Abstract:
Sewage waste represents an ecosystem of complex and interactive microbial consortia
which proliferate with different kinetics according to their individual genetic as
well as metabolic potential. We performed metagenomic shotgun sequencing on
Ion-Torrent platform, to explore the microbial community structure, their biological
interactions and associated functional capacity of pre-treated/raw sludge (RS) and posttreated/dried sludge (DS) of wastewater treatment plant. Bacterial phylotypes belonging
to Epsilonproteobacteria (45.80%) dominated the RS with relatively few Archaea
(1.94%) whereas DS has the dominance of beta-(30.23%) and delta- (13.38%)
classes of Proteobacteria with relatively greater abundance of Archaea (7.18%). In
particular, Epsilonproteobacteria appears as a primary energy source in RS and sulfurreducing
bacteria with methanogens seems to be in the potential syntrophic association
in DS. These interactions could be ultimately responsible for carrying out aminoacid
degradation, aromatic compound degradation and degradation of propionate
and butyrate in DS. Our data also reveal the presence of key genes in the sludge
microbial community responsible for degradation of polycyclic aromatic hydrocarbons.
Potential pathogenic microbes and genes for the virulence factors were found to be
relatively abundant in RS which clearly reflect the necessity of treatment of RS. After
treatment, potential pathogens load was reduced, indicating the sludge hygienisation
in DS. Additionally, the interactions found in this study would reveal the biological
and environmental cooperation among microbial communities for domestic wastewater
treatment.
