Phenol degradation and heavy metals tolerance of Antarctic yeasts

BLASER, GISELLE; MAC CORMACK, WALTER; MARTORELL, MARIA M.; FIGUEROA, LUCIA I. C.; FERNANDEZ, PABLO M.; RUBERTO, LUCAS

Kuala Lumpur

Conferencia; XXXIV Scientific Committee on Antarctic Research Open Science Conference 2016; 2016

SCAR

In cold environments, biodegradation of organic pollutants and heavy metals bioconvertion requires the activity of cold-adapted or cold-tolerant microorganisms, which have adjusted their metabolism to function optimally at low temperature, In this work, the ability to utilize phenol for growth and tolerate different heavy metals was investigated in 140 culturable cold-adapted yeasts isolated from Antarctica at 15°C. The biodegradation of phenol (2.5 mM) was tested in agitated submerged cultures in YNB medium with (NH4)2SO4, whereas heavy metal tolerance was assayed in Petri dishes containing agarized YM medium. The growth at different temperatures (5, 25 and 30°C) was also investigated. After the end of the screening scheme, DNA of the selected yeasts was extracted (using the standard glass-beads method with a lysis buffer) for molecular identification by sequencing of 26S rRNA gene D1/D2 domain and internal transcribed spacers (ITS1-5.8S-ITS2) region.  After the growth temperature assay, 67% of the yeasts could be classified as psicrotolerant as they were able to growth in all the range of temperature tested, while the other 33% could be classified as psicrophilic as they did not growth at 25 or 30°C.  Thirty percent of the yeasts were able to utilize phenol (2.5 mM) as C source. In relation to heavy metals, 82%, 63% and 25% were tolerant to 1 mM of Cu(II), Cd(II) and Cr(VI) respectively, but only 18% tolerate all of them. In addition, 16% could be classified as sensitive, showing no growth after 14 d. Only four yeast were able to grow using phenol and tolerate all metals tested.  All the selected yeasts belong to genera and species previously reported as common for Antarctic soils, and have also been profusely reported in Arctic or near-Arctic regions or associated with Alpine or Andean glaciers; representing well cold adapted yeasts. The isolates here reported, able to remove phenol and tolerate heavy metals at low temperatures could be valuable as inocula for cold wastewater treatment in extremely cold environments.