Accumulation of poly (3-hydroxybutyric acid) by some soil Streptomyces

In a limited-scale survey, 55 soil streptomycetes were screened for the acc umulation of poly (3-hydroxybutyrate) [PHB]. Only 18% of the isolates accum ulated PHB ranging between 1.9-7.8% of the dry biomass, The promising isola te DBCC-719, identified as Streptomyces griseorubiginosus, accumulated PHB amounting to 9.5% of the mycelial dry mass in the early stationary phase wh en grown in chemically defined medium with 2% (wt/vol) glucose as the sole source of carbon. Nitrogen-limiting conditions were inhibitory to growth an d PHB accumulation. The isolated polymer was highly soluble in chloroform, gave a sharp peak at 235 nm on digestion with concentrated H2SO4, and had a characteristic infrared spectrum.