Effects of Malachite Green on the Microbiomes of Milkfish Culture Ponds

Abstract

Intensive fish farming through aquaculture is vulnerable to infectious diseases that can increase fish mortality and damage the productivity of aquaculture farms. To prevent infectious diseases, malachite green (MG) has been applied as a veterinary drug for various microbial infections in aquaculture settings worldwide. However, little is known regarding the consequences of MG and MG-degrading bacteria (MGDB) on microbial communities in milkfish culture ponds (MCPs). In this study, small MCPs were used as a model system to determine the effects of MG on the microbial communities in MCPs. The addition of MG led to cyanobacterial blooms in the small MCP. The addition of MGDB could not completely reverse the effects of MG on microbial communities. Cyanobacterial blooms were not prevented. Microbial communities analyzed by next generation sequencing revealed that cyanobacterial blooms may be due to increase of nitrogen cycle (including nitrogen fixation, nitrate reduction and anammox) associated microbial communities, which raised the levels of ammonium in the water of the small MCP. The communities of anoxygenic phototrophic bacteria (beneficial for aquaculture and aquatic ecosystems) decreased after the addition of MG. The results of this investigation provide valuable insights into the effects of MG in aquaculture and the difficulties of bioremediation for aquatic environments polluted by MG.

Structural and functional comparisons of the environmental microbiota of pond and tank environments at different locations for the commercial aquaculture of American shad

“…Arias et al (2006) found that bacterial communities in a catfish aquaculture setting varied from pond to pond at a given time point. Yang et al (2021) suggested that closed pond systems usually support high fish densities and constitute a very favorable environment for the rapid spread of infectious bacteria and acute outbreaks of disease. Fern andez et al (2014) reported that the composition and diversity of the bacterial microbiota affect oysters during culture.…”

“…Yang et al . (2021) suggested that closed pond systems usually support high fish densities and constitute a very favorable environment for the rapid spread of infectious bacteria and acute outbreaks of disease. Fernández et al .…”