UV irradiation of natural organic matter (NOM): impact on organic carbon and bacteria
UV irradiation of natural organic matter (NOM): impact on organic carbon and bacteria
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DOI：
10.1007/s00027-011-0239-y
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发表时间：
2012-07-01
期刊：
影响因子：
2.4
通讯作者：
Grossart, Hans-Peter
中科院分区：
文献类型：
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作者：
Paul, Andrea;Dziallas, Claudia;Grossart, Hans-Peter
紫外诱导溶解有机物（DOC）的转化通常伴随着分子量和芳香性的降低，以及可被异养菌用作底物的低分子量（LMW）物质的增加。此外，反应瞬态的生成和DOC的矿化发生。为了更好地了解辐照后开始的修饰，并区分可能的化学和生物修饰，我们从挪威和德国选择了不同的天然有机物质（NOM）。采用紫外辐照法对水溶液进行处理，并将其分为两等分样品。其中一份样品采用NaN3抗菌处理，两份样品均采用高压阻垢色谱（HPSEC）分析。在所有样品中，我们都发现了紫外线照射后典型的NOM修饰。紫外线照射的NOM样品孵育（bbb7天）导致LMW物质水平降低，芳香性增加。与这些碳组分的变化平行，观察到细菌细胞数量的增加。通过对扩增的16S rRNA基因进行变性梯度凝胶电泳（DGGE）分析，发现未照射和紫外线照射的NOM的细菌群落组成不同，紫外线对α -变形菌门、β -变形菌门和Bacteriodetes的特定成员进行了选择。我们的研究结果表明，经过NOM的紫外线照射后，特定的细菌成员很好地适应了低pH、高LMW DOC浓度和氧化应激，因此在紫外线照射的腐殖质上生长良好。
UV-induced transformation of dissolved organic matter (DOC) is often accompanied by reduction of molecular weight and aromaticity and an increase of low-molecular weight (LMW) matter that can be utilized as a substrate by heterotrophic bacteria. Moreover, the generation of reactive transients and mineralization of DOC occurs. For a better understanding of the modification that starts after irradiation and to distinguish between possible chemical and biological modifications, we selected different natural organic matter (NOM) from Norway and Germany. The aqueous solutions were treated by UV irradiation and divided into two aliquot samples. NaN3 anti-bacterial treatment was applied to one sample, and high-pressure size-exclusion chromatography (HPSEC) analysis was used for both. In all samples, we found typical modifications of NOM after UV irradiation. Incubation (> 7 days) of UV-irradiated NOM samples resulted in lower levels of LMW matter and increased aromaticity. Parallel to these changes of carbon fractions, an increase in bacterial cell numbers was observed. Addition of NaN3 to NOM, however, inhibited the reduction of LMW matter, indicating that microbial activity accounted for the observed changes in NOM. Analysis of the bacterial community composition by denaturing gradient gel electrophoresis (DGGE) of the amplified 16S rRNA genes revealed that bacterial communities of non-irradiated and UV-irradiated NOM were different and that UV selected for specific members of alpha-proteobacteria, beta-proteobacteria, and Bacteriodetes. Our results imply that after UV-irradiation of NOM, specific bacterial members are well adapted to low pH, high LMW DOC concentrations, and oxidative stress, and therefore thrive well on UV-irradiated humic matter.