分别利用葡萄糖或葡萄糖酸钠与十一碳酸、月桂酸与十一碳酸为混合碳源进行嗜水气单孢菌（Aeromonas hydrophila）菌株4AK4 的摇瓶培养，实现了含有32羟基戊酸（3HV）单体的聚羟基脂肪酸酯的微生物合成。当使用葡萄糖或葡萄糖酸钠与十一碳酸为混合碳源时，野生型A. hydrophila 4AK4及含有32羟基丁酸辅酶A合成基因phaA 和phaB的重组A. hydrophila 4AK4（pTG01）能够合成32羟基丁酸（3HB）与3HV的共聚物，且葡萄糖或葡萄糖酸钠与十一碳酸比例为1∶1时最利于细胞生长和PHA 的积累。当使用月桂酸和十一碳酸为混合碳源时，A. hydrophila 4AK4能够合成3HB、3HV与β2羟基己酸（3HHx）的共聚物，且随着混合碳源中十一碳酸的含量增加，A. hydrophila 4AK4合成的PHA中3HV的比例增加，而3HB和3HHx的比例降低。

应用新型二维傅里叶变换红外（2D FT IR）相关光谱研究细菌合成聚羟基丁酸酯（PHB）在升温时的预熔行为以及降温后的重结晶过程。在25～220℃的变温过程中测得动态红外光谱。着重讨论了在热力学干扰导致红外谱图中羰基峰（1700～1770cm-1）和醚键（1230～1310cm-1）吸收强度的波动。结果表明，这种影响来自样品中PHB的结晶态和非晶态之间的相态变化。二维谱图分析表明，在热熔过程中，结晶态的消失并不同时引起完全非晶态的出现，暗示在分子排列高度有序的晶态和非晶态之间存在某种中间态，PHB晶体向非晶态转变时必须经过一个预熔过程。在红外谱图上这个中间态很可能对应着由二维分析显示出来的位于1730cm-1的吸收峰。同时，在PHB熔体从非晶态逐渐生成晶体的过程中也探测到了中间态的存在。

Pathways for extracellular production of chiral D-(3)-3-hydroxybutyric acid (3HB) and D-(3)-3-hydroxyalkanoic acid (mcl-3HA) were constructed by co-expression of genes of L-ketothiolase (phbA), acetoacetyl-CoA reductase (phbB) and 3-hydroxyacyl-ACP CoA transacylase (phaG), respectively, in Escherichia coli strain DH5K. The effect of acrylic acid and glucose on production of both 3HB and mcl-3HA was investigated. It was found that the addition of acrylic acid significantly increased production of 3HB and mcl-3HA consisting of 3-hydroxyoctanoic acid and 3-hydroxydecanoic acid in a ratio of 1:3 from 199mg l31 to 661mg l31 and from 27mg l31 to 135mg l31, respectively, in shake flask studies when glucose was present in the medium at the very beginning of fermentation. The timing of glucose addition had no effect on 3HB production. In contrast, mcl-3HA production was affected by glucose addition, an mcl-3HA concentration of 193mg l31 was obtained when glucose was added to the culture at 12h. A more than seven-fold increase was obtained when compared with that in medium containing glucose at the beginning of fermentation. However, a decrease in production of 3HB and mcl-3HA was found when glucose was added at 12h to the culture containing acrylic acid. The repressive effect of acrylic acid on acetic acid production was also evaluated and discussed.

Generalized two-dimensional (2D) Fourier transform infrared correlation spectroscopy was used to investigate the effect of the comonomer compositions on the crystallization behavior of two types of biosynthesized random copolymers, poly (hydroxybutyrate-co-hydroxyhexanoate) and poly (hydroxybutyrate-co-hydroxyvalerate). The carbonyl absorption band around 1730cm 1 was sensitive to the degree of crystallinity. 2D correlation analysis demonstrated that the 3-hydroxyhexanoate units preferred to remain in the amorphous phase of the semicrystalline poly(hydroxybutyrate-co-hydroxyhexanoate) copolymer, resulting in decreases in the degree of crystallinity and the rate of the crystallization process. The poly(hydroxybutyrate-co-hydroxyvalerate) copolymer maintained a high degree of crystallinity when the 3-hydroxyvalerate fraction was increased from 0 to 25mol% because of isodimorphism. The crystalline and amorphous absorption bands for the carbonyl bond for this copolymer, therefore, changed simultaneously.

Polymer scaffold systems consisting of poly (hydroxybutyrate-co-hydroxyhexanoate) PHBHHx)/polyhydroxybutyrate (PHB) (PHBHHx/PHB) were investigated for possible application as a matrix for the three-dimensional growth of chondrocyte culture. Blend polymers of PHBHHx/PHB were fabricated into three-dimensional porous scaffolds by the salt-leaching method. Chondrocytes isolated from rabbit articular cartilage (RAC) were seeded on the scaffolds and incubated over 28 days, with change of the culture medium every 4 days. PHB scaffold was taken as a control. Methylthiazol tetrazolium (MTT) (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltertra-zolium bromide) assay was used to quantitatively examine the proliferation of chondrocytes. Results showed that chondrocytes proliferated better on the PHBHHx/PHB scaffolds than on PHB one. The maximal cell densities were all observed after 7 days of incubation. As for the blend polymers, cells grew better on scaffolds consisting of PHBHHx/PHB in ratios of 2:1 and 1:2 than they did on PHBHHx/PHB of 1:1. Scanning electron microscopy (SEM) also showed that large quantities of chondrocytes grew initially on the surface of the scaffold. After 7 days, they further grew into the open pores of the blend polymer scaffolds. Morphologically, cells found on the surface of the scaffold exhibited a flat appearance and slowly form confluent cell multilayers starting from 14 to 28 days of the growth. In contrast, cells showed rounded morphology, formed aggregates and islets inside the scaffolds. In addition, chondrocytes proliferated on the scaffold and preserved their phenotype for up to 28 days.