Biodiversity of Tehran freshwater cyanobacteria and remote sensing analysis of reservoirs

ABSTRACT

Analysis of cyanobacterial diversity is an important step towards identifying new biological resources for production of bioactive compounds. In this study cyanobacterial surface coverage was assessed through satellite image analysis of Tehran drinking water reservoirs in late summer and early autumn of 2018. We also analysed freshwater cyanobacteria including seven local strains purified from surface water samples. Following a polyphasic taxonomic approach combining morphological and molecular methods the culturable strains were classified into Synechococcales and Oscillatoriales, representing at least three families and four genera. Similarity-based analysis of their partial 16S rRNA genes showed 93.4–97.0% sequence identity among the strains from different ecosystems. Considering 95–96% as the overall cut-off for discriminating bacterial species, strains UTMC6011 and UTMC6013 are likely to be new species. Physiological characterization of the new strains and nine others isolated previously by our group from another freshwater ecosystem led to identification of seven nitrogen-fixing, 11 sulphide-tolerant, three salt-tolerant and three heterotrophic strains. Further taxonomic analyses are needed to support investigation of their biotechnological potential.

Highlights

• The biodiversity and physiology of cyanobacteria in the main drinking water reservoirs of the megacity, Tehran, were studied by remote sensing and sample analysis.

• Seven cyanobacterial strains were isolated from the two freshwater lakes. Similarity-based analysis of obtained 16S rRNA gene sequence showed 93.4–97.0% sequence similarity with the strains from other ecosystems.

• Cyanobacterial isolates of these freshwater reservoirs included seven N₂-fixing, 11 sulphide-tolerant, three salt-tolerant and three heterotrophic strains.

KEYWORDS:

• Biodiversity
• freshwater cyanobacteria
• freshwater reservoir ecosystem
• phylogeny
• polyphasic approach
• remote sensing

Acknowledgements

The authors would like to thank Prof. Alexander V. Pinevich, Dr Svetlana G. Averina and Dr Olga Gavrilova for their valuable comments related to the isolation and morphological studies of cyanobacterial strains.

Disclosure statement

The authors state the absence of any competing interests.

Supplementary material

The following supplementary material is accessible via the Supplementary Content tab on the article’s online page at https://doi.org/10.1080/09670262.2023.2261113.

Supplementary fig. S1 Phylogenetic tree constructed based on 16S rDNA partial sequences. Obtained sequences aligned and phylogenetic tree constructed using ClustalW and MEGA7 softwares, respectively. 55 cyanobacterial sequences were included and three species of Chloroflexus were used as outgroups. A Maximum likelihood algorithm involving 1000 times boot-strap analyses was performed. Asterisks show strains isolated from Tehran freshwaters. * the isolated strains in this study.

Supplementary table S1. Main characteristics of Tehran dams.

Supplementary table S2. Measured values of water quality parameters and cyanobacteria concentration in one ml of samples.

Supplementary table S3. Morphometric characteristics of isolated cyanobacteria in this study.

Supplementary table S4. The physiological characteristics of cyanobacterial strains of Tehran dams. (+) growth, (−) lack of growth.

Authors contributions

Y. Tavakoli: Sampling, lab experiments and drafting the manuscript; F. Mohammadipanah: Conceptualization and revising the paper; S. Hamzeh: Remote sensing analysis; A. Sedighi: Remote sensing analysis.

Additional information

Funding

This research was partially funded by Iran National Science Foundation and University of Tehran.