# Relations Between Core Taxa and Metabolic Characteristics of Bacterial Communities in Litopenaeus vannamei Ponds and Their Probiotic Potential

## TL;DR

This study identifies key bacteria in shrimp ponds that are linked to water purification and could be used as probiotics.

## Contribution

The study reveals new correlations between core bacterial taxa and metabolic functions, suggesting novel probiotic candidates like Tropicimonas.

## Key findings

- Keystone taxa like Bacillus and Tropicimonas are strongly correlated with carbon source utilization in pond bacterial communities.
- Co-introducing Tropicimonas and Bacillus reduced nitrite and nitrate removal time in aquaculture wastewater to 24–48 hours.
- New genera such as Tropicimonas show probiotic potential and have not yet been applied in aquaculture.

## Abstract

Microorganisms play a crucial role in purifying aquaculture water bodies. However, there is limited understanding regarding the core species of bacterial communities in aquaculture ponds and their metabolic functions. Using 16S rRNA gene sequencing technology, network analysis, and Biolog EcoPlates, we identified keystone and core taxa of bacterial communities in Litopenaeus vannamei ponds and investigated their correlations with their community’s carbon source utilization abilities based on Biolog EcoPlates. We found that keystone and core taxa in bacterial communities were significantly correlated with the carbon source utilization abilities of bacterial communities. The positively correlated core taxa include (1) Bacillus, Flavobacterium, Brevibacillus, and Paenibacillus, which are used as probiotics in aquaculture, and (2) Candidatus Aquiluna, Dechloromonas, Sulfurifustis, Terrimicrobium, Alsobacter, and Gemmobacter, which have been reported to play a role in nitrogen removal. Furthermore, the positively correlated Tropicimonas (Rhodobacterales: Rhodobacteraceae) in aquaculture has not yet been applied. By nitrogen degradation experiments in aquaculture wastewater, we confirmed the synergistic relationship between the genera Tropicimonas and Bacillus. The co-introduction of Tropicimonas sediminicola SDUM182003 and Priestia aryabhattai HG1802 or Bacillus subtilis XQ1804 into the aquaculture tailwater reduced the time required for the removal rates of nitrite nitrogen and nitrate nitrogen to reach over 90% by 24–48 h. Our research reveals the correlation between core taxa and community carbon source utilization, indicating that the core taxa of bacterial communities play a crucial role in the metabolic functions of the community, and offering a reference for exploring new bacterial genera with probiotic potential.