Caracterização fisiológica e análise filogenética de bactérias termotolerantes do semiárido paraibano

Abstract

The caatinga is a unique biome that, even with the advancement of agroindustry, is still underexplored for ends that are not plant extractivism, agriculture or livestock farming. The present environmental conditions positively pressured the resident organisms to adapt to diverse factors such as high temperatures, water shortage, exposure to UV radiation and extremely oligotrophic soils. There is a little information on caatinga microbiota, about its diversity and production of biomolecules. The present work had the objective to determine the physiological characteristics and perform the phylogenetic analysis of bacteria isolated from root-free, rhizospheric and rhizoplane soil of the grass Aristida adscensionis L. of native pasture at the São João do Cariri region, Paraiba state, Brazil. In this work were analyzed 36 isolates of bacteria in culture mediums with different concentrations of nutrients, and at the presence of 10% NaCl. The production of pectinases, proteases and lipases were performed using the respective substrates: citrus pectin, casein and residual vegetal oil. Subsequently, the use of sugars as carbon sources, the resistance to antibiotics and the molecular characterization of the bacterial isolates was done. All analyzed isolates showed growth on the nutrient agar, 10x and 100x diluted nutrient agar. All isolates produced proteases and most of them lipases. Pectinases were produced mostly by isolates of rhizoplane of A. adscensionis. The vast majority of isolates showed sensitivity to the antibiotics streptomycin, chloramphenicol and vancomycin. Nine isolates submitted to molecular analysis belonged to the Bacillaceae family and showed similarity with the species of the genera Bacillus (7 isolates) and Anoxybacillus (2 isolates). Some isolates showed the potential for more detailed research on the production of proteolytic and lipolytic enzymes.