Effects of pH on biomass, maximum specific growth rate and extracellular enzyme production by three species of cutaneous propionibacteria grown in continuous culture

Abstract

Three cutaneous propionibacteria, P. acnes, P. avidum and P. granulosum, were grown in chemostats using semi-synthetic medium at various pH values. Growth occurred between pH 4.5 and 7.5 for P. acnes and pH 5.0 and 8.0 for P. avidum and P. granulosum. The highest μ(max) was at pH 6.0 for the three species. Maximum biomass production was obtained at pH 6.0 for P. acnes and P. avidum and at pH 7.5 for P. granulosum. Extracellular enzyme production occurred over the entire pH growth range when denaturation of the enzymes was taken into account. However, detectable activity of the enzymes was found in a narrower range of pH due to the denaturation of the enzymes at low or high pH values. The highest production of enzymes occurred at pH values between 5.0 and 6.0, apart from the production of hyaluronate lyase of P. granulosum (pH 6.0 to 7.0) and the proteinase of P. acnes and P. avidum (pH 5.0 to 7.5). P. acnes produced a lipase, hyaluronate lyase, phosphatase and proteinase activity. P. avidum produced a lipase and proteinase activity. P. granulosum produced a lipase and hyaluronate lyase.