Abstract 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 Paenibacillus alvei 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-1 FPase, 8.11 U.mL-1 CMCase, and 2.74 U.mL-1 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-1 Tween 80, and 5.0 g. L-l yeast extract using Lactobacillus delbrueckii. The conversion efficiency of lactic acid from the cellulose of ATDPL was 98.71%, and the lactic acid productivity was 0.719 g. L-1 h-1. 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.

中文翻译：

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肺类芽孢杆菌的耐热纤维素酶生物合成及其在同时糖化发酵生产乳酸中的应用

摘要 纤维素椰枣废物可能具有有益的生物技术应用，可实现生态友好型利用。本研究报告了嗜热纤维素酶产生细菌的分离及其在利用枣椰叶生产乳酸中的应用。通过 16S rRNA 基因测序，该分离株被鉴定为肺类芽孢杆菌。使用碱处理的枣椰叶 (ATDPL) 在 48 小时获得最大纤维素酶产量，产生 4.50 U.mL-1 FPase、8.11 U.mL-1 CMCase 和 2.74 U.mL-1 β-葡萄糖苷酶。纤维素酶活性在pH 5.0和50°C下最佳，并且在较宽的温度（40-70°C）和pH（4.0-7.0）范围内具有良好的稳定性，证明了其在同步糖化和发酵中的适用性。乳酸发酵优化为4天，pH 5.0，50℃，ATDPL 6.0%纤维素，30 FPU/g纤维素，1.0g。L-1 吐温 80 和 5.0 克。使用德氏乳杆菌 (Lactobacillus delbrueckii) 的 Ll 酵母提取物。ATDPL的纤维素转化为乳酸的效率为98.71%，乳酸产率为0.719g。L-1 h-1。碱处理通过降低木质素含量和纤维素结晶度，对纤维素酶和乳酸的生产表现出有价值的影响。这项研究的结果为使用椰枣叶进行微生物工业应用提供了可靠的程序。