Uncovering the ecophysiological potential of Motilimonas through genomic profiling analysis

The Motilimonas genus was proposed in 2017 and presently include three recognized species isolated from various environments. This genus is still poorly characterized, and its ability to degrade chitin has recently been reported. A genomic profiling analysis was conducted on the seven Motilimonas genomes (family Psychromonadaceae) available in the NCBI database. The phylogenetic study suggests that Motilimonas sp. E26, Motilimonas sp. 1MG-2023 G1M02 and Motilimonas sp. Spo1₁ could form a new clade distinct from other already existing clades within the Motilimonas genus (i. e. M. cestriensis, M. pumila and M. eburnea). The genomic features of all Motilimonas genomes are consistent with a moderately copiotrophic lifestyle. For instance, they encode proteins involved in chemotaxis, motility, type IV pili biosynthesis, sugar phosphotransferase systems (PTS) and chitin degradation. Additional shared traits include aerobic respiration, a preference for sugars over organic acids as carbon sources, the use of a “compatible solute” strategy to tolerate osmotic stress in saline environments, and, except for M. cestriensis MKS20T, the ability to perform nitrate reduction. Furthermore, all Motilimonas genomes encode a diversity of secretion systems. For example, each genome contains one or several complete type I secretion systems (T1SS), one complete T2SS, and four genomes (Motilimonas sp. Spo1₁, M. sp. E26, M. sp. 1MG-2023 G1M02 and Motilimonas sp. KMU-193) harbor a complete type VI secretion system (T6SS). Notably, only M. pumila PLHSC7-2T possesses genes encoding a complete type III secretion system (T3SS). These findings provide new insights into the ecological versatility and adaptive strategies of the Motilimonas genus. The next step will involve genome-resolved analyses of metagenomic datasets with the objective to investigate the functional ecology of Motilimonas in a broader range of environments contributing to the better understanding of their ecological distribution.