ena-STUDY-BEN GURION UNIVERSITY-30-12-2020-13:27:06:466-321
Diet restriction highlights forces shaping the microbial network in the gut of sea urchin Tripneustes gratilla elatensis
The ability of algivorous sea urchins to gain energy from diets with a single alga species makes them favorable for the study of related changes in the gut microbial network. In order to ascertain whether changes are led by specific microbes in the assembly we compared individuals' niche breadth, associations, and centrality in the networks of the three major regions in the gut of sea urchin Tripneustes gratilla elatensis restricted to diet with alga species Ulva fasciata or Gracilaria conferta, or when nursed algal-free pelleted feed. Dietary Ulva fasciata induced unique microbes and associations which formed a denser and highly connected network while the pelleted feed, which lacks any marine footprint, resulted with a much lower connectivity between nodes with fragile chain-associations and greater competition on available resources. Among other core or hub microbes we identified Bacteriodetes, and Firmicutes as the keystone taxa in the gut with persistent occurrence in the different niches. The former revealed high strain variability and assumed to rapidly evolve in the gut via spreading of new strains to unique niches in which they are central microbes in the local network. When fed different diets, various strains of Bacteroidetes and Spirochaetes maintained community connectivity as central hub nodes while other strains were determined as driver microbes that rewired the network under particular diet via changes in own associations, associating microbes and centrality.
The ability of algivorous sea urchins to gain energy from diets with a single alga species makes them favorable for the study of related changes in the gut microbial network. In order to ascertain whether changes are led by specific microbes in the assembly we compared individuals' niche breadth, associations, and centrality in the networks of the three major regions in the gut of sea urchin Tripneustes gratilla elatensis restricted to diet with alga species Ulva fasciata or Gracilaria conferta, or when nursed algal-free pelleted feed. Dietary Ulva fasciata induced unique microbes and associations which formed a denser and highly connected network while the pelleted feed, which lacks any marine footprint, resulted with a much lower connectivity between nodes with fragile chain-associations and greater competition on available resources. Among other core or hub microbes we identified Bacteriodetes, and Firmicutes as the keystone taxa in the gut with persistent occurrence in the different niches. The former revealed high strain variability and assumed to rapidly evolve in the gut via spreading of new strains to unique niches in which they are central microbes in the local network. When fed different diets, various strains of Bacteroidetes and Spirochaetes maintained community connectivity as central hub nodes while other strains were determined as driver microbes that rewired the network under particular diet via changes in own associations, associating microbes and centrality.