Abstract Description

The extensive use of contraceptive and reproductive drugs consisting of synthetic forms of progesterone and estrogen hormones has resulted in the continuous release of these hormones into the aquatic system via municipal wastewater discharge, leading to contamination of waterbodies. Their accumulation, even in trace concentrations (1 - 10 ng/L), exhibits serious endocrine-disruptive activity on aquatic species, affecting sexual development, reproduction, and immune function. This highlights the urgent need for their effective and sustainable removal strategies. In this regard, microbial degradation offers a cost-efficient approach for removing these persistent hormones due to the catabolic capabilities of microorganisms. This study aims to demonstrate the potential of the indigenous microbial community from municipal wastewater for the degradation of steroid hormones. Through successive enrichment for three weeks, a microbial consortium capable of utilising steroid hormones as the sole carbon source was obtained. Kinetic analyses revealed zero-order degradation for progesterone and first-order kinetics for estradiol. By analysing the metagenomes from municipal wastewater, we identified the diversity of steroid-degrading microorganisms present in its environment. The comparative metagenome analysis between non-enriched and enriched samples, established by Illumina sequencing, showed significant compositional alterations in the microbial community after the steroid enrichment treatment. Through relative abundance ranking and network analyses, several key bacterial genera, including Pseudomonas, Methylobacillus, Paracoccus, and Comamonas, were identified to contribute to the steroid hormone degradation process. Functional gene analysis implicated steroid dehydrogenase, monooxygenase, dioxygenase, and hydrolase activities in the breakdown of these hormones. By integrating degradation kinetics with metagenomic insights, this study successfully identified key microbial drivers and elucidated the natural mechanisms for steroid hormone degradation, providing a foundation for bioremediation strategies in wastewater environments.