Fermentation of sugar cane bagasse hemicellulose hydrolysate to l(+)-lactic acid by a thermotolerant acidophilic Bacillus sp.^**

Abstract

Sugar cane bagasse hemicellulose, hydrolyzed by dilute H2SO4, supplemented with mineral salts and 0.5% corn steep liquor, was fermented to L(+)-lactic acid using a newly isolated strain of Bacillus sp. In batch fermentations at 50 degrees C and pH 5, over 5.5% (w/v) L(+)-lactic acid was produced (89% theoretical yield; 0.9 g lactate per g sugar) with an optical purity of 99.5%.

Isolation and Characterization of Acid-Tolerant, Thermophilic Bacteria for Effective Fermentation of Biomass-Derived Sugars to Lactic Acid

“…Since these bacteria are effective in SSF of cellulose to lactate in mineral salts medium with 0.5% (wt/vol) of CSL (Fig. 1), as well as in hemicellulose acid hydrolysate medium (18,19), the taxonomic positions of these isolates were determined by using the fatty acid profile and 16S rRNA (DNA) sequence.…”

“…In these fermentations, growth was restricted to the first 6 to 8 h, and the cell yield was limited by decreasing pH due to lactic acid accumulation. pH-controlled fermentations were performed in 500-ml vessels with 250 or 300 ml of medium in a custom-designed pH-stat (18,19). The mineral salts solution described above supplemented with CSL (0.5% [wt/vol]) and glucose or xylose (3% [wt/vol]) served as the growth medium.…”

“…New gram-positive bacterial strains were recently reported that can grow and ferment at pH 5.0 and at temperatures up to 60°C, conditions that are optimal for cellulose hydrolysis by fungal enzymes (18,19). These new isolates produced L(ϩ)-lactic acid as the major fermentation product during SSF processes with low levels of cellulase (7.5 filter paper units [FPU]/g of glucan).…”

A review of pentose utilizing bacteria from bagasse hemicellulose

“…This is necessary in order to explore the possibility of a dynamic relationship during the industrial process. Further information would be available by measuring their presence and numbers at various, specific stages of the degradation process (Patel et al, 2004;Miho et al, 2008).…”

Genome Sequence of the Thermophilic Strain Bacillus coagulans2-6, an Efficient Producer of High-Optical-Purity l -Lactic Acid

“…Only a fragment of pyrophosphokinase in the phosphoketolase pathway was predicted, which suggested the pentose mainly lost in the transaldolase/transketolase pathway. Compared with the phosphoketolase pathway, the transaldolase/transketolase pathway could produce 1.67 mol of lactic acid per mol pentose, whereas the phosphoketolase pathway produces only 1 mol of lactic acid in addition to 1 mol acetate (10).…”