Li Chaofeng, Lin Xiaofeng, Ling Xing, Li Shuo, Fang Hao
College of Life Sciences, Northwest A&F University, 22 Xinong Road, Yangling, Xianyang, 712100, Shaanxi, China.
Biomass Energy Center for Arid and Semi-Arid Lands, Northwest A&F University, 22 Xinong Road, Yangling, Xianyang, 712100, Shaanxi, China.
Biotechnol Biofuels. 2021 Apr 30;14(1):110. doi: 10.1186/s13068-021-01961-7.
The biomanufacturing of D-glucaric acid has attracted increasing interest because it is one of the top value-added chemicals produced from biomass. Saccharomyces cerevisiae is regarded as an excellent host for D-glucaric acid production.
The opi1 gene was knocked out because of its negative regulation on myo-inositol synthesis, which is the limiting step of D-glucaric acid production by S. cerevisiae. We then constructed the biosynthesis pathway of D-glucaric acid in S. cerevisiae INVSc1 opi1Δ and obtained two engineered strains, LGA-1 and LGA-C, producing record-breaking titers of D-glucaric acid: 9.53 ± 0.46 g/L and 11.21 ± 0.63 g/L D-glucaric acid from 30 g/L glucose and 10.8 g/L myo-inositol in fed-batch fermentation mode, respectively. However, LGA-1 was preferable because of its genetic stability and its superior performance in practical applications. There have been no reports on D-glucaric acid production from lignocellulose. Therefore, the biorefinery processes, including separated hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF) and consolidated bioprocessing (CBP) were investigated and compared. CBP using an artificial microbial consortium composed of Trichoderma reesei (T. reesei) Rut-C30 and S. cerevisiae LGA-1 was found to have relatively high D-glucaric acid titers and yields after 7 d of fermentation, 0.54 ± 0.12 g/L D-glucaric acid from 15 g/L Avicel and 0.45 ± 0.06 g/L D-glucaric acid from 15 g/L steam-exploded corn stover (SECS), respectively. In an attempt to design the microbial consortium for more efficient CBP, the team consisting of T. reesei Rut-C30 and S. cerevisiae LGA-1 was found to be the best, with excellent work distribution and collaboration.
Two engineered S. cerevisiae strains, LGA-1 and LGA-C, with high titers of D-glucaric acid were obtained. This indicated that S. cerevisiae INVSc1 is an excellent host for D-glucaric acid production. Lignocellulose is a preferable substrate over myo-inositol. SHF, SSF, and CBP were studied, and CBP using an artificial microbial consortium of T. reesei Rut-C30 and S. cerevisiae LGA-1 was found to be promising because of its relatively high titer and yield. T. reesei Rut-C30 and S. cerevisiae LGA-1were proven to be the best teammates for CBP. Further work should be done to improve the efficiency of this microbial consortium for D-glucaric acid production from lignocellulose.
D - 葡萄糖二酸的生物制造已引起越来越多的关注，因为它是由生物质生产的高附加值化学品之一。酿酒酵母被认为是生产D - 葡萄糖二酸的优良宿主。
由于opi1基因对肌醇合成具有负调控作用，而肌醇合成是酿酒酵母生产D - 葡萄糖二酸的限制步骤，因此将opi1基因敲除。然后我们在酿酒酵母INVSc1 opi1Δ中构建了D - 葡萄糖二酸的生物合成途径，并获得了两株工程菌株LGA - 1和LGA - C，在分批补料发酵模式下，分别从30 g/L葡萄糖和10.8 g/L肌醇中生产出创纪录的D - 葡萄糖二酸滴度：9.53±0.46 g/L和11.21±0.63 g/L D - 葡萄糖二酸。然而，LGA - 1因其遗传稳定性和在实际应用中的优越性能而更受青睐。目前尚无关于从木质纤维素生产D - 葡萄糖二酸的报道。因此，对包括分离水解发酵（SHF）、同步糖化发酵（SSF）和联合生物加工（CBP）在内的生物精炼工艺进行了研究和比较。发现使用由里氏木霉（T. reesei）Rut - C30和酿酒酵母LGA - 1组成的人工微生物群落进行CBP，在发酵7 d后具有相对较高的D - 葡萄糖二酸滴度和产量，分别从15 g/L微晶纤维素中生产出0.54±0.12 g/L D - 葡萄糖二酸，从15 g/L蒸汽爆破玉米秸秆（SECS）中生产出0.45±0.06 g/L D - 葡萄糖二酸。为了设计更高效的用于CBP的微生物群落，发现由里氏木霉Rut - C30和酿酒酵母LGA - 1组成的团队是最佳的，具有出色的工作分工和协作。
获得了两株高滴度生产D - 葡萄糖二酸的工程酿酒酵母菌株LGA - 1和LGA - C。这表明酿酒酵母INVSc1是生产D - 葡萄糖二酸的优良宿主。木质纤维素是比肌醇更优的底物。对SHF、SSF和CBP进行了研究，发现使用由里氏木霉Rut - C30和酿酒酵母LGA - 1组成的人工微生物群落进行CBP因其相对较高的滴度和产量而具有前景。里氏木霉Rut - C30和酿酒酵母LGA - 1被证明是CBP的最佳搭档。应进一步开展工作以提高该微生物群落从木质纤维素生产D - 葡萄糖二酸的效率。
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