Arocha-Garza Hector Fernando, Canales-Del Castillo Ricardo, Eguiarte Luis E, Souza Valeria, De la Torre-Zavala Susana
Facultad de Ciencias Biológicas, Instituto de Biotecnología, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico.
Facultad de Ciencias Biológicas, Laboratorio de Biología de la Conservación, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico.
PeerJ. 2017 May 2;5:e3247. doi: 10.7717/peerj.3247. eCollection 2017.
The phylum Actinobacteria constitutes one of the largest and anciently divergent phyla within the Bacteria domain. Actinobacterial diversity has been thoroughly researched in various environments due to its unique biotechnological potential. Such studies have focused mostly on soil communities, but more recently marine and extreme environments have also been explored, finding rare taxa and demonstrating dispersal limitation and biogeographic patterns for Streptomyces. To test the distribution of Actinobacteria populations on a small scale, we chose the extremely oligotrophic and biodiverse Cuatro Cienegas Basin (CCB), an endangered oasis in the Chihuahuan desert to assess the diversity and uniqueness of Actinobacteria in the Churince System with a culture-dependent approach over a period of three years, using nine selective media. The 16S rDNA of putative Actinobacteria were sequenced using both bacteria universal and phylum-specific primer pairs. Phylogenetic reconstructions were performed to analyze OTUs clustering and taxonomic identification of the isolates in an evolutionary context, using validated type species of from previously phylogenies as a reference. Rarefaction analysis for total Actinobacteria and for Streptomyces isolates were performed to estimate species' richness in the intermediate lagoon (IL) in the oligotrophic Churince system. A total of 350 morphologically and nutritionally diverse isolates were successfully cultured and characterized as members of the Phylum Actinobacteria. A total of 105 from the total isolates were successfully subcultured, processed for DNA extraction and 16S-rDNA sequenced. All strains belong to the order Actinomycetales, encompassing 11 genera of Actinobacteria; the genus was found to be the most abundant taxa in all the media tested throughout the 3-year sampling period. Phylogenetic analysis of our isolates and another 667 reference strains of the family Streptomycetaceae shows that our isolation effort produced 38 unique OTUs in six new monophyletic clades. This high biodiversity and uniqueness of Actinobacteria in an extreme oligotrophic environment, which has previously been reported for its diversity and endemicity, is a suggestive sign of microbial biogeography of Actinobacteria and it also represents an invaluable source of biological material for future ecological and bioprospecting studies.
放线菌门是细菌域中最大且分化时间古老的门类之一。由于放线菌具有独特的生物技术潜力，其多样性已在各种环境中得到深入研究。此类研究主要集中在土壤群落，但最近也对海洋和极端环境进行了探索，发现了稀有分类群，并展示了链霉菌的扩散限制和生物地理模式。为了在小尺度上测试放线菌种群的分布，我们选择了极度贫营养且生物多样的夸特罗锡耶纳斯盆地（CCB），它是奇瓦瓦沙漠中的一个濒危绿洲，采用依赖培养的方法，在三年时间里使用九种选择性培养基，评估楚林斯系统中放线菌的多样性和独特性。使用细菌通用引物对和门特异性引物对，对假定的放线菌的16S rDNA进行测序。利用先前系统发育中的经过验证的模式种作为参考，进行系统发育重建，以在进化背景下分析OTU聚类和分离株的分类鉴定。对贫营养的楚林斯系统中间泻湖（IL）中的总放线菌和链霉菌分离株进行了稀疏分析，以估计物种丰富度。总共成功培养并鉴定出350个形态和营养多样的分离株，它们属于放线菌门。总共105个分离株成功传代培养，进行DNA提取和16S - rDNA测序。所有菌株都属于放线菌目，包括11个放线菌属；在整个三年采样期内，在所测试的所有培养基中，该属被发现是最丰富的分类群。对我们的分离株和链霉菌科的另外667个参考菌株进行系统发育分析表明，我们的分离工作在六个新的单系分支中产生了38个独特的OTU。这种在极端贫营养环境中放线菌的高生物多样性和独特性，此前已因其多样性和地方性而被报道，这是放线菌微生物生物地理学的一个暗示性标志，它也代表了未来生态和生物勘探研究的宝贵生物材料来源。
