Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, WI, 53726, USA.
Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
Biodegradation. 2021 Apr;32(2):179-192. doi: 10.1007/s10532-021-09932-3. Epub 2021 Mar 6.
Rhodopseudomonas palustris is a model microorganism for studying the anaerobic metabolism of aromatic compounds. While it is well documented which aromatics can serve as sole organic carbon sources, co-metabolism of other aromatics is poorly understood. This study used kinetic modeling to analyze the simultaneous degradation of aromatic compounds present in corn stover hydrolysates and model the co-metabolism of aromatics not known to support growth of R. palustris as sole organic substrates. The simulation predicted that p-coumaroyl amide and feruloyl amide were hydrolyzed to p-coumaric acid and ferulic acid, respectively, and further transformed via p-coumaroyl-CoA and feruloyl-CoA. The modeling also suggested that metabolism of p-hydroxyphenyl aromatics was slowed by substrate inhibition, whereas the transformation of guaiacyl aromatics was inhibited by their p-hydroxyphenyl counterparts. It also predicted that substrate channeling may occur during degradation of p-coumaroyl-CoA and feruloyl-CoA, resulting in no detectable accumulation of p-hydroxybenzaldehyde and vanillin, during the transformation of these CoA ligated compounds to p-hydroxybenzoic acid and vanillic acid, respectively. While the simulation correctly represented the known transformation of p-hydroxybenzoic acid via the benzoyl-CoA pathway, it also suggested co-metabolism of vanillic acid and syringic acid, which are known not to serve as photoheterotrophic growth substrate for R. palustris.
沼泽红假单胞菌是研究芳香族化合物厌氧代谢的模式微生物。虽然已经有充分的文献记载了哪些芳香族化合物可以作为唯一的有机碳源，但其他芳香族化合物的共代谢作用却知之甚少。本研究使用动力学建模来分析玉米秸秆水解物中存在的芳香族化合物的同时降解，并对不支持沼泽红假单胞菌作为唯一有机底物生长的芳香族化合物的共代谢进行建模。模拟预测，对香豆酰酰胺和阿魏酰酰胺分别水解为对香豆酸和阿魏酸，并进一步通过对香豆酰辅酶 A 和阿魏酰辅酶 A 转化。该模型还表明，对羟苯基芳香族化合物的代谢受到基质抑制的影响，而愈创木基芳香族化合物的转化受到其对羟苯基同类物的抑制。它还预测，在对香豆酰辅酶 A 和阿魏酰辅酶 A 的降解过程中可能发生基质通道化，导致在这些 CoA 连接化合物分别转化为对羟苯甲酸和香草酸时，没有可检测到的对羟基苯甲醛和香草醛积累。虽然该模拟正确地代表了已知的通过苯甲酰辅酶 A 途径转化为对羟苯甲酸的过程，但它也暗示了香草酸和丁香酸的共代谢作用，而这些物质已知不能作为沼泽红假单胞菌的光异养生长底物。
