Thermal Inactivation of a Heat-Resistant Lipase Produced by the Psychrotrophic Bacterium Pseudomonas fluorescens

Abstract
Lipase from P. fluorescens was studied for thermostability at temperatures ranging from 100-160.degree. C. The heat treatments were in 2 media, and heating times necessary to inactivate 90% of the enzyme at constant temperature were extremely long even at high temperatures, e.g., 3.6 min at 140.degree. C in nutrient broth and 2.0 min at 140.degree. C in skim milk. The increments of temperature to reduce these heating times 90% were 37.0.degree. C in nutrient broth and 38.9.degree. C in skim milk. The lipase was inactivated only partly after 20 h at 20.degree. C in 8 M urea, 6 M guanidine hydrochloride and 1.0% sodium dodecyl sulfate. Four percent 2-mercaptoethanol showed no effect.

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