铜陵铜尾矿废弃地生物土壤结皮中的蓝藻多样性

生物土壤结皮是生态系统原生演替过程中的一个早期阶段,在铜陵铜尾矿废弃地自然生态恢复过程中生物土壤结皮在尾矿废弃地表面广泛分布.以生长在铜陵杨山冲和铜官山2处铜尾矿废弃地的生物土壤结皮为研究对象,运用常规培养方法和变性梯度凝胶电泳技术(PCR-DGGE)对不同群落生物土壤结皮中的蓝藻多样性及优势类群进行研究.结果表明2种研究方法所获得的蓝藻种类组成具有明显差异.显微观察结果表明常规培养试验中主要蓝藻类群为微囊藻属(Microcystis)、色球藻属(Chroococcus)、颤藻属(Oscillatoria)、念珠藻属(Nostoc)和浮鞘丝藻属(Planktolyngbya),其中优势种类主要为铜绿微囊藻(Microcystis aeruginosa)、断裂颤藻(Oscillatoria fracta)和细浮鞘丝藻(Planktolyngbya subtilis)；提取样品中微生物总DNA,对蓝藻16SrRNA进行PCR-DGGE分析,回收DGGE图谱中24个条带进行测序分析,结果显示,所有序列与GenBank数据库中的近缘蓝藻的相似性系数均在93％以上,其中优势蓝藻类群主要隶属于微鞘藻属(Microcoleus)和细鞘丝藻属(Leptolyngbya),裸地(YL)处和木贼群落下尾矿表面(YM)的生物土壤结皮中优势蓝藻类群主要为微鞘藻属,而黄色真藓-藻类混合结皮(YT)和白茅群落( YB,TG)下的生物土壤结皮中的优势类群主要隶属于细鞘丝藻属.

Cyanobacterial diversity in biological soil crusts on wastelands of copper mine tailings

Biological soil crusts are an initial stage of primary ecological succession, and are widely distributed on the wasteland surfaces of copper mine tailings that are undergoing natural ecological restoration. We investigated the cyanobacterial diversity and the dominant taxa in biological soil crusts growing on Yangshanchong and Tongguanshan copper mine tailings. We used conventional cultivation and fingerprinting by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Biological soil crust samples were collected from moss-algal crusts of the Imperata cylindrica community of the Tongguanshan and Yangshanchong mine wastelands, moss-algal crusts of the Yangshanchong mine wasteland, moss-algal crusts of the Hippochaete ramosissimum community of the Yangshanchong mine wasteland, and moss-algal crusts of the Zoysia sinica community of the Yangshanchong mine wasteland. The surface layers of tailings samples from bare wasteland without plant communities were collected for comparison. Conventional cultivation and molecular methods showed somewhat different cyanobacterial species composition. Microscopic observation showed that Microcystis, Chroococcus, Oscillatoria, Nostoc, and Planktolyngbya were the main taxa cultivated, and dominant species included Microcystis aeruginosa, Oscillatoria fracta, and Planktolyngbya subtilis. Different samples showed different species composition; however, M. aeruginosa was found in all biological soil crusts from wastelands at different developmental stages. It was abundant in the crusts of the I. cylindrica community of the Tongguanshan mine wasteland, in the moss-algal crusts of the Yangshanchong mine wasteland, and in the bare wasteland without the colonization by plant communities. Three 16S rRNA cyanobacterial-specific primers, CYA359F (forward), CYA781R(a) and CYA781R(b) (reverse), were used to assess the molecular diversity of these communities. The 16S rRNA gene was analyzed by PCR-DGGE. Shannon-Wiener diversity indices were calculated based on PCR-DGGE banding patterns. The cyanobacterial diversity index of the same sample had obvious differences as shown by the assignments of the reverse primers, except for the moss-algal crusts from the Z. sinica community of the Yangshanchong mine wasteland. Twenty-four DGGE bands were excised from the DGGE gel and sequenced. All the 16S rRNA sequences showed at least 93% similarity with known sequences in the NCBI database. A phylogenetic analysis indicated that four sequences could be identified as related to Microcoleus (95%-98% similarity), two were affiliated with Leptolyngbya (95%-96%), and one grouped with Phormidium (97%). The other 17 sequences belonged to uncultivated cyanobacteria. Microcoleus was the dominant cyanobacteria in biological soil crusts from bare wasteland and in the H. ramosissimum community. Leptolyngbya was the dominant taxon in moss-algal crusts and in crusts from the Imperata cylindrica var. major community.