Solamento e screening de fungos produtores de enzimas hidrolíticas de bacupari (Garcinia Gardneriana) em fermentação espontânea

Abstract

Even today there are few studies analyzing the microbial biodiversity of the Amazon. Amazonian fruits can be the primary habitat and source of energy in the life cycle of many fungi, and these microorganisms are recognized as potential sources of hydrolytic enzymes. In this sense, the objective of this work was to characterize the autochthonous fungal microbiota, as well as to isolate and select filamentous fungi and yeasts from the Amazonian bacupari fruit (Garcinia gardneriana) in spontaneous fermentation, according to their potential for the production of pectinase, invertase and lipase enzymes. Whole bacupari fruits (peel, pulp and seed) were macerated in sterilized plastic bags and left to ferment for 15 days at 30 ºC. Samples for monitoring the physicochemical changes and microbiological analyzes were collected on days 0, 3, 6, 9, 12 and 15 of fermentation. The titratable acidity of the fresh fruit was 1.24 (g/100g citric acid), during fermentation the titratable acidity decreased from 1.3 at time 3 to 0.5 g lactic acid/100 g fruit at time 15, the pH fluctuated slightly, reaching 6.61 on day 15, close to that found at the beginning of fermentation. Moisture, crude fiber and ash contents showed a slight reduction, while lipids and proteins increased during the fermentation process of the fruit. Total reducing sugars were partially consumed (72.7% or 1.7g/100g), which was expected due to their consumption by microorganisms. In the identification of the fungal community, a total of 59,988 sequences and 19 different fungal species were obtained, being time 6 with the highest abundance. The fungal population ranged from 5.30x105 CFU/g to 8.41x105 CFU/g, during the spontaneous fermentation of bacupari, with 106 yeasts and 22 filamentous fungi isolated. The yeast colonies were mostly circular, white, with entire, opaque and flat margins. Yeast cells were predominantly ovoid. The filamentous fungi were commonly presented as hyphae, filamentous margin, purple in color, without elevation. In the selection of strains on plates, 106 isolates (100%) produced invertase, 23 isolates (21.69%) secreted lipase and none produced pectinase. In a quantitative evaluation, 4 filamentous fungi showed potential for the production of hydrolytic enzymes, with BCF 5.5, the best producer of invertase (1.0 U/mL) and BCF 23.2, standing out in the production of lipase (0.05 U/mL). Among yeasts, isolates BCL 5.1 and BCL 18.3 produced 0.8 U/mL of invertase and BCL 29.4 produced 0.07 U/mL of lipases.