Indian Oil Corporation Limited, R&D Centre, Sector 13, Faridabad 121007, Haryana, India.
Indian Oil Corporation Limited, R&D Centre, Sector 13, Faridabad 121007, Haryana, India.
Enzyme Microb Technol. 2023 Oct;170:110292. doi: 10.1016/j.enzmictec.2023.110292. Epub 2023 Jul 22.
Biodiesel production from used cooking oil is sustainable alternative, for bio-energy production. The process generates residual crude glycerol (RCG) as the major energy-rich waste which can be used to produce various bio-based chemicals like 1,3-propanediol (1,3-PDO) through biotechnological interventions. This RCG contains several impurities like methanol, soap, organic materials, salts non-transesterified fatty acids and metals in varied concentrations. These impurities significantly affect yield and productivity of the bio-process due to their marked microbial toxicity. In this work, previously isolated Clostridium butyricum L4 was immobilized on various abundantly available cheap bio-wastes (like rice straw, activated carbon and corn cob) to explore advantages offered and improve tolerance to various feed impurities. Amongst these, shredded rice straw was found most suitable candidate for immobilization and results in maximum improvement in 1,3-PDO production (18.4%) with highest porosity (89.28%), lowest bulk density (194.48Kg/m), and highest cellular biofilm density (CFU/g-8.4 ×10) amongst the three matrices. For practical purposes, recyclability was evaluated and it was concluded that even after reusing for five successive cycles the production retained to ∼82.4%. Subsequently, polynomial model was developed using 30 runs central composite factorial design experiments having coefficient of regression (R²) as 0.9520, in order to predict yields under different immobilization conditions for 1,3-PDO production. Plackett-Burman was employed (Accuracy= 99.17%) to screen significant toxic impurities. Based on statistical analysis six impurities were found to be significantly influential on PDO production in adverse manner. With negative coefficient of estimate (COE) varying in decreasing order: Linoleic acid >Oleic acid >Stearic acid >NaCl>K2SO4 >KCl. The study illustrates practical application for repurposing waste glycerol generated from biodiesel plants, thus developing improved agnostic process along with yield production models.
从废弃食用油生产生物柴油是一种可持续的生物能源生产替代方案。该过程会产生大量富含能量的残余粗甘油（RCG）作为主要废物，可通过生物技术干预用于生产各种生物基化学品，如 1,3-丙二醇（1,3-PDO）。这种 RCG 含有几种杂质，如甲醇、肥皂、有机物质、盐、未转化的脂肪酸和各种浓度的金属。由于其显著的微生物毒性，这些杂质会严重影响生物过程的产量和生产力。在这项工作中，先前分离出的丁酸梭菌 L4 被固定在各种丰富的廉价生物废物（如稻草、活性炭和玉米芯）上，以探索所提供的优势并提高对各种饲料杂质的耐受性。在这些生物废物中，发现切碎的稻草是最适合固定的候选物，可将 1,3-PDO 的产量提高 18.4%（最高孔隙率 89.28%、最低堆积密度 194.48 Kg/m³和最高细胞生物膜密度 CFU/g-8.4×10）。出于实际目的，对可回收性进行了评估，结果表明，即使在连续使用五倍后，产量仍保持在 82.4%左右。随后，使用 30 次中心复合因子设计实验进行多项式模型开发，回归系数（R²）为 0.9520，以预测不同固定化条件下 1,3-PDO 产量。采用 Plackett-Burman 法（准确度=99.17%）筛选出显著的毒性杂质。根据统计分析，发现有六种杂质以不利的方式对 PDO 产量有显著影响。估计系数（COE）呈递减顺序：亚油酸>油酸>硬脂酸>NaCl>K2SO4>KCl。该研究说明了从生物柴油厂产生的废甘油再利用的实际应用，从而开发了改进的、通用的工艺以及产量生产模型。
