The production of short-chain-length polyhydroxyalkanoates (scl-PHAs) in a sugarcane biorefinery setting has been demonstrated to be an effective strategy to reduce production costs. Medium-chain-length PHA (mcl-PHA) have elastomeric properties and are more suitable for high value-added applications, but its industrial production is not yet established. Mcl-PHA synthesis occurs via different metabolic routes and thus requires distinct microorganisms and substrates compared to scl-PHA. In the present study, sucrose-derived carbohydrates were evaluated as co-substrates for the production of mcl-PHA from decanoic acid (DA). Fermentation strategies were investigated to produce mcl-PHA with enriched dominant monomer content, which is desirable for commercial applications. The mcl-PHA production was investigated in carbon-limited, fed-batch fermentations with wild-type and β-oxidation knockout mutant strains of Pseudomonas putida KT2440. The experimental results demonstrated that a mixture of glucose and fructose was a suitable co-feed with DA for mcl-PHA production, yielding equivalent results to those obtained with starch-derived glucose, a more traditional feedstock for PHA production. The use of a β-oxidation-impaired strain was essential to attain high dominant monomer content. A near-homopolymeric mcl-PHA was produced under exponential feeding, containing 99 mol% of 3-hydroxydecanoate. This work demonstrates the potential for near-homopolymeric mcl-PHA production in a sugarcane biorefinery, using hydrolyzed sucrose and DA.

甘蔗生物精炼厂生产短链多羟基链烷酸酯（scl-PHA）已被证明是降低生产成本的有效策略。中链长度的PHA（mcl-PHA）具有弹性，更适合于高附加值的应用，但是其工业生产尚未建立。Mcl-PHA的合成通过不同的代谢途径发生，因此与scl-PHA相比，需要不同的微生物和底物。在本研究中，蔗糖衍生的碳水化合物被评估为由癸酸（DA）生产mcl-PHA的共底物。研究了发酵策略以生产具有丰富的主要单体含量的mcl-PHA，这对于商业应用是理想的。对mcl-PHA的生产进行了碳极限分析，恶臭假单胞菌KT2440。实验结果表明，葡萄糖和果糖的混合物适合与DA一起用于mcl-PHA生产，与使用淀粉衍生的葡萄糖（一种用于PHA生产的传统原料）获得的结果相当。使用β-氧化受损的菌株对于获得高的主要单体含量是必不可少的。在指数进料下产生了近均聚物的mcl-PHA，其含有99mol％的3-羟基癸酸酯。这项工作证明了使用水解蔗糖和DA在甘蔗生物精炼厂生产近均聚mcl-PHA的潜力。