| Autor: |
Bertoldi S; Department of Molecular Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, 04318 Leipzig, Germany., Mattos PDMAS; Department of Molecular Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, 04318 Leipzig, Germany., de Carvalho CCCR; Department of Bioengineering, iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal., Kruse L; Institute of Molecular Enzyme Technology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, 40204 Düsseldorf, Germany., Thies S; Institute of Bio- and Geosciences IBG-1: Biotechnology, Forschungszentrum Jülich, 52428 Jülich, Germany., Heipieper HJ; Department of Molecular Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, 04318 Leipzig, Germany., Eberlein C; Department of Molecular Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, 04318 Leipzig, Germany. |
| Abstrakt: |
Many species of the genus Pseudomonas are known to be highly tolerant to solvents and other environmental stressors. Based on phylogenomic and comparative genomic analyses, several Pseudomonas species were recently transferred to a new genus named Halopseudomonas . 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 Halopseudomonas strains were assessed regarding their tolerance toward different n -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 Halopseudomonas strains showed EC50 values up to two-fold lower than those previously detected for Pseudomonas putida . In addition, the activity of the cis-trans isomerase of unsaturated fatty acids (Cti), which is an urgent stress response mechanism known to be present in all Pseudomonas species, was monitored in the five Halopseudomonas strains. Although several of the tested species were known to contain the cti gene, no significant phenotypic activity could be detected in the presence of the assayed stressors. A bioinformatic analysis of eight cti -carrying Halopseudomonas strains examining promotor binding sites, binding motifs and signal peptides showed that most of the cti genes have a lipoprotein signal peptide and promotor regions and binding motifs that do not coincide with those of Pseudomonas . These insights represent putative reasons for the absence of the expected Cti activity in Halopseudomonas , which in turn has always been observed in cti -carrying Pseudomonas . The lack of Cti activity under membrane stress conditions when the cti gene is present has never been documented, and this could represent potential negative implications on the utility of the genus Halopseudomonas for some biotechnological applications. |
