Structure and Topology of Microbial Communities in the Major Gut Compartments of Melolontha melolontha Larvae (Coleoptera: Scarabaeidae)

Abstract

Physicochemical gut conditions and the composition and topology of the intestinal microbiota in the major gut compartments of the root-feeding larva of the European cockchafer (Melolontha melolontha) were studied. Axial and radial profiles of pH, O 2 , H 2 , and redox potential were measured with microsensors. Terminal restriction fragment length polymorphism (T-RFLP) analysis of bacterial 16S rRNA genes in midgut samples of individual larvae revealed a simple but variable and probably nonspecific community structure. In contrast, the T-RFLP profiles of the hindgut samples were more diverse but highly similar, especially in the wall fraction, indicating the presence of a gut-specific community involved in digestion. While high acetate concentrations in the midgut and hindgut (34 and 15 mM) corroborated the presence of microbial fermentation in both compartments, methanogenesis was confined to the hindgut. Methanobrevibacter spp. were the only methanogens detected and were restricted to this compartment. Bacterial 16S rRNA gene clone libraries of the hindgut were dominated by clones related to the Clostridiales. Clones related to the Actinobacteria, Bacillales, Lactobacillales, and ␥-Proteobacteria were restricted to the lumen, whereas clones related to the ␤-and ␦-Proteobacteria were found only on the hindgut wall. Results of PCR-based analyses and fluorescence in situ hybridization of whole cells with group-specific oligonucleotide probes documented that Desulfovibrio-related bacteria comprise 10 to 15% of the bacterial community at the hindgut wall. The restriction of the sulfate-reducer-specific adenosine-5-phosphosulfate reductase gene apsA to DNA extracts of the hindgut wall in larvae from four other populations in Europe suggested that sulfate reducers generally colonize this habitat.

Alteration of the Ileal Microbiota of Weanling Piglets by the Growth-Promoting Antibiotic Chlortetracycline

“…Three sequences from porcine GI tracts that were communicated prior to the description of the species are highly homologous to Turicibacter (27). Turicibacter has also been reported from insect hindguts, dairy wastewaters, and raw milk (8,9,34). However, as only one species has been cultured (3), the physiological diversity of the members of this genus is unknown.…”

Integrating nutrition and immunology: A new frontier

“…Gut microbes also play a role in invertebrate biology (Dillon and Dillon, 2003) and digestive process [Brune, 2011 [Lundgren, 2010, and recently the composition of microbe gut populations has been described in a variety of insect species, including bees (Jeyaprakash et al, 2003;Mohr and Tebbe, 2006), beetles (Egert et al, 2005;Lehman et al, 2009;Nardi et al, 2006;Zhang and Jackson, 2008), flies (Cox and Gilmore, 2007;Ren et al, 2007;Ryu et al, 2008;Shin et al, 2011;Wong et al, 2011), lepidopterans (Pauchet et al, 2010;Xiang et al, 2006) and termites (Hongoh et al, 2003). In Drosophila, the microbiome regulates host metabolic homeostatic and developmental programs by modulating the insulin/insulin-like growth factor (Shin et al, 2011).…”

Beneficial interactions between insects and gut bacteria

“…Members belonging to Actinobacteria are most numerous, besides Proteobacteria. Methanogenic archea was exclusively identifi ed only in the hindgut besides Desulfovibrio related bacteria were limited to the hindgut wall [16]. Interestingly, in both termites and coleopteran beetles, there is a clear compartmentalization of the gut into regions of acidic and alkaline pH, each harboring specifi c groups of microbes [17].…”