Screening and selection of Anabaena spp. for desiccation tolerance through physiological parameters and multivariate analysis

Increase in desiccation is one of the adverse impacts of global climate change that limits the growth of microorganisms including cyanobacteria. Reduction in growth and nitrogen fixation by cyanobacteria due to desiccation is expected to severely restrict their application of cyanobacteria as biofertilizer. Therefore, in the present study the desiccation tolerance potential of ten different species of nitrogen fixing Anabaena strains commonly observed in rice fields was evaluated. The ten different species of Anabaena were grown in BG-11 medium supplemented with polyethylene glycol (10% w/v) and the desiccation tolerance potential was evaluated in terms of several important physiological parameters. Based on the physiological parameters and multivariate analysis the most desiccation tolerant species of Anabaena were identified. Desiccation-tolerant Anabaena fertilissima and Anabaena variabilis showed better growth, chlorophyll, carotenoid, sugar and protein content. They also accumulated the lowest levels of malondialdehyde and peroxides and showed higher superoxide dismutase activity. Physiological parameters such as carotenoid, sugar, nitrogenase activity and proline were also found to contribute significantly to the demarcation of Anabaena sp. and showed positive correlation with chlorophyll. The large diversity observed in the physiological parameters among the different species of Anabaena can be effectively used to screen and select desiccation-tolerant cyanobacteria as bio-inoculants to enhance desiccation tolerance in plants.