Structural and functional stability of regenerated cyanobacteria following immobilization

Cyanobacterial preservation is important to ensure availability of pure strains for research without repeating the extensive process of isolation and purification. Preservation techniques should be able to conserve various wild-type characteristics of a strain and deter any loss of phenotypic characters that were originally present in the organism. In the present study, immobilization of four different cyanobacterial strains in calcium alginate beads was studied extensively to evaluate the merits of this technique in conserving various characteristics of these strains over a long period of time. Since the immobilized cultures were stored in dehydrated conditions and in dark for a period of 3 years, their viability and retention of assorted characteristics were of interest to credit this method for cyanobacterial preservation. Morphological investigations carried out using SEM provided excellent proof in favor of the technique. In addition, various biochemical analyses showed retention of growth rate, heterocyst frequency, and photosynthetic and respiratory abilities as well as performances of various enzymes of nitrogen metabolism such as nitrogenase, glutamine synthetase, nitrate reductase, and nitrite reductase. An investigation into molecular fingerprints of the organisms using PCR also presented proof of genetic stability in the organisms stored immobilized in calcium alginate beads for 3 years in dark under dehydrated conditions.