Objectif
Novel thermotolerant methylotrophic bacilli were isolated in order to elucidate their pathways(s) of methanol metabolism and mode(s) of regulation. By means of genetic and physiological manipulation, metabolism was guided towards an overproduction of important biochemicals. Environmental parameters were independently manipulated using chemostat culture techniques and specific gene functions disrupted to determine where precisely the regulation of metabolite flux resides.
Thermophilic bacilli capable of growth on methanol as the sole carbon substrate were isolated in pure culture and characterized metabolically. All strains possessed an nicotinamide adenine dinucleotide (NAD) linked methanol (alcohol) dehydrogenase (MDH) and generally grew on methanol with a very high efficiency. MDH had a low affinity for methanol but, along with reduced nicotinamide adenine dinucleotide (NADH) oxidase and hexulose phosphate synthase, was synthesized at very high levels. Similarly, Bacillus stearothermophilus synthesized glycerol kinase at extremely high levels and, when growing in glycerol-limited chemostat culture, had up to 40% (weight for weight) of its total protein as this 1 enzyme. Clearly, these organisms possess highly efficient expression systems. Studies of glucose metabolism in yeast revealed novel information on the role of cyclic adenosine monophosphate (cAMP) and protein phosphorylation in the regulation of glucose uptake and fermentation.
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MADRID
Espagne