Characterization of microbial communities degrading natural organic compounds in activated sludge through 16S rRNA sequencing and mass spectrometry

In industrial settings, the improper discharge of untreated wastewater into natural water bodies can cause environmental damage. This study investigated the biodegradation potential and microbial composition of wastewater and activated sludge collected from a natural compound extraction factory. Activated sludge was cultured in a bioreactor, and changes in chemical oxygen demand (COD) were measured to assess microbial degradation capacity. The microbial community in activated sludge was characterized using 16S rRNA sequencing. Taxa potentially involved in biodegradation were identified on the basis of the literature. A shake flask experiment was conducted in which the target compound (geniposide) was introduced into the wastewater and cultured with activated sludge, followed by an analysis of concentration changes by using liquid chromatography-mass spectrometry. After 10 days of bioreactor cultivation, the COD removal rate reached approximately 89%, indicating effective degradation by the sludge. The 16S rRNA sequencing and literature review revealed Mycobacterium and Defluviicoccus as the dominant genera potentially involved in the degradation of organic compounds in the wastewater. Additionally, the liquid chromatography-mass spectrometry results from the shake flask experiment revealed significant reductions in both geniposide and its downstream metabolite genipin, further confirming their degradation by the sludge. This study provides foundational insights into the microbial community involved in wastewater treatment at natural compound extraction factories. Future research should isolate and optimize specific bacterial strains to enhance treatment efficiency.