Bioconversion of organic biomass such as plant hydrolysate and organic waste into valuable biochemicals is very challenging. In this study, carbohydrate-rich watermelon rinds and protein-rich okara (soybean waste) were converted into biofuels of ethanol, isobutanol, and methylbutanols using an engineered Escherichia coli and Bacillus subtilis mixed-whole cell biotransformation. The engineered E. coli expressed the genes alsS, kivD, ilvC, ilvD, and yqhD, and the engineered B. subtilis expressed the genes leuDH, kivD, and yqhD. The growth inhibition of the B. subtilis strain, which was reduced by 50% with addition of 1 mM furfural, was restored by the addition of 1 g/mL of activated carbon. The ratio of the E. coil and B. subtilis was optimized depending on carbohydrate and protein composition of the hydrolysate. When the carbohydrate levels were high, a 4:1 ratio of engineered E. coli to B. subtilis led to the highest overall biofuel (1.1 g/L) and isobutanol (80%) production. Viability analysis of the engineered E. coli to B. subtilis strains showed that the E. coli strain had higher activity at the beginning of the biotransformation period, while the B. subtilis strain exhibited higher activity in the later stages. The results of the present study provide important information for future biochemical production research, particularly regarding the diversification of organic waste resources.

将诸如植物水解产物和有机废物之类的有机生物质生物转化为有价值的生物化学物质是非常具有挑战性的。在这项研究中，利用工程化的大肠杆菌和枯草芽孢杆菌混合全细胞生物转化技术，将富含碳水化合物的西瓜皮和富含蛋白质的豆渣（大豆废料）转化为乙醇，异丁醇和甲基丁醇的生物燃料。工程大肠杆菌表达了alsS，kivD，ilvC，ilvD和yqhD基因，而枯草芽孢杆菌则表达了leuDH，kivD和yqhD基因。枯草芽孢杆菌的生长抑制通过添加1 g / mL活性炭可恢复通过添加1 mM糠醛减少50％的菌株。根据水解产物的碳水化合物和蛋白质组成，优化了大肠杆菌和枯草芽孢杆菌的比例。当碳水化合物水平高时，工程大肠杆菌与枯草芽孢杆菌的比例为4：1，从而导致最高的整体生物燃料（1.1 g / L）和异丁醇（80％）的产量。工程化大肠杆菌对枯草芽孢杆菌菌株的活力分析表明，大肠杆菌菌株在生物转化期开始时具有较高的活性，而枯草芽孢杆菌菌株在后期显示较高的活性。本研究的结果为今后的生化生产研究提供了重要的信息，特别是关于有机废物资源的多样化。