木质纤维素是一种有价值的生物质,用于合成聚羟基丁酸酯(PHB)的可再生底物,一种生态友好的生物聚合物。在这项研究中,细菌菌株E5-3是从日本的土壤中分离出来的;通过16SrRNA基因测序将其鉴定为伯克霍尔德氏菌菌株E5-3。该菌株在37°C下显示出最佳生长,初始pH为9。它表现出不同的代谢能力,处理广泛的碳基材,包括木糖,葡萄糖,蔗糖,甘油,纤维二糖,and,特别是,棕榈油。棕榈油诱导最高的细胞生长,PHB含量为65重量%。该菌株对源自木质纤维素水解物的潜在发酵抑制剂表现出固有的耐受性,耐受3g/L5-羟甲基糠醛和1.25g/L乙酸。采用补料分批发酵策略与葡萄糖的组合,木糖,和纤维二糖导致PHB产量是传统分批发酵的2.7倍。油棕树干水解物的使用,没有抑制剂预处理,在补料分批发酵装置中导致显著的细胞生长,PHB含量为45%wt,相当于10g/L菌株E5-3产生的木糖衍生PHB的物理化学属性包括722kDa的分子量,数均分子量为191kDa,和3.78的多分散指数。该PHB的无定形结构显示出4.59°C的玻璃化转变温度,而其结晶对应物的熔点为171.03℃。这项研究突出了木质纤维素原料的潜力,尤其是油棕树干水解物,用于通过双歧杆菌菌株E5-3的补料分批发酵生产PHB,该菌株具有较高的抑制剂耐受性。
Lignocellulosic biomass is a valuable, renewable substrate for the synthesis of polyhydroxybutyrate (PHB), an ecofriendly biopolymer. In this study, bacterial strain E5-3 was isolated from soil in Japan; it was identified as Burkholderia ambifaria strain E5-3 by 16 S rRNA gene sequencing. The strain showed optimal growth at 37 °C with an initial pH of 9. It demonstrated diverse metabolic ability, processing a broad range of carbon substrates, including xylose, glucose, sucrose, glycerol,
cellobiose, and, notably, palm oil. Palm oil induced the highest cellular growth, with a PHB content of 65% wt. The strain exhibited inherent tolerance to potential fermentation inhibitors derived from lignocellulosic hydrolysate, withstanding 3 g/L 5-hydroxymethylfurfural and 1.25 g/L acetic acid. Employing a fed-batch fermentation strategy with a combination of glucose, xylose, and
cellobiose resulted in PHB production 2.7-times that in traditional batch fermentation. The use of oil palm trunk hydrolysate, without inhibitor pretreatment, in a fed-batch fermentation setup led to significant cell growth with a PHB content of 45% wt, equivalent to 10 g/L. The physicochemical attributes of xylose-derived PHB produced by strain E5-3 included a molecular weight of 722 kDa, a number-average molecular weight of 191 kDa, and a polydispersity index of 3.78. The amorphous structure of this PHB displayed a glass transition temperature of 4.59 °C, while its crystalline counterpart had a melting point of 171.03 °C. This research highlights the potential of lignocellulosic feedstocks, especially oil palm trunk hydrolysate, for PHB production through fed-batch fermentation by B. ambifaria strain E5-3, which has high inhibitor tolerance.