Application Of Polyhydroxyalkanoates-Exploit The 3-hydroxyalkanoate Methyl Ester As Biofuels

Polyhydroxyalkanoate (PHA) is biopolyester accumulated by many bacterial. Due to its biodegradability and biocompatibility, it has attract much attention and extensive researches in plastic industry, biomedical area etc.In this study, it was the first time to correlate the PHA including poly3-hydroxybutyrate (PHB) and medium chain length PHA (MCL PHA) with the biofuels. Meanwhile, 3-hydroxyacyl-ACP:CoA transacylase (PhaG) encoding gene phaG from P.putida was cloned and transferred into A.hydroxyphila 4AK4 hoping the engineered A.hydroxyphila 4AK4 can synthesize PHBHHx using glucose. In this research, the PHB and MCL PHA was conversed into 3HB methyl ester and medium chain length 3HA methyl esters respectively using acid-catalyzed hydrolysis method. Gas chromatography (GC) and Furier transform infra red spectrum (FTIR) were used to have qualitative and quantitative analysis of the produced 3HB M and MCL HAM. It was found that recovery percent of 3HB M and MCL HAM is 52% and 65% respectively and purity of both 3HB M and MCL HAM was above 95%. Combustion heat of 3HB M, MCL HAM, ethanol, n-propanol, n-butanol, 0# diesel, 90# gasoline and 3HB M or MCL HAM based blended fuels were investigated and compared. It was found that 3HB M has a combustion heat of 19.43KJ/g and MCL HAM has a combustion heat of 36.5KJ/g. The combustion heat of ethanol is 27.32KJ/g and diesel has the highest combustion heat valuing at 54.62KJ/g. For the 3HB M or MCL HAM based blended fuels, both 3HB M and MCL HAM can enhance the combustion heat of ethanol. For example, 10% (w/w) addition of 3HB M or MCL HAM can enhance the combustion heat of ethanol (27.32KJ/g) to 32.88KJ/g and 36.86KJ/g respectively. For n-propanol and n-butanol, the addition of 3HB M or MCL HAM can also enhance their combustion heat while the change is smaller than that of ethanol. For example, 10% addition of 3HB M or MCL HAM can enhance the combustion heat of n-propanol (34.32KJ/g) to 36.66KJ/g. In addition, the increased contents of 3HB M or MCL HAM in the blended fuels have little impact on the combustion heat of the blended fuels. In the blended fules of 3HB M or MCL HAM with diesel or gasoline, the 3HB M or MCL HAM lowered the combustion heat of diesel or gasoline.Finally, the expression of PhaG in A.hydroxyphila 4AK4 was also studied. In this study, the phaG gene was successfully cloned on plasmid pLZZC08. The plasmid pLZZC08 containing phaG gene was successfully transferred into A.hydroxyphila 4AK4. However, the engineered A.hydroxyphila 4AK4 failed to accumulate PHBHHx using glucose as substrate. Further experiments are in progress.