A bacterium that produced a large amount ofpoly(y-glutamic acid) (PGA) when it was grown aerobically in a culture medium containing ammonium salt and sugar as sources of nitrogen and carbon, respectively, was isolated from soil. The bacterium, strain T AM-4, was classified as Bacillus subti/is. The maximum PGA production (22.1 mg/ml) was obtained when it was grown in a medium containing 1.8% ammonium chloride and 7.5% fructose at 30°C for 96 h with shaking. Some properties of the PG A obtained at different times of cultivation were investigated by gel permeation chromatography, SDS-PAGE, and measurement of viscosity, and calculation of the D/L ratio of glutamic acid constituting PGA. The results suggested that PGA was elongated with no changes in the diastereoisomer ratio in the molecule.

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