Estabelecimento de técnicas de criopreservação para manutenção do Banco de Microalgas do Instituto de Biologia - Universidade Federal da Bahia

Abstract

Microalgae are photosynthetic microorganisms found in diverse habitats and capable of producing a high number of compounds of scientific, biotechnological and economic interest. The preservation of the characteristics of microalgae in culture collections has fundamental importance for the study of its biotechnological potential and biodiversity, however, the maintenance of microalgae in a liquid medium can affect the synthesis of compounds of importance for bioprospecting due to mutations, in addition to the risks of contamination. In order to reduce these risks, cryopreservation is an alternative for the maintenance of this material, this technique is widely used in the conservation of microbial biodiversity, which consists of exposing it to cryogenic temperatures, therefore, it is a viable resource for the maintenance of algal species, assisting in the preservation of biochemical characteristics, with a reduction in the growth rate, inbreeding and generating less damage to the genome. The cryopreservation process, however, can cause damage to cells called cryoinjuries, so the use of cryoprotectantes may be necessary. This research aimed to test and adapt cryopreservation protocols for Desmodesmus brasiliensis and Chaetoceros muelleri collected from the Microalgae Bank of the Laboratory of Bioprospection and Biotechnology of the Institute of Biology of the Federal University of Bahia, as well as to evaluate the efficiency and toxicity of cryoprotectants dimethylsulfoxide and methanol in the cryopreservation of the two species and calculate the growth rate for each species. Among the two microalgae tested in the present study, frozen at -80°C for twenty days, it was possible to cryopreserve D. brasiliensis, even without the addition of cryoprotectants, showing the highest growth rate. C. gracilis did not survive the freezing stage, under any of the treatments employed, therefore it is necessary to test new cryoprotectants and cryopreservation methodologies for the species. In view of the results, it is concluded that it is possible to cryopreserve species kept in a liquid medium in biobanks using a species-specific methodology, given their different characteristics.