Ortiz-Bermúdez Patricia, Hirth Kolby C, Srebotnik Ewald, Hammel Kenneth E
Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA.
Proc Natl Acad Sci U S A. 2007 Mar 6;104(10):3895-900. doi: 10.1073/pnas.0610074104. Epub 2007 Feb 26.
Soils and decayed plant litter contain significant quantities of chlorinated aromatic polymers that have a natural but largely unknown origin. We used cupric oxide ligninolysis coupled with gas chromatography/mass spectrometry to show that Curvularia inaequalis, a widely distributed litter ascomycete, chlorinated the aromatic rings of lignin in wood that it was degrading. In aspen wood decayed for 24 weeks, two chlorolignin fragments, 5-chlorovanillin and 2-chlorosyringaldehyde, were each found at approximately 10 mug/g of wood (dry weight). These levels resemble those of similar structures generally found in unpolluted environmental samples. Fractionation of the extractable proteins followed by tandem mass spectrometric analysis showed that the colonized wood contained a previously described C. inaequalis chloroperoxidase that very likely catalyzed lignin chlorination. Chlorolignin produced by this route and humus derived from it are probably significant components of the global chlorine cycle because chloroperoxidase-producing fungi are ubiquitous in decaying lignocellulose and lignin is the earth's most abundant aromatic substance.
土壤和腐烂的植物凋落物含有大量氯化芳香聚合物，其来源天然但大多未知。我们使用氧化铜木质素分解结合气相色谱/质谱法表明，不等弯孢菌（一种广泛分布的凋落物子囊菌）在降解木材中的木质素时会氯化其芳香环。在腐烂24周的杨木中，两种氯代木质素片段，5-氯香草醛和2-氯丁香醛，各自在约10微克/克木材（干重）中被发现。这些水平与通常在未受污染的环境样品中发现的类似结构的水平相似。对可提取蛋白质进行分级分离，然后进行串联质谱分析表明，被定殖的木材含有一种先前描述的不等弯孢菌氯过氧化物酶，它很可能催化了木质素氯化。通过这种途径产生的氯代木质素及其衍生的腐殖质可能是全球氯循环的重要组成部分，因为产生氯过氧化物酶的真菌在腐烂的木质纤维素中无处不在，而木质素是地球上最丰富的芳香物质。
