Screening of Lactobacillus plantarum LPM21 with F1F0-ATPase â-subunit Mutation Used as Probiotics Adjunct in Sichuan Pickle

The F1F0-ATPase beta-subunit mutation strain L. plantarum LPM21 was screened to resolve the postacidification of Sichuan pickle products caused by the probiotic adjunct cultures L. plantarum during product handling, transportation or storage at ambient temperature. Ser-268 mutation into Leu-268 in F1F0-ATPase 13-subunit of LPM21, located in the interaction interface of F1F0-ATPase alpha- and beta-subunit, triggered a 43.44% drop in the ATPase activity. In MRS broth, LPM21 could not grow under desired pH 4.2 and its acid production was about 1/2 of parent L. plantarum CCTCC 207202. When LPM21 cultures were incorporated into aseptic Sichuan pickle products, the pH of products was 4.3 after 7 d incubation at 30 degrees C, above the critical pH limit of 4.2. Furthermore, LPM21 viable count with 7.27 log CFU mL(-1) satisfied the criteria for a probiotic food product. Therefore, L. plantarum LPM21 as probiotic adjunct has the potential for reducing the post-acidification of probiotic Sichuan pickle.