Study the physiological characteristics of Fischerella sp. Strain FS 18 under extreme, alkalin condition and relative and extreme limitation of CO2 at different times.

Subject Areas : Bio-fertilizer

Samaneh Diyanat ¹ , Shademan Shokravi ² , homa mahmoodzadeh akharat ³

1 - دانشکده علوم
2 - Faculty of Basic Science of Gorgan Azad University
3 - Department of Biology, Mashhad Branch, Islamic Azad University, Mashhad, Iran

Received: 2023-12-20 Accepted : 2025-01-17

Keywords: : Cyanobactria , Fischerella, p H, Photosynthesis , Time,

Abstract :

For the first time, the effect of extreme alkaline conditions (pH 12) in two short (24 hours) and long (120 hours) periods of extreme and relatively carbon dioxide limitation (aeration, no aeration, no carbon dioxide inoculation) on the survival, growth, pigment content, phycobilisome structure and function, and oxygen liberation rate were investigated in the native Stigonomatal cyanobacterium Fischerella sp.FS 18 has been investigated. The results showed that the Cyanobactrium had survival in both periods. That seems to relate with entering the exponential phase of growth, without lag phase that is a kind of acclimatization to alkalin condition. The results of the absorption spectra in the light-harvesting antennae in two areas of carotenoid and phycocyanin indicateted compliance with the conditions. Cyanobacteria do not produce phycoerythrin under the applied conditions. The shift in the absorption peak of chlorophyll and phycobilisome pigments decreasesed especially in 120 hours. The amount of oxygen liberated in extreme limitation of carbon dioxide was 21.95and 38.92µmol O2/medw in 24 hours and 120 hours is equivalent to 21.95 micromoles of oxygen per milligram of dry weight per minute, and in 120 hours is equivalent to 38.92 micromoles of oxygen per milligram of dry weight per minute. Finally, Fischerella sp showed a decrease in terms of growth, photosynthetic pigments, and rate of photosynthesis in pH 12 than optimum pH 10 but this decrease is not so much that it can be considered as an obstacle for delet survival and growth.