Extracellular protease activity of different Pseudomonas strains: dependence of proteolytic activity on culture conditions.
OBJECTIVE
This study investigated the effect of growth conditions on proteolytic activity of a Pseudomonas strain, named Pseudomonas sp. LBSA1, isolated from bulk raw milk. It was compared with three Pseudomonas chlororaphis and one Pseudomonas fluorescens strain from culture collections.


RESULTS
Bacteriae were grown in a minimal salt medium. For all the strains, addition of 1% (v/v) skim milk to the growth medium was sufficient to induce protease production in 48-h culture. Addition of 1 mmol l(-1) calcium chloride permitted the detection of proteolytic activity of four strains in 48-h cultures but not for Pseudomonas sp. LBSA1. The five strains presented two patterns of proteolytic activity when grown in the minimal salt medium supplemented with 2% (v/v) skim milk at various temperatures for 48 h. Two electrophoretic protease patterns were also obtained from the zymogram of extracellular medium for the five strains.


CONCLUSIONS
The growth conditions permitting protease production are variable and do not depend on the genus of the producing strain.


CONCLUSIONS
For the first time a study on proteolytic activity of P. chlororaphis strains is reported. Among the tested criteria, zymograms of extracellular medium were the only ones that permitted distinguishing the P. chlororaphis strains from the P. fluorescens strain.
Nicodème
M
M
Laboratoire des BioSciences de l'Aliment (LBSA), Faculté des Sciences et Techniques, Université Henri Poincaré-Nancy, 54506 Vandoeuvre-lès-Nancy Cedex, France.
Grill
J-P
JP
Humbert
G
G
Gaillard
J-L
JL
D000818:Animals; D002122:Calcium Chloride / Q000494:pharmacology; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D008892:Milk / Q000382:microbiology; D010447:Peptide Hydrolases / Q000378:metabolism*; D011549:Pseudomonas / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D011551:Pseudomonas fluorescens / Q000201:enzymology / Q000254:growth & development; D013045:Species Specificity; D013696:Temperature
D003470:Culture Media; D010447:Peptide Hydrolases; D002122:Calcium Chloride