The beetle genus Cephaloleia has evolved in association with tropical ginger plants and for many species their specific host plant associations are known. Here we show that the core microbiome of six closely related Costa Rican Cephaloleia species comprises only eight bacterial groups, including members of the Acinetobacter, Enterobacteriacea, Pseudomonas, Lactococcus, and Comamonas. The Acinetobacter and Enterobacteriacea together accounted for 35% of the total average 16S rRNA ribotypes recovered from all specimens. Further, microbiome diversity and community structure was significantly linked to beetle diet breadth, between those foraging on less than two plant types (specialists) versus over nine plant types (generalists). Moraxellaceae, Enterobacteriaceae, and Pseudomonadaceae were highly prevalent in specialist species, and also present in eggs, while Rickettsiaceae associated exclusively with generalist beetles. Bacteria isolated from Cephaloleia digestive systems had distinct capabilities and suggested a possible beneficial role in both digestion of plant-based compounds, including xylose, mannitol, and pectin, and possible detoxification, via lipases. Cephaloleia species are currently expanding their diets to include exotic invasive plants, yet it is unknown whether their microbial community plays a role in this transition. In this study, colonization of invasive plants was correlated with a dysbiosis of the microbiome, suggesting a possible relationship between gut bacteria and niche adaptation.

Bacteria use diverse immune systems to defend themselves from ubiquitous viruses termed bacteriophages (phages). Many anti-phage systems function by abortive infection to kill a phage-infected cell, raising the question of how these systems are regulated to avoid activation and cell killing outside the context of infection. Here, we identify a transcription factor associated with the widespread CBASS bacterial immune system, that we term CapW. CapW forms a homodimer and binds a palindromic DNA sequence in the CBASS promoter region. Two crystal structures of CapW reveal how the protein switches from a DNA binding-competent state to a ligand-bound state that cannot bind DNA due to misalignment of dimer-related DNA binding domains. We show that CapW strongly represses CBASS gene expression in uninfected cells, and that CapW disruption likely results in toxicity due to uncontrolled CBASS expression. Our results parallel recent findings with BrxR, a transcription factor associated with the BREX anti-phage system, and suggest that CapW and BrxR are the founding members of a family of universal anti-phage signaling proteins.

The beetle genus Cephaloleia has evolved in association with tropical ginger plants and for many species their specific host plant associations are known. Here we show that the core microbiome of six closely-related Costa Rican Cephaloleia species comprises only 8 bacterial groups, including members of the Acinetobacter, Enterobacteriacea, Pseudomonas, Lactococcus, and Comamonas. The Acinetobacter and Enterobacteriacea together accounted for 35% of the total average 16S rRNA ribotypes recovered from all specimens. Further, microbiome diversity and community structure was significantly linked to beetle diet breadth, between those foraging on <2 plant types (specialists) versus 9+ plants (generalists). Moraxellaceae, Enterobacteriaceae, and Pseudomonadaceae were highly prevalent in specialist species, and also present in eggs, while Rickettsiaceae associated exclusively with generalist beetles. Bacteria isolated from Cephaloleia digestive systems had complementary capabilities and suggested a possible beneficial role in both digestion of plant-based compounds, including xylose, mannitol, and pectin, and possible detoxification, via lipases. Cephaloleia species are currently expanding their diets to include exotic invasive plants, yet it is unknown whether their microbial community plays a role in this transition. In this study, colonization of invasive plants was correlated with a dysbiosis of the microbiome, suggesting a possible relationship between gut bacteria and niche adaptation. 33 The beetle genus Cephaloleia has evolved in association with tropical ginger plants and for many species 34 their specific host plant associations are known. Here we show that the core microbiome of six closely-35 related Costa Rican Cephaloleia species comprises only 8 bacterial groups, including members of the 36 Acinetobacter, Enterobacteriacea, Pseudomonas, Lactococcus, and Comamonas. The Acinetobacter and 37 Enterobacteriacea together accounted for 35% of the total average 16S rRNA ribotypes recovered from all 38 specimens. Further, microbiome diversity and community structure was significantly linked to beetle diet 39 breadth, between those foraging on <2 plant types (specialists) versus 9+ plants (generalists). 40 Moraxellaceae, Enterobacteriaceae, and Pseudomonadaceae were highly prevalent in specialist species, 41 and also present in eggs, while Rickettsiaceae associated exclusively with generalist beetles. Bacteria 42 isolated from Cephaloleia digestive systems had complementary capabilities and suggested a possible 43 beneficial role in both digestion of plant-based compounds, including xylose, mannitol, and pectin, and 44 possible detoxification, via lipases. Cephaloleia species are currently expanding their diets to include 45 exotic invasive plants, yet it is unknown whether their microbial community plays a role in this transition. 46 In this study, colonization of invasive plants was correlated with a dysbiosis of the microbiome, 47 suggesting a possible relationship between gut bacteria and niche adaptation. 49 I...

The beetle genus Cephaloleia has evolved in association with tropical ginger plants and for many species their specific host plant associations are known. Here we show that the core microbiome of six closely-related Costa Rican Cephaloleia species comprises only 8 bacterial groups, including members of the Acinetobacter, Enterobacteriacea, Pseudomonas, Lactococcus, and Comamonas. The Acinetobacter and Enterobacteriacea together accounted for 35% of the total average 16S rRNA ribotypes recovered from all specimens. Further, microbiome diversity and community structure was significantly linked to beetle diet breadth, between those foraging on <2 plant types (specialists) versus 9+ plants (generalists). Moraxellaceae, Enterobacteriaceae, and Pseudomonadaceae were highly prevalent in specialist species, and also present in eggs, while Rickettsiaceae associated exclusively with generalist beetles. Bacteria isolated from Cephaloleia digestive systems had complementary capabilities and suggested a possible beneficial role in both digestion of plant-based compounds, including xylose, mannitol, and pectin, and possible detoxification, via lipases. Cephaloleia species are currently expanding their diets to include exotic invasive plants, yet it is unknown whether their microbial community plays a role in this transition. In this study, colonization of invasive plants was correlated with a dysbiosis of the microbiome, suggesting a possible relationship between gut bacteria and niche adaptation.PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.26692v1 | CC BY 4.0 Open Access |