Taxonomic profiling of bacteria and fungi in freshwater sewer receiving hospital wastewater

Abstract

Consistent discharges of hospital wastewaters (HWWs) pose ecological risk to the biome of the receiving environment with cumulative effect on its healthiness. Understanding the taxonomic profile of microorganisms in the impacted systems is required to establish taxa that are bio-indicators of toxicants, and provide possible taxa for mitigating ecotoxicity of the HWWs. Geochemistry, pollution status and ecotoxicity of heavy metals (HMs) in HWW-impacted sewer (LU) were assessed. The microbiome profiling was based on 16S rDNA and ITS of 18S rDNA metagenomes. The degree of HMs contamination exceeded 50 and HMs pollution load index of LU was severe (1,084), which consequently exerted severe risk (1,411,575 toxic response factors) with very high toxic responses of Co, Cu, Pb, and Cd. Eco-toxicological impact of the HMs on LU skewed microbiome towards Proteobacteria (43%), Actinobacteria (18%), and about 5% apiece for Chloroflexi, Acidobacteria, Plantomycetes, and Bacteroidetes. Likewise, the relative abundance of in LU inclined towards Ascomycota (59%), Basidiomycota (17%) and unclassified Eukarya_uc_p (16%). Exclusively found in LU sediments were 44,862 bacterial species and 42,881 fungi taxa, while 72,877 and 53,971 species of bacteria and fungi, respectively, were found missing. Extinction and emergence of bacteria and fungi taxa in LU were in response to HMs ecotoxicity and the need for natural attenuation processes respectively. The profiled taxa in LU may be plausible in bioremediation strategies of the impacted system, and in designing knowledge-based bioreactor system for the treatment of HWWs before discharge into the environment.