Recently, the Agricultural Microbial Resource Team of the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) has made new advances in the relationship and driving mechanism between antagonistic and genetic distance in Bacillus. The results were published in Nature Communications.

According to Prof. Ruifu Zhang, microbes live in the same habitat compete for resources by competition nutrient and antagonism.

As an important selecting process, interspecific competition is a key factor affecting the assembly and evolution of microbial communities. Exploring the driving factors and biological mechanisms affecting microbial interspecific competition is an important scientific issue in microbial ecology. It will provide a theoretical basis for the construction of synthetic community based on microbial interaction.

Generally, a closer genetic relationship between microbes would lead stronger competition for nutrients. However, the relationship between the antagonism and genetic distance between microbes and the driving mechanism are unclear.

Based on the comparative genomic analysis of more than 4,000 Bacillus strain, the study showed that the distribution of secondary metabolite biosynthetic gene clusters (BGCs) in genome of microbes were positively correlated with their phylogenetic relationships. They further found that the antagonism between representative Bacillus was significantly positively correlated with both the genetic distance and BGC distance between strains. Finally, the experiments using mutant strains proved that the inhibition of various Bacillus strain by the model plant-beneficial Bacillus velezensis SQR9  was dependent on the its unique BGCs, which are unique to the antagonistic bacteria but lack in the target bacteria.

In conclusion, the study revealed that the distribution and phylogenetic consistance of secondary metabolite synthesis gene clusters in Bacillus drove the positive correlation between the antagonism and genetic distance in Bacillus. The result not only explains the important ecological problem of the relationship between species competition and affinities proposed by Darwin in "Origin of the Species", but also provides a theoretical basis for designing microbial fertilizers made by synthetic community.

The research was funded by the National Natural Science Foundation of China and the Science and Technology Innovation Project of the Chinese Academy of Agricultural Sciences.

Paper link: https://www.nature.com/articles/s41467-022-28668-z