Detection of extracellular bound proteinase in EPS-producing lactic acid bacteria cultures on skim milk agar.
OBJECTIVE
Skim milk agar was developed to investigate extracellular cell-bound proteinase in yogurt cultures, Streptococcus thermophilus and Lactobacillus bulgaricus.


RESULTS
The Lact. bulgaricus cultures produced more extracellular cell-bound proteinase than did Strep. thermophilus cultures. Strong positive correlations between the size of the exopolysaccharide (EPS) layer and extracellular cell-bound proteinase were found for both Streptococcus and Lactobacillus cultures.


CONCLUSIONS
Strong positive linear relationships existed between the EPS size and colony size and the diameter of clear zone and colony size for Streptococcus cultures, whereas weak positive linear relationships were observed for Lactobacillus cultures.


CONCLUSIONS
These data are useful to validate the relationship between extracellular proteinase and the EPS size of LAB. Also, a convenient medium to detect the presence of extracellular cell-bound proteinase of LAB is valuable for dairy industries.
Pailin
T
T
Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS, USA.
Kang
D H
DH
Schmidt
K
K
Fung
D Y
DY
D000818:Animals; D003470:Culture Media; D010450:Endopeptidases / Q000378:metabolism*; D007778:Lactobacillus / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D008892:Milk / Q000382:microbiology; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D013291:Streptococcus / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism
D003470:Culture Media; D011135:Polysaccharides, Bacterial; C098632:exopolysaccharide, Streptococcus; D010450:Endopeptidases