| Summary: | Organic olvent-tolerant strains of the Gram-negative bacterial genus <i>Pseudomonas</i> are discussed as potential biocatalysts for the biotechnological production of various chemicals. However, many current strains with the highest tolerance are belonging to the species <i>P. putida</i> and are classified as biosafety level 2 strains, which makes them uninteresting for the biotechnological industry. Therefore, it is necessary to identify other biosafety level 1 <i>Pseudomonas</i> strains with high tolerance towards solvents and other forms of stress, which are suitable for establishing production platforms of biotechnological processes. In order to exploit the native potential of <i>Pseudomonas</i> as a microbial cell factory, the biosafety level 1 strain <i>P. taiwanensis</i> VLB120 and its genome-reduced <i>chassis</i> (GRC) variants as well as the plastic-degrading strain <i>P. capeferrum</i> TDA1 were assessed regarding their tolerance towards different <i>n</i>-alkanols (1-butanol, 1-hexanol, 1-octanol, 1-decanol). Toxicity of the solvents was investigated by their effects on bacterial growth rates given as the EC50 concentrations. Hereby, both toxicities as well as the adaptive responses of <i>P. taiwanensis</i> GRC3 and <i>P. capeferrum</i> TDA1 showed EC50 values up to two-fold higher than those previously detected for <i>P. putida</i> DOT-T1E (biosafety level 2), one of the best described solvent-tolerant bacteria. Furthermore, in two-phase solvent systems, all the evaluated strains were adapted to 1-decanol as a second organic phase (i.e., OD<sub>560</sub> was at least 0.5 after 24 h of incubation with 1% (<i>v/v</i>) 1-decanol), which shows the potential use of these strains as platforms for the bio-production of a wide variety of chemicals at industrial level.
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