Abstract
BackgroundThe influence of carbon dioxide and oxygen on microbial secondary metabolite producers and the maintenance of these two parameters at optimal levels have been studied extensively. Nevertheless, most studies have focussed on their influence on specific product formation and condition optimization of established processes. Considerably less attention has been paid to the influence of reduced or elevated carbon dioxide and oxygen levels on the overall metabolite profiles of the investigated organisms. The synergistic action of both gases has garnered even less attention.ResultsWe show that the composition of the gas phase is highly important for the production of different metabolites and present a simple approach that enables the maintenance of defined concentrations of both O2 and CO2 during bioprocesses over broad concentration ranges with a minimal instrumental setup by using endogenously produced CO2. The metabolite profiles of a myxobacterium belonging to the genus Chondromyces grown under various concentrations of CO2 and O2 showed considerable differences. Production of two unknown, highly cytotoxic compounds and one antimicrobial substance was found to increase depending on the gas composition. In addition, the observation of CO2 and O2 in the exhaust gas allowed optimization and control of production processes.ConclusionsMyxobacteria are becoming increasingly important due to their potential for bioactive secondary metabolite production. Our studies show that the influence of different gas partial pressures should not be underestimated during screening processes for novel compounds and that our described method provides a simple tool to investigate this question.
Highlights
The influence of carbon dioxide and oxygen on microbial secondary metabolite producers and the maintenance of these two parameters at optimal levels have been studied extensively
In a Streptomyces clavuligerus culture, 100% pO2 saturation maintained over the whole cultivation time resulted in cephamycin C production 2.4-fold higher than that obtained from an uncontrolled experiment, where pO2 dropped below 40%
Influence of O2 and CO2 tension on secondary metabolite production This test was performed with a novel Chondromyces strain SBCm007 isolated in our laboratory
Summary
The influence of carbon dioxide and oxygen on microbial secondary metabolite producers and the maintenance of these two parameters at optimal levels have been studied extensively. It was shown that high oxygen concentrations after the exponential growth phase of Amycolatopsis orientalis are crucial for vancomycin biosynthesis, the biosynthetic machinery is present at high and low pO2 [11]. These effects can be explained by regulatory influence of O2 on gene expression levels and enzyme function, but another important factor is the presence of O2 as a substrate, which can e.g. influence the proportion of tetracycline, oxytetracycline and chlortetracycline yield in several Streptomyces strains cultivated at elevated pressure [12]. Epo506, was observed preferentially at higher O2 concentrations [13]
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