Lemos Paulo C, Serafim Luísa S, Reis Maria A M
Chemistry Department, CQFB/REQUIMTE, FCT/Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
J Biotechnol. 2006 Mar 23;122(2):226-38. doi: 10.1016/j.jbiotec.2005.09.006. Epub 2005 Oct 25.
The production of polyhydroxyalkanoates from acetate and propionate by two mixed cultures well adapted to each of these substrates was evaluated. Sludge fed with acetate (A), produced a homopolymer of hydroxybutyrate (HB), whereas sludge fed with propionate (P) produced a copolymer of HB and HV (hydoxyvalerate). Switching the substrate feeds, propionate to sludge A and acetate to culture P, a terpolymer of HB, HV and hydroxymethylvalerate (HMV) was obtained with culture A and a copolymer of P(HB/HV) by sludge P. Regardless of the population used, the polymer yield and productivity were much higher for acetate than for propionate. Feeding a mixture of acetate and propionate, in equal parts, to both cultures resulted in an increase of HV units produced per C mol of propionate consumed, relative to the situation where only propionate was used. The individual use of butyrate and valerate by culture A was also studied. Butyrate produced a homopolymer whereas valerate was stored as a terpolymer of P(HB/HV/HMV). The polymer yields on acetate and butyrate were higher than those on propionate and valerate. The polymer productivity was higher for acetate and propionate than for butyrate and valerate. Results showed that the polymer composition, and consequently the polymer properties, could be manipulated by varying the volatile fatty acid feed composition and/or the population.
评估了两种分别适应乙酸盐和丙酸盐的混合培养物从乙酸盐和丙酸盐生产聚羟基脂肪酸酯的情况。用乙酸盐（A）喂养的污泥产生了羟基丁酸（HB）的均聚物，而用丙酸盐（P）喂养的污泥产生了HB和HV（羟基戊酸）的共聚物。将底物进料进行切换，即向污泥A中加入丙酸盐，向培养物P中加入乙酸盐，用培养物A获得了HB、HV和羟甲基戊酸（HMV）的三元共聚物，用污泥P获得了P(HB/HV)共聚物。无论使用哪种菌群，乙酸盐的聚合物产量和生产率都比丙酸盐高得多。向两种培养物中均等量加入乙酸盐和丙酸盐的混合物，相对于仅使用丙酸盐的情况，每消耗1 C mol丙酸盐所产生的HV单元有所增加。还研究了培养物A单独使用丁酸盐和戊酸盐的情况。丁酸盐产生了均聚物，而戊酸盐则以P(HB/HV/HMV)的三元共聚物形式储存。乙酸盐和丁酸盐的聚合物产量高于丙酸盐和戊酸盐。乙酸盐和丙酸盐的聚合物生产率高于丁酸盐和戊酸盐。结果表明，可以通过改变挥发性脂肪酸进料组成和/或菌群来控制聚合物组成，进而控制聚合物性能。
