Phylogeographic analysis of entomopathogenic nematophilic symbiotic bacteria using 16s rDNA gene sequencing

Abstract : 

In our study, we have isolated and identified three symbiotic bacteria (SRK2, SRK6, SRK8) from the intestine of Heterorhabditis indica nematode and two symbiotic bacteria (SRK1, SRK7) vesicle of Steinernema glaseri nematode based on their 16s rDNA sequences. Phylogenetic studies were conducted to infer their evolutionary relationships with closely related organisms isolated from entomopathogenic nematodes. These organisms have shown 98-99% sequence similarity with Photorhabdus spp. and Xenorhadus spp. SRK1 and SRK7 strains (Xenorhadus spp.) genetically more diverged than SRK2, SRK6 and SRK8 strains (Photorhabdus spp.). SRK2, SRK6 and SRK8 strains were highly grouped with ARG, Iran8, FR42, Az36 and TT01 strains of Photorhabdus luminescens in the tree, and phylogeographically related to FR42 and FR32 strains isolated from France. SRK1 strain was phylogenetically related to the Xenorhabdus poinarii strain Iran2 whereas SRK7 strain corresponded with CN03 strain from China. Overall, we found SRK2, SRK6 and SRK8 strains showing the strain equivalency to the P. luminescens. SRK1 and SRK1 strains were equivalent to the X. poinarii and X. stockiae, respectively. Thus, a symbiotic association between bacteria and entomopathogenic nematodes is widespread in nature occurring in every type of ecological niche


Keyword : 

Nematode, Photorhabdus, Xenorhabdus, Symbiotic bacteria, Phylogeny, Molecular evolution, Genetic variation, Insect cadavers


Author(s) : , M. Razia, R. Karthik Raja, K. Padmanaban, P. Chellapandi, S. Sivaramakrishnan
Downloads : 208


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