Is it possible to restore the reduced coenzyme Q10 production of a varied strain of Gluconobacter?

Different strains of a bacterial culture can undergo phenotypic variation upon continuous passages. These changes often cause a reduction or loss of bacterial metabolic potential and ultimately lead to a decrease in production yield. The aim of this study was to address this question; is it possible to restore the reduced coenzyme Q10 production of a varied strain of Gluconobacter to a higher level? The main strain studied in this study was Gluconobacter japonicus FM10, from which the FM20 strain was obtained. FM20 strain was a varied strain whose ability on coenzyme Q10 production was reduced during some continuous passages. FM30 strain was obtained from FM20 strain by restricting the available oxygen. The amount of coenzyme Q10 produced by all three strains was measured. The activities of glycerol dehydrogenase and sorbitol dehydrogenase were also measured. The results showed that coenzyme Q10 production in FM30 strain that had been exposed to restricted oxygen was several times higher (6.3 mg/L) than the varied FM20 strain (0.8 mg/L), and even the original FM10 strain (2.7 mg/L). The investigation of the enzymes activities showed that glycerol dehydrogenase and sorbitol dehydrogenase activities of FM30 strain were higher than those of the others (0.66 and 0.52 U mg^-1, respectively). It can be concluded that by using some strategies, the metabolic potential of some varied strains can be restored. For strictly aerobic bacteria, Gluconobacter, the oxygen restriction may be an effective strategy for the restoration of coenzyme Q10 production ability.