Light and carbon sources addition alter microbial community in biofloc-based Litopenaeus vannamei culture systems

Abstract

Biofloc technology (BFT) is a new water treatment technology for intensive aquaculture. Developing diverse and stable microbial communities is the core technology for BFT. However, information about how different management strategies can affect the microbial communities in the BFT system is limited. In this study, we conducted a 49-day trial to investigate how the two factors (light and carbon sources addition) alter the microbial community in biofloc-based Litopenaeus vannamei culture systems. Results demonstrated that both light and addition of carbon sources caused significantly different water qualities in nitrite (NO2−-N), nitrate (NO3−-N), soluble reactive phosphorus (SRP), total organic carbon (TOC), and chlorophyll-a (Chl-a) in the culture systems. Carbon sources addition increased the bacterial richness but not its diversity. Principal component analysis (PCA) indicated both the two factors affected the distribution of microbial community in the system. Different dominant taxa were identified by linear discriminant analysis effect size (LEfSe) in different systems. The denitrification bacteria genus Paracoccus was identified in the systems provided with both light and carbon sources, but some harmful bacteria, such as the genus Leucothrix, were identified in the systems with carbon sources added but without provided light. Redundancy analysis showed that water quality parameters influenced the bacterial communities. Spearman correlation analysis indicated that the abundance of Paracoccus was significantly positively correlated with NO2−-N, NO3−-N and TOC. And the abundance of Leucothrix was positively correlated with NO3−-N and negatively correlated with total ammonia nitrogen (TAN). Results from the present study provide useful information to maintain healthy microbial environments in biofloc-based aquaculture systems.