Response of a rice field cyanobacterium Anabaena sp. to physiological stressors

Abstract

The impact of physiological factors such as heat, salinity and L-methionine-DL-sulfoximine (MSO) on growth and total protein profile was studied in a rice field cyanobacterium, Anabaena sp. There was a gradual decrease in growth rate of the organism with increase in incubation time at 47°C; by 168 h of incubation there was essentially no growth. NaCl concentration > 5 mM inhibited growth of the organism, and there was apparently no growth at > 200 mM NaCl-supplemented media. Similarly, growth was inhibited with MSO concentration > 5 μM and there was no growth in cultures treated with > 100 μM MSO. SDS-PAGE protein profile after heat stress revealed a decline in the synthesis of several proteins but at the same time, synthesis of a new set of proteins of approximately 60–65 kDa was induced after 12 and 24 h of incubation and the same was completely eliminated after 96 h of incubation. Cultures treated with 10 mM of NaCl did not show any change in the protein pattern. In contrast, 100 mM NaCl treated cultures elicited a number of new proteins at around 29, 32, 40 and 70 kDa. Most of the protein bands disappeared in the cultures treated with 500 mM NaCl. Cultures treated with 10 μM MSO did not show any change in the appearance of the protein bands, whereas the cultures treated with 100 μM MSO showed a drastic decline in the intensity of all protein bands. The results indicate that different stressors exert specific effects on cyanobacterial protein synthesis.