Novel, non-symbiotic isolates of Neorhizobium from a dryland agricultural soil
- Published
- Accepted
- Subject Areas
- Agricultural Science, Biodiversity, Microbiology, Soil Science
- Keywords
- Non-symbiotic, Direct isolation, rpoB, 16S rDNA, nifH, nodC, repABC, phylogeny, genome sequencing, Neorhizobium
- Copyright
- © 2018 Soenens et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2018. Novel, non-symbiotic isolates of Neorhizobium from a dryland agricultural soil. PeerJ Preprints 6:e26724v1 https://doi.org/10.7287/peerj.preprints.26724v1
Abstract
Semi-selective enrichment, followed by PCR screening, resulted in the successful direct isolation of fast-growing Rhizobia from a dryland agricultural soil. Over 50% of these isolates belong to the genus Neorhizobium, as concluded from partial rpoB and near-complete 16S rDNA sequence analysis. Further genotypic and genomic analysis of five representative isolates confirmed that they form a coherent group within Neorhizobium, closer to N. galegae than to the remaining Neorhizobium species, but clearly differentiated from the former, and constituting at least one new genomospecies within Neorhizobium. All the isolates lacked nod and nif symbiotic genes but contained a repABC replication / maintenance region, characteristic of rhizobial plasmids, within large contigs from their draft genome sequences. These repABC sequences were related, but not identical, to repABC sequences found in symbiotic plasmids from N. galegae, suggesting that the non-symbiotic isolates have the potential to harbor symbiotic plasmids. This is the first report of non-symbiotic members of Neorhizobium from soil.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Schematic representation of the semi-selective enrichment procedure to isolate fast-growing Rhizobia from the Tomejil soil
PCR amplification of a genomic DNA band from Tomejil Neorhizobium sp. strains with fnrN primers
(A) Agarose gel electrophoresis separation of PCR products. (B) Schematic representation of the genomic region amplified by fnrN primers in Tomejil Neorhizobium sp. strains (see text).
