strains, which have an optimal fermentation temperature of 30–
42 C, thermophilic Bacillus sp. NL01 strain has a much higher fermentation
temperature at about 50 C. This enables its batch and
fed-batch fermentations under open non-sterilized conditions.
Moreover, the L-lactic acid produced in this study was from lowcost
biomass, lignocellulosic hydrolyzates. Considering the substrate
cost, many attempts of microbial lactic acid production from
cheap and renewable substrates had been reported, but most used
Lactobacillus strains (Table 1). Recently, several Bacillus sp. strains
had been isolated for lactic acid production. In comparison with
other Bacillus sp. strains, a relatively better result for lactic acid
production was obtained in this study. Besides, all methods used
in this study would greatly reduce the production cost. These results
are encouraging and demonstrate the feasibility of L-lactic
acid production at a low price.