Acclimation of soil cyanobacterium Fischerella sp. FS 18 under NaCl stress

In this research we showed the effect of NaCl on growth, photosynthesis and antimicrobial activity in cyanobacterium Fischerella sp. FS18. The cyanobacterium was treated with different concentrations of NaCl (NaCl-free, 0.5 & 1%). Results revealed that the growth rate was higher in NaCl-free and salinity did not inhibit growth of other treatments. Similar results were seen in the case of other physiological processes. The light-saturated photosynthetic rate was higher in NaCl-free and it decreased with increasing salinity. Regarding antimicrobial responses, aqueous, petroleum ether and methanol extracts of the strain were examined against four bacteria and two fungi for antimicrobial purposes. The Results indicated that the growth of Staphylococcus epidermidis PTCC 1114 was inhibited by all treatments. Aqueous extract did not have any inhibitory effect on Bacillus subtilis PTCC 1204. None of the treatments had decreasing effect on Gram negative bacteria Entrococcus feacalis ATCC 8043 and Escherichia coli PTCC 1047. Among the fungi, Candida kefyr ATCC 1140 was more sensitive. Totally it is concluded that Fischerella ambigua FS18 has more antimicrobial activity in saline environments. Also growth and photosynthesis of this strain decrease (but not inhibit) with increasing NaCl, the potential that makes it valuable for use as biofertilizer in paddy fields.