Abstract
Cyanobacteria, the major photosynthetic organisms, cover a large surface area of this planet. These organisms, being photosynthetic, have the capacity for sequestration of atmospheric carbon dioxide, a significant greenhouse gas that causes global warming. In this work, we have collected, developed pure culture, and identified 25 cyanobacterial species from semi arid agricultural rice fields of western Odisha with the high-temperature environmental setting. The purpose was to screen the cyanobacteria that can survive and grow at high temperatures with high photosynthetic efficiency. Cyanobacteria belong to genera Nostoc, Anabaena, Calothrix, and Hapalosiphon are observed to survive at 45°C. Among the cyanobacterial species, Anabaena iyengarii 17-SKD-2014 was found to exhibit higher growth, protein content, photosynthetic pigments, and photosynthetic O2 evolution at 45°C in comparison to other cyanobacterial isolates. Further, this cyanobacterium was grown at 50°C to analyze the cellular viability, and only up to ninth day incubated culture could recover from high-temperature stress after transferring to 25°C. Even though this indigenous cyanobacterial species failed to survive at 50°C in the laboratory conditions beyond a time limit, but this could be biotechnologically manipulated for effective carbon dioxide sequestration contributing to minimization of global warming.
Highlights
Cyanobacteria, the most diversified microorganisms, inhabit terrestrial as well as aquatic environments
We have examined the distribution and thermo-tolerance of mesophilic indigenous cyanobacteria found in the paddy fields of Western Odisha
Twenty-five axenic cyanobacterial isolates belonging to four genera, namely Anabaena, Nostoc, Calothrix, and Hapalosiphon, predominantly found in paddy fields, were subjected to high-temperature treatment (45°C) for 15 days (Table 1) to observe their visible survivability and it was noted that 12 different isolates could tolerate the heat
Summary
Cyanobacteria, the most diversified microorganisms, inhabit terrestrial as well as aquatic environments. They are widely distributed in various environments, ranging from hot springs, volcanic islands[1], hot deserts[2], sandy soils[3], highaltitude rivers, lakes, and seas[4,5,6] to fresh-water ecosystems[7]. Necessary to study the adaptive and tolerance mechanisms they develop in response to changing stress conditions[8,9]. These microorganisms can acclimatize their growth to various environmental pressures with specific changes in their morphology, metabolism, and genetic makeup[10,11,12,13]. Global warming and the current environmental scenario increase the importance of temperature as one of the major stress factors that could be examined to understand the survival strategy of these microorganisms
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