Identification of glutaminase-producing lactic acid bacteria isolated from Nham, a traditional Thai fermented food and characterisation of glutaminase activity of isolated Weissella cibaria

Abstract

Five glutaminase-producing lactic acid bacteria were isolated from Nham, a Thai fermented pork sausage. Weisella cibaria (MSS1, MSS2, MSS3, and MBP5) and Leuconostoc citreum (MHV2) were identified by carbohydrate metabolism tests and 16S rDNA sequence -based phylogenetic analysis. Of these, W. cibaria MSS2 had the highest glutaminase activity (0.0085 U/mg) among them. The specific activity of glutaminase (0.024 U/mg) was obtained in static culture at 20 °C using the modified MRS medium in which sucrose was substituted for glucose. The enzyme retained 40% of its original activity in the presence of 15% NaCl, which is about 2 -folds higher than the activity of glutaminase from Aspergillus oryzae.