Characterization of microbialite-forming cyanobacteria in a tropical lagoon: Tikehau Atoll, Tuamotu, French Polynesia
Characterization of microbialite-forming cyanobacteria in a tropical lagoon: Tikehau Atoll, Tuamotu, French Polynesia
复制标题
DOI：
10.1046/j.1529-8817.2003.02180.x
复制
发表时间：
2003-10-01
影响因子：
2.9
通讯作者：
Sprachta, S
中科院分区：
文献类型：
--
作者：
Abed, RMM;Golubic, S;Sprachta, S
对法属波利尼西亚Tikehau环礁泻湖底栖蓝细菌的自然种群进行了研究，采用野外观察、光镜观察、培养和分子测序相结合的方法。该方法评估了它们的表型(形态和生态)和遗传型多样性。利用蓝藻特异的引物，从自然种群和养殖种群中获得了16S rRNA基因的部分序列(约450bp)。获得的序列与公共数据库中可获得的全套16S rRNA序列相关地聚为六个独立的系统发育簇。在许多情况下，系统发育聚类与某些形态特征相关。例如，盐下螺旋藻可以用分子和显微方法在形态种水平上进行鉴定。经鉴定，其形态类型为海藻Symploca hynoids(Kutz.)Ex Gomont)TK22，Phormidium sp.TK1和P.laysanense(Lemmerman)TK14聚为一类。有趣的是，形态发生菌(Blennothrix)与形态相似但浮游的海洋蓝藻毛霉(Trichodesum)聚在一起，这表明了一种关系。属于形态分类群的其他序列具有非常窄的毛状体，被发现是多系系。在18个月的时间里，用从田间种群中获得的接种物进行增菌培养。随着时间的推移，所有培养物中的主导地位都发生了变化，有利于一组毛发狭窄的蓝藻菌株，这些菌株在表型和系统发育上与主导原始样品的自然种群不同。通过培养而丰富的菌株的序列聚为两个明确的系统发育组，可能识别新的分类群。这些集群可能代表了机会主义物种的利基，进化出来的目的是利用环境中的短期营养尖峰。
Natural populations of benthic cyanobacteria in the lagoon of Tikehau Atoll in French Polynesia were studied using a polyphasic approach that combined field observations, LM, culturing, and molecular sequencing. The approach assessed their phenotypic (morphotypic and ecological) and genotypic diversity. Partial sequences ( approximately 450 bp long) of the PCR-amplified 16S rRNA gene were obtained from both natural and cultured populations using cyanobacteria-specific primers. The sequences obtained clustered into six separate phylogenetic clusters in relation to the complete set of 16S rRNA sequences available in public databases. Phylogenetic clustering correlated in many cases with some morphological characteristics. For example, Spirulina subsalsa could be identified to the morphospecies level using both molecular and microscopic approaches. Morphotypes identified as Symploca hydnoides (Kutz. ex Gomont) TK22, Phormidium sp. TK1, and P. laysanense (Lemmerman) TK14 formed a distinct cluster. The morphogenus Hydrocoleum (Blennothrix) clustered interestingly close to the morphologically similar, but planktonic, marine cyanobacterium Trichodesmium, suggesting a relationship. Other sequences belonging to morphotaxa with very narrow trichomes were found to be polyphyletic. Enrichment cultures, with inoculum obtained from field populations, were followed over a period of 18 months. Dominance in all cultures shifted over time in favor of a set of cyanobacterial strains with narrow trichomes, which were phenotypically and phylogenetically different from natural populations dominating the original samples. Sequences from strains enriched by cultivation clustered into two well-defined phylogenetic groups, possibly identifying new taxa. These clusters may represent a niche of opportunistic species, evolved to exploit short-term nutrient spikes in the environment.