Salamanca-Cardona Lucia, Scheel Ryan A, Mizuno Kouhei, Bergey N Scott, Stipanovic Arthur J, Matsumoto Ken'ichiro, Taguchi Seiichi, Nomura Christopher T
Department of Chemistry, State University of New York, College of Environmental Science and Forestry, Syracuse, NY 13210, USA.
Department of Creative Engineering, National Institute of Technology, Kitakyushu College, 5-20-1 Shii, Kokuraminami-ku, Kitakyushu 802-0985, Japan.
J Biosci Bioeng. 2017 May;123(5):547-554. doi: 10.1016/j.jbiosc.2016.12.019. Epub 2017 Feb 23.
Developing Escherichia coli strains that are tolerant to acetate toxicity is important in light of an increased interest in the efficient utilization of lignocellulosic biomass feedstocks for the biosynthesis of value-added products. In this study, four strains known to produce polyhydroxyalkanoates (PHAs) from the typical hemicellulosic sugar xylose were tested for their tolerance to acetate. E. coli RSC10 was found to be tolerant of acetate, both in growth and fermentation studies. In the presence of acetate the strain showed a >2-fold increase in overall yields compared to using xylose alone as the feedstock. More importantly, the strain was found to be able to utilize acetate as a feedstock for biosynthesis of PHAs, with complete depletion of acetate (25 mM) at 9 h when acetate was the sole feedstock. Higher concentrations of acetate showed greater inhibition of fermentation than growth with a reduction of 90% in PHA yields at 100 mM. Additionally, the present work provides data to support the potential of acetate as a modulator for the control of composition of PHAs that incorporate lactate (LA) monomers into the copolymer from hemicellulose derived sugars.
鉴于人们对高效利用木质纤维素生物质原料进行增值产品生物合成的兴趣日益浓厚，开发对乙酸毒性具有耐受性的大肠杆菌菌株具有重要意义。在本研究中，测试了四种已知能从典型半纤维素糖木糖生产聚羟基脂肪酸酯（PHA）的菌株对乙酸的耐受性。在生长和发酵研究中，发现大肠杆菌RSC10对乙酸具有耐受性。与仅使用木糖作为原料相比，在乙酸存在下，该菌株的总产率提高了两倍以上。更重要的是，发现该菌株能够利用乙酸作为PHA生物合成的原料，当乙酸是唯一原料时，9小时内乙酸（25 mM）完全耗尽。较高浓度的乙酸对发酵的抑制作用大于对生长的抑制作用，在100 mM时PHA产率降低90%。此外，本研究提供的数据支持了乙酸作为一种调节剂的潜力，该调节剂可用于控制从半纤维素衍生糖中将乳酸（LA）单体掺入共聚物的PHA的组成。
