كليدواژه :
Heterocystous cyanobacteria , morphological variations , morphometric analysis , Z8 medium
چكيده فارسي :
Studying the cyanobacteria strains grown on different culture media has led to controversies when they are identified by classic keys. Hence, the main target of this study is to identify cyanobacteria strains and compare their distribution in different soil, then identification the culture media with the highest stability and least effect on their variations. In this regard, soils samples of Ala gol, Aji gol, and Alma gol lakes belong to Golestan province (north of Iran), were collected and cyanobacteria taxa were isolated, and identified. In addition, an attempt was made to determine their incidence with some physicochemical characteristics of the soils. Morphological observation showed that five different strains were identified in Ajigol, four different strains in Alagol, and two different strains in Alma gol. Results of morphological identification showed that, Nostoc punensis and Anabaena sp. are common in Ala gol and Aji gol lakes, except Alma gol lake, where its EC was the highest and Dulcicalothrix alborzica and Neowestiellopsis persica were the only species found in the stands. Then two strains of Nostoc punensis and Desmonostoc salinum which had very variable morphology in culture media, were grown on Z8 and BG11 culture media without nitrogen, and morphological variations of cells were measured from the inoculating time up to the end of the stationary phase of their growth. In addition, morphological variations showed that, vegetative cells and akinetes of both strains changed into spiral form and large and heterocytes also had a bony form on BG11 medium but retained their natural form in Z8 medium. Accordingly, the Z8 medium is suggested to be used for its stability as preferred culture media to provide less morphological variations.
