Hussain Asif, Liao Hui, Ahmad Khalil, Ahsan Muhammad, Hussain Muhammad Iftikhar, Iqbal Muhammad Waheed, Aqeel Sahibzada Muhammad, Hussain Arif, Xia Xiaole
The Key Laboratory of Industrial Biotechnology of Ministry of Education, College of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, PR China.
Laboratory of Biochemistry, Department of Biotechnology, Faculty of Biological Sciences, University of Malakand,Dir Lower, Chakdara 18800, Khyber Pakhtunkhwa,Pakistan.
J Appl Microbiol. 2023 Feb 16;134(2). doi: 10.1093/jambio/lxac061.
The second generation (2 G) biofuels were introduced to solve the issues associated with first-generation biofuel (dependency on food materials) and fossil fuels, such as reservoirs diminution, high demand, price fluctuation, and lethal greenhouse gases emission. Butanol and ethanol are the main 2 G biofuels. They are used as a disinfectant, antiseptic, and chemical solvent in the pharmaceutical, plastic, textiles, cosmetics, and fuel industries. Currently, their bacterial biological production from lignocellulosic material at the industrial level with primitive microorganisms is under development and not economical and qualitative compatible as compared to that of fossil origin, due to the slow growth rate, low titer, recalcitrant nature of lignocellulose, strain intolerance to a higher amount of butanol and ethanol, and strain inability to tolerate inhibitors accumulated during pretreatment of lignocellulosic materials. Therefore, metabolic engineering strategies such as redirection of carbon flux, knocking out competing pathways, enhancing strain robustness and wide range of substrate utilization ability, and overexpression of enzymes involved in their biological synthesis have been applied to bacteria for enhancing their ability for 2 G ethanol and butanol production in a highly cost-effective amount from lignocellulosic materials. Herein, we summarized and reviewed the progress in metabolic engineering of bacterial species such as Clostridium spp,Escherichia coli, and Zymomonas mobilis for the synthesis of 2 G butanol and ethanol, especially from lignocellulosic materials.
第二代（2G）生物燃料的出现是为了解决与第一代生物燃料（依赖粮食原料）和化石燃料相关的问题，如水库减少、需求高、价格波动以及致命的温室气体排放。丁醇和乙醇是主要的2G生物燃料。它们在制药、塑料、纺织、化妆品和燃料行业中用作消毒剂、防腐剂和化学溶剂。目前，利用原始微生物在工业水平上从木质纤维素材料中进行细菌生物生产丁醇和乙醇仍在开发中，与化石来源相比，在经济性和质量兼容性方面都存在不足，这是由于生长速度缓慢、滴度低、木质纤维素的顽固性质、菌株对较高含量丁醇和乙醇的耐受性差，以及菌株无法耐受木质纤维素材料预处理过程中积累的抑制剂。因此，代谢工程策略，如碳通量重定向、敲除竞争途径、增强菌株鲁棒性和广泛的底物利用能力，以及过表达参与其生物合成的酶，已被应用于细菌，以提高它们从木质纤维素材料中高效经济地生产2G乙醇和丁醇的能力。在此，我们总结并综述了梭菌属、大肠杆菌和运动发酵单胞菌等细菌物种在代谢工程方面的进展，这些进展主要涉及2G丁醇和乙醇的合成，尤其是从木质纤维素材料中合成。
