Methane Production and Methanogenic Archaea in the Digestive Tracts of Millipedes (Diplopoda)

Abstract

Methane production by intestinal methanogenic Archaea and their community structure were compared among phylogenetic lineages of millipedes. Tropical and temperate millipedes of 35 species and 17 families were investigated. Species that emitted methane were mostly in the juliform orders Julida, Spirobolida, and Spirostreptida. The irregular phylogenetic distribution of methane production correlated with the presence of the methanogen-specific mcrA gene. The study brings the first detailed survey of methanogens’ diversity in the digestive tract of millipedes. Sequences related to Methanosarcinales, Methanobacteriales, Methanomicrobiales and some unclassified Archaea were detected using molecular profiling (DGGE). The differences in substrate preferences of the main lineages of methanogenic Archaea found in different millipede orders indicate that the composition of methanogen communities may reflect the differences in available substrates for methanogenesis or the presence of symbiotic protozoa in the digestive tract. We conclude that differences in methane production in the millipede gut reflect differences in the activity and proliferation of intestinal methanogens rather than an absolute inability of some millipede taxa to host methanogens. This inference was supported by the general presence of methanogenic activity in millipede faecal pellets and the presence of the 16S rRNA gene of methanogens in all tested taxa in the two main groups of millipedes, the Helminthophora and the Pentazonia.

Gut microbiota ofSpodoptera frugiperda(J.E. Smith) larvae as revealed by metatranscriptomic analysis

“…Moreover, even though it has been suggested that they could affect plants (Taffner et al, ), which would in turn affect pest insects, there is scant information on their importance and the roles they play in these hosts (Gurung, Wertheim, & Falcao Salles, ). Until very recently, methanogenic and non‐methanogenic Archaea from Phylum Euryarchaeota had only been reported in the hindguts of methane producing arthropods—beetles, cockroaches, termites, and millipedes—where there is limited oxygen availability (Brune, ; Egert et al, ; Hara, Shinzato, Seo, Oshima, & Yamagishi, ; Shinzato, Matsumoto, Yamaoka, Oshima, & Yamagishi, ; Šustr, Chroňáková, Semanová, Tajovský, & Šimek, ; Tinker & Ottesen, ). Nevertheless, a shotgun metagenomic analysis of the gut content of P. xylostella larvae identified Euryarchaeota DNA in very low proportions (Xia et al, ).…”

Methane fluxes from coastal sediments are enhanced by macrofauna

“…Analysis of the mcrA gene has successfully been applied to monitor methanogens in soil invertebrate guts 43 , 44 . Detection of mcrA genes in starved bivalves suggests that the methane was not produced by ingested microbes.…”

The microbiome of pest insects: it is not just bacteria

“…In insects, methanogenic and non‐methanogenic archaea belonging to the phylum Euryarchaeota, have been reported in beetles, cockroaches, termites, and millipedes. The methanogenic archaea are usually present in the hindguts, an environment with limited oxygen availability (Shinzato et al., ; Hara et al., ; Šustr et al., ; Tinker & Ottesen, ). Ziganshina et al.…”