Novel hydrocarbon-utilizing soil mycobacteria synthesize unique mycocerosic acids at a Sicilian everlasting fire

Abstract. Soil bacteria rank among the most diverse groups of organisms on Earth and actively impact global processes carbon cycling, especially in emission greenhouse gases like methane, CO2 higher gaseous hydrocarbons. An abundant group soil are mycobacteria, which colonize various terrestrial, marine anthropogenic environments due to their impermeable cell envelope that contains remarkable lipids. These have been found be highly at petroleum gas seep areas, where they might utilize released However, function lipid biomarker inventory these mycobacteria poorly studied. Here, soils from Fuoco di Censo seep, an everlasting fire (gas seep) Sicily, Italy, were investigated for presence via 16S rRNA gene sequencing fatty acid profiling. The contained high relative abundances (up 34 % reads assigned) phylogenetically close Mycobacterium simiae complex more distant well-studied M. tuberculosis hydrocarbon-utilizing paraffinicum. showed decreasing mycocerosic acids (MAs), unique with increasing distance seep. major MAs this tentatively identified as 2,4,6,8-tetramethyl tetracosanoic 2,4,6,8,10-pentamethyl hexacosanoic acid. Unusual mid-chain methyl branches positions C-12 C-16 (i.e., 2,12-dimethyl eicosanoic 2,4,6,8,16-pentamethyl acid) also present. molecular structures different those or bovis relatively ?13C-depleted values (?38 ‰ ?48 ‰), suggesting a direct indirect utilization methane ethane. structurally combination depleted ?13C offer new tool study role hydrocarbon consumers cycle.