Enhanced Degradation of Acid Orange 52 Using a Polyextremophilic Ascomycete in Stirred Tank Bioreactor

A polyextremophilic fungal strain, A. flavus QMS-8, previously isolated from the hypersaline soil taken from the rhizospheric region of the neem tree, Azadirachta indica (Meliaceae), was recognized as the proficient strain for decolorization of Acid Orange 52, a toxic dye employed in textile operations. A. flavus QMS-8 immobilized on Luffa cylindrica (Cucurbitaceae) attained 80.6% and consecutively complete dye degradation within a hydraulic retention time of 12–24 h in a stirred tank reactor even at salinities of 1–5% and environmental temperatures ranging in between 34 and 39 °C under optimized settings. The SEM micrographs revealed the attachment of fungal hyphae on L. cylindrica , while enzyme profiling demonstrated the participation of laccase (0.17 IU mL −1) , manganese peroxidase (0.16 IU mL −1 ), and lignin peroxidase (0.06 IU mL −1 ) in the degradation of Acid Orange 52. The decolorized samples were assessed through a UV-Vis spectrophotometer and HPLC which did not provide any information about the formation of aromatic amines or any other metabolite. The values of biological oxygen demand, chemical oxygen demand, total dissolved solids, and total suspended solids were reduced from 2836, 3000, 3415, and 360 mg L −1 to 615, 1179, 916, and 145 mg L −1 , respectively, and aligned closely with the established criteria set forth by the NEQ. Phytotoxicity and cytotoxicity assays of effluent treated in STR demonstrated a significant reduction in the toxic impact of dye on plants and microbial cells, suggesting that the luffa immobilized A. flavus QMS-8 employed in this study holds promise for mitigating the potentially harmful effects associated with Acid Orange 52. These results offer valuable insights into the efficacy and potential environmental benefits of the bioremediation approach for textile effluent investigated in this research.