Lactic Acid Production from Pretreated Hydrolysates of Corn Stover by a Newly Developed Bacillus coagulans Strain

An inhibitor-tolerance strain, Bacillus coagulans GKN316, was developed through atmospheric and room temperature plasma (ARTP) mutation and evolution experiment in condensed dilute-acid hydrolysate (CDH) of corn stover. The fermentabilities of other hydrolysates with B . coagulans GKN316 and the parental strain B . coagulans NL01 were assessed. When using condensed acid-catalyzed steam-exploded hydrolysate (CASEH), condensed acid-catalyzed liquid hot water hydrolysate (CALH) and condensed acid-catalyzed sulfite hydrolysate (CASH) as substrates, the concentration of lactic acid reached 45.39, 16.83, and 18.71 g/L by B . coagulans GKN316, respectively. But for B . coagulans NL01, only CASEH could be directly fermented to produce 15.47 g/L lactic acid. The individual inhibitory effect of furfural, 5-hydroxymethylfurfural (HMF), vanillin, syringaldehyde and p -hydroxybenzaldehyde (pHBal) on xylose utilization by B . coagulans GKN316 was also studied. The strain B . coagulans GKN316 could effectively convert these toxic inhibitors to the less toxic corresponding alcohols in situ . These results suggested that B . coagulans GKN316 was well suited to production of lactic acid from undetoxified lignocellulosic hydrolysates.