AEM
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Mayerhofer, H. J.
Right arrow Articles by Lu, M.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Mayerhofer, H. J.
Right arrow Articles by Lu, M.
Agricola
Right arrow Articles by Mayerhofer, H. J.
Right arrow Articles by Lu, M.

 Previous Article  |  Next Article 

Appl Environ Microbiol. 1973 January; 25(1): 44-48
Copyright © 1973 American Society for Microbiology. All Rights Reserved.

Characterization of a Heat-Stable Protease of Pseudomonas fluorescens P261

H. J. Mayerhofer2, R. T. Marshall, C. H. White3 and Margaret Lu

a Department of Food Science and Nutrition, University of Missouri, Columbia Missouri 65201

ABSTRACT

A heat-stable, extracellular proteolytic enzyme was isolated from Pseudomonas fluorescens P26. Brain heart infusion broth (Fisher Scientific Co.), pH 7.5, and incubation at 21 C provided the optimal conditions for bacterial growth for enzyme production. The organism had a D value of 2.6 min at 62.8 C (145 F). The enzyme, however, was quite heat-stable, requiring 15 hr at 62.8 C, 8 hr at 71.4 C, and 9 min at 121 C for complete inactivation. Milk, whey, and casein each had a protective effect on the enzyme against heat inactivation. Purification was accomplished by growth of organisms in broth, centrifugation, sterilization by filtration, ammonium sulfate precipitation (55% saturation), dialysis (against six changes of water), and protein separation by passage through a Sephadex G-100 column. Ultracentrifugation revealed a single band with a sedimentation coefficient of 1.51 which suggested a molecular weight of approximately 23,000. As little as 0.2 unit of the purified enzyme caused detectable flavor defects during 30 days of storage at 4 C, and the Hull test for liberation of tyrosine compared favorably in sensitivity with the sensory method in milk.

FOOTNOTES

2 Present address: Pfizer, Inc., Terra Haute, Ind.

3 Present address: Department of Dairy Science, University of Georgia, Athens.

1 Contribution from the Missouri Agricultural Experiment Station, Journal Series no. 6499.

Appl Environ Microbiol. 1973 January; 25(1): 44-48
Copyright © 1973 American Society for Microbiology. All Rights Reserved.





Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. Microbiol. Mol. Biol. Rev. Eukaryot. Cell All ASM Journals

Copyright © 1973 by the American Society for Microbiology. All rights reserved.