Aggregicoccus is a myxobacterial genus inherently deficient in fruiting genes.
Myxobacteria are fascinating and important prokaryotes with remarkable multicellular behaviors, which make them a model system for studying prokaryotic development and cooperation. Although there have been sporadic discoveries of myxobacterial species unable to fruit, it is unclear whether the non-fruiting characteristic is due to taxon-specific genetic deficiency or suboptimal cultivation conditions. Aggregicoccus is a non-fruiting myxobacterial genus typified by a single validly published species, Ag. edonensis. In this study, we report five novel Aggregicoccus strains, which are classified into three novel type species, Ag. lacus, Ag. agri, and Ag. guangxiensis, based on polyphasic taxonomic analysis. All the Aggregicoccus strains are unable to produce fruiting bodies, but can still sporulate. We compared the genome differences between Aggregicoccus and Myxococcus; both genera belong to the Myxococcaceae family, and all the genomes are of similar sizes. The results showed that the Aggregicoccus strains are inherently deficient in the fruiting body-associated genomic information (FAGI). We propose an assessment of FAGI for the classification of non-fruiting myxobacterial species.IMPORTANCEFruiting body formation is traditionally regarded as a defining trait of myxobacteria. Here, we report that Aggregicoccus spp., including six strains of four species, can sporulate but are deficient in the fruiting body-associated genomic information (FAGI). This demonstrates that the non-fruiting characteristic in Aggregicoccus stems from inherent genetic deficiencies rather than suboptimal cultivation. Our findings highlight the need to assess FAGI presence in classifying non-fruiting lineages, innovate the isolation method, and refine our understanding of the diversity and evolution of the myxobacteria.