A microbial floc consisting of a community of microbes embedded in extracellular polymeric substances matrix can provide microbial resistances to toxic chemicals and harsh environments. Phenol is a toxic environmental pollutant and a typical lignin-derived phenolic inhibitor. In this study, we genetically engineered Escherichia coli cells by expressions of diguanylate cyclases (DGCs) to promote proteinaceous and aliphatic biofloc formation. Compared with the planktonic E. coli cells, the biofloc-forming cells improved phenol removal rate by up to 2.2-folds, due to their substantially improved tolerance (up to 149%) to phenol and slightly enhanced cellular activity (20%) of phenol hydroxylase (PheH). The engineered bioflocs also improved E. coli tolerance to other toxic compounds such as furfural, 5-hydroxymethylfurfural, and guaiacol. Additionally, the strategy of the engineered biofloc formation was applicable to Pseudomonas putida and enhanced its tolerance to phenol. This study highlights a strategy to form engineered bioflocs for improved cell tolerance and removal of toxic compounds, enabling their universality of use in bioproduction and bioremediation.

中文翻译：

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工程细菌生物絮凝物的形成增强了苯酚的去除和细胞耐受性。

由嵌入细胞外聚合物质基质中的微生物群落组成的微生物絮凝物可为微生物提供对有毒化学物质和恶劣环境的抵抗力。苯酚是一种有毒的环境污染物，是一种典型的木质素衍生的酚类抑制剂。在这项研究中，我们通过表达双鸟苷酸环化酶（DGC）来基因工程改造大肠杆菌细胞，以促进蛋白质和脂肪族生物絮凝物的形成。与浮游性大肠杆菌细胞相比，形成生物絮凝剂的细胞将苯酚的去除率提高了2.2倍，这是因为它们对苯酚的耐受性大大提高（高达149％），并且苯酚的细胞活性略有提高（20％）羟化酶（PheH）。改造后的生物絮凝剂还提高了大肠杆菌对糠醛，5-羟甲基糠醛和愈创木酚等其他有毒化合物的耐受性。另外，工程絮凝物形成的策略适用于恶臭假单胞菌，并增强了其对苯酚的耐受性。这项研究强调了形成工程生物絮凝剂的策略，以改善细胞耐受性和去除有毒化合物，从而使其在生物生产和生物修复中具有普遍用途。