Bacterial communities in the hepatopancreas of different isopod species

This study aims to describe animal bacterial associations with culture independent methods. Bacterial communities in the hepatopancreas of the following 7 species of isopods (Pericaridea, Crustacea, Arthropoda) from 3 habitat types were investigated: 2 subtidal species Idotea baltica (IB) and I. wosnesenskii (IG); 2 intertidal species Ligia occidentalis (LO) and L. pallasii (LP), and 3 terrestrial species Armadillidium vulgare (A), Oniscus asellus (O) and Porcelio scaber (P) Oniscus asellus (O) and Porcelio scaber (P). CARD FISH and 16S clone libraries form environmental samples isolated from the hepatopancreas of isopods were used to describe the bacterial communities. Previous work has described two species of symbionts of terrestrial isopods and found very low diversity (predominately only one species per host). Clone libraries from some but not all species in this study included sequences closely related to previously described isopod symbionts with the majority clustering around Candidatus Hepatoplasma crinochetorum (Firmicutes, Mollicutes). These sequences clustered by host species confirming published results of host specificity. Closely related sequences to the other described symbiont 'Candidatus Hepatincola porcellionum' (α-Proteobacteria, Rickettsiales) were only obtained from the hepatopancreas of L. pallasii. Counts of bacterial abundance obtained with CARD FISH (Probe EUB I-III) ranged between 1.9 x 10 – 1.7 x 10 bacteria per hepatopancreas, this numbers are 2 to 3 orders of magnitude lower than previously published counts of DAPI stained cells.