RODRIGUEZ maria eugenia
congresos y reuniones científicas
Biodiversity and biotechnological potential of yeast from native plant fruits from Patagonia
Mar del Plata
Congreso; VIII Congreso Argentino de Microbiología General (SAMIGE); 2012
Edible native plants from North Patagonia constitute an important source of yeast strains with interesting features to be potentially applied in the regional industry. The aim of this work was to study the yeast biodiversity associated to the fruits of three native plants from North Patagonia (Schinus johnstonii ?Molle-, Ephedra ochreata ?Solupe-, and Lycium chilense ?Yaoyín-) and to evaluate features of interest for biotechnological processes, such as enzymatic and killer activities. Sampling of the native fruits was carried out for two consecutive years (2010-2011). Total yeasts were isolated on GPY-agar plates after different preisolation tratments: A) Sonication and agitation of fruits in sterile water, B) Incubation of fruits on a selective medium supplemented with 8% ethanol at 10°C (30 days) and 30°C (15 days) and C) Natural fermentation of aseptically macerated fruits. Yeasts were identified by PCR-RFLP analysis of ITS1-5,8S-ITS2 region and confirmed by sequencing. After treatment A, total yeast count from Yaoyín fruits was 0,82 x 102±0,58 x 102 UFC/fruit, 8,15 x 102± 2,02 x102 UFC/fruit from Solupe and 2,53 x 105±1,86 x 105 UFC/fruit from Molle. The most frequent yeast species from Yaoyín after treatment A were Cryptococcus saitoi (51,3%) and Cryptococcus albidus (28,2%). Aureobasidium pullulans (17,8%) and Debaryomyces hansenii and Candida glabrata (14,3% each) were the most frequent species from Solupe and C. saitoi (46,9%) and A. pullulans (30,6%) from Molle. After preisolation method B, the most frequent species was Pichia kudriavzevii (63,0%) independently from the analyzed fruit plant; while after treatment C the most frequent species were C. saitoi (28,6%) and A. pullulans (15,9%). A qualitative screening of some relevant enzymatic activities (protease, pectinase, xylanase, β-xylosidase, α-ramnosidase and β-glycosidase) was carried out on solid media using isolates representative of each different plant and preisolation treatment. All isolates evaluated showed β-glucosidase activity. Additionally, the isolates belonging to A. pullulans presented the complete set of enzymatic activities tested. C. albidus and Periconia prolific evidenced protease activity and Rhodotorula nothofagi and Cryptococcus aerius showed pectinase activity. Regarding killer activity, only the 16% of the studied strains showed a positive phenotype against collection strains C. glabrata NCYC 388 and S. cerevisiae P351. This work represents the first survey of yeasts associated with native plants fruits in North Patagonia. Our results strongly support the need for different preisolation treatments in order to have a complete picture of the microbial communities associated with fruit surfaces. Additionally, we demonstrated that native plants are a valuable reservoir of yeast biodiversity that can be assessed for industrial applications