Abstract
BackgroundMethanol is present in most ecosystems and may also occur in industrial applications, e.g. as an impurity of carbon sources such as technical glycerol. Methanol often inhibits growth of bacteria, thus, methanol tolerance may limit fermentative production processes.ResultsThe methanol tolerance of the amino acid producing soil bacterium Corynebacterium glutamicum was improved by experimental evolution in the presence of methanol. The resulting strain Tol1 exhibited significantly increased growth rates in the presence of up to 1 M methanol. However, neither transcriptional changes nor increased enzyme activities of the linear methanol oxidation pathway were observed, which was in accordance with the finding that tolerance to the downstream metabolites formaldehyde and formate was not improved. Genome sequence analysis of strain Tol1 revealed two point mutations potentially relevant to enhanced methanol tolerance: one leading to the amino acid exchange A165T of O-acetylhomoserine sulfhydrolase MetY and the other leading to shortened CoA transferase Cat (Q342*). Introduction of either mutation into the genome of C. glutamicum wild type increased methanol tolerance and introduction of both mutations into C. glutamicum was sufficient to achieve methanol tolerance almost indistinguishable from that of strain Tol1.ConclusionThe methanol tolerance of C. glutamicum can be increased by two point mutations leading to amino acid exchange of O-acetylhomoserine sulfhydrolase MetY and shortened CoA transferase Cat. Introduction of these mutations into producer strains may be helpful when using carbon sources containing methanol as component or impurity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-015-0558-6) contains supplementary material, which is available to authorized users.
Highlights
Methanol is present in most ecosystems and may occur in industrial applications, e.g. as an impurity of carbon sources such as technical glycerol
Metabolism of methanol is typically initiated by its oxidation, which can be catalyzed by many different enzymes such as pyrroloquinoline quinone (PQQ)-dependent methanol dehydrogenase e.g. in Methylobacterium extorquens [15], class I alcohol dehydrogenase e.g. in humans [16] or alcohol oxidase e.g. in Candida boidinii [17]
Adaptive laboratory evolution of C. glutamicum in the presence of methanol Experimental evolution in selective medium was used to achieve a genetic adaption to the presence of methanol and thereby increasing the methanol tolerance of C. glutamicum
Summary
Methanol is present in most ecosystems and may occur in industrial applications, e.g. as an impurity of carbon sources such as technical glycerol. Methanol naturally occurs in most ecosystems and is the second most abundant organic gas in the atmosphere besides methane [1]. The major source for methanol is the emission by plants [2]. The decay of plants, biomass burning or atmospheric oxidation of methane give rise to methanol [3]. One example of microbial production of methanol in nature is the pectin degradation by Clostridium butyricum [4]. According to its high abundance, degradation of methanol is a common feature in nature. Methanol can be utilized as a carbon and energy source by a wide variety of eukaryotic and prokaryotic methylotrophs [14]. Metabolism of methanol is typically initiated by its oxidation, which can be catalyzed by many different enzymes such as pyrroloquinoline quinone (PQQ)-dependent methanol dehydrogenase e.g. in Methylobacterium extorquens [15], class I alcohol dehydrogenase e.g. in humans [16] or alcohol oxidase e.g. in Candida boidinii [17]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
