The novel isolated thermotolerant bacteria Bacillus thermoamylovorans strain PHA005 was obtained from palm oil mill effluent. This strain showed an ability to produce medium-chain-length polyhydroxyalkanoates (mcl-PHAs) at 50.77% of dry cell weight (DCW) using sodium octanoate. Therefore, the production of mcl-PHA was enhanced by optimising the effects of nutrients and environmental conditions. The optimal conditions were 3.0 g/L sodium octanoate, a carbon to nitrogen ratio of 5:1 (0.02 g/L ammonium chloride), 45 °C incubation, initial pH 7.0 and agitation speed at 150 rpm. Under optimal conditions, the maximum mcl-PHA accumulation increased from 50.77% to 63.27% of DCW and 2.75 ± 0.03 g/L cell growth, 1.74 ± 0.02 g/L mcl-PHA concentration was achieved after 120 h cultivation. The composition of mcl-PHA contained C8-C18 while 3-hydroxyhexadecanoic (3HHD) was found at the highest composition (39.25 mol%) which has not been previously reported.

新型分离的耐热细菌嗜热芽孢杆菌菌株PHA005获自棕榈油厂的流出物。该菌株显示出使用辛酸钠以干细胞重量（DCW）的50.77％产生中链长度的聚羟基链烷酸酯（mcl-PHA）的能力。因此，通过优化养分和环境条件的影响可以提高mcl-PHA的产量。最佳条件为3.0 g / L辛酸钠，碳氮比为5：1（0.02 g / L氯化铵），45°C孵育，初始pH 7.0和150 rpm的搅拌速度。在最佳条件下，mcl-PHA的最大积累量从DCW的50.77％增加到63.27％，细胞生长2.75±0.03 g / L，120 h培养后达到1.74±0.02 g / L的mcl-PHA浓度。mcl-PHA的成分包含C8-C18，而3-羟基十六烷酸（3HHD）的成分最高（39。