C. Henriette et al., PROTEASE AND LIPASE PRODUCTION BY A STRAIN OF SERRATIA-MARCESCENS (532-S), Journal of industrial microbiology, 12(2), 1993, pp. 129-135
Production of both exolipase and exoprotease activities by Serratia ma
rcescens 532 S isolated from an aerobic fixed-biomass reactor were str
ongly influenced by nutritional factors which acted as inducers or rep
ressors. In batch culture, protease and lipase activities were produce
d after the exponential phase. NH4Cl, amino acids and simple carbon so
urces caused repression of protease activity. At a concentration of 1.
5 g L-1, the individual addition of maltose, mannitol, acetate, fructo
se or glucose, repressed exoprotease production, with the greatest eff
ect by glucose. An inverse relationship existed between exoprotease sy
nthesis and increasing glucose concentrations. Lipids activated lipase
production, the most significant increase occurred when Tween 80 was
added in the medium. Thus, glucidolytic, proteolytic and lipolytic act
ivities could be efficiently expressed in batch cultures only successi
vely. At low dilution rate of chemostat cultures with a constant gluco
se input concentration of 2 g L-1, glucidolytic, proteolytic and lipol
ytic activities were produced, but did not have the same regulation: a
t D values < 0.08 h-1, the level of protease activity dropped while th
at of lipase showed a corresponding increase. Above these values, incr
easing D led to a decrease of the two hydrolase activities, at the lev
el of the specific activities as well as in the specific rate of biosy
nthesis of each enzyme. Similar results were obtained in chemostat cul
ture with a constant specific growth rate of 0.04 h-1 with increasing
glucose input concentrations, i.e. protease and lipase activities decr
eased when the specific glucose uptake rates were enhanced.