Istituto di Chimica e Tecnologia dei Polimeri, Consiglio Nazionale delle Ricerche, Via P. Gaifami, 18, 95126 Catania, Italy.
Int J Biol Macromol. 2011 Jan 1;48(1):137-45. doi: 10.1016/j.ijbiomac.2010.10.013. Epub 2010 Oct 28.
Pseudomonas aeruginosa produced medium chain length poly(3-hydroxyalkanoates) (mcl-PHAs) when grown on substrates containing very long chain fatty acids (VLCFA, C>20). Looking for low cost carbon sources, we tested Brassica carinata oil (erucic acid content 35-48%) as an intact triglyceride containing VLCFA. Oleic (C18:1), erucic (C22:1), and nervonic (C24:1) acids were also employed for mcl-PHA production as model substrates. The polymers obtained were analyzed by GC of methanolyzed samples, GPC, 1H and 13C NMR, ESI MS of partially pyrolyzed samples, and DSC. The repeating units of such polymers were saturated and unsaturated, with a higher content of the latter in the case of the PHA obtained from B. carinata oil. Statistical analysis of the ion intensity in the ESI mass spectra showed that the PHAs from pure fatty acids are random copolymers, while the PHA from B. carinata oil is either a pure polymer or a mixture of polymers. Weight-average molecular weight varied from ca. 56,000 g/mol for the PHA from B. carinata oil and oleic acid, to about 120,000 g/mol for those from erucic and nervonic acids. The PHAs from erucic and nervonic acids were partially crystalline, with rubbery characteristics and a melting point (Tm) of 50°C, while the PHAs from oleic acid and from B. carinata oil afforded totally amorphous materials, with glass transition temperatures (Tg) of -52°C and -47°C, respectively.
铜绿假单胞菌在含有超长链脂肪酸 (VLCFA，C>20) 的基质上生长时会产生中链长度聚(3-羟基烷酸酯) (mcl-PHA)。为了寻找低成本的碳源，我们测试了 Brassica carinata 油 (芥酸含量 35-48%) 作为含有 VLCFA 的完整三酸甘油酯。油酸 (C18:1)、芥酸 (C22:1) 和神经酸 (C24:1) 也被用作 mcl-PHA 生产的模型底物。通过甲酯化样品的 GC、GPC、1H 和 13C NMR、部分热解样品的 ESI MS 和 DSC 分析得到的聚合物。这些聚合物的重复单元既有饱和的也有不饱和的，而 B. carinata 油得到的 PHA 中后者的含量更高。ESI 质谱中离子强度的统计分析表明，纯脂肪酸的 PHAs 是无规共聚物，而 B. carinata 油的 PHA 要么是纯聚合物，要么是聚合物的混合物。重均分子量从 B. carinata 油和油酸的 PHA 的约 56000 g/mol 变化到芥酸和神经酸的 PHA 的约 120000 g/mol。芥酸和神经酸的 PHAs 部分结晶，具有橡胶特性，熔点 (Tm) 为 50°C，而油酸和 B. carinata 油的 PHAs 则形成完全无定形材料，玻璃化转变温度 (Tg) 分别为-52°C 和-47°C。
