Are enzymes transported in soils by water fluxes?
Are enzymes transported in soils by water fluxes?
复制标题
酶在土壤中是通过水通量运输的吗？
DOI：
10.1016/j.soilbio.2022.108633
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发表时间：
2022
影响因子：
9.7
通讯作者：
Kravchenko, Alexandra
中科院分区：
文献类型：
--
作者：
Guber, Andrey;Blagodatskaya, Evgenia;Kravchenko, Alexandra
胞外水解酶在土壤中的运输一直是一个令人怀疑的问题。对其重要性的考虑是：(I)当酶保持紧密接近时，其生产者受益最大；(Ii)酶是大分子，由于对细小的土壤颗粒和有机物具有高亲和力，流动性低。然而，土壤矿物胶体(SMC)也可以作为酶运输的载体，胞外酶也与其有亲和力，并且已知它可以促进土壤中各种化学物质和微生物的运输。由于目前的文献缺乏关于酶在土壤中运输的信息，我们的目标是确定酶是否被运输，如果是的话，它们是以游离形式还是以胶体结合的形式运输。我们用四种水解酶，即β-葡萄糖苷酶、酸性磷酸酶、纤维二糖水解酶和木糖苷酶，在质地不同的土壤中进行了柱子传输实验。将含有酶的淋洗液应用于土柱顶部，同时测量柱子流出物中的酶活性、SMC和电导率。我们的结果为酶与土壤胶体的联合运输提供了证据。与粗SMC相关的酶(1μm)占出水总酶活性的52-88%。其余的酶活性归因于与有机胶体、细小的SMC(1μm)和溶液中的游离酶有关的酶。这项研究表明，土壤悬浮液中的离子强度对酶活性及其从土壤胶体中释放的双重影响。
Transport of extracellular hydrolytic enzymes in soils has always been a subject of doubt. The considerations against its importance are that (i) enzymes benefit their producers the most when they remain in close proximity; and (ii) enzymes are large molecules with low mobility due to high affinity to fine soil particles and organic matter. However, soil mineral colloids (SMC), to which extracellular enzymes also have an affinity and which are known to facilitate transport of a broad variety of chemicals and microorganisms in soils, can serve as vehicles for enzyme transport as well. Since current literature lacks information on enzyme transport in soils, our goal was to determine whether enzymes are transported and, if so, whether they are transported in a free- or in a colloid-associated form. We conducted column transport experiments with four hydrolytic enzymes, namely,β-glucosidase, acid-phosphatase, cellobiohydrolase, and xylosidase, in soils with contrasting textures. The eluents containing enzymes were applied on top of soil columns, while enzyme activities, SMC, and electrical conductivity were measured in the effluents from the columns. Our results provided evidence of joint enzyme transport with soil colloids. The enzymes associated with the coarse SMC (1 μm < Ø) contributed 52–88% of the total enzyme activity in the effluents. The remaining enzyme activity was attributed to the enzymes associated with organic colloids, fine SMC (Ø < 1 μm) and free enzymes in solution. This study suggested a dual effect of ionic strength in the soil suspension on enzyme activity and their release from soils with soil colloids.