Department of Agro-Industry, Faculty of Biotechnology, Assumption University, Bangkok, Thailand.
National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathumthani, Thailand.
Biotechnol Bioeng. 2018 Jan;115(1):70-81. doi: 10.1002/bit.26449. Epub 2017 Oct 23.
Lignocellulose pretreatment produces various toxic inhibitors that affect microbial growth, metabolism, and fermentation. Zymomonas mobilis is an ethanologenic microbe that has been demonstrated to have potential to be used in lignocellulose biorefineries for bioethanol production. Z. mobilis biofilm has previously exhibited high potential to enhance ethanol production by presenting a higher viable cell number and higher metabolic activity than planktonic cells or free cells when exposed to lignocellulosic hydrolysate containing toxic inhibitors. However, there has not yet been a systematic study on the tolerance level of Z. mobilis biofilm compared to planktonic cells against model toxic inhibitors derived from lignocellulosic material. We took the first insight into the concentration of toxic compound (formic acid, acetic acid, furfural, and 5-HMF) required to reduce the metabolic activity of Z. mobilis biofilm and planktonic cells by 25% (IC ), 50% (IC ), 75% (IC ), and 100% (IC ). Z. mobilis strains ZM4 and TISTR 551 biofilm were two- to three fold more resistant to model toxic inhibitors than planktonic cells. Synergetic effects were found in the presence of formic acid, acetic acid, furfural, and 5-HMF. The IC of Z. mobilis ZM4 biofilm and TISTR 551 biofilm were 57 mm formic acid, 155 mm acetic acid, 37.5 mm furfural and 6.4 mm 5-HMF, and 225 mm formic acid, 291 mm acetic acid, 51 mm furfural and 41 mm 5-HMF, respectively. There was no significant difference found between proteomic analysis of the stress response to toxic inhibitors of Z. mobilis biofilm and planktonic cells on ZM4. However, TISTR 551 biofilms exhibited two proteins (molecular chaperone DnaK and 50S ribosomal protein L2) that were up-regulated in the presence of toxic inhibitors. TISTR 551 planktonic cells possessed two types of protein in the group of 30S ribosomal proteins and motility proteins that were up-regulated.
木质纤维素预处理会产生各种有毒抑制剂，这些抑制剂会影响微生物的生长、代谢和发酵。运动发酵单胞菌是一种能够生产乙醇的微生物，它被证明有潜力用于木质纤维素生物炼制厂生产生物乙醇。先前的研究表明，运动发酵单胞菌生物膜在暴露于含有有毒抑制剂的木质纤维素水解物时，比浮游细胞或游离细胞具有更高的存活细胞数和更高的代谢活性，因此具有提高乙醇产量的巨大潜力。然而，目前还没有系统地研究运动发酵单胞菌生物膜与浮游细胞相比对木质纤维素材料衍生的模型有毒抑制剂的耐受水平。我们首次深入了解了有毒化合物（甲酸、乙酸、糠醛和 5-HMF）的浓度，这些化合物需要将运动发酵单胞菌生物膜和浮游细胞的代谢活性降低 25%（IC ）、50%（IC ）、75%（IC ）和 100%（IC ）。ZM4 和 TISTR 551 两种运动发酵单胞菌生物膜对模型有毒抑制剂的抗性比浮游细胞高 2-3 倍。在存在甲酸、乙酸、糠醛和 5-HMF 的情况下，发现了协同作用。ZM4 和 TISTR 551 运动发酵单胞菌生物膜的 IC 分别为 57mm 甲酸、155mm 乙酸、37.5mm 糠醛和 6.4mm 5-HMF，225mm 甲酸、291mm 乙酸、51mm 糠醛和 41mm 5-HMF。在 ZM4 上，对运动发酵单胞菌生物膜和浮游细胞对有毒抑制剂的应激反应的蛋白质组学分析没有发现显著差异。然而，TISTR 551 生物膜表现出两种蛋白质（分子伴侣 DnaK 和 50S 核糖体蛋白 L2），在有毒抑制剂存在时上调。TISTR 551 浮游细胞在 30S 核糖体蛋白和运动蛋白组中存在两种上调的蛋白质类型。
