Influence of low temperature and salinity stress on growth behaviour and pigment composition of Antarctic and tropical isolates of a diazotrophic cyanobacterium Anabaena

Abstract

Specific growth rates and pigment contents, viz. chlorophyll-a, phycocyanin and carotenoids were measured in axenic unialgal cultures of Antarctic and tropical isolates of Anabaena grown at various temperatures and salinity levels (50-300 mM, NaCl). Antarctic isolate exhibited growth at 5°C which was not evident in case of tropical isolate. Moderate salinity (50 mM, NaCl) enhanced the growth of Antarctic isolate whereas growth of tropical isolate was suppressed at all the concentrations of NaCl tested. Unlike tropical isolate an increase in pigment content of Antarctic isolate was observed at 5°C . Data of present study reveal that pigment synthesis and growth is not suppressed in Antarctic isolate of Anabaena at low temperature and moderate salinity stress. It is concluded that Antarctic isolate of Anabaena is much tolerant to low temperature and salinity with respect to its tropical counterpart.