Thermostable cellulase biosynthesis from Paenibacillus alvei and its utilization in lactic acid production by simultaneous saccharification and fermentation

Abstract

<jats:title>Abstract</jats:title><jats:p>Cellulosic date palm wastes may have beneficial biotechnological applications for eco-friendly utilization. This study reports the isolation of thermophilic cellulase-producing bacteria and their application in lactic acid production using date palm leaves. The promising isolate was identified as <jats:italic>Paenibacillus alvei</jats:italic> by 16S rRNA gene sequencing. Maximum cellulase production was acquired using alkaline treated date palm leaves (ATDPL) at 48 h and yielded 4.50 U.mL<jats:sup>-1</jats:sup> FPase, 8.11 U.mL<jats:sup>-1</jats:sup> CMCase, and 2.74 U.mL<jats:sup>-1</jats:sup> β-glucosidase. The cellulase activity was optimal at pH 5.0 and 50°C with good stability at a wide temperature (40-70°C) and pH (4.0-7.0) range, demonstrating its suitability in simultaneous saccharification and fermentation. Lactic acid fermentation was optimized at 4 days, pH 5.0, 50°C, 6.0% cellulose of ATDPL, 30 FPU/ g cellulose, 1.0 g. L<jats:sup>-1</jats:sup> Tween 80, and 5.0 g. L<jats:sup>-l</jats:sup> yeast extract using <jats:italic>Lactobacillus delbrueckii</jats:italic>. The conversion efficiency of lactic acid from the cellulose of ATDPL was 98.71%, and the lactic acid productivity was 0.719 g. L<jats:sup>-1</jats:sup> h<jats:sup>-1</jats:sup>. Alkaline treatment exhibited a valuable effect on the production of cellulases and lactic acid by reducing the lignin content and cellulose crystallinity. The results of this study offer a credible procedure for using date palm leaves for microbial industrial applications.</jats:p>