Gg. Pritchard et T. Coolbear, THE PHYSIOLOGY AND BIOCHEMISTRY OF THE PROTEOLYTIC SYSTEM IN LACTIC-ACID BACTERIA, FEMS microbiology reviews, 12(1-3), 1993, pp. 179-206
The inability of lactic acid bacteria to synthesize many of the amino
acids required for protein synthesis necessitates the active functioni
ng of a proteolytic system in those environments where protein constit
utes the main nitrogen source. Biochemical and genetic analysis of the
pathway by which exogenous proteins supply essential amino acids for
growth has been one of the most actively investigated aspects of the m
etabolism of lactic acid bacteria especially in those species which ar
e of importance in the dairy industry, such as the lactococci. Much in
formation has now been accumulated on individual components of the pro
teolytic pathway in lactococci, namely, the cell envelope proteinase(s
), a range of peptidases and the amino acid and peptide transport syst
ems of the cell membrane. Possible models of the proteolytic system in
lactococci can be proposed but there are still many unresolved questi
ons concerning the operation of the pathway in vivo. This review will
examine current knowledge and outstanding problems regarding the prote
olytic system in lactococci and also the extent to which the lactococc
al system provides a model for understanding proteolysis in other grou
ps of lactic acid bacteria.