Recovering a biotechnological important Spirulina platensis strain: isolation and maintenance of monocultures

1RAMAYON MJ, PIZZOLINI IC, GOZZI MS, ZIELLA PA, PITTA-ALVAREZ SI

Florianopolis

Congreso; IV Latin American Congress of Algae Biotechnology (CLABA) and the IV Workshop of the Brazilian Network of Marine Algae Biotechnology (WSREDEALGAS),; 2013

Brazilian Network of Marine Algae Biotechnology and Federal University of Santa Catarina

Within the framework of launching and developing a Microalgae Culture Laboratory in the Plant Biotechnology Lab at the Argentine Business University (UADE), several activities were initiated with the purpose of building a culture collection for use in large-scale cultivation for the production of biomass and diverse biomolecules with industrial applications. This study refers, specifically, to one of the first activities to be conducted in this new laboratory, and it is related to the recovery of a strain of Spirulina platensis, originally from Italy. This strain had been grown massively over twenty years in the Province of Buenos Aires (Argentina) in pools in greenhouses that are not currently in use. The significance of the recovery of this particular strain lies in that it is already adapted to the environmental conditions of the temperate climate of the Province of Buenos Aires. This adaptation, which is usually a very long process, represents an advantage for the development of new enterprises since it is an essential step to obtain optimum yields of biomass production. Spirulina is a photosynthetic cyanobacterium which has spiral trichomes. It is very popular in algal biotechnology because it is easy to cultivate and harvest and it is an important biological resource due to its high protein content and the presence of vitamins, minerals and antioxidants. In terms of its morphology, Spirulina presents polymorphisms associated with the degree of coiling of the trichomes. To carry out its recovery, a water sample from the inside of greenhouse in disuse was taken, and it was observed by light microscopy. A few filaments with ?super-coiled" morphology were detected. Spirulina was accompanied by other microalgae that were identified as Chlorella and Chrococcus. This coexistence is usual in natural environments. To isolate the strain of interest, the fact that Spirulina grows with high pH values was taken into consideration. Aliquots of the original sample were taken and they were cultured in Zarrouk medium with the following pH values: 9, 10, 11 and 12. After a week, it was observed that in cultures with pH 9, the algae Chrococcus and Chlorella were predominant, while in the remaining pH conditions Spirulina was the main one. The highest numbers of Spirulina filaments were found in the medium with pH 11. As a result, an aliquot of this culture was transferred to fresh medium with pH 11 and, through successive subcultures, a monoculture was obtained. In terms of morphology, it was observed that when Spirulina was transferred to Zarrouk medium with pH 11 under controlled conditions of light and temperature, it reverted to its original morphology, constituted by regular helices. These morphological types can revert between them according to environmental factors such as light intensity and amount of nutrients. Interpretations related to these observations will be discussed. Furthermore, discussions related to the future applications of this actively growing strain in the Microalgae Culture Laboratory (UADE) will be presented.