Aspergillus da seção Nigri de Interesse Biotecnológico Isolados de solo e serrapilheira

Abstract

Brazil is the country with the greatest biological diversity , presenting the widest continental biota of the Earth. The Atlantic Forest corresponds an area of 13 % of the brazilian territory, sheltering a large portion of this diversity. The fungi are extremely important organisms for the functioning of these ecosystems. Fungi commonly isolated from soil stands out species of Aspergillus. The members of the section Nigri are among the most important in the genus Aspergillus because are common worldwide and feature economical and biotechnological potential. Their identification is considered difficult and complex due to high genetic diversity. Therefore, the taxonomy of Aspergillus section Nigri has been investigated using morphological, biochemical and molecular data. Some species are responsible for causing food deterioration and mycotoxins production, however, other are important producers of organic acids, antibiotics and extracellular enzymes. Among produced the enzymes by these fungi, we can cite cellulases, amylases, peptidases, pectinase and phytase which have applications in several industrial sectors such as textile, food and drinks, agroindustry of animal feed, sillage, pharmaceutical, etc. The objective was to identify Aspergillus section Nigri species isolated from litter and soil through morphological, biochemical and molecular characterization, as well as to evaluate the enzymatic potential of these isolates. For these study were collected 198 samples from litter and soil (0-5 and 5-10 cm depth) during the two periods, rainy and dry the Atlantic Forest Biome belonging to the Minas Gerais State. After isolation, 42 Black Aspergillus were identified using macroscopic and microscopic criteria on CYA 25 and 37 °C, MEA 15, 25, 33, 36 and 40 °C for a period of 10 days. For biochemical analysis, was used CREA, MEA-Boscalid for 7 days at 25 °C, and Ehrlich test. The molecular analysis was performed by sequencing the ITS1 and ITS4 regions. The enzymatic potential was evaluated through enzymatic index, a semi -quantitative parameter used to evaluate the production of hydrolytic enzymes by fungi in solid medium. The study revealed the existence of 6 different groups, showing a good dicersity of species of Aspergillus section Nigri of. In the rainy season there was a greater richness of these species, where it was found 92.8 %, while in the dry season it was found only 7.2%. The groups I and II were identified through morphological and molecular characterization belonging to uniseriate species of Aspergillus aculeatus and Aspergillus aculeatinus, respectively, and the groups III, IV and VI was morphologically suggested to belong bisseriate species of the "aggregate Niger ," Group III = Aspergillus tubingensis, Group IV = Aspergillus niger, Group VI = Aspergillus foetidus and Group V could not be identified. According to enzymatic potential, only a pectinase enzyme not was produced by these species, but none species was potentially considered producers the tested enzymes, because the enzymatic index it was not satisfactory