Resumo

The São Paulo Zoo has an organic composting unit (OCU) which processes all the waste from about 3000 native and exotic animals. The waste is mixed with plant debris from the Atlantic Forest in a ratio of 30 parts of Carbon to 1 part of Nitrogen, in aerobic condition, to produce 600 tons compost/year. This is a self-sustainable process since the final compost generated has been used as fertilizer in the Zoo’s farm to fertilize the land, which produces most of the food consumed by the animals in the park. In this work we isolated yeast cells from this material which may have biotechnological applications. Two yeast collections were assembled (CL001 and CL002) containing 46 isolates each. CL001 comprises yeasts isolated from several samples of different compost piles, collected over six months period and CL002 was assembled from 5 samples collected in a single compost pile over a 90 days period. The yeasts were mainly identified by mass spectrometry (MALDI-TOF-MS). However some isolates could not be identified by this method, due to lack of similar profile in the Brucker Daltonics database. In these cases sequencing of conserved regions of ribosomal DNA (18S and D1/D2) was employed in order to identify genus and species. Nine different genera and twenty-four species were identified. In order to address the potential biotechnological application of these yeasts, both collections were screened for isolates capable of hydrolytic enzyme secretion (amylase, protease, cellulase, pectinase) and bioremediation of toxic compounds. Among the two collections fourteen yeasts were able to secrete hydrolytic enzymes, twenty-five were capable of utilizing n-hexadecane, a xenobiotic substance (as sole carbon source) one is tolerant to Pb²⁺ and nine were tolerant to Mn²⁺, both ions are recognized as inorganic endocrine disruptors. These results confirm the initial hypothesis that the OCU of São Paulo Zoo is a source of diverse yeasts species with potential biotechnological application.