Itani Ghida Nouhad, Smith Colin Andrew
Department of Biology, American University of Beirut, Beirut, Lebanon.
Sci Rep. 2016 Mar 4;6:22657. doi: 10.1038/srep22657.
Dust rains may be particularly effective at delivering microorganisms, yet their biodiversities have been seldom examined. During 2011 and 2012 in Beirut, Lebanon, 16 of 21 collected rainfalls appeared dusty. Trajectory modelling of air mass origins was consistent with North African sources and at least one Southwest Asian source. As much as ~4 g particulate matter, ~20 μg DNA, and 50 million colony forming units were found deposited per square meter during rainfalls each lasting less than one day. Sequencing of 93 bacteria and 25 fungi cultured from rain samples revealed diverse bacterial phyla, both Gram positive and negative, and Ascomycota fungi. Denaturing Gradient Gel Electrophoresis of amplified 16S rDNA of 13 rains revealed distinct and diverse assemblages of bacteria. Dust rain 16S libraries yielded 131 sequences matching, in decreasing order of abundance, Betaproteobacteria, Alphaproteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, Cyanobacteria, Epsilonproteobacteria, Gammaproteobacteria, and Deltaproteobacteria. Clean rain 16S libraries yielded 33 sequences matching only Betaproteobacteria family Oxalobacteraceae. Microbial composition varied between dust rains, and more diverse and different microbes were found in dust rains than clean rains. These results show that dust rains deliver diverse communities of microorganisms that may be complex products of revived desert soil species and fertilized cloud species.
尘雨在传播微生物方面可能特别有效，然而其生物多样性很少被研究。2011年至2012年期间，在黎巴嫩贝鲁特，收集到的21场降雨中有16场似乎带有沙尘。气团源地的轨迹模型与北非源地以及至少一个西南亚源地一致。每次持续时间不到一天的降雨期间，每平方米发现沉积有约4克颗粒物、约20微克DNA和5000万个菌落形成单位。对从雨水样本中培养出的93种细菌和25种真菌进行测序，揭示了革兰氏阳性和阴性的不同细菌门以及子囊菌门真菌。对13场降雨的扩增16S rDNA进行变性梯度凝胶电泳，揭示了不同且多样的细菌组合。尘雨16S文库产生了131个序列，按丰度递减顺序匹配β-变形菌纲、α-变形菌纲、厚壁菌门、放线菌门、拟杆菌门、蓝细菌、ε-变形菌纲、γ-变形菌纲和δ-变形菌纲。清洁雨水16S文库产生了仅与草酸杆菌科β-变形菌纲家族匹配的33个序列。尘雨之间的微生物组成各不相同，并且在尘雨中发现的微生物比清洁雨中更多样化且不同。这些结果表明，尘雨传播了多样的微生物群落，这些群落可能是复苏沙漠土壤物种和受精云物种的复杂产物。
