Abstract:To screen out lactic acid bacteria with probiotic effects，a bacterial strain RS3 was selected from kimchi and identified as Enterococcus faecium through colony morphology observation，biochemical experiment，and 16 S rRNA sequencing analysis.The optimal proliferation conditions were optimized to efficiently obtain E.faecium RS3 cells.Single-factor screening and central composite design in response surface methodology were applied to study the liquid medium and proliferation conditions for E.faecium RS3.The optimized medium contained 15 g/L lactose，25 g/L tryptone，10 g/L beef extract and 5 g/L sodium chloride，with initial pH 8.2，and the culture temperature was 37℃.Compared with results under pre-optimized culture conditions，the cell biomass under the optimized culture conditions increased by 54.9% and the lactic acid yield increased by 53%.This study was expected to lay the foundation for later large-scale culture and probiotic development.