Wetland environmental bioreactor system contributes to the decomposition of cellulose
Wetland environmental bioreactor system contributes to the decomposition of cellulose
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DOI：
10.1002/ece3.5326
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发表时间：
2019-07-02
影响因子：
2.6
通讯作者：
Toyohara, Haruhiko
中科院分区：
文献类型：
--
作者：
Liu, Wen;Tanimura, Aya;Toyohara, Haruhiko
最近，许多种栖息在湿地的水生无脊椎动物已被证明具有内源性纤维素酶，继发现白蚁有纤维素酶基因编码在自己的基因组中，而不是依赖于共生细菌分解纤维素。湿地已被经验证明在分解陆地来源的难以降解的多糖如纤维素中发挥重要作用。然而，纤维素酶产生菌与湿地之间的作用机制尚不清楚，这给湿地生态功能的评价带来很大困难。在这里，我们发现，大型底栖双壳类，日本蚬，分泌其纤维素酶的湿地沉积物。分泌的纤维素酶被固定在沉积物的组分中。此外，在C. japonica可以触发其纤维素酶分泌水平。这些发现表明了一种新的湿地纤维素分解机制。湿地的分解能力以前只归因于含有纤维素酶的微生物和/或无脊椎动物。我们的研究结果表明，底栖动物提供湿地与他们的酶作为分解剂，而湿地沉积物作为固定支架的酶。该系统在湿地生态系统中发挥着重要作用，被我们称为“环境生物反应器系统”。
Recently, numerous species of aquatic invertebrates inhabiting wetlands have been shown to possess endogenous cellulase, following the discovery that termites have cellulase genes encoded in their own genome rather than relying on symbiotic bacteria for decomposing cellulose. Wetlands have been empirically shown to play an important role in the decomposition of land-originating hard-to-degrade polysaccharides such as cellulose. However, the mechanism that connects the cellulase producer and the wetlands remains unknown, which makes it very difficult to evaluate the ecological function of wetlands. Here we found that a macrobenthic bivalve, Corbicula japonica, secretes its cellulase to the wetland sediment. Secreted cellulases are immobilized in the components of the sediment. Moreover, adding cellulose or glucose to C. japonica could trigger its cellulase secretion level. These findings suggest a novel wetland cellulose decomposition mechanism. The decomposition ability of wetlands was previously ascribed only to microbes and/or invertebrates that contain cellulases. Our findings suggest that benthic animals supply wetlands with their enzymes as decomposition agents, while wetland sediments serve as immobilization scaffolds for the enzymes. This system, which was named by us an "environmental bioreactor system," could provide a key function in wetlands.