MALDI-TOF MS profiling and exopolysaccharide production properties of lactic acid bacteria from Kunu-zaki - A cereal-based Nigerian fermented beverage.

MALDI-TOF MS is a technique for high-throughput characterization of foodborne microbiota, however, its application for studying African traditional fermented foods is limited. A total of 164 out of 220 lactic acid bacterial (LAB) isolates from Kunu-zaki were identified using MALDI-TOF MS, with 100% identity of representative strains compared to 16S rRNA gene sequencing. MALDI-TOF MS profiling combined with 16S rRNA gene sequencing revealed a total of 15 LAB species in Kunu-zaki, where the most predominant species were Lactiplantibacillus plantarum (40.46%), Weissella confusa (27.27%), and Pediococcus pentosaceus (15.00%). Phenotypic screening of all isolates revealed strains of W. confusa (57), Lactiplantibacillus sp. (9), Companilactobacillus musae (1), Ligilactobacillus saerimneri (1) and Leuconostoc citreum (1) that are capable of producing dextran and/or fructan. Dextransucrase genes were detected in all EPS-producing strains by PCR. Weissella confusa YKDIA1 and YKDIA4 produced 11.93 and 11.70 g/L dextran from millet-sorghum flour hydrolysate-sucrose, respectively. Kunu-zaki produced using W. confusa YKDIA1 had high water holding capacity (100%) and viscosity ranging from 49.46-139.24 mPas. In this study, MALDI-TOF MS adequately revealed the LAB species composition in Kunu-zaki in a high-throughput strategy and further, the dominant occurrence of EPS-producing LAB strains and their potentials to influence the rheological properties of Kunu-zaki were demonstrated.