Project description:We performed differential RNA-sequencing (dRNA-seq) experiments in both minimal medium (MM) plus β-hydroxybutyrate (β-HB) and MM plus tetralin (THN) of Sphingopyxis granuli strain TFA. The objective was mapping the Transcription Start Site (TSS) of each gene in the genome in both conditions, detecting non-coding RNAs (ncRNAs) and comparing the gene expression profile in a preferential carbon source (β-HB) versus tetralin (an aromatic pollutant). The dRNA-seq technique consists of using a termination exonuclease (TEX) to allow the discrimination of primary and processed transcripts. Furthermore, to detect Hfq-bound RNAs we co-immunoprecipitated RNA from the wild type strain (negative control) and a TFA strain with an Hfq-3xFlag tagged version (MPO501 strain) using an anti-3xFlag antibody and performed RNA-sequencing from the precipitated RNA.
Project description:BackgroundSphingomonads are Alphaproteobacteria that belong to the Sphingomonas, Novosphingobium, Sphingopyxis or Sphingobium genera, They are physiologically diverse and broadly distributed in nature, playing important roles in oligotrophic environments and in the degradation of recalcitrant polyaromatic compounds, Sphingopyxis is a poorly studied genus of which only one representative (S. alaskensis RB2256) has been deeply characterized. In this paper we analyze the genomic features of S. granuli strain TFA (formerly Sphingomonas macrogoltabida) in comparison with the available Sphingopyxis sequenced genomes, to describe common characteristics of this genus and to highlight unique characteristics of strain TFA.ResultsThe TFA genome has been assembled in a single circular chromosome of 4.7 Mb. Genomic sequence analysis and proteome comparison re-assigned the TFA strain to the Sphingopyxis genus and the S. granuli species. Some regions of the TFA genome show high similarity (ca. 100%) to other bacteria and several genomic islands have been detected. Pathways for aromatic compound degradation have been predicted but no growth of TFA has been detected using these as carbon or nitrogen sources. Genes for nitrate respiration have been identified as TFA exclusive. Experimental data on anaerobic growth of TFA using nitrate as a terminal electron acceptor are also provided.ConclusionsSphingopyxis representatives form a compact phylogenetic group (with the exception of S. baekryungensis DSM 16222) that share several characteristics, such as being naturally resistant to streptomycin, having only one ribosomal operon, a low number of prophages and CRISPR sequences, absence of selenoproteins and presence of ectoin and other biosynthesis pathways for secondary metabolites. Moreover, the TFA genome organization shows evidence of the presence of putative integrative and conjugative elements (ICE) responsible for the acquisition of several characteristics by horizontal transfer mechanisms. Sphingopyxis representatives have been described as strict aerobes but anaerobic growth using nitrate as a terminal electron acceptor might confer an environmental advantage to the first S. granuli strain characterized at genomic level.