TY - JOUR
T1 - Flocculation-related gene identification by whole-genome sequencing of Thauera aminoaromatica MZ1T floc-defective mutants
AU - Prombutara, P.
AU - Allen, M. S.
N1 - Funding Information:
This work was supported by the University of North Texas. We thank Gary Sayler and the Center for Environmental Biotechnology at the University of Tennessee for the WT strains of MZ1T. We also thank Jose Calderon of the Chemistry Department, University of North Texas, for his assistance with FTIR.
Publisher Copyright:
© 2016, American Society for Microbiology. All Rights Reserved.
PY - 2016
Y1 - 2016
N2 - Thauera aminoaromatica MZ1T, a floc-forming bacterium isolated from an industrial activated-sludge wastewater treatment plant, overproduces exopolysaccharide (EPS), leading to viscous bulking. This phenomenon results in poor sludge settling and dewatering during the clarification process. To identify genes responsible for bacterial flocculation, a whole-genome phenotypicsequencing technique was applied. Genomic DNA of MZ1T flocculation-deficient mutants was subjected to massively parallel sequencing. The resultant high-quality reads were assembled and compared to the reference genome of the wild type (WT). We identified nine nonsynonymous mutations and one nonsense mutation putatively involved in EPS biosynthesis. Complementation of the nonsense mutation located in an EPS deacetylase gene restored the flocculating phenotype. The Fourier transform infrared (FTIR) spectra of EPS isolated from the wild type showed a reduced C=O peak of the N-acetyl group at 1,665 cm-1 compared to the spectra of MZ1T floc-deficient mutant EPS, suggesting that the WT EPS was partially deacetylated. Gene expression analysis also demonstrated that the putative deacetylase gene transcript increased before flocculation occurred. These data suggest that targeting deacetylation processes via direct chemical modification of EPS or enzyme inhibition may prove useful in combating viscous bulking in this and related bacteria.
AB - Thauera aminoaromatica MZ1T, a floc-forming bacterium isolated from an industrial activated-sludge wastewater treatment plant, overproduces exopolysaccharide (EPS), leading to viscous bulking. This phenomenon results in poor sludge settling and dewatering during the clarification process. To identify genes responsible for bacterial flocculation, a whole-genome phenotypicsequencing technique was applied. Genomic DNA of MZ1T flocculation-deficient mutants was subjected to massively parallel sequencing. The resultant high-quality reads were assembled and compared to the reference genome of the wild type (WT). We identified nine nonsynonymous mutations and one nonsense mutation putatively involved in EPS biosynthesis. Complementation of the nonsense mutation located in an EPS deacetylase gene restored the flocculating phenotype. The Fourier transform infrared (FTIR) spectra of EPS isolated from the wild type showed a reduced C=O peak of the N-acetyl group at 1,665 cm-1 compared to the spectra of MZ1T floc-deficient mutant EPS, suggesting that the WT EPS was partially deacetylated. Gene expression analysis also demonstrated that the putative deacetylase gene transcript increased before flocculation occurred. These data suggest that targeting deacetylation processes via direct chemical modification of EPS or enzyme inhibition may prove useful in combating viscous bulking in this and related bacteria.
UR - http://www.scopus.com/inward/record.url?scp=84961275737&partnerID=8YFLogxK
U2 - 10.1128/AEM.02917-15
DO - 10.1128/AEM.02917-15
M3 - Article
C2 - 26712552
AN - SCOPUS:84961275737
SN - 0099-2240
VL - 82
SP - 1646
EP - 1652
JO - Applied and Environmental Microbiology
JF - Applied and Environmental Microbiology
IS - 6
ER -