초록
<P><B>Abstract</B></P> <P>For the efficient production of lignocellulosic ethanol, a technology of recycling yeast cells at a high-solid load was developed. The yeast <I>Saccharomyces cerevisiae</I> TJ14 grew up to 5.0 × 10<SUP>7</SUP> cells/mL at 39 °C during the simultaneous saccharification and fermentation of hydrothermally pretreated rice straw. By exploiting the viability of the cells, a portion of the fermentation residue was recycled, yielding 52.3 g/L ethanol (90.3% yield) at 1.12 g/(L·h) in six batches. This result is attributable to the maintenance of a viable cell count (cells/mL) on the order of 10<SUP>7</SUP>. In accordance with this principle, the effects of low-cost nutrients on yeast recycling were elucidated, where 0.125% corn steep liquor was deemed sufficient for fermenting rice straw and empty fruit bunch hydrolysates. The supplementation of sugarcane molasses into bagasse was found to be a practical approach, resulting in 63.5–67.7 g/L ethanol and 5.3 × 10<SUP>6</SUP>–4.4 × 10<SUP>7</SUP> cells/mL in six batches. Here, we describe that the high cell-growth potential in industrially relevant media minimizes the retention of lignocellulosic residues in subsequent batches, thus eliminating the problematic operations in yeast recycling.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cell recycle technology for lignocellulosic ethanol fermentation was developed. </LI> <LI> The performance of <I>Saccharomyces cerevisiae</I> at a high solid load was investigated. </LI> <LI> The robust yeast produced 52.3 g/L ethanol (90.3% yield) in six batches. </LI> <LI> Supplementation of 0.125% CSL was sufficient for rice straw and empty fruit bunch. </LI> <LI> In the sugarcane industry, the first- and second-generation processes were integrated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>