Hidden diversity underground: ant- and nest-associated bacterial communities revealed by meta-genomic analyses
Hiroyuki Shimoiji, Hideomi Itoh , Yu Matsuura , Yoshitomo Kikuchi , Hiroyuki Shimoiji
Kwansei Gakuin University, Japan; AIST, Japan ; University of the Ryukyus, Japan ; AIST, Japan ; Kwansei Gakuin University, Japan
Symbiotic relationships between insects and bacteria are omnipresent in nature, wherein bacterial symbionts provide insect hosts with diverse adaptive functions. Previous studies on such symbioses have focused on the impacts of symbionts on solitary insect hosts, their host-symbiont co-evolution, and genome evolution. However, little is known about the interactions between social insects and associated bacteria, especially in the contexts of caste differentiation and environmental factors. In this study, we aimed to uncover and compare bacterial floras of castes and nests in an ant Diacamma sp. based on bacterial 16S rRNA gene amplicon sequencing analysis with a high throughput sequencer. Bacterial phylogenetic analyses revealed that the ant society had clearly different bacterial floras among foragers, other castes (nurses, males, and queens) and ambient soils. The bacterial floras of almost all foragers and a part of nurses were dominated by a single species of the Firmicutes, while it accounted for extremely low proportions in queens and males. The detailed phylogenetic analysis estimated that this Firmicutes is closely related to a specific bacterium repeatedly detected from other ant species. Strikingly, in contrast to the simple bacterial floras in foraging workers, dominant bacterial species in queens were considerably different among colonies. Moreover, in clustering analyses, community structures of bacterial floras of queens, males and nurses altogether formed distinct clusters in a colony-dependent manner. Together, we will discuss hypothetical mechanisms for the assembly of caste/colony-specific bacterial communities and how ant nesting activities could affect soil microbiota.