PROTEOLYTIC POTENTIAL OF YEASTS ISOLATES FROM HONEY OF CAATINGA NATIVE BEES

Honey is used as therapeutic since the beginning of human civilization. The honey from stingless bees has antimicrobial, antiviral, anti-inflammatory, antioxidant activities and physicochemical properties, such as high sugar concentration, low water activity and acid pH. These properties make it an inhospitable environment for the growth and/or development of most microorganisms, causing them to remain in a state of latency, being the ones able to withstand it considered extreme tolerant organisms. Because fungi are excellent enzyme producers, they produce a variety of hydrolytic enzymes, especially proteases, being expected that the enzymes will have greater stabilization under adverse conditions, such as low water activity and pH variations. The objective of this study was to evaluate the proteolytic potential of yeasts isolated from honey of stingless bees native to the Caatinga Scaptotrigona sp. and Partamona cupira collected in the Serra Talhada, Pernambuco. The stock cultures were inoculated in test tubes containing Malt Extract Agar for seven days of growth. From stock cultures suspensions were made in sodium chlorate 0.9% solution equivalent to 0.5 tube of the McFarland scale, corresponding to a concentration of approximately 107 Colony Forming Units (CFU)/mL. From suspension, 50µL were inoculated in central point of Petri plates containing protease specific media using casein, and incubated at 28 ± 1 °C for 5 days. All experiment was performed in triplicate. After that, measurements of colony diameter and halo + colony were performed using the Enzymatic Relation Index (ERI= D / d), where D equals the total diameter (halo + colony) and d to the colony diameter, measured with the aid of a caliper. Twenty-three isolates belonging to the genera Candida, Pseudozyma and Zygosaccharomyces were tested, of which 83% presented proteolytic production, with an ERI ranging from 1.00 to 3.83. Among the isolates, one isolate of Candida apicola and one isolate Zygosaccharomyces sp. showed higher production of proteases, with ERI of 3.3 and 3.28, respectively. The results of the present study reiterate the importance of the bioprospection of such yeasts in enzymatic production and other metabolites of economic importance. Considering the methodological measures adopted, the isolates Candida apicola and Zygosaccharomyces sp. nov. 1 12I are excellent proteases producers, being able to be indicated for future studies of enzyme identification and immobilization.