Nitrogen fixation associated with both natural grasslands and grain crops of Oregon was studied using the acetylene-reduction assay. A number of the grasses collected has some acetylene-reducing activity. Agrostis tenuis Sibth. had substantially greater activity than any of the other species, with a mean rate estimated at 37 g N2 fixed per hectare per day. Assuming 100 days of activity, about 3 kg of N2 would be fixed per hectare per year. This quantity of nitrogen may be important in the maintenance of this species under natural conditions. Nitrogen-fixing microorganisms were isolated from the root surfaces of some of the grasses. Cultures of Bacillus macerans, Bacillus polymyxa, and Enterobacter cloacoa were isolated from wheat roots as were two cultures which have not been assigned a specific taxonomic classification. Strains of N2-fixing Bacillus species and Gram-negative aerobic bacteria were isolated from Festuca and Agrostis.

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Commercial fermented sausages that contained significant numbers of viable coagulase-positive staphylococci were found to have the growth localized in the outermost areas of the sausage where oxygen tension was highest. Staphylococci were found to be more acid-tolerant aerobically than anaerobically. With

The number of Rhizobium meliloti cells in the soil of alfalfa (Medicago sativa L.) fields and the effectiveness and pH resistance of strains of R. meliloti isolated from the soil were analyzed for their relationships to soil parameters. Soil samples were collected from three alfalfa‐growing areas of Oregon and analyzed for pH, exchangeable H, soil bases, P, N, and organic matter content, and cation exchange capacity. The number of infective R. meliloti cells was estimated using the plant‐infection assay. The nodulation effectiveness of each isolated R. meliloti strain was ranked using alfalfa growth response in tube culture and in comparison to uninoculated no N and N‐amended controls. The ability of each strain to initiate growth in media adjusted to pH values of 4.5, 5.0, 5.5, 6.0, and 6.5 was determined. The number of R. meliloti cells in the soil was greater with increased soil pH and with decreased age of the alfalfa stand. Although the average ability of the strains of rhizobia to initiate growth at low pH increased with age of the alfalfa stand from which they were isolated, the strain effectiveness decreased with stand age. Average effectiveness of the strains increased with inoreased soil percent base saturation and with decreased soil exchangeable H, N, and organic matter contents.