RESUMO
Three strains of Azotobacter chroococcum were studied to produce poly- beta hydroxybutyrate as a inclusion body by whey degradation. Optimum degradation whey results were obtained when using whey broth as a fermentation medium without extra salt, temperature at 35°C and pH 7 [P<0.05]. Lambda max for whey broth medium was determined probably about 400 nm. The effect of different nitrogenous rich compounds [NH[4]NO[3], Bactopeptone, Casein, Yeast extract, Meat extract, Protease peptone and Tryptone] on whey degradation showed that incorporation of nitrogenous compounds into the medium did not increase whey degradation by Azotobacter chroococcum 1723 [P<0.05]. But poly- beta hydroxyl-butyrate production was increased in presence Meat extract up to 75% of the cell dry weight after 48h. The addition of nitrogenous sourced [except ammonium nitrate] had a positive effect on poly- beta hydroxyl-butyrate production as it peaked in the presence of Meat extract and 4.43 g/L was accumulated in comparison to 0.5g at diazotrophically growing cells. Increasing the O[2] values resulted by shaking at 122 rpm in decreased poly- beta hydroxyl-butyrate yield form 4.43 to 0.04 g/L. The results show that this medium supports the growth of strain 1735 and also that this waste could be utilized as a carbon and nitrogen source. Production of poly- beta hydroxyl-butyrate by using whey as a medium looks promising, since the use of inexpensive feed-stocks for poly- beta hydroxyl-butyrate is essential if bioplastics are to become competitive products