Abstract
The low yield as bottleneck problem limits the application of microbial flocculant in water treatment. However, genetic information of microbial flocculant-producing strains can guide the regulation of microbial flocculant production, but it remains unknown. Agrobacterium tumefaciens F2 produced polysaccharide-based microbial flocculants in the fermentation medium but none in Luria Bertani medium; hence, the transcriptome was used to analyze the potentially associated genes with the production of microbial flocculants. Glucose, mannose, rhamnose, and galactose are the main sugar monomers, and genes (manA, glmM, manC, rfb genes, exo genes, etc.) with changed expression levels related to sugar monomers metabolism potentially participated in the biosynthesis of polysaccharide-based microbial flocculants. exoC, exoP, and manC were confirmed to participate in the biosynthesis via constructing the mutants F2-dexoC, F2-dexoP, and F2-dmanC. An exoF2 gene cluster was annotated due to the high percentage of matches between the genome sequences of strains F2 and C58, and exo genes in their genome sequences showed the similarity of 86~92%. The hypothetical pathway for the biosynthesis of polysaccharide-based microbial flocculants in strain F2 was proposed, laying the basis for the production yield regulation.
Key points
• An exo F2 gene cluster in the polysaccharide biosynthesis was annotated.
• exoC, exoP, and manC genes participated in the polysaccharide biosynthesis.
• A hypothetical biosynthesis pathway of polysaccharide in flocculant was proposed.
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04 September 2020
In the original publication of the article, it was published under the title ���Applied microbiology and biotechnology uncovering the biosynthetic pathway of polysaccharide-based microbial flocculant in Agrobacterium tumefaciens F2���.
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Acknowledgments
This work was supported by the National Natural Science Foundation of China (no. 51578179).
Author contribution statement
A. Li and F. Ma conceived and designed the research. S.S. Pi and L. Feng conducted the experiments. J.G. Qiu and H.P. Zhao contributed new reagents or analytical tools. S.S. Pi and D. Wu analyzed the data. S.S. Pi wrote the manuscript. All authors read and approved the manuscript.
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Pi, S., Qiu, J., Li, A. et al. Applied microbiology and biotechnology uncovering the biosynthetic pathway of polysaccharide-based microbial flocculant in Agrobacterium tumefaciens F2. Appl Microbiol Biotechnol 104, 8479–8488 (2020). https://doi.org/10.1007/s00253-020-10850-2
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DOI: https://doi.org/10.1007/s00253-020-10850-2