Transformants obtained above were inoculated in a 8 ml LB medium containing 50 μg/ml ampicillin in a large test tube, and cultured at 30° C. for 17 hr. The culture medium was inoculated at 1% in a 8 ml medium containing 100 μg/ml ampicillin [16 g/L dipotassium hydrogen phosphate, 14 g/L potassium dihydrogen phosphate, 5 g/L ammonium sulfate, 1 g/L citric acid (anhydrous), 5 g/L casamino acid (manufactured by Difco), 10 g/L glucose, 10 mg/L vitamin Bl, 25 mg/L magnesium sulfate heptahydrate, 50 mg/L iron sulfate heptahydrate, 100 mg/L L-proline, adjusted with 10 mol/L sodium hydroxide to pH 7.2, and glucose, vitamin B1, magnesium sulfate heptahydrate and iron sulfate heptahydrate were separately autoclaved and added] in a test tube, and cultured at 30° C. for 24 hr. The culture medium was centrifuged and a culture supernatant was obtained. The accumulated amounts of culture products in the culture supernatant were quantified by high performance liquid chromatography (HPLC). The results are shown in Table 1. In glycerol medium, xylose medium and arabinose medium, they were used as carbon sources instead of glucose. The accumulated amounts of the culture products obtained by using these media are shown in Table 2-Table 4.
