Diversidade microbiana e atividade enzimática de fungos provenientes de terra preta antropogênica do Baixo Amazonas

Abstract

The Anthropogenic Dark Earth (TPA) is presented in the form of small spots randomly distributed, especially in central and eastern Amazon. Denominations, as well as its unique characteristics, are due to human action of indigenous civilizations that lived in these archaeological sites. The large amount of stable organic matter present in these archaeological sites comes from the indigenous dumps where remains of animals, vegetables, fecal waste, human bodies, ceramic fragments, lithic artifacts and pyrogenic carbon were deposited. Among the microorganisms present in this soil, yeasts play a key role in the industry and the environment. This group is correlated with fermentation processes of various types of sugars, production of vitamins, enzymes, extracellular factors micocinogênicos. The objective of this study is to evaluate the diversity of microorganisms in TPA using electrophoresis on denaturing gradient gel (PCR-DGGE), relating the results with the physico-chemical characteristics of the soil. In addition, tolerance test at high temperatures, glucose and ethanol production enzymes and mycotoxins were conducted to select strains with possible biotechnological potential. We obtained 88 (eighty eight) isolated yeast. Of these, none bore the temperature was 50 ° C or tolerant to 50% glucose medium, and five (5) isolates (5.7%) 30% ethanol tolerated in the middle. Of the 88 isolates, thirteen (13) isolates (14.8%) had great activity for the production of amylase activity, 25 (twenty five) isolates (22%) were strongly positive for production caseinase and thirteen (13) isolates (14.8%) had great activity for the production of gelatinase. Still, 66 (sixty-six) isolates (75%) were positive for production of the enzyme cellobiase and (55.7%) were positive for esterase enzyme. To evaluate the mycocinogenic activity, 88 isolates were tested against strains of Candida krusei and Candida albicans. No isolate showed activity against C. krusei and 22 (twenty two) isolates (25%) showed activity against C. albicans. A 16S rRNA region (V6-V8 region) was sequenced for identification of prokaryotic and 18S rRNA region and the internal transcribed spacer (ITS) for identifying eukaryotes. The PCR-DGGE profiles of 18S rRNA region and ITS identified genera of yeast and filamentous fungi. The genera found for bacteria were Bacillus, Klebsiella, Pantoea, Enterobacter, Lactobacillus, Escherichia, Leuconostoc and actinomycetes, as Streptomyces and Mycobacterium. In fungal community, we observed the presence of Zygosaccharomyces, Lachancea, Saccharomyces, Cladosporium, Candida, Penicillium and Zygomycetes ascomycetes and uncultured. The pH value of the soil was 6.2. The soil had high levels of minerals, sodium except for (not detected) and aluminum (~ 0.1 cmol / dm3). The organic matter was found at a concentration of 3.84 dag / kg. Some groups of microorganisms had not been previously associated with soil TPA. Microbial diversity observed associated with chemical results demonstrate that high fertility of the soil, suggest that the same can be a source of microorganisms of interest.