MOLECULAR AND PHYSIOLOGICAL CHARACTERIZATION OF NATIVE PICHIA KUDRIAVZEVII STRAINS FROM PATAGONIA

DEL MÓNACO S.; LOPES C.A.; RODRÍGUEZ M.E

Mar del Plata

Congreso; VIII Congreso Argentino de Microbiología General (SAMIGE); 2012

During the last few years, the potential use of the yeast Pichia Kudriavzevii in the biotechnological industry has been studied given its resistance to environmental stress. Particularly, the use of this species could be advantageous in the enological industry, regarding its adaptation to fermentative conditions and its capability to improve organoleptic properties of wine. The aim of this work was to analyze genetically and physiologically 24 strains of Pichia Kudriavzevii: 23 isolates obtained from fruits of native plants in the mount ecoregion, Schinus johnstonii (Molle, 3), Ephedra ochreata (Solupe, 11) and Lycium chilense (Yaoyín, 9), 3 isolates from enological environments (Alto Valle region) and 10 strains from different origins belonging to the NRRL collection (Y-5396, type strain; Y-7179; Y-134; YB-236; YB-238; Y-7724; Y-7750; Y-27196; Y-420; Y-870). The molecular characterization at strain level was carried out performing two experimental approaches: (a) RFLP of the mitochondrial DNA (mtDNA) using restriction enzymes Hinf I, Dde I and Rsa I, and (b) RAPD patterns (using primers OPA 9, OPA 12, OPA 14 y OPA 15). The RFLP-mtDNA with Hinf I showed a higher diversity of restriction profiles: A profile (all the native isolates), B profile (YB-236 and Y-27196), C profile (YB-238 and Y-7750), D profile (Y-5396), E profile (Y-134), F profile (Y-7179), G profile (Y-7724), H profile (Y-420) and I profile (Y-870). On the other hand, the RFLP-mtDNA with Dde I allowed to detect 6 different profiles (A: all the native isolates; B: Y-5396, Y-7179; C: Y-134, YB-236; D: YB-238, Y-7724, Y-7750, Y-27196; E: Y-420; F: Y-870), while the RFLP with Rsa I presented less diversity, with only 4 different profiles. The dendrogram based on RAPDs data concurred with the results in RFLP-mtDNA. Both experimental approaches indicated that all native isolates have a higher genetic relationship among each other (forming a single cluster) and a marked distance from the collection strains of different origins. Then, a phenotypic characterization was carried out, based in physiological aspects relevant for the enological industry: killer activity and killer sensitivity against a panel of killers yeasts (from our own collection and from a commercial collection), and detection of enzymatic activity in solid media for protease, pectinase, xylanase and wine aroma enhancing enzymes such as β-xylosidase, α-ramnosidase y β-glycosidase. Results indicate that all the isolates showed protease activity after 16 h of culture, a feature that is not typically found in yeasts, and a 95 % of the isolates showed β-glycosidase activity when esculin was used as a substrate. Another relevant aspect observed is the absence of killer activity in the strains studied. All these results obtained support the fact that our native isolates of Pichia Kudriavzevii present interesting features to be potentially applied in the biotechnological industry