Molecular Characterization of the Archaeal Diversity in Vlasa Hot Spring, Bulgaria, by using 16S rRNA and Glycoside Hydrolase Family 4 Genes

ABSTRACT

Biodiversity in the archaeal community from Vlasa hot spring, Velingrad, Bulgaria was investigated by sequence analysis of PCR amplified fragments of 16S rDNA and a metabolic gene of glycoside hydrolase 4 family (GH4). The 16S rRNA gene analysis demonstrated that the spring was inhabited predominantly by Crenarchaeota affiliated to two orders, Desulfurococcales (families Pyrodictiaceae and Desulfurococcaceae) and Thermoproteales. Almost half of the 16S rDNA clones were affiliated with hyperthermophilic anaerobic sulfate reducer Thermosphaera aggregans. Five 16S rDNA sequences were under cut off value of 97% homology to those of Genbank database and suggested the existence of novel phylogenetic units in the community. The archaeal diversity of the studied hot spring was further analyzed through sequence analysis of metagenomicaly cloned GH4 gene fragments. The comparative 16SrDNA and GH4 phylogenetic analyses demonstrated good correlation of the phylogenetic tree topology from both approaches, corresponding to the affiliation of the identified 16S rDNA sequences predominantly to organotrophic metabolizing taxons. The opportunity for simultaneous application of two molecular approaches, 16S rDNA and metabolite genes analyses for in dept characterization of environmental samples and directed metagenomic identification and cloning of metabolite genes of industrial interest is discussed.

Keywords:

• terrestrial hot spring
• thermophilic archaea
• 16S rRNA gene analysis
• protein phylogeny
• glycosyl hydrolase family 4