Engineered bacterial biofloc formation enhancing phenol removal and cell tolerance
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.
KeywordsEngineered bioflocs Diguanylate cyclase Phenol removal Guaiacol Enhanced tolerance
We thank Prof. Ningyi Zhou (Shanghai Jiaotong University, China) for his helpful suggestions and Prof. Luying Xun (Shandong University, China) and Prof. Rubing Liang (Shanghai Jiaotong University, China) for E. coli BL21(DE3)-groELS and P. putida KT2440, respectively.
This work was sponsored by the National Key R&D Program of China (2018YFA0901200), Science and Technology Commission of Shanghai Municipality (18JC1413600), and Natural Science Foundation of Shanghai (18ZR1420500). This work was also funded in part by Open Project Program of CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), LMM and LAMB, SCSIO, CAS (Grant No. 2018011010).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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