INFLUENCE OF TEMPERATURE ON SOME BIOCHEMICAL CHARACTERISTICS OF PSEUDOMONAS ASSOCIATED WITH SPOILAGE OF CHICKEN

Studies were conducted with four cultures of Pseudomonas isolated from frozen chicken. The effect of temperature on some biochemical activities of the organisms was evaluated and the individual response of the cultures to temperature was determined. Growth, survival and production of the green fluorescent pigment, pyoverdine, and extra‐cellular proteinase and lipase activities were used as indices of the ability of pseudomonads to produce spoilage. The four isolates differed in their ability to perform the metabolic functions mentioned. The cultures were incubated at 15°, 5°, −18°, and −29°C. Assays for proteolysis were made by means of a dye binding method; lipolysis was determined by titration of free fatty acids released from chicken fat, and a photo‐fluorometer was used to measure fluorescent pigment. Growth was determined by colony count. At temperatures above 0°C, survival was better and growth and enzyme activity were more extensive at 5° than at 15°C. Proteinase activity increased continuously, even when viable cells were decreasing; lipase production was correlated with growth. Formation of pyoverdine declined faster than did cell numbers. Survival of the cultures was better at −18° than at −29°C, Impairment of pyoverdine secretion was observed after exposure of the organisms to freezing temperatures, but the activity of the extracellular enzymes was not affected at temperatures below 0°C. No marked differences were observed among cultures in rate of cell division, but maximum populations, survival of organisms and stability of the proteolytic, lipolytic and fluorescent activities of the isolates were inversely related to biochemical activity above 0°C. Copyright © 1969, Wiley Blackwell. All rights reserved