Proteinase Activity of Pseudomonas fluorescens Grown in Cold Milk Supplemented with Nitrogen and Carbon Sources

Abstract Extracellular proteinase activity varied when Pseudomonas fluorescens was grown at 7°C in UHT milk supplemented with different substrates. Addition of glutamine (5m M ) and glutamic acid (10m M ) reduced proteinase activity by 35 and 50%, respectively, and 6m M galactose and 10m M lactate supplements reduced activity to about one-half of that in the unsupplemented control. Glucose addition (9m M ) delayed the onset of proteinase production by 24h compared with that for the control culture. These results suggest that the onset of proteinase production could depend on a repressor role of certain milk components or on a low energy status in Pseudomonas cells as a result of the exhaustion of the more easily used substrates. However, differences were not significant between intracellular concentrations of ATP for control and glucose-supplemented cultures.

[1]  R. Mckellar.  Enzymes of Psychrotrophs in Raw Food , 1989 .

[2]  A. Faulkner,et al.  Changes in the concentration of metabolites in milk from cows fed on diets supplemented with soyabean oil or fatty acids , 1989, Journal of Dairy Research.

[3]  L. Fernández,et al.  Compositional Changes in Cold Raw Milk Supporting Growth of Pseudomonas fluorescens NCDO 2085 before Production of Extracellular Proteinase. , 1987, Journal of Food Protection.

[4]  D. Fairbairn,et al.  The effect of nitrogen and carbon sources on proteinase production by Pseudomonas fluorescens. , 1987, The Journal of applied bacteriology.

[5]  M. Griffiths,et al.  Effect of Aeration on Extracellular Enzyme Synthesis by Psychrotrophs Growing in Milk During Refrigerated Storage. , 1984, Journal of food protection.

[6]  A. Owen,et al.  A procedure for the complete clarification of milk of various species and its suitability for use with colorimetric measurements , 1984, Journal of Dairy Research.

[7]  B. Kitchen,et al.  Glucose levels in normal and mastitic milk , 1984, Journal of Dairy Research.

[8]  Pieter Walstra,et al.  Dairy chemistry and physics , 1984 .

[9]  J. O'Callaghan,et al.  Effect of substrate on the regulation of exoprotease production by Pseudomonas aeruginosa ATCC 10145. , 1983, Journal of general microbiology.

[10]  T. Patel,et al.  Extracellular Heat-Resistant Proteases of Psychrotrophic Pseudomonads. , 1983, Journal of Food Protection.

[11]  R. Mckellar.  Factors influencing the production of extracellular proteinase by Pseudomonas fluorescens. , 1982, The Journal of applied bacteriology.

[12]  B. Law,et al.  A new method for the detection of microbial proteolytic enzymes in milk , 1982, Journal of Dairy Research.

[13]  N. Kuhn,et al.  Metabolic significance of milk glucose , 1981, Journal of Dairy Research.

[14]  S. Jensen,et al.  Nutritional factors controlling exocellular protease production by Pseudomonas aeruginosa , 1980, Journal of bacteriology.

[15]  B. Law.  Enzymes of psychrotrophic bacteria and their effects on milk and milk products , 1979, Journal of Dairy Research.

[16]  B. Law,et al.  The effect of lipolytic Gram-negative psychrotrophs in stored milk on the development of rancidity in Cheddar cheese , 1976, Journal of Dairy Research.

[17]  H. Juffs.  Effects of temperature and nutrients on proteinase production by Pseudomonas fluorescens and Ps. aeruginosa in broth and milk. , 1976, The Journal of applied bacteriology.

[18]  P. Coulet,et al.  Fast and reliable organic acid determination in fermented milk using an enzyme-electrode based analyser , 1989 .

[19]  William M. Fogarty,et al.  Microbial enzymes and biotechnology , 1983 .

[20]  C. Keen,et al.  Iron, copper, zinc, and manganese in milk. , 1981, Annual review of nutrition.

[21]  J. E. Nahra,et al.  Direct sterilization of heat-sensitive fluids by a free-falling-film sterilizer. , 1980 .