Candida pseudoglaebosaandKodamaea ohmeriare capable of degrading alkanes in the presence of heavy metals

Abstract

The aim of this study was to examine four strains of two yeast species in relation to their capability for assimilating alkanes in the presence of heavy metals (HMs). The four strains tested were Candida pseudoglaebosa ENCB-7 and Kodamaea ohmeri ENCB-8R, ENCB-23, and ENCB-VIK. Determination was made of the expression of CYP52 genes involved in alkane hydroxylation. When exposed to Cu 2+ , Zn 2+ , Pb 2+ , Cd 2+ , and As 3+ at pH 3 and 5, all four strains could assimilate several n-alkanes having at least six carbon atoms. The three K. ohmeri strains could also utilize branched alkanes, cycloalkanes, and n-octanol as sole carbon sources. Kinetic assays demonstrated greater biomass production and specific growth of the yeasts exposed to long-chain n-alkanes.Fragments of paralogous CYP52 genes of C. pseudoglaebosa ENCB-7 and K. ohmeri ENCB-23 were amplified, sequenced, and phylogenetically evaluated.Reverse-transcription polymerase chain reaction revealed that n-nonane and n-decane induced to CpCYP52-G3, CpCYP52-G9, and CpCYP52-G10. KoCYP52-G3 was induced with n-decane and n-octanol. Also, CpCYP52-G3 and CpCYP52-G9 were induced by glucose. In conclusion, C. pseudoglaebosa and K. ohmeri were able to degrade several alkanes in the presence of HMs and under acidic conditions. These yeasts harbor paralogous alkane-induced CYP52 genes, which display different profiles of transcriptional expression.

Phylogeny, evolution, and potential ecological relationship of cytochrome CYP52 enzymes in Saccharomycetales yeasts

“…However, the presence of a reduced number of CYP52 paralogs in M. guilliermonii represents a particular phenomenon where the number of CYP52 cytochromes and the number of hydrophobic substrates that this yeast can utilize are not correlated. Similar to M. guilliermondii, K. ohmeri displays a broad hydrocarbonoclastic phenotype, but its CYP52 content is very reduced 20 . Therefore, in M. guilliermondii and other yeasts with few CYP52 enzymes, CYP52 duplication was apparently not necessary in their adaptation to hydrocarbon-rich environments.…”

“…Hydrocarbon and fatty acid assimilation assays. The assays were performed in liquid mineral medium in 96-well plates according to a previously described protocol 20 . In brief, the C4-C10 n-alkanes and branched alkanes were tested in the vapor phase, while fatty acids and n-hexadecane were added to the liquid phase at a 1% final concentration.…”

“…www.nature.com/scientificreports www.nature.com/scientificreports/ ohmeri, and Y. lipolytica are induced by n-alkane or fatty acid substrates 13,14,16,19 and repressed by glycerol 13,16 or glucose 20 .…”