Department of Chemistry, State University of New York, College of Environmental Science and Forestry, 318 Jahn Lab, 1 Forestry Dr, Syracuse, NY, 13210, USA.
Appl Microbiol Biotechnol. 2014 Jan;98(2):831-42. doi: 10.1007/s00253-013-5398-4. Epub 2013 Nov 28.
Microbial conversion of plant biomass to value-added products is an attractive option to address the impacts of petroleum dependency. In this study, a bacterial system was developed that can hydrolyze xylan and utilize xylan-derived xylose for growth and production of polyhydroxyalkanoates (PHAs). A β-xylosidase and an endoxylanase were engineered into a P(LA-co-3HB)-producing Escherichia coli strain to obtain a xylanolytic strain. Although PHA production yields using xylan as sole carbon source were minimal, when the xylan-based media was supplemented with a single sugar (xylose or arabinose) to permit the accumulation of xylan-derived xylose in the media, PHA production yields increased up to 18-fold when compared to xylan-based production, and increased by 37 % when compared to production from single sugar sources alone. ¹H-Nuclear magnetic resonance (NMR) analysis shows higher accumulation of xylan-derived xylose in the media when xylan was supplemented with arabinose to prevent xylose uptake by catabolite repression. ¹H-NMR, gel permeation chromatography, and differential scanning calorimetry analyses corroborate that the polymers maintain physical properties regardless of the carbon source. This study demonstrates that accumulation of biomass-derived sugars in the media prior to their uptake by microbes is an important aspect to enhance PHA production when using plant biomass as feedstock.
微生物将植物生物质转化为增值产品是解决对石油依赖影响的一种有吸引力的选择。在这项研究中，开发了一种能够水解木聚糖并利用木聚糖衍生的木糖进行生长和生产聚羟基烷酸酯（PHA）的细菌系统。将β-木聚糖酶和内切木聚糖酶工程化到生产 P(LA-co-3HB)的大肠杆菌菌株中，以获得木聚糖降解菌株。尽管以木聚糖作为唯一碳源的 PHA 生产产率最低，但当以木聚糖为基础的培养基中补充单糖（木糖或阿拉伯糖）以允许在培养基中积累木聚糖衍生的木糖时，与以木聚糖为基础的生产相比，PHA 生产产率增加了 18 倍，与仅从单糖来源生产相比，增加了 37%。¹H-核磁共振（NMR）分析表明，当木聚糖与阿拉伯糖一起补充时，培养基中木聚糖衍生的木糖积累更高，以防止木糖被分解代谢物阻遏作用吸收。¹H-NMR、凝胶渗透色谱和差示扫描量热法分析证实，聚合物无论碳源如何，都保持物理性质。这项研究表明，在微生物吸收之前在培养基中积累生物质衍生的糖是使用植物生物质作为原料提高 PHA 生产的一个重要方面。
