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Punjabi University (2014)

Cyanobacterial diversity of cold desert and hot water springs of north western himalayas

Singh, Yadvinder

Titre : Cyanobacterial diversity of cold desert and hot water springs of north western himalayas

Auteur : Singh, Yadvinder

Université de soutenance : Punjabi University

Grade : Doctor of Philosophy (PhD) 2014

Résumé
Cyanobacterial diversity from cold desert and hot water springs of North-Western Himalayas has been studied using polyphasic approach. A total of 625 cyanobacterial isolates were cultured from 150 samples : 497 isolates from 6 hot water springs of Himachal Pradesh and 128 isolates from 3 hot water springs of Uttarakhand ; and 460 isolates were cultured from 220 samples collected from cold desert of Lahaul-Spiti, Himachal Pradesh. The cyanobacterial diversity was represented by 60 species belonging to 21 genera. The isolates from hot water springs were represented by 22 species of 11 genera while isolates from cold desert area were represented by 38 species of 16 genera. Five genera were present exclusively in hot water springs and 10 genera were present exclusively in cold desert area while 6 genera were common to both hot water springs and cold desert area. A total of 220 cyanobacterial isolates, out of 625 isolates from hot water springs, and 226 cyanobacterial isolates out of 460 isolates form cold desert area, representing morpho-species from each sampling site were subjected to molecular characterization by amplified rDNA restriction analysis, 16S rRNA gene, rbcL gene and cpcB-IGS-cpcA phycocyanin locus region sequencing for elucidating their identity, diversity and phylogenetic relationships. ARDRA analysis revealed 22 groups of isolates from hot water springs and 38 groups of isolates from cold desert area. Sequence analysis of 16S rRNA gene, rbcL gene and cpcB-IGS-cpcA phycocyanin locus region revealed that identity of majority of cyanobacterial species from both habitats was congruent with the identity based on morphological features. The identity of 3 taxa ; Leptolyngbya sp. PUPCCC 112.22, Phormidium sp. PUPCCC 118.2 and Phormidium sp. PUPCCC 118.3 from hot water springs and 6 taxa ; Leptolyngbya sp. PUPCCC 112.9, Leptolyngbya sp. PUPCCC 112.11, Planktothrix sp. PUPCCC 108.5, Planktothrix sp. PUPCCC 108.6, Nostoc sp. PUPCCC 405.3 and Nostoc sp. PUPCCC 405.7 from cold desert area, based on both morphological features and molecular markers, did not match with known cyanobacterial species, indicating these are potential candidates as new species. The phylogenetic relationships based on molecular markers, in most cases were consistent with the taxonomic assignments based on their morphological features. Phylogenetic analyses also revealed that taxa from hot water springs and cold desert area of NorthWestern Himalayas belonging to Nostocales and Stigonematales are monophyletic, whereas those belonging to Chroococcales and Oscillatoriales are polyphyletic.

Non-heterocystous filamentous forms dominated hot water springs as well as cold desert area. Oscillatoriales were dominant in both types of habitats in terms of species abundance. Based on the nutrient contents, Sissu Lake is classified as mesotrophic while Chandra Tal, Suraj Tal and Deepak Tal are ultra-oligotrophic and hot water springs are moderately alkaline with varied nutrient contents. Canonical correspondence analysis revealed temperature, pH, conductivity, and nitrogen, sulphur and phosphate as major factors influencing distribution of cyanobacteria in hot water springs, whereas their distribution in lakes of cold desert area were influenced by temperature, pH and nutrient level.

Mots clés : Cyanobacterial diversity, cold desert, hot water springs, north-western Himalayas, 16S rRNA gene, canonical correspondence analysis

Présentation et version intégrale

Page publiée le 12 octobre 2016, mise à jour le 2 février 2021