88D-7 |
Identification of yeasts isolated from "tepache", a traditional fermented fruit beverage, through traditional and molecular taxonomy |
R. MORENO-TERRAZAS1, P. E. Lappe-Oliveiras2, R. Vazquez-Juarez3, S. Huerta-Ochoa4, I. Guerrero-Legarreta4, and E. J. Vernon-Carter5. (1) D. I., Universidad Iberoamericana, Prolong. Paseo de la Reforma # 880, Mexico City, 01210, Mexico, (2) I.B., UNAM, (3) L.B.O.M., CIBNOR-La Paz, (4) DB, UAM-I, (5) IPH, UAM-I Traditional fermented beverages made from fruit pulps or juices such as "tepache", undergo spontaneous fermentation. Several microbial groups such as yeasts participate in this process, which show morphological, physiological and biochemical characteristics which vary from those described in the diagnosis of the type species in the literature. The objective of this work was to ascertain through molecular taxonomy the identity of yeast species, isolated from "tepache" commercial samples, in comparison with traditional taxonomy techniques. Of 27 isolated yeasts from 2 samples (A and B), 8 representative strains identified by traditional taxonomy techniques in accordance to the schemes of Yarrow, following the keys of Kreger-van Rij, Barnett et al., and Kurtzman and Fell, were selected for checking their identity through molecular taxonomy(region sequence D1/D2 of 26S DNAr). DNA was obtained from cultures aged 24 h in GYEP, extracted with chloroform-phenol, amplified by PCR with primers NL1 and NL4. Marking and sequencing was done with the technique of Saenger et al. 4 strains of Saccharomyces cerevisiae were identified from sample A, three from the intermediate fermentation, and one from the final fermentation steps, all with 99 and 100% homologies. An extra strain was Kloeckera apis confirming its identity without differences with the diagnosis, but with a 94% homology. In sample B in the intermediate fermentation step, the strain identified as Candida sphaerica was reidentified as Candida intermedia with 99% homology. In the final product the identification of Saccharomyces cerevisiae was confirmed with 99% homology. The strain traditionally identified as Kloeckera apis was reidentified as Kloeckera africana with 98% homology. Molecular taxonomy allows the reidentification of strains occurring in little studied substrates, initially identified by traditional taxonomy, that differ from the diagnosis of the type species.
Session 88D, Food Microbiology: General
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