Coupled organic matter degradation and dynamic extracellular polysaccharide turnover by an alkaline...

Previous studies demonstrated that an alkaline microbial consortium (AMC) effectively reduced the chemical oxygen demand (COD) of maize lime cooking wastewater (nejayote). This study evaluated AMC in a bubble column photobioreactor (BCP) using nejayote as substrate to simultaneously promote biomass and extracellular polysaccharides (EPS) production while mitigating environmental impact. After 7 days of fermentation, the inoculated treatment (NB) achieved 97.8 % total suspended solids (TSS) increase compared to 14.7 % in the control, demonstrating that this bioreactor configuration effectively prevents opportunistic microorganism growth. NB exhibited a pH decline (11.1-9.4), increased dissolved oxygen (29.7 %-78.1 %), elevated conductivity, and oxidizing redox conditions, indicating establishment of a metabolically active photosynthetic system that reduced COD by 46 %. Conversely, the control maintained initial alkaline and reducing conditions, consistent with minimal biological activity. Monosaccharide analysis revealed active pentose metabolism and incorporation of fucose into the extracellular matrix, contributing to bioflocculation and culture stability. These results demonstrate the potential of microalgae and cyanobacteria consortia as a sustainable strategy for nejayote remediation, enabling concurrent waste treatment and biopolymer production.