ABSTRACT
From a sustainability standpoint, utilizing lignocellulose-based
material for lactic acid production is highly advantageous. By-products
generated by pre-treatment of biomass, however, tend to exhibit an
inhibitory effect on microbial hosts. Supplementation of neutralizing
agents also produces harmful waste for the environment. Here, we report
a rapid and non-neutralized fermentation by an original strain,Saccharomyces cerevisiae BTCC3. This robust host was
metabolically engineered by the double disruption of PDC1/5 and
the introduction of L-LDH . Within only 15 h, 51% of glucose from
sugarcane bagasse (SCB) hydrolysate was converted to lactic acid
(productivity at 1.69 g·L-1·h-1)
without neutralizing agent supplementation at any stage of fermentation.
Cultivation using YPD medium under similar conditions achieved
productivity of 3.68 g·L-1·h-1 and
the strain could still generate lactic acid after several
glucose-feeding treatment without neutralization. This study is the
first report of lactic acid production from SCB using a genetically
modified host in a process that requires neither detoxification nor
neutralization. Overall, this method offers an alternative to tolerance
engineering that involves extensive genetic manipulations.