INFLUENCE OF AMMONIUM-SALTS AND CANE MOLASSES ON GROWTH OF ALCALIGENES-EUTROPHUS AND PRODUCTION OF POLYHYDROXYBUTYRATE

The production of polyhydroxybutyrate (PHB) by Alcaligenes eutrophus D SM 545 was studied in a synthetic medium with 3% glucose at pH 7.0 sup plemented with several ammonium substrates and cane molasses. Growth w as measured by dry cell weight, and the PHB content was measured by ga s chromatography. The effects of ammonium sources such as sulfate, nit rate, phosphate, and chloride salts and those of different ammonium su lfate concentrations were evaluated. The best growth and PHB productio n were obtained with ammonium sulfate; however, NH4+ concentrations be tween 0.5 and 1.5 g/liter showed no significant difference. Ammonium s ulfate,vas therefore used as the sole source of NH4+ for experiments w ith cane molasses as the growth activator. Optimal growth and PHB prod uction were obtained with 0.3% molasses. However, the yields of biomas s (39 to 48%) and PHB (17 to 26%) varied significantly among the diffe rent ammonium substrates and cane molasses concentrations.