ISOLATION AND IDENTIFICATION OF YEASTS ASSOCIATED WITH Apis mellifera

Bees are key pollinating species worldwide. Their colonies are exposed to different factors of agricultural ecosystems throughout the year, and these environmental variables may affect the microbial balance of individuals and beehive. Therefore, studies of the microbiota associated with bees are important to elucidate new species that may present biotechnological applications. Thus, the work aimed to isolate and characterize yeasts of the European bees Apis mellifera pollinator of the plant Antigon leptopus, popularly known as "amor-agarradinho" located in Lavras-MG. In this way, ten bees were captured directly from the plant during pollination and placed alive on plates containing Yeast Extract Peptone Glucose (YEPG - pH 3.5) for 30 minutes. The procedure was performed with a bee per plate and incubation conditions of 28 °C for 48 h. The functional characteristics of the yeasts vectored by A. mellifera were measured by physiological and biochemical tests analyzing their abilities to assimilate and ferment maltose, galactose, trehalose, raffinose, glucose and sucrose. The results used for identification were taken from the Fungal Biodiversity Center site and by identification keys according to the literature. In addition, the isolates were analyzed using the technique of protein profile analysis (MALDI-TOF MS) and grouped together in dendrograms. Five distinct morphotypes of yeasts were isolated from the bees. Morphological analysis showed that isolates exhibited colors ranging from white to cream. Results of MALDI-TOF MS allowed grouping only 2 morphotypes, characterizing a clade. The functional characteristics reveled that after 21 days of analysis only one morphotype did not ferment any of the carbohydrates. Besides, two morphotypes did not ferment galactose, trehalose or raffinose. Regarding to the assimilation test, except for a morphotype, all showed ability to assimilate the carbohydrates tested. The assimilation of galactose, maltose, sucrose and trehalose as presented in this study suggests that the isolates are originated from plants part, such as fruits, flowers and nectaries, what is justified by the direct transport of insects, especially bees, which carry yeasts from flowers for honey production and to reserve in nests. Therefore, it was concluded that of the 5 morphotypes obtained through the analysis of the protein profile via MALDI-TOF, three were not identified and two were recognized as Candida viswanathii and Pichia fermentans, species that were already isolated from bees.