• Microbiology and Biotechnology Letters
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• v.19 no.1
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• pp.94-99
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• 1991

- The further study for the identification of the previously reported pink-pigmented facultative methylotrophic bacterium (PPFM) GL-10 was carried out. The PPFM GL-10 was Gram nagative, rod, and motile by a single polarly inserted flagellum. The colonies were smooth, pink, circular, along with convex with entire margin. The isolate could utilize C1 compounds and a variety of multicarbon substrates as sole carbon and energy source. The isolate was obligately aerobic, and exhibited both catalase and oxidase activities. The deoxyribonucleic acid base composition was 65-67 mol% guanine plus cytosine. The isolate was mostly identical with Methylobacterium extorquens and named Methylobacterium sp. strain GL-10. Methylobacterium GL-10 accumulated a copolyester of 3-hydroxybutyrate and 3-hydroxyvalerate (poly-3HB/3 HV) when grown in nitrogen-free culture media containing sodium propionate as substrate at the second polyester accumulation stage. The composition of copolyester, as determined from $^1h$ NMR spectra, was 23 mol% of 3-hydroxyvalerate (3HV).

• KSBB Journal
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• v.6 no.1
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• pp.35-43
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• 1991

The production of poly-$\beta$-hydroxybutyrate(PHB) from methanol by batch and fed-batch cultivations of Methylobacterium sp. GL-10 was studied. PHB accumulation was stimulated by the nutrients deficiency including, NH4+, SO42-, and K+. The nitrogen deficiency was the most critical factor for PHB accumulation. In batch cultivation, the maximum cell concentration and PHB content were 1.86g/l and 0.62g/l, respectively, with 1.0%(v/v) of methanol and 0.5g/1 of ammonium sulfate. The mass doubling time of Methylobacterum sp. GL-10 was in the range of 4-5 hrs. The cell growth and PHB accumulation were severely inhibited at the methanol concentration over than 2% (v/v). To overcome methanol Inhibition, constant feeding and intermittent feedillg fed-batch cultivations were adopted, using C/N molar ratio as a control factor. In constant feeding fed-batch process, cell concentration was increased up to 2.67g/1, and PHB yield was enhanced from 0.33 of batch culture to 0.53. The relatively low cell concentration was caused by methanol accumulated in culture broth at late growth phase. To prevent methanol accumulation and to maximize PHB production, DO-state intermittent fed-batch cultivation was attempted. The cell and PHB concentration was reached up to 4.55g/1 and 1.80g/1, respectively. It was possible to maintain methanol concentration low and also to feed nutrient of desired C/N molar ratio.