Otto Benjamin, Beuchel Carl, Liers Christiane, Reisser Werner, Harms Hauke, Schlosser Dietmar
Institute of Biology, General and Applied Botany, University of Leipzig, 04103 Leipzig, Germany Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, 04318 Leipzig, Germany
Faculty of Natural Sciences III, Institute of Agricultural and Nutritional Science, Martin Luther University of Halle-Wittenberg, 06099 Halle (Saale), Germany.
FEMS Microbiol Lett. 2015 Jun;362(11). doi: 10.1093/femsle/fnv072. Epub 2015 Apr 28.
In order to explore the abundance and potential environmental functions of green algal laccases, we screened various algae for extracellular laccase-like activities, characterized basic features of these activities in selected species and exemplarily studied the transformation of environmental pollutants and complex natural compounds by the laccase of Tetracystis aeria. Oxidation of the classical laccase substrate ABTS was found to be widespread in chlorophycean algae. The oxidation activity detected in members of the 'Scenedesmus' clade was caused by an unknown thermostable low-molecular-mass compound. In contrast, species of the Moewusinia, including Chlamydomonas moewusii and T. aeria, excreted putative 'true' laccases. Phenolic substrates were oxidized by these enzymes optimally at neutral to alkaline pH. The Tetracystis laccase efficiently transformed bisphenol A, 17α-ethinylestradiol, nonylphenol and triclosan in the presence of ABTS as redox mediator, while anthracene, veratrylalcohol and adlerol were not attacked. Lignosulfonate and humic acid underwent slight (de)polymerization reactions in the presence of the laccase and mediator(s), probably involving the oxidation of phenolic constituents. Possible natural functions of the enzymes, such as the synthesis of complex polymers or detoxification processes, may assist the survival of the algae in adverse environments. In contaminated surface waters, laccase-producing green algae might contribute to the environmental breakdown of phenolic pollutants.
为了探究绿藻漆酶的丰度及其潜在的环境功能，我们筛选了多种藻类以检测其胞外漆酶样活性，对所选物种中这些活性的基本特征进行了表征，并以四囊藻属的漆酶为例研究了环境污染物和复杂天然化合物的转化。发现经典漆酶底物ABTS的氧化在绿藻纲藻类中广泛存在。在“栅藻”进化枝成员中检测到的氧化活性是由一种未知的热稳定低分子量化合物引起的。相比之下，包括莱茵衣藻和四囊藻在内的穆氏藻属物种分泌的是假定的“真正”漆酶。这些酶在中性至碱性pH条件下能最佳地氧化酚类底物。在ABTS作为氧化还原介质存在的情况下，四囊藻漆酶能有效转化双酚A、17α-乙炔雌二醇、壬基酚和三氯生，而蒽、藜芦醇和阿多二醇则不受影响。在漆酶和介质存在的情况下，木质素磺酸盐和腐殖酸发生了轻微的（解）聚合反应可能涉及酚类成分的氧化。这些酶可能的自然功能，如合成复杂聚合物或解毒过程，可能有助于藻类在不利环境中生存。在受污染的地表水中，产漆酶的绿藻可能有助于酚类污染物的环境降解。
