Construction of a hybrid consortium and its potential in milk fermentation

• Positive interaction of Leuconostoc strains on probiotic lactobacilli. • A hybrid consortium was constructed. • Milk fermentation was achieved by the hybrid consortium. • Robust growth of probiotic Lb. plantarum with limited amount of Leuconostoc . • Exopolysaccharide production and texture contribution by the consortium. Manufacture of probiotic milk products has been restricted by the unfavorable growth of probiotic strains in milk circumstances. This issue is of broad concern as milk is regarded as an ideal carrier for probiotics. Synthetic microbial community has emerged as a promising strategy for microbial engineering over recent years. This study aimed to elucidate the microbial interactions between Leuconostoc and Lactobacillus in traditional fermented foods (TFF), and to improve the growth of probiotic Lactobacillus in milk via microbial community construction. Extensive positive interaction of Leuconostoc towards Lactobacillus was proposed based on the microbial co-existence analysis on TFF worldwide. Further, Leuconostoc strains were isolated from TFF samples and the interactions were testified in vitro using probiotic Lactiplantibacillus plantarum ST-Ⅲ as a tested strain. Results confirmed the positive interaction and indicated that strength of positive effect on ST-Ⅲ varied with the origin of Leuconostoc strains. The strongest positive effect was observed in BD1710, an isolate from traditional fermented milk. Finally, a hybrid consortium was designed accordingly and the bi-directional interaction analysis indicated that BD1710 efficiently improved the growth of ST-Ⅲ, whereas the vigorous growth of ST-Ⅲ restricted the further growth of BD1710. Importantly, introduction of this hybrid consortium into skim milk yielded a fermented milk with 10 8 CFU/mL of probiotic ST-Ⅲ as well as benefits endowed by Leuconostoc -derived EPS polymer, highlighting its potential as a starter culture for probiotics-enriched fermented milk products.