Identificação de actinobactérias em solos de cerrado mineiro durante estação de baixa pluviosidade

Abstract

Soils house a broad range of microbial species fundamental to the health of them, since the present bacterial population can alter the chemical and physical composition of the soil. It contributes towards the sustainability of cities and towns, of farming and takes part in most of the biogeochemical cycles in the planet, in spite of being an important source of new drugs and other metabolites of industrial interest. Actinobacteria colonize mainly the soils. It is a group of gram-positive bacteria capable of degrading macromolecules present in soil, mainly proteins. The cerrado soils house a rich diversity of populations of actinobacteria yet not very well explored, constituting an excellent source for the search of new enzymes. Minas Gerais cerrado soils of the regions of Arcos, Luminárias and Passos, were surveyed as to the physicochemical characteristics and to the microbial diversity in the dry season. The samples of soils of the three regions proved acidic, though, in Luminárias, a high concentration of aluminum (0.6-1.5 mol/dm3) was found. The bacterial population during the dry season in the towns of Arcos, Luminárias and Passos, in Aaronson’s medium was, respectively, of 7.274; 7.124 and 7.33 log CFU/ml and in the vitamin-humic acidic medium, it was of 6.568; 6.864 and 6.738 log UFC/ml, in the same order. The species of Actinobacteria found in each region differ from one another and among the culture media utilized; proving that different culture media result into greater species diversity. Three genera predominated in all the soil samples: Arthrobacter, Streptomyces and Microbacterium, which are ubiquitous microorganisms and colonize typically the soils. A number of species isolated presented literature data which corroborate its use in several biotechnological processes and in bioremediation, chiefly suggesting further research