Cultivation-dependent assessment, diversity, and ecology of haloalkaliphilic bacteria in arid saline systems of southern Tunisia.
Cultivation-dependent assessment, diversity, and ecology of haloalkaliphilic bacteria in arid saline systems of southern Tunisia.
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DOI：
10.1155/2013/648141
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发表时间：
2013
影响因子：
--
通讯作者：
Cherif A
中科院分区：
文献类型：
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作者：
El Hidri D;Guesmi A;Najjari A;Cherif H;Ettoumi B;Hamdi C;Boudabous A;Cherif A
嗜盐嗜碱菌是适应在高盐浓度和碱性pH值条件下生长的多极体。在这项工作中，我们从突尼斯南部5个不同的盐碱系统中分离出122个嗜盐细菌，通过对23个样品的浓缩，在含10%盐的培养基上和pH为10的条件下最佳生长。根据16S-23S rRNA内转录间隔区(ITS-PCR)的扩增，将收集的样品分为44个群。对16S rRNA基因进行系统发育分析和测序，可以鉴定出13个属和20个不同的物种。3株革兰氏阳性菌与唾液芽孢杆菌16S rRNA序列同源性在95%~96%之间，可能代表新种或新属。除了研究地点之间细菌多样性的差异外，还发现了几个物种生态位的相关性，如盐壳中的海洋杆菌，沙地中的Nester enkania，以及沙漠植物盐角草根际中的Salinicoccus。进一步对收集的细胞外酶的生产进行了评估。活性测试表明，革兰氏阳性菌大多具有活性，特别是对蛋白水解酶、脂肪酶、DNA酶和淀粉酶的产生。我们的总体结果表明，突尼斯南部盐碱系统中的嗜盐嗜碱菌具有巨大的表型和系统发育多样性，这是新谱系和代谢物的宝贵来源。
Haloalkaliphiles are polyextremophiles adapted to grow at high salt concentrations and alkaline pH values. In this work, we isolated 122 haloalkaliphilic bacteria upon enrichments of 23 samples from 5 distinct saline systems of southern Tunisia, growing optimally in media with 10% salt and at pH 10. The collection was classified into 44 groups based on the amplification of the 16S–23S rRNA internal transcribed spacers (ITS-PCR). Phylogenetic analysis and sequencing of the 16S rRNA genes allowed the identification of 13 genera and 20 distinct species. Three gram-positive isolates showing between 95 and 96% of 16S rRNA sequence homology with Bacillus saliphilus could represent new species or genus. Beside the difference in bacterial diversity between the studied sites, several species ecological niches correlations were demonstrated such as Oceanobacillus in salt crust, Nesterenkonia in sand, and Salinicoccus in the rhizosphere of the desert plant Salicornia. The collection was further evaluated for the production of extracellular enzymes. Activity tests showed that gram-positive bacteria were mostly active, particularly for protease, lipase, DNase, and amylase production. Our overall results demonstrate the huge phenotypic and phylogenetic diversity of haloalkaliphiles in saline systems of southern Tunisia which represent a valuable source of new lineages and metabolites.