Early Observations of the Growth and Polyhydroxybutyrate Content of Gamma Irradiated Azotobacter vinelandii

Azotobacter vinelandii is a well-known producer of polyhydroxybutyrate. An A. vinelandii strain ΔAvin₁6040 was used for this study. The bacterial strain was treated by gamma irradiation in a Gamma Cell Acute Irradiation Facility available at the Malaysian Nuclear Agency, used as a "tool" for bacterial strain modification as well as improvement. A total of 93 irradiated bacterial cells were selected for analysis. All the irradiated bacteria were cultivated in mineral salt medium and their polyhydroxybutyrate content were quantitated according to the crotonic acid methodology. Sucrose was provided as the carbon source. When cultivated in the mineral salt medium, the irradiated A. vinelandii ÄAvin₁6040 displayed different physical appearances including culture turbidity and various culture colours from greenish to opaque. Early detection of the polyhydroxybutyrate content in the irradiated ÄAvin₁6040 cells ranged from approximately 10 – 2000 mg/L as compared to 12 – 97 mg/L in the non-irradiated ÄAvin₁6040 cells. (author)