Isolation of lactic acid bacteria from plants of the coastal Satoumi regions for use as starter cultures in fermented milk and soymilk production

Abstract

Abstract The Ministry of the Environment, Government of Japan, defines a Satoumi as a coastal area where biological productivity and biodiversity has increased through human intervention. To identify new starter cultures, we isolated and screened lactic acid bacteria (LAB) with acid resistance and lactose-utilising ability from 94 algal or plant samples obtained from five Satoumi regions in Japan. Among the 138 LAB isolates, 10 were identified as acid (pH 5.0)-tolerant and milk and/or soymilk-fermenting LAB. Among these, six isolates were identified as Lactobacillus plantarum, and four were identified as Lactococcus lactis, respectively. Of the selected strains, only two strains, Lc. lactis Miura-SU2 and Lc. lactis Boso-SU1, lowered milk pH and produced curd. Lc. lactis Miura-SU2 imparted a suitable flavour to the fermented milk. All of the 10 selected LAB showed soymilk fermentation capability. In addition, a suitable flavour was imparted to fermented soymilk by Lc. lactis Miura-SU2. Fermentation by Lb. plantarum Tennozu-SU1 clearly increased the superoxide anion radical scavenging capacity of soymilk. These results suggest that Lc. lactis Miura-SU2 and Lb. plantarum Tennozu-SU1 have potential for use as starter cultures and/or functional components for fermented milk and/or soymilk production.