The gut microbiota structure of the terrestrial isopod Porcellionides pruinosus (Isopoda: Oniscidea)

Abstract

We used a combination of culture-dependent and independent approaches to study in depth the microbial community associated with the digestive tract of the terrestrial isopod Porcellionides pruinosus (Brandt, 1833). Specimens from different sampling sites in Tunisia harbored distinct microbiota profiles indicating the impact of both host origin and environmental factors on shaping the microbial flora within P. pruinosus. Our results revealed unexpected bacterial diversity especially via metagenomic analysis; a total of 819 operational taxonomic units (OTUs) assigned to two major bacterial phyla; Proteobacteria and Bacteroidetes. We used Nutrient Agar to isolate the cultivable fraction of bacteria associated with the gut of three geographically distant populations of P. pruinosus. The isolated bacteria belong to Actinobacteria, Firmicutes and Proteobacteria. Enrichment cultures on carboxymethylcellulose (CMC) medium gave evidence that the gut of this Oniscidea harbors cellulolytic Firmicutes and Proteobacteria probably involved in the lignocellulose degradation and then in mediating the functional role of terrestrial isopods as litter decomposers and regulators of nutrient cycling in soil ecosystems.

Functional similarity, despite taxonomical divergence in the millipede gut microbiota, points to a common trophic strategy

“…In contrast, the much smaller G. connexa , with a typical positive and hence oxidative gut [ 16 ], comprised nearly 50% Proteobacteria . Similar taxonomic composition, dominated by Proteobacteria with low proportions of Bacteroidota , is common to many arthropods [ 87 ], including other millipedes [ 88 ], terrestrial isopods [ 89 , 90 ], beetles [ 91 , 92 ], and in many bamboo-feeding Hemiptera, Orthoptera, Lepidoptera, and Coleoptera [ 11 ], where the redox conditions in the gut are expected to be positive. Conversely, termites and cockroaches, with typical anoxic guts and active fermentation, typically have lower proportions of Proteobacteria and are dominated by Bacteroidota and Firmicutes , similar to E. pulchripes [ 93 – 95 ].…”

Terrestrial crustaceans (Arthropoda, Crustacea): taxonomic diversity, terrestrial adaptations, and ecological functions

“…Passing through the digestive canal, saprotrophic microflora changes both in density and in species composition ( Hartenstein 1964 , 1982 ; Coughtrey et al 1980 ; Ineson and Anderson 1985 ). Recent studies of gut microbiota in the woodlice Armadillidium vulgare and Porcellionides pruinosus revealed a very diverse bacterial community that varies between host populations, suggesting an important proportion of environmental microbes in the gut-associated microbiota ( Bouchon et al 2016 ; Delhoumi et al 2020 ). Microbial inoculation of leaf litter increased litter palatability ( Hartenstein 1964 ; Hassall et al 1987 ; Rushton and Hassall 1983 ) and quality ( Ullrich et al 1991 ; Uesbeck and Topp 1995 ; Zimmer and Topp 1997 , 2000 ) by reducing the C/N ratio and/or quantity of phenolic compounds ( Kuiters and Sarink 1986 ; Poinsot-Balaguer et al 1993 ; Zimmer 1999 , 2002a ).…”

Red mark syndrome: Is the aquaculture water microbiome a keystone for understanding the disease aetiology?

“…(Szokoli et al, 2016). Studies on terrestrial isopods suggested that Candidatus Hepatincola is extracellular (Wang et al, 2004), horizontally transmitted (Wang et al, 2007) and may have a specific role in host trophic adaptation (Delhoumi et al, 2020).…”