skin. The observations explain the relative ineffectiveness of carcass cleaning procedures and the increased recovery of microorganisms by destructive compared with non‐destructive sampling techniques.

Abstract: Fundamental concepts in food microbiology are presented in a text which emphasizes new information and reviews the science of food microbiology for the reader with some biological background. The necessity for maintaining food in a safe and wholesome manner becomes more important as world population increases, and creates a need for a text to bring food microbiology up to date. Subjects discussed include general aspects of food and its associated microorganisms; methods of estimating numbers of microbes; conditions influencing microbial growth; sources of microorganisms; food borne illnesses; food spoilage; indicator organisms; useful microorganisms; and microorganism control, with special attention to methods of bacterial destruction and growth retardation. As new foods are marketed, the microbiology of processed foods becomes more significant. Regulations for food standards and safety are described. Bibliographies follow each chapter, so the reader has access to many references in the literature.

Dental caries is observed only in the presence of certain microorganisms, particularly Streptococcus mutans. Caries-inducing microorganisms tend to be highly acidogenic. The cariogenic potential of sweeteners in man has been demonstrated both in vitro and in vivo. Other sweeteners, both natural and artifical, are less cariogenic than sucrose. A positive correlation exists between human plaque and daily consumption of sugar in tea or coffee. The cariogenic potential and metabolism of sucrose and sweeteners are compared. Sucrose causes dental caries and has been implicated in coronary heart disease and obesity. Safety of the alternatives to sucrose is still in question. Synthetic sweeteners and natural sweeteners are compared to sucrose to assess their relative sweetness.

This study was planned to develop a useful selective medium for differentiating Rhizobium meliloti in soils or inocula. The objective was to define a medium which will permit growth of rhizobia and restrain growth of other microorganisms which might inhibit or mask growth of the desired strains of Rhizobium. A yeast mannitol agar medium reinforced with 500 µg/ml pentachloronitrobenzene, 1.5 µg/ml brilliant green, 1.0 µg/ml sodium azide, and 25 µg/ml Congo red proved to be very effective in differentiating R. meliloti from other species of rhizobia as well as other forms of soil microorganisms native to Oregon. Antibiotic resistance as a marker can also be used in association with the selective medium to study the ecology of rhizobia in soil or other environments. However, antibiotic resistance is apparently not a stable character and deserves frequent testing, particularly in long-term studies.

Fermentation is a method of food preparation to develop desirable characteristics, flavor, aroma, texture, and keeping quality. Certain bacteria, yeasts and molds have adapted to protect foodstuffs from changes by other microorganisms and to retain essential nutrient substances. Various fermentation processes are interrelated. The microbial, physical, chemical, and organoleptic changes are important to mankind. Growth and fermentation by several species of microorganisms usually develop in sequence. Fermentation is an inexpensive, effective means of food preservation that could be utilized in alleviating world food problems. The ultimate goal of research and fermentation studies should be control, inhibition, or elimination of undesirable microbial species concomitant with favoring growth and fermentation by desired species. Specific fermentation processes for milk, vegetables, sausage, cereal, alcohol and spices are discussed.

Abstract: Students are presented with a basic introduction to food microbiology for use in catering, dietetics, home economics, and food preparation practices. The growth and biochemical activity of microorganisms in food chemistry is described, along with sterilization and disinfection techniques which destroy them. Microbes play a significant role in causing food poisoning and foodborne infections. Cross-contamination or bad storage practices may transfer food poisoning organisms to susceptible foods; preventive measures and standards of cleanliness break this chain of events. The principles of microbial spoilage, food preservation and food fermentation are reviewed. Pests which consume and contaminate stored food transmit harmful microorganisms. Prevention and control procedures are needed whenever foods are handled to ensure food sanitation. An appendix summarizes legislation related to food hygiene and the microbiological quality of food.