High diversity and suggested endemicity of culturable Actinobacteria in an extremely oligotrophic desert oasis
- Published
- Accepted
- Subject Areas
- Biodiversity, Biogeography, Ecology, Microbiology
- Keywords
- Actinobacteria, Cuatro Cienegas, endemism, diversity, Streptomyces
- Copyright
- © 2017 Arocha-Garza 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
- 2017. High diversity and suggested endemicity of culturable Actinobacteria in an extremely oligotrophic desert oasis. PeerJ Preprints 5:e2893v1 https://doi.org/10.7287/peerj.preprints.2893v1
Abstract
The phylum Actinobacteria constitutes one of the largest and anciently divergent phyla within the Bacteria domain. Actinobacterial diversity has been thoroughly researched in various environments due to its unique biotechnological potential. Such studies have focused mostly on soil communities, but more recently marine and extreme environments have also been explored, finding rare taxa and demonstrating dispersal limitation and biogeographic patterns for Streptomyces. To test the distribution of Actinobacteria populations on a small scale, we chose the extremely oligotrophic and biodiverse Cuatro Cienegas Basin (CCB), an endangered oasis in the Chihuahuan desert to assess the diversity and uniqueness of Actinobacteria in the Churince System with a culture-dependent approach over a period of three years, using nine selective media. The 16S rDNA of putative Actinobacteria were sequenced using both bacteria universal and phylum-specific primer pairs. Phylogenetic reconstructions were performed to analyze OTUs clustering and taxonomic identification of the isolates in an evolutionary context, using validated type species of Streptomyces from previously phylogenies as a reference. Rarefaction analysis for total Actinobacteria and for Streptomyces isolates were performed to estimate species´ richness in the intermediate lagoon (IL) in the oligotrophic Churince system. A total of 350 morphologically and nutritionally diverse isolates were successfully cultured and characterized as members of the Phylum Actinobacteria. 105 from the total isolates were successfully subcultured, processed for DNA extraction and 16S-rDNA sequenced. All strains belong to the order Actinomycetales, encompassing 11 genera of Actinobacteria; the genus Streptomyces was found to be the most abundant taxa in all the media tested throughout the 3-year sampling period. Phylogenetic analysis of our isolates and another 667 reference strains of the family Streptomycetaceae shows that our isolation effort produced 38 unique OTUs in six new monophyletic clades. This high biodiversity and uniqueness of Actinobacteria in an extreme oligotrophic environment, which has previously been reported for its diversity and endemicity, is a suggestive sign of microbial biogeography of Actinobacteria and it also represents an invaluable source of biological material for future ecological and bioprospecting studies.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Supplementary Table 1. Table containing data from Actinobacteria isolated from CCB
Sequence analysis of the cultured Actinobacteria isolated from the intermediate lagoon in Churince system, based on partial 16S rDNA gene sequencing.
Supplementary Figure 1. Complete phylogenetic reconstruction of phylum Actinobacteria based on 16S rDNA sequence
Phylum Actinobacteria Phylogenetic tree based on 16S rRNA sequences using Maximum Likelihood (ML) algorithm for representative CCB-isolated Actinobacteria and their closely related type strains. Bootstrap values based on 1000 replicates.
Supplementary Figure 2. NJ Phylogenetic tree for Complete Streptomycetaceae family
Phylogenetic tree based on a data set of 667 16S rRNA sequences of the Streptomycetaceae family using the neighbour-joining method. Bootstrap values based on 1000 replicates.
Data set for phylogenies
Complete data set used for phylogenetic analyses.