Efeito da limitação de luz e nutrientes na alocação para estruturas adaptativas em cianobactérias associadas epifiticamente às raizes de Salvinia auriculata

Abstract

Cyanobacteria are prokaryotic organisms, belonging to the group of bacteria, which perform oxygen photosynthesis and, some strains, are able to perform biological nitrogen fixation

(FBN) through the enzyme nitrogenase. You can organize different cell phones, be single- celled, colonizers or filaments, the latter being able to produce adaptable structures such as

heterocystes, akinets and hormogonium, depending on the conditions and resources of the environment. They are found in several habitats, both aquatic as part of the setting, as well as terrestrial in the sun, forming part of groups with other organisms such as the Azolla aquatic fern, and being part of the peripheral as in Salvinia auriculata. This is an aquatic fern known for quickly occupying bodies of water in conditions favorable to its growth. Understanding how the cyanobacteria associated with the roots of this fern can produce structures adaptable to changes in environmental factors, such as light and nutrients, can be important for understanding how these actions can be used for growth and reproduction. Thus, the objective of the work was to verify the effects of limitation by light and nutrients on the production of heterocystes, akinets and hormogonium by the epiphytic cyanobacteria in the roots of S. auriculata and isolated them, in addition to verifying the clonal growth (branches) of this macrophyte. aquatic. For this, an experiment was carried out in the greenhouse using sombrite (70%) for manipulating light and Hoagland's Solution (force 50%) for manipulating nutrients. The results demonstrated that light and nutrient factors affect the production of three types of adaptive structures. Heterocystes are used in the greatest number when there is a lack of nutrients and in full sun. Akinets are used mainly in the absence of nutrients and in the shade. The hormones were used in procedures with nutrients and mainly in the shade. The production of amino acids was negatively correlated with the production of hormogonium, in the two treatments with a shortage of nutrients,the number of akinetes produced was 630 against just 11 hormogonium. During the seven months of cyanobacterial stripping and plating, we obtained 13 morphologically distinct strains in the isolation process. Regarding the clonal growth of 1, as measured by the increase in the number of branches, there was an increase in the number of them in treatments with nutrients, regardless of the light factor, corroborating the hypothesis that this macrophyte grows vigorously in eutrophic environments.