Shift in Structural and Functional Diversity of Algal Community: An Ecophysiological Reason

Abstract

Cyanobacteria are the most ancient lineages of the domain Bacteria and have been playing a crucial role in shaping our planet through their highly proliferating nature in harsh environmental conditions because of their adaptability to grow along with other photosynthetic and heterotrophic microbial community with varied ranges of salinity, pH, temperature, radiation and water potential. Rise in temperature is reported to be the deciding factor in bringing down the microbial community diversity of hot springs. Here, for the first time, we reported the current status of the variability in community structure and predicted metabolic activity among cyanobacteria population of two sulfur hot springs Atri at 48°C and Taptapani at 58°C from the state of Odisha, Eastern India using metagenomics approach. We further tried to establish the relationship between the differential occurrences of cyanobacteria clades with those of coexisting non-cyanobacteria clades chloroflexi from our previously published findings of hot spring microbial diversity analysis. The predominance of mesophilic Arthronema (83.81%) in Taptapani and shifting predominance of thermophilic Leptolyngbya (96.25%) in Atri as discovered through 16S rRNA gene Illumina sequencing of their metagenomics DNA as a function of temperature are the intriguing features of the present study. Differential presence of cyanobacteria community at the phylum level in these two hot springs was trying to correlate with unequal coexistence of chloroflexi, the non-cyanobacteria members’ and the possible influence of physiochemical parameters including temperature. Variation in cyanobacteria diversity and composition of these hot springs as revealed through sequence analysis were also evinced by respective differences in richness, evenness and Shannon diversity indices. These two ecologically distinct tropical sulfur rich alkaline hot springs, Taptapani at 48°C harboring mesophiles and Atri at 58°C comprising thermophiles situated in the Eastern Ghats foothills of India provides a opportunity to understand the eco-physiological reasons behind the differences in structural and functional profile of cyanobacteria community.