Abstract

Biodiesel, fatty acid methyl ester (FAME), is an environmentally friendly alternative fuel produced by transesterification of renewable lipid feedstocks for diesel engines. Methanolysis of waste frying oil (WFO) was catalyzed by Rhizopus stolonifer 1aNRC11 mutant F whole-cell lipase that produced under solid state fermentation (SSF) using wheat bran (WB) and black cumin meal as the main substrate. Cultivation SSF parameters of R. stolonifer mutant were optimized using Plackett-Burman (PB) experimental design and Face-centred Central Composite Design (FCCD), taking FAME yield as a response for whole-cell lipase production ability. PB results showed that cultivation temperature, medium pH and moisture content were the most significant parameters, which were selected for optimization by FCCD. The optimal determined conditions were as follows: WB (10 g), black cumin meal (6%, w/w of WB), fodder yeast (1%, w/w of WB), moisture content (1.5 g water/g solid), inoculum size (3 discs), initial pH (8), and cultivation time (4 day) at 28 °C. With R. stolonifer mutant cultivated in the optimized conditions, the FAME yield reached 82.6% that was close to the predicted yield of 85.7%. The analysis of variance showed that the model was statistically significant (p value of .0001) and could explain 89% of the variability in the response. These results indicated that the optimization conditions increased biodiesel production by about 43% compared to the basal medium (57.60%). The optimization of SSF conditions using low cost components makes the whole-cell lipase production process from the R. stolonifer 1aNRC11 mutant F economically effective for application in biodiesel production from WFO.

摘要

生物柴油，脂肪酸甲酯（FAME），是通过柴油发动机的可再生脂质原料的酯交换反应生产的环保替代燃料。以麦麸（WB）和黑孜然粉为主要底物，在固态发酵（SSF）条件下产生的根茎腐霉（Rhizopus stolonifer） 1aNRC11突变F全细胞脂肪酶催化废煎炸油（WFO）的甲醇分解。菜栽培SSF参数使用Plackett-Burman（PB）实验设计和以面心为中心的中央复合设计（FCCD）对突变体进行了优化，以FAME产量作为对全细胞脂肪酶生产能力的响应。PB结果表明，培养温度，培养基pH值和水分含量是最重要的参数，这些参数已通过FCCD进行了优化。最佳确定条件如下：WB（10 g），黑孜然粉（6％，w / w WB），饲料酵母（1％，w / w WB），水分（1.5 g水/ g固体） ），接种量（3片），初始pH（8）和28°C的培养时间（4天）。与R. stolonifer在优化条件下培养的突变体，FAME收率达到82.6％，接近预期的85.7％。方差分析表明，该模型具有统计学意义（p值为.0001），可以解释响应中89％的变异性。这些结果表明，与基础培养基（57.60％）相比，优化条件使生物柴油产量提高了约43％。使用低成本组件优化SSF条件使得由stolonifer 1aNRC11突变体F产生的全细胞脂肪酶生产工艺在经济上有效地应用于WFO生产生物柴油。