Microalgal and cyanobacterial diversity of two selected hot springs of Garhwal Himalaya, Uttarakhand, India

Abstract

In the present study, two distantly located geothermal springs, namely Badrinath Hot Spring (BHS) and Yamunotri Hot Spring (YHS) of Garhwal Himalaya were investigated for their cyanobacterial and microalgal diversity. A total of 56 species belonging to 10 microalgal and 13 cyanobacterial genera were chronicled from the selected hot springs along the gradients of temperature and other physicochemical factors. The most abundant photosynthetic forms in both springs were cyanobacteria. Synechococcus elongatus was fairly abundant in the studied springs as compared to other algal species. The different morphotypes of Synechococcus sp. were reported across the temperature gradient of 40 to 60 °C. Cyanobacterial and microalgal diversity measured by Shannon’s diversity index (H`) decreased drastically in BHS as the temperature reached > 50 °C. Mastigocladus laminosus was reported in BHS as temperature ranged from 55 to 60 °C, but not observed in YHS. Some diatoms, like Navicula sp., Nitzschia sp., Cocconeis sp., etc. were reported in BHS but were absent from YHS. The Canonical correspondence analysis confirms that pH, PO43– and temperature were influential factors, while ANOSIM and SIMPER analyses suggested a restricted distribution pattern of microalgae and cyanobacteria in two geographically secluded hot springs of Garhwal Himalaya. Moreover, the capability of these diverse algal forms to grow luxuriantly at elevated temperatures may be utilized in generating biomass feedstocks for the production of high-value bioactive compounds and algal biofuel, particularly in harsh outdoor conditions prevailing in tropical and subtropical areas. These algae may also be used in the bioremediation of wastewaters and sequestration of hot industrial flue gases. The genes and proteins enabling them to survive at extremely high temperatures may upgrade our understanding about the mechanisms of thermal tolerance, which would be useful in the production of industrially important thermostable enzymes/proteins.