Comparative Genomics Provides Insight into the Function of Broad-Host Range Sponge Symbionts

Area of Science:

• Marine microbiology and symbiosis
• Genomics and evolutionary biology
• Invertebrate-microbe interactions

Background:

• Marine sponges (phylum Porifera) host diverse microbial symbionts, with origins potentially dating back to the Precambrian period.
• Globally distributed bacterial taxa like Entoporibacteria, SAUL, and Tethybacterales associate with a wide range of sponge hosts.
• Limited knowledge exists regarding the functional roles and evolutionary history of Tethybacterales and SAUL symbionts.

Purpose of the Study:

• To characterize the genomes and functional potential of the Tethybacterales order.
• To compare Tethybacterales with the well-studied Entoporibacteria symbionts.
• To investigate the evolutionary history and host association patterns of these broad-host range symbionts.

Main Methods:

• Addition of 11 new genomes to the Tethybacterales order.
• Identification of a novel family within Tethybacterales.
• Comparative genomic analysis of Tethybacterales and Entoporibacteria.
• Association analysis with low-microbial abundance (LMA) and high-microbial abundance (HMA) sponges.

Main Results:

• Functional potential differs significantly among the three Tethybacterales families.
• Tethybacterales and Entoporibacteria show preferential associations with LMA and HMA sponges, respectively.
• Evidence suggests multiple independent acquisition events of these symbionts rather than a single coevolutionary event.

Conclusions:

• The functional potential of broad-host range symbionts is conserved at the family level within Tethybacterales.
• Tethybacterales and Entoporibacteria likely perform distinct functions within their respective LMA and HMA sponge hosts.
• Multiple symbiotic association events have shaped the evolutionary history of these widespread marine bacterial symbionts.