Bioprospecting Aspergillus section Nigri in Atlantic Forest soil and plant litter

ABSTRACT: The use of fungi as a source of enzymes has become widespread in various industrial and commercial areas, and Aspergillus section Nigri has significant potential for producing enzymes. The aim of this study was to isolate Aspergillus section Nigri from plant litter and soil from the Atlantic Forest biome and evaluate it with regards to hydrolytic enzyme production. The trials for producing the enzymes were carried out in Petri dishes, using different culture mediums adapted for microbial growth and with the respective substrates for inducing enzyme production - cellulase (carboxymethyl cellulose), protease (skimmed milk), amylase (soluble starch), pectinase (citrus pectin), and phytase (Pikovskaya medium). Forty-two fungi were isolated, 16.7% derived from the plant litter layer and 83.3% derived from soil at a depth of 0 to 5 cm and 5 to 10 cm. All of the isolated lineages presented amylase, protease, and phytase production, with 90.4% producing cellulase and no lineage producing pectinase. From the results, the significant potential for Atlantic Forest fungi as hydrolytic enzyme producers could be perceived. The enzymatic activity evaluations presented a satisfactory result when compared with the scientific literature.摘要：真菌作为酶源的应用已在诸多工业与商业领域得到广泛普及，黑曲霉组（Aspergillus section Nigri）在酶类生产方面具备显著应用潜力。本研究旨在从大西洋森林生物群系（Atlantic Forest biome）的植物枯落物与土壤中分离黑曲霉组菌株，并对其水解酶（hydrolytic enzyme）生产能力开展评估。酶生产实验均在培养皿（Petri dishes）中开展，采用适配微生物生长的不同培养基，并以对应底物诱导酶合成：以羧甲基纤维素（carboxymethyl cellulose）为底物诱导纤维素酶（cellulase）生成，以脱脂牛奶（skimmed milk）为底物诱导蛋白酶（protease）生成，以可溶性淀粉（soluble starch）为底物诱导淀粉酶（amylase）生成，以柑橘果胶（citrus pectin）为底物诱导果胶酶（pectinase）生成，植酸酶（phytase）的诱导则采用皮克维亚培养基（Pikovskaya medium）。本研究共分离得到42株真菌，其中16.7%来源于植物枯落物层，83.3%来源于0~5 cm及5~10 cm土层的土壤样本。所有分离得到的菌株均具备淀粉酶、蛋白酶与植酸酶生产能力，其中90.4%的菌株可产纤维素酶，无菌株可产生果胶酶。由实验结果可见，大西洋森林来源的真菌作为水解酶生产菌具备显著应用潜力。酶活性（enzymatic activity）检测结果与现有科学文献报道相比表现优异。