Intracellular Burkholderia Symbionts Induce Extracellular Secondary Infections; Driving Diverse Host Outcomes that Vary by Genotype and Environment [article]

Niloufar Khojandi, Tamara S Haselkorn, Madison N Eschbach, Rana A Naser, Susanne DiSalvo
2018 bioRxiv   pre-print
Symbiotic associations impact and are impacted by their surrounding ecosystem. The association between Burkholderia bacteria and the soil amoeba Dictyostelium discoideum is a tractable model to unravel the biology underlying symbiont-endowed phenotypes and their impacts. Several Burkholderia species stably associate with D. discoideum and typically reduce host fitness in food-rich environments while increasing fitness in food-scarce environments. Burkholderia symbionts are themselves inedible
more » ... their hosts but induce co-infections with secondary bacteria that can serve as a food source. Thus, Burkholderia hosts are farmers that carry food bacteria to new environments, providing a benefit when food is scarce. We examined the ability of specific Burkholderia genotypes to induce secondary co-infections and assessed host fitness under a range of co-infection conditions and environmental contexts. Although all Burkholderia symbionts intracellularly infected Dictyostelium, we found that co-infections are predominantly extracellular, suggesting that farming benefits are derived from extracellular infection of host structures. Furthermore, levels of secondary infection are linked to conditional host fitness; B. agricolaris infected hosts have the highest level of co-infection and have the highest fitness in food scarce environments. This study illuminates the phenomenon of co-infection induction across Dictyostelium associated Burkholderia species and exemplifies the contextual complexity of these associations.
doi:10.1101/448399 fatcat:5m42jivfqbg5ddts4u4aoyfnsu