Evaluation of the Robustness Under Alkanol Stress and Adaptability of Members of the New Genus

Many species of the genus are known to be highly tolerant to solvents and other environmental stressors. Based on phylogenomic and comparative genomic analyses, several species were recently transferred to a new genus named . Because of their unique enzymatic machinery, these strains are being discussed as novel biocatalysts in biotechnology. In order to test their growth parameters and stress tolerance, five strains were assessed regarding their tolerance toward different -alkanols (1-butanol, 1-hexanol, 1-octanol, 1-decanol), as well as to salt stress and elevated temperatures. The toxicity of the solvents was investigated by their effects on bacterial growth rates and presented as EC50 concentrations. Hereby, all strains showed EC50 values up to two-fold lower than those previously detected for . In addition, the activity of the isomerase of unsaturated fatty acids (Cti), which is an urgent stress response mechanism known to be present in all species, was monitored in the five strains. Although several of the tested species were known to contain the gene, no significant phenotypic activity could be detected in the presence of the assayed stressors. A bioinformatic analysis of eight -carrying strains examining promotor binding sites, binding motifs and signal peptides showed that most of the genes have a lipoprotein signal peptide and promotor regions and binding motifs that do not coincide with those of . These insights represent putative reasons for the absence of the expected Cti activity in , which in turn has always been observed in -carrying . The lack of Cti activity under membrane stress conditions when the gene is present has never been documented, and this could represent potential negative implications on the utility of the genus for some biotechnological applications.