Aeromonas hydrophila CGMCC 0911 isolated from lake water was found to be able to synthesize a polyhydroxyalkanoate (PHA) copolymer (PHBHHx) consisting of 3-hydroxybutyrate (HB) and 4-6mol% 3- hydroxyhexanoate (HHx). The wild-type bacterium accumulated 49% PHBHHx containing 6mol% HHx in terms of cell dry weight (CDW) when grown on lauric acid for 48h. When A. hydrophila CGMCC 0911 expressed the Acyl-CoA dehydrogenase gene (yafH) of Escherichia coli, the recombinant strain could accumulate 47% PHBHHx, while the HHx content reached 17.4mol%. The presence of changing glucose concentration in the culture changed the HHx content both in wild type and recombinant A. hydrophila CGMCC 0911. When 5g1-1 glucose was added to a culture containing 5g 1-1 lauric acid as co-substrate, 45% PHBHHx/CDW consisting of 8.8mol% HHx was produced by wild-type A. hydrophila CGMCC 0911 compared with only 5% in the absence of glucose. When the recombinant A. hydrophila CGMCC 0911 was grown on a mixed substrate containing lauric acid and 8-10g 1-1g lucose, the HHx content could be further increased to 35.6mol%. When the glucose concentration exceeded 10g1-1, cell growth, PHA content and mole percentages of HHx in PHBHHx were significantly reduced.