• KSBB Journal
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• v.18 no.5
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• pp.404-407
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• 2003

Two recombinant Escherichia coli strains, GCSC6576 harboring a plasmid pSYL107 containing the Ralstonia eutropha polyhydroxyalkanoate (PHA) biosynthesis genes and a fadR atoC mutant LS5218 harboring a plasmid pJC4 containing the Alcaligenes latus PHA biosynthesis genes were compared for their ability to synthesize poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV) from whey. The 3HV fraction could be increased by acetic acid induction and oleic acid supplementation in flask cultures of recombinant E. coli GCSC6576. With the pH-stat fed-batch culture of recombinant E. coli LS5218, we obtained a cell concentration, a P(3HB-co-3HV) concentration, a P(3HB-co-3HV) content, and a 3HV fraction of 31.8 g/L, 10.6 g/L, 33.4%, and 6.26 mol%, respectively in 39 h.

• KSBB Journal
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• v.19 no.4
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• pp.327-330
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• 2004

An inducible expression system of poly[(R)-3-hydroxybutyrate] (PHB) depolymerization was established in metabolically engineered Escherichia coli with the PHB biosynthesis genes. The Ralstonia eutropha PHB depolymerase gene was cloned in a vector system containing the PHB biosynthesis genes and expressed under inducible promoter. Recombinant E. coli harboring the PHB biosynthesis genes and depolymerase gene was first cultured for the accumulation of PHB, and then the depolymerase was expressed resulting in the degradation of accumulated PHB into (R)-3-hydroxybutyric acid (R3HB). R3HB could be produced with the concentration of 7.6 g/L in flask culture. Two different PHB biosynthesis genes from Alcaligenes latus and R. eutropha were compared for the production of R3HB. This strategy can be used for the production of enantiomerically pure (R)-hydroxycarboxylic acids with high concentration.

• Journal of Microbiology
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• v.38 no.2
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• pp.99-104
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• 2000

Hydrogen peroxide has been used in cleaning the piping of an advanced high-purity water system that supplies ultra-high purity water (UHPW) for 16 megabyte DRAM semiconductor manufacturing. The level of hydrogen peroxide-resistant bacteria in UHPW water was monitored prior to and after disinfecting the piping with hydrogen peroxide. Most of the bacteria isolated after hydrogen peroxide disinfection were highly resistant to hydrogen peroxide. However, the percentage of resistant bacteria decreased with time. The hydrogen peroxide-resistant bacteria were identified as Micrococcus luteus, Bacillus cereus, Alcaligenes latus, Xanthomonas sp. and Flavobacterium indologenes. The susceptibility of the bacteria to hydrogen peroxide was tested as either planktonic cells or attached cells on glass. Attached bacteria as the biofilm on glass exhibited increased hydrogen peroxide resistnace, with the resistance increasing with respect to the age of the biofilm regrowth on piping after hydrogen peroxide treatment. In order to optimize the cleaning strategy for piping of the high-purity water system, the disinfecting effect of hydrogen preoxide and peracetic acid on the bacteria was evaluated. The combined use of hydrogen peroxide and peracetic acid was very effective in killing attached bacteria as well as planktonic bacteria.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.6
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• pp.371-374
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• 2002

Production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)［P(3HB/V)］, by fed-batch culture of recombinant Escherichia coli harboring a plasmid containing the Alcaligenes latus polyhy-droxyalkanoate (PHA) biosynthesis genes, was examined in two pilot-scale fermentors with air supply only, In a 30 L fermentor having a XLa value of 0.11 S­$^1$, the final P(3HB/V) concentration and the P(3HB/V) content obtained were 29.6 g/L and 70.1 wt%, respectively giving a productivity of 1.37 g P(3HB/V)/L-h. In a 300 L fermentor having a XLa of 0.03 S­$^1$, the P(3HB/V) concentration and the P(3HB/V) content were 20.4 g/L and 69 wt%, respectively giving a productivity of 1.06g P(3HB/V)/L-h. These results suggest that economical production of P(3HB/V) is possible by fed-batch culture of recombinant E. coli in a large-scale fermentor having low KLa value.