Cyanobacteria are filament-forming photosynthetic Bacteria, which are thought to have been the first oxygen-producing organisms to have evolved, thereby having a profound impact on the evolution of the Earth's atmosphere and biosphere. They are still ubiquitous organisms today, and play an important ecological role in many environments. Traditionally, Cyanobacteria were classified on the basis of their morphological characteristics, but the advent of genetic techniques has shown that this classification system was of little value, with convergent evolution producing similar forms in many distantly related lineages, and many species able to produce different morphologies in different environments.
In a paper published in the journal Diversity on 5 March 2024, Kaihui Gao of the Zhejiang Provincial Key Laboratory for Subtropical Water Environment and Marine Biological Resources Protection at Wenzhou University, Yao Cheng of the College of Life Sciences and Technology at Harbin Normal University, Rouzhen Geng of the Research Center for Monitoring and Environmental Sciences of the Taihu Basin & East China Sea Ecological Environment Supervision and Administration Authority, Peng Xiao and He Zhang, also of the Zhejiang Provincial Key Laboratory for Subtropical Water Environment and Marine Biological Resources Protection, and of the National and Local Joint Engineering Research Center of Ecological Treatment Technology for Urban Water Pollution at Wenzhou University, Zhixu Wu of the Hangzhou Bureau of Ecology and Environment, Fangfang Cai of the Hubei Key Laboratory of Animal Nutrition and Feed Science at Wuhan Polytechnic University, and Renhui Li, again of the Zhejiang Provincial Key Laboratory for Subtropical Water Environment and Marine Biological Resources Protection, and of the National and Local Joint Engineering Research Center of Ecological Treatment Technology for Urban Water Pollution at Wenzhou University, describe a new species of Cyanobacteria from Qiandao Lake in Zhejiang Province, China.
Qiandao Lake is an artificial reservoir formed in 1959 by the damming of the Xin'an River, which created a lake which covers an area of 573 km² and holds 17.8 km³ of water. The lake also has over a thousand islands, and makes a popular tourist destination.
Gao et al. collected samples from the surface of the lake, which were cultivated in the laboratory, producing a bright blue-green or olive-green Cyanobacterium, with simple filaments lacking nodules. The filaments are long, and become thicker as they age, reaching a maximum of about 4.0 μm in diameter. Individual cells are 1.7 to 2.7 μm in length and have rounded ends.
A genetic analysis of the Cyanobacterium utilising the 16S rRNA gene, which is commonly used as a molecular marker for identifying Prokaryotes, revealed that it could be placed confidently within the genus Pegethrix, which is surprising, as all previously described members of the genus are nodule-forming and have been found growing on surfaces of soil, stones, and rocks, and at thermal springs. The new species is named Pegethrix qiandaoensis, meaning 'from Qiandao'.
The discovery of Pegethrix qiandaoensis emphasises the importance of genetic methods in the study of Cyanonacterial relationships. The species is morphologically and ecologically quite distinct from other members of the genus, and would probably not have been placed in the same family using traditional classification techniques, but genetic analysis shows a close relationship between all species of Pegethrix.
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