Regeneration of textile wastewater deteriorated microbial diversity of soil microcosm through bioaugmentation

Textile dye contamination is a serious concern that reduces soil productivity by destabilizing microbial community structures. Here, we investigated the influence of bioaugmentation on the degradation of a mixture of dyes (MOD) and textile industry effluent (TIE) in soil microcosms using eight different dye-degrading bacteria. The biodegradation potential improved in bioaugmented microcosms, especially in the initial phase. The bioaugmented MOD and TIE microcosms exhibited 98.33% and 94.19% decolorization, and 96.92% and 95% reduction in chemical oxygen demand, respectively, within 30 days. Activities of azoreductase, veratryl alcohol oxidase, lignin peroxidase, and tyrosinase were induced by > three-fold in bioaugmented microcosms. Changes in alpha diversity indicated significant alterations in microbial dynamics due to MOD and TIE feeding. The Rheinheimera, Kocuria, Ruminococcaceae UCG-010, Ralstonia and Pseudomonas assemblages were predominant after exposure to MOD and TIE, indicating their key role in dye degradation. The bacteria used for augmentation, namely, Staphylococcus, Bacillus, Arthrobacter and Pseudomonas dominantly survived in soil microcosms. Xenobiotic pathways including benzoate, aminobenzoate, chloroalkane and chloroalkene degradation contributed in dye's detoxification as per illustration of functional annotation of metagenomes. This study indicates a mutualistic-symbiotic relationship between augmented bacteria and soil microflora with enhanced detoxification of xenobiotics leading to a sustainable approach for restoration of contaminated lands.