Growth of grass carp enhances microbial sulfur cycling in aquaculture ponds

We surveyed aquaculture pond sediments cultured with different sized grass carps, found that the physical characteristics of sediment were obviously different. In the larval ponds, the sediments colored in dark and have off-flavors, whereas the color of sediment in large-sized fish ponds is gray with no obvious smell, which indicating that fish size may impact the accumulation and consumption of sulfur related substance. To test our hypothesis, we examined the difference of microbial community composition in ponds cultured with three size fish, by selecting the genes of 16S rRNA, dsrB and soxB as molecular markers Hence, we verified our hypothesis by selecting the genes of dsrB and soxB as molecular markers, assisting with qPCR as quantitative methods. Aquaculture pond sediments cultured with large grass carps have more microbial diversity and abundance than small fish, especially associated with microbial sulfur cycling. Sulfur compounds and sediment re-suspension are main factors that effect the microbial composition.