Zaldivar J, Martinez A, Ingram L O
Institute of Food and Agricultural Sciences, Department of Microbiology and Cell Science, University of Florida, P.O. Box 110700, Gainesville, Florida 32611, USA.
Biotechnol Bioeng. 1999 Oct 5;65(1):24-33. doi: 10.1002/(sici)1097-0290(19991005)65:1<24::aid-bit4>3.0.co;2-2.
Bioethanol production from lignocellulosic raw-materials requires the hydrolysis of carbohydrate polymers into a fermentable syrup. During the hydrolysis of hemicellulose with dilute acid, a variety of toxic compounds are produced such as soluble aromatic aldehydes from lignin and furfural from pentose destruction. In this study, we have investigated the toxicity of representative aldehydes (furfural, 5-hydroxymethlyfurfural, 4-hydroxybenzaldehyde, syringaldehyde, and vanillin) as inhibitors of growth and ethanol production by ethanologenic derivatives of Escherichia coli B (strains KO11 and LY01). Aromatic aldehydes were at least twice as toxic as furfural or 5-hydroxymethylfurfural on a weight basis. The toxicities of all aldehydes (and ethanol) except furfural were additive when tested in binary combinations. In all cases, combinations with furfural were unexpectedly toxic. Although the potency of these aldehydes was directly related to hydrophobicity indicating a hydrophobic site of action, none caused sufficient membrane damage to allow the leakage of intracellular magnesium even when present at sixfold the concentrations required for growth inhibition. Of the aldehydes tested, only furfural strongly inhibited ethanol production in vitro. A comparison with published results for other microorganisms indicates that LY01 is equivalent or more resistant than other biocatalysts to the aldehydes examined in this study.
利用木质纤维素原料生产生物乙醇需要将碳水化合物聚合物水解成可发酵糖浆。在用稀酸水解半纤维素的过程中，会产生多种有毒化合物，如来自木质素的可溶性芳香醛和来自戊糖分解的糠醛。在本研究中，我们研究了代表性醛类（糠醛、5-羟甲基糠醛、4-羟基苯甲醛、丁香醛和香草醛）作为大肠杆菌B产乙醇衍生物（KO11和LY01菌株）生长和乙醇生产抑制剂的毒性。按重量计算，芳香醛的毒性至少是糠醛或5-羟甲基糠醛的两倍。除糠醛外，所有醛类（和乙醇）在二元组合测试时毒性具有加和性。在所有情况下，与糠醛的组合都具有意外的毒性。尽管这些醛类的效力与疏水性直接相关，表明存在疏水作用位点，但即使在浓度为生长抑制所需浓度的六倍时，也没有一种醛类会造成足够的膜损伤以导致细胞内镁泄漏。在所测试的醛类中，只有糠醛在体外强烈抑制乙醇生产。与其他微生物已发表结果的比较表明，LY01与其他生物催化剂相比，对本研究中检测的醛类具有同等抗性或更强抗性。
