Fungal Biodiversity from the Yungas Rainforest: Discovering a Hidden Microbial Potential.

FARIÑA J I; VIÑARTA S; PAJOT H; DELGADO O D; DE FIGUEROA L I C

EEUU

Congreso; IUMS 2005; 2005

International Union of Microbiologyical Societies

Background The Yungas consists on a humid forest discontinuously extended from Venezuela to the north west of Argentina. Along with Misiones rainforest, has been considered the richest place on genetics and one of the most threatened ecosystems in the world. Sampling in the Pedemontana forest (Tucumán, Argentina) aimed the isolation of indigenous fungal species that may be as yet, hidden resources for biotechnology.Methods Different samples were aseptically collected from the Yungas foothills (Tucumán). Pieces of fungi were immediately inoculated onto MYSA plates. Soil and liquid samples were diluted and spread on MYSA. After incubation at 20°C colony morphotypes were isolated. Enzyme activities were screened on MYSA agar plus the substrates: cellulase, 0.5% w/v carboxy methylcellulose; xylanase, 1% w/v xylan; amylase, 1% w/v starch; chitinase, 0.5-1% w/v RBB-chitin; laminarinase, 0.05% w/v laminarin-azure; β-galactosidase, 0.2% w/v lactose; pectinase, 1% w/v pectin; lipase, 3% v/v olive oil; protease, 0.5% w/v skimmed milk; dye-decolourization, 200 ppm Vilmafix Blue RR-BB. Antimicrobial activity was assayed according to Kekessy & Piguet.Results From 71 samples, about 280 fungal pure isolates were obtained. Soils showed similar colony counts: M.54 = 1.35 × 105 cfu/g; M.41 = 6.84 × 105 cfu/g; M.37 = 1.71 × 105 cfu/g and M.29 = 9.9 × 104 cfu/g. Water samples exhibited lower values: M.69 = 5 × 104 cfu/ml; M.55 = 3.7 × 102 cfu/ml. Despite lower counts, water samples revealed the highest diversity, M.37 and M.54 were intermediate and, M.41 and M.29 were the least diverse. Most of the isolates were positive for at least one of the screened activities: hydrolytic enzymes, dye-decolourization or antimicrobial production. A wide spectrum of biotechnological potential was encountered among the tested isolates and those bearing the highest activities were selected and stored for further characterization.Conclusions Finding new enzyme- or antimicrobial-producers opens new frontiers for biotechnology. This screening program allowed to detect a fungal potential that has been hidden up to date. Knowledge on what these fungi may be doing within their own community would be useful to understand how they cooperate from the ecological point of view, by playing key roles during nutrient recycling.