Biofilm feeding: Microbial colonization of food promotes the growth of a detritivorous arthropod

Abstract

Feeding on plant material is common among animals, but how different animals overcome the dietary deficiencies imposed by this feeding strategy is not well understood. Microorganisms are generally considered to play a vital role in the nutritional ecology of plant feeding animals. Commonly microbes living inside animal bodies are considered more important, but recent studies suggest external microbes significantly shape plant-feeding strategies in invertebrates. Here we investigate how external microbes that typically form biofilm on primary plant material affect growth rates in a terrestrial isopod species Porcellio scaber. We experimentally manipulated the amount of biofilm on three different primary diet sources and quantified growth and survival of individuals that fed on food with either a small or large amount of biofilm. In addition, we tested how dietary manipulation shapes the composition of bacterial communities in the gut. The presence of visible biofilm significantly affected the growth of isopods: individuals that fed on the primary diet source with a large amount of biofilm gained more mass than individuals feeding on a diet with marginal biofilm. Diet also significantly affected the bacterial gut community. The primary diet source mainly determined the taxonomic composition of the bacterial community in the isopod gut, whereas the amount of biofilm affected the relative abundance of bacterial taxa. Our study suggests that terrestrial isopods may cope with low-quality plant matter by feeding on biofilm, with decomposition of plant material by organisms outside of the feeding organism (here a terrestrial isopod) probably playing a major role. Future investigations may be directed towards the primary diet source, plant matter, and the secondary diet source, biofilm, and should assess if both components are indeed uptaken in detritivorous species.

The Terrestrial Isopod Microbiome: An All-in-One Toolbox for Animal–Microbe Interactions of Ecological Relevance

“…The latter excludes different host genotypes as the primary driver of microbiome composition in this species and makes a shift due to environmentally acquired bacteria all the more likely. The effect of different food sources on the gut microbiome has been more formally tested in P. scaber , confirming that different food sources shape taxonomic composition of the gut microbiome at the phylum level ( Horvathova et al, 2016 ).…”

“…Another recently published investigation of the hindgut microbiome in P. scaber using Illumina sequencing ( Horvathova et al, 2016 ) enables us for the first time to compare the gut microbiomes of two isopod species: while the gut microbiome of P. scaber was similar to that of A. vulgare in terms of bacterial diversity at the phylum level (20 phyla), microbiome composition was quite different: Proteobacteria represented by far the most abundant phylum in both species (approximately 85%) but Alphaproteobacteria were more abundant than Gammaproteobacteria in A. vulgare , whereas the opposite was the case in P. scaber . Similarly, the Mollicutes Hepatoplasma and Bacilloplasma accounted for 8.5% of the gut microbiome in A. vulgare , while they were negligible in P. scaber (0.72%).…”

Microbial diversity associated to the intestinal tract of soil invertebrates

“…Our study showed that gut bacteria from several invertebrate species were dominated by phylum Proteobacteria, Bacteroidetes, and Firmicutes. Proteobacteria is the most representative phylum among all insects studied so far (Jones et al, 2013;Yun et al, 2014;Horváthová et al, 2016).…”

Pollen Stoichiometry May Influence Detrital Terrestrial and Aquatic Food Webs

“…For organisms feeding on plant materials, the proportion of non-C elements in their food may be more limiting than energy (Pokarzhevskii et al, 2003;Moe et al, 2005) and diet supplementation with high-quality resources may promote the development of animals feeding on dead plant matter Weiner, 2014, 2016;Filipiak et al, 2016;Horvathova et al, 2016). Hence, it might be advantageous to include in the diet plant matter that is nutritive, easily available in considerable mass and relatively easily digestible, i.e., pollen.…”