Avaliação de enzimas de fungos da Amazônia visando a melhora do processamento das fibras da malva (Urena lobata L., 1753)

Abstract

The cultivation of caesarweed (Urena lobata) is cultural in the State of Amazonas since 1970 and the production of these fibers has had its ups and downs in the local economy. Currently, they are cultivated by riverside dwellers, being one of the main crops in the State of Amazonas. Malviculturists face some adversities in the process of obtaining fiber, such as onychomycosis, dermatoses, in addition to the risk of attacks by venomous animals. The Amazon region is potentially rich in microorganisms and among these are endophytic fungi, fungi associated with aquatic environments and soil. In chapter I, the microorganisms isolated and preserved from the tissues of in natura and macerated caesarweed are presented, in addition to the environments associated with their planting, obtaining 191 preserved fungi from a total of 344 isolated microorganisms. The fungi were grouped and 10% of the total of each group was sequenced, obtaining 24 different species with biotechnological potentials reported in the literature. In chapter II, Fusarium pseudocircinatum (1290) and Corynespora torulosa (1291) strains were evaluated for their potential for lignocellulase production using dried and crushed caesarweed as substrate in Manachini and GLBN 40 mineral salt solutions over 10 days under agitation. in submerged cultivation. The enzymatic extracts were filtered in a vacuum filtration system (Millipore 0.22 µm) and the lignocellulases activities were quantified. C. torulosa was the best producer of laccase (8,691 U/L), MnP (5,353 U/L), β-glucosidase (0.3285 U/mL) and CMCase (0.7038 U/mL) and F. pseudocircinatum was the best producer of FPase (1.29 U/mL), xylanase (12.05 U/mL) and pectinase (0.18 U/mL). None of the strains showed Lignin Peroxidase activity. In chapter III, the strains F. pseudocircinatum, Trichoderma longibrachiatum and Talaromyces pratensis were evaluated for pectinase production varying the temperature (28, 30 and 32° C), pH (4, 5 and 6) and cultivation time (3, 4 and 5 days) using dry caesarweed (5%) as substrate in submerged cultivation. F. pseudocircinatum showed the highest peak of pectinase production (0.2261 U/mL) under test conditions 28 °C, pH 6, on the 4th day of cultivation. Under these conditions, 18 fungi were tested for pectinase production and the three best strains [F. pseudocircinatum (1290) 0.2261 U/mL, Westerdykella dispersa, (1321) 0.2113 U/mL) and Diaporthe eucalyptorum, (1300) 0.1981 U/mL] were subjected to xylanase quantification [1290 (4.6113 U/mL), 1321 (2.7388 U/mL) and 1300 showed no activity] and CMCase [1300 (0.1003 U/mL), 1321 (0.0887 U/mL) and 1290 showed no activity]. Strains 1290 and 1321 were selected for production on a larger scale and for the shredding test where caesarweed stalks (10 cm) were submerged in an enzymatic solution at concentrations of 50, 100 and 200 mg/mL, at temperatures of 40 and 50 °C and collected at 3, 5 and 7 days. Both enzymatic extracts promoted fiber softening and defibration. The extract of the strain of F. pseudocircinatum (1290), temperature of 40 °C, 200 mg/mL and 7 days of incubation was more efficient in the defibration of caesarweed, allowing the reduction of the maceration time. Therefore, this research aimed to evaluate the potential of fungal enzymes for the processing of caesarweed in search of an alternative that provides a reduction in the defibering time and improves the quality of the fibers.