Effects of peanut shells serving as a carbon source and microbial carrier on bacterial community structure in Penaeus...

Intensive shrimp aquaculture systems often suffer from water quality deterioration and disease outbreaks. Biofloc technology is one of the sustainable management strategies for shrimp culture, while the choice of organic carbon source critically influences microbial community dynamics. This study investigated the effects of peanut shells (an abundant agricultural by-product) on the bacterial community in shrimp rearing water in Penaeus vannamei culture systems. Over a 28-day controlled experiment, the peanut shell-amended system exhibited significantly lower ammonia and nitrite concentrations than the control, indicating improved nitrogen removal. Overall bacterial diversity and community structure showed only moderate shifts with no significant change compared with the control, the relative abundances of Bacteroidetes, Flavobacteriaceae, and Saprospiraceae showed increasing trends, but were not statistically significant. Redundancy analysis identified phosphate and nitrate as key environmental factors associated with community succession. Functional prediction showed that peanut shells enhanced pathways related to quorum sensing, secretion systems, and organic matter degradation, while reducing biosynthetic activity. Neutral community modeling further revealed that peanut shells did not notably alter the assembly processes across the whole culture period, and these limited changes were mainly attributed to the selective enrichment of potential beneficial bacteria such as Rhodobacteraceae taxa. These findings indicate that peanut shells exert a gentler perturbation on the microbial ecosystem compared to readily degradable carbon sources like molasses or glucose, which are known to provoke more drastic community reassembly. This work highlights the potential of peanut shells as a sustainable carbon supplement for improving water quality in a sustainable manner in shrimp aquaculture.