title: Phylogenetic analysis of actinobacterial populations associated with Antarctic Dry Valley mineral soils.
abstract: Despite the apparent severity of the environmental conditions in the McMurdo Dry Valleys, Eastern Antarctica, recent phylogenetic studies conducted on mineral soil samples have revealed the presence of a wide diversity of microorganisms, with actinobacteria representing one of the largest phylotypic groups. Previous metagenomic studies have shown that the majority of Antarctic actinobacterial populations are classified as 'uncultured'. In this study, we assessed the diversity of actinobacteria in Antarctic cold desert soils by complementing traditional culture-based techniques with a metagenomic study. Phylogenetic analysis of clones generated with actinobacterium- and streptomycete-specific PCR primers revealed that the majority of the phylotypes were most closely related to uncultured Pseudonocardia and Nocardioides species. Phylotypes most closely related to a number of rarer actinobacteria genera, including Geodermatophilus, Modestobacter and Sporichthya, were also identified. While complementary culture-dependent studies isolated a number of Nocardia and Pseudonocardia species, the majority of the cultured isolates (> 80%) were Streptomyces species--although phylotypes affiliated to the genus Streptomyces were detected at a low frequency in the metagenomic study. This study confirms that Antarctic Dry Valley desert soil harbours highly diverse actinobacterial communities and suggests that many of the phylotypes identified may represent novel, uncultured species.
authors.affiliation: Department of Biotechnology, Institute for Microbial Biotechnology and Metagenomics, University of the Western Cape, Private Bag, Bellville, Cape Town, South Africa.
authors.forename: Olubukola O
authors.initials: OO
authors.lastname: Babalola
authors.forename: Bronwyn M
authors.initials: BM
authors.lastname: Kirby
authors.forename: Marilize
authors.initials: M
authors.lastname: Le Roes-Hill
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Cook
authors.forename: S Craig
authors.initials: SC
authors.lastname: Cary
authors.forename: Stephanie G
authors.initials: SG
authors.lastname: Burton
authors.forename: Don A
authors.initials: DA
authors.lastname: Cowan
mesh_terms: D039903:Actinobacteria / Q000145:classification* / Q000302:isolation & purification*; D000864:Antarctic Regions; D044822:Biodiversity; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D020459:Genes, rRNA; D008969:Molecular Sequence Data; D010802:Phylogeny; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D012988:Soil Microbiology
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S