Sanitary quality and diversity of culturable bacteria and yeast in processed and in natura yerba mate (Ilex paraguariensis A. St.-Hil.)

Abstract

Yerba mate (Ilex paraguariensis) is a native plant of the southern region of Brazil, whose leaves, after processing, are used as a beverage by Brazilian, Argentinean, Paraguayan and Uruguayan inhabitants. The purpose of this work was to verify the sanitary quality of the processed yerba mate (presence of thermophilic and mesophilic bacteria, molds and yeasts, Salmonella sp. and coliforms), and to evaluate the microbial diversity (bacteria and yeasts) in leaves and in the processed yerba mate. Sample collections were carried out monthly from January to June 2013, in a yerba mate plantation fields (leaves) and from the local commerce (processed yerba mate) of Vargeão city, Santa Catarina state, Brazil. Standard methods were used to determine the bacteria and fungi counts, as well as to isolate bacteria and yeasts from leaves and processed yerba mate. Bacteria and yeasts identification was carried out through biochemical and physiological assays, and by rDNA gene sequencing. The main thermophilic bacterium found in processed yerba mate and leaves was Bacillus licheniformis. The mesophilic bacteria that predominated in leaves were Pantoea ananatis, Staphylococcus sciuri and Staphylococcus epidermidis, while in processed yerba mate there was a predominance of Bacillus megaterium, Bacillus amyloliquefaciens and Klebsiella pneumoniae. The most frequent yeasts identified in leaves were Aureobasidium pullulans and Sympodiomycopsis sp., and those identified in the processed yerba mate were Rhodosporidium kratochvilovae, Rhodotorula mucilaginosa and Sporobolomyces nylandii. All microbiological parameters for processed yerba mate were in line with the current Brazilian legislation, as well as the parameters established by the WHO.