Authors: Hee Wook Ryu Kyung Suk Cho Philip R Goodrich ChangHo Park
Publish Date: 2009/02/03
Volume: 13, Issue: 6, Pages: 651-658
Abstract
This study examined the effect of adding glucose yeast extract and inorganic salts to swine wastewater SWW in a batch culture on the production of a biodegradable plastic polyhydroxyalkanoate PHA A bacterial strain Azotobacter vinelandii UWD was used to produce PHA without limiting the noncarbon nutrients The addition of glucose 30 g/L to the SWW medium increased the level of cell growth 44∼70 times and PHA production 38∼85 times depending upon the dilution of SWW A 50 dilution of SWW was found to be optimal considering the dry cell weight 940 g/L PHA content 58 wt and hydroxyvalerate HV mol fraction in the PHA 43 mol A 75 SWW medium was more advantageous for producing PHA with a higher HV fraction 71 mol at the expense of losing 22 of PHA production The undiluted SWW medium produced less than one third of the PHA compared with the 50 SWW medium but the HV fraction was the highest 108 mol Regarding the effect of the glucose concentration at 20 g/L glucose the dry cell weight and level of PHA production increased to 934 g/L 063 g PHA/g dry cell weight and 590 g/L respectively At 50 g/L glucose there was no significant increase in PHA production For the glucosesupplemented 30 g/L 50 SWW medium the addition of a nitrogen source 1 g/L of yeast extract did not increase the level of cell growth or PHA production because the CN ratio 231 was already close to the optimal value 221 Better aeration increased the productivity of PHA External nitrogen supplements 1 g/L of yeast extract and other essential mineral salts was not necessary for bacterial growth because they were contained in the SWW These results suggest that SWW is an excellent feedstock for producing larger amounts of the valueadded material PHA if it is combined with carbohydraterich organic waste
Keywords: