营养盐与盐双重胁迫下水体中浮游细菌的响应

Response of Freshwater Bacterial Community to the Double Stress of Salinity and Nutrients

为阐释干旱地区内陆湖泊微生物群落对营养盐和盐双重胁迫的响应机制,针对干旱、半干旱地区许多湖泊水体受咸化与富营养化双重影响的特点,通过454高通量测序16S rRNA基因和多元统计分析,研究水体营养盐和盐的添加对细菌群落结构、多样性变化的影响.结果表明,盐与营养盐的输入引起了水体中细菌群落组成和多样性的显著变化,具体表现为：①随着盐度（以w计）的升高,α-变形菌纲（Alphaproteobacteria）的相对丰度显著增加,从对照处理的16.0%±4.6%增至SO（贫营养-盐水）处理的39.8%±18.1%;但会受到水体营养水平的制约.②富营养水平下,微咸条件（盐度为1.5‰）有利于细菌类群丰富度的增加,BE-30（微咸-富营养处理培养30 d样品）的Shannon-Wiener多样性指数（4.62）显著高于FE-30（淡水-富营养处理培养30 d样品,2.08）和SE-30（高盐-富营养处理培养30 d样品,1.69）;③高盐（盐度为3.0‰）条件下,随着水体中营养盐含量的增加,喜营养的嗜盐细菌类群大量繁殖（SE-30中无法分类的Comamonadaceae科的相对丰度达到69.3%）,因而降低了水体中细菌群落的多样性.研究显示,α-变形菌纲和无法分类的Comamonadaceae科对盐与营养盐的变化较为敏感,可作为干旱区湖泊咸化和富营养化过程的参考类群.

To characterize the dual impacts of salinization and eutrophication in aquatic ecosystems in arid regions,16 S rRNA gene based high-throughput sequencing and multivariate statistical analysis were employed to investigated the changes of bacterial communities and diversity in freshwater of inland arid regions in response to a manipulated supply of salinity and inorganic nutrients. The results showed that the addition of salinity and nutrients induced a clear shift in the bacterial communities and diversity. Detailed analysis results showed that： 1） Alphaproteobacteria increased from 16. 0% ± 4. 6% in the control（ C） group to 39. 8% ± 18. 1% in the saline-oligotrophic（ SO） group with increased salinity,although it might be restrained by different nutrient levels. 2） Brackish habitats（ 1. 5‰） facilitated enhanced bacterial diversity in the eutrophic water. For example,the Shannon-Wiener diversity index of sample BE-30（ 4. 62） was significantly higher than that of samples FE-30（ 2. 08） and SE-30（ 1. 69）. 3） Nutrient-loving Betaproteobacteria（ especially69. 3% unclassified Comamonadaceae in sample SE-30） showed fast growth in response to elevated nutrient concentrations,but the bacterial diversity in the saline habitats decreased significantly with the increased nutrients. Alphaproteobacteria and unclassifiedComamonadaceae showed their sensitivities to the change in salinity and nutrients,and they might be used as indicator bacterial taxa to identify the salinization and eutrophication process in lakes in arid regions.