Hawaiian bobtail squid symbiont, Leisingera sp. ANG-M7, uses a “combined arms” strategy to overcome competitor resistance

Competition between bacteria can impact the ability to colonize a host. In the accessory nidamental gland (ANG) reproductive symbiosis of the Hawaiian bobtail squid, Euprymna scolopes, symbionts colonize various epithelium lined tubules of adult females. We hypothesize that symbionts may use competitive mechanisms to determine ANG tubule colonization outcomes. One ANG strain, Leisingera sp. ANG-M7, was found to inhibit another ANG symbiont, Leisingera sp. ANG-DT, in vitro. Transposon mutagenesis was used to determine the genes required for this antimicrobial activity. Seven ANG-M7 transposon mutants were found with significantly decreased ability to inhibit ANG-DT compared to WT ANG-M7. Of these mutants, three strains (P08F1, P24E3, P40B12) were selected for transcriptome sequencing to look for shared pathways that were significantly different from WT. Overall design: RNA-seq profiling of Leisingera sp. ANG-M7 WT and transposon mutants (P08F01, P24E03, P40B12) grown in SWT broth, 29°C, 200 rpm, for 8 hours.