l-Lactic acid production by combined utilization of agricultural bioresources as renewable and economical substrates through batch and repeated-batch fermentation of Enterococcus faecalis RKY1

•l-Lactic acid (>97.5% optical purity) was produced from hydrol, SCR, and malt.•Cell-recycle repeated-batch fermentation could improve lactic acid productivity.•By application of the process, a high cell density (26.3g/L) was attained.•Nitrogen sources were successfully substituted by SCR and malt.•Lactic acid productivity of 6.37g/L/h was obtained from agricultural bioresources.