Terracidiphilus gabretensis gen. nov., sp. nov., an abundant and active forest soil acidobacterium important in organic matter transformation

Abstract

Understanding the activity of bacteria in coniferous forests is highly important, due to the role of these environments as a global carbon sink. In a study of the microbial biodiversity of montane coniferous forest soil in the Bohemian Forest National Park (Czech Republic), we succeeded in isolating bacterial strain S55T, which belongs to one of the most abundant operational taxonomic units (OTUs) in active bacterial populations, according to the analysis of RNA-derived 16S rRNA amplicons. The 16S rRNA gene sequence analysis showed that the species most closely related to strain S55T include Bryocella elongata SN10T (95.4% identity), Acidicapsa ligni WH120T (95.2% identity), and Telmatobacter bradus TPB6017T (95.0% identity), revealing that strain S55T should be classified within the phylum Acidobacteria, subdivision 1. Strain S55T is a rod-like bacterium that grows at acidic pH (3 to 6). Its phylogenetic, genotypic, phenotypic, and chemotaxonomic characteristics indicate that strain S55T corresponds to a new genus within the phylum Acidobacteria; thus, we propose the name Terracidiphilus gabretensis gen. nov., sp. nov. (strain S55T=NBRC 111238T=CECT 8791T). This strain produces extracellular enzymes implicated in the degradation of plant-derived biopolymers. Moreover, analysis of the genome sequence of strain S55T also reveals the presence of enzymatic machinery required for organic matter decomposition. Soil metatranscriptomic analyses found 132 genes from strain S55T being expressed in the forest soil, especially during winter. Our results suggest an important contribution of T. gabretensis S55T in the carbon cycle in the Picea abies coniferous forest.