Cytomorphological and nitrogen metabolic enzyme analysis of psychrophilic and mesophilic Nostoc sp.: a comparative outlook

Abstract

Cyanobacterial diazotrophs play a significant role in environmental nitrogen economy despite their habitat either tropical or polar. However, the phenomenon by which it copes with temperature induced stress is poorly understood. Temperature response study of psychrophilic and mesophilic Nostoc strains explores their adaptive mechanisms. The selected psychrophilic and mesophilic strains were confirmed as Nostoc punctiforme and Nostoc calcicola respectively, by ultrastructure and 16S rDNA phylogeny. The psychrophilic strain has extensive glycolipid and polysaccharide sheath along with characteristic deposition of cyanophycin, polyhydroxybutyrate granules, and carboxysomes. This is possibly an adaptive strategy exhibited to withstand the freezing temperature and high intense of ultraviolet rays. The biomass measured in terms of dry weight, protein, and chlorophyll indicated a temperature dependant shift in both the psychrophilic and mesophilic strains and attained maximum growth in their respective temperature niches. At low temperature, psychrophilic organism exhibited nitrogenase activity, while mesophilic strains did not. The maximum glutamine synthetase activity was observed at 4°C for psychrophilic and 37°C for mesophilic strains. Activity at 4°C in psychrophilic strains revealed their energetic mechanism even at low temperature. The nitrate and nitrite reductase of both psychrophilic and mesophilic strains showed maximum activity at 37°C denoting their similar nitrogen assimilating mechanisms for combined nitrogen utilization. The activity studies of nitrogen fixation/assimilation enzymes have differential effects at varying temperatures, which provide valuable insights of physiological contribution and role of Nostoc strains in the biological nitrogen cycle.

A Taxon-Wise Insight Into Rock Weathering and Nitrogen Fixation Functional Profiles of Proglacial Systems

“…These phyla are usually associated with soil environment and root symbiosis ( Rudnick et al, 1997 ; Gtari et al, 2012 ). In addition to Nostoc , the nitrogen fixers Bradyrhizobium , Geobacter , Paraburkholderia , and Frankia ( Sellstedt and Richau, 2013 ; Calderoli et al, 2017 ; Thangaraj et al, 2017 ; Choi and Im, 2018 ; Hara et al, 2019 ) were abundant in all our studied systems ( Figure 7 ). The same dominant nitrogen fixers were found in Nash et al (2018) where Nostoc , Geobacter , Rhizobium , Polaromonas , and Frankia were found dominant in all three forefield systems.…”

Plant Biostimulants from Cyanobacteria: An Emerging Strategy to Improve Yields and Sustainability in Agriculture

“…Cyanobacteria are ubiquitous in nature and their presence has long been reported in different soils (agriculture soils, rice fields, mines, desert lands, marshy soils) where they are responsible for bringing positive effects in different ecological situations [ 34 , 35 ]. Since the 1950s, application to soil of dry biomass (bio-inoculation) of different cyanobacteria, initially called “algalization”, has been shown to improve growth, health, and yields of various crops [ 36 , 37 ].…”

Preferential adsorption of uranium by functional groups of the marine unicellular cyanobacterium Synechococcus elongatus BDU130911

“…Marine cyanobacteria are considered to offer more advantages due to their high adaptability and applicability (Thangaraj et al 2017). These organisms are also known to sequester radionuclides through an extracellular metalbinding process that involves ionic interaction, precipitation, complexation, co-ordination, etc.…”