Gamma radiation-induced mutagenesis in cyanobacteria: screening for salt-stress tolerance
1998
Castillo, J. | Constantino, R. | Garcia, M.J. | Quijance, L. | Cao, E.(Philippines Univ. Diliman, Diliman, Quezon City (Philippines). Inst. of Biology) Loveria, M.
This study was designed to screen for the halotolerant potential of two unicellular isolates and two filamentous species. A comparison of the growth responses, chlorophyll a content and DNA profiles of the non-irradiated and irradiated cyanobacteria exposed to varying salt concentrations were done. The cultures were exposed to the following concentrations of NaCl and KCl; 0, 60, 120, 180 and 240 mM and the g-radiation dosage were as follows: 2, 4, 6, and 10 kilorads (Kr). Analysis of the growth response curves showed that filamentous strains (Nostoc commurie and N. carneum) were able to survive at higher NaCl/KCl concentrations in comparison to unicellular isolates (designated as Bolinao 33 and Lingayan 20). In the filamentous strains, highest growth response to NaCl treatment was attained at 60 mM (in 6 Kr dosage). On the other hand, in the unicellular forms, the highest level of concentration where the highest growth response was attained was at 0 mM (nm-irradiated for NaCl treatment, likewise for KCl it was observed at 60 mM (in 10 Kr dosage). Higher concentration of salts exposed to different dosages of radiation reduced chlorophyll content of the cyanobacteria. Statistical analysis revealed that there were no significant differences noted when the salt-treated and untreated cells were exposed to different dosages of g-radiation (2, 6, and 10 Kr)
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