title: Bioremediation of chromium by the yeast Pichia guilliermondii: toxicity and accumulation of Cr (III) and Cr (VI) and the influence of riboflavin on Cr tolerance.
abstract: A comparative study has been made on the sensitivity of the yeast Pichia guilliermondii to Cr (III) and Cr (VI) as well as on the Cr uptake potential at growth-inhibitory concentrations of chromium. The strains used in the study were either isolated from natural sources or obtained from a laboratory strain collection. The results show that most of the natural strains were more tolerant to chromium and were able to grow in the presence of 5 mM Cr (III) or 0.5 mM Cr (VI), that is at concentrations which substantially inhibited the growth of laboratory strains. The cellular Cr content after treatment was similar for both strain types and ranged from 1.2-4.0 mg/g d.w. and 0.4-0.9 mg/g d.w., for Cr (III) and Cr (VI) forms, respectively, however, in one case of a natural strain it reached the value of 10 mg Cr (III)/g dry mass. Natural-source strains were grouped into four groups based on the yeasts' differential response to Cr (III) and Cr (VI). Hexavalent Cr-resistant mutants of a P. giuilliermondii laboratory strain, which revealed markedly changed capabilities of chromium accumulation, were obtained by means of UV-induced mutagenesis. Cr (VI) treatment triggered oversynthesis of riboflavin and the addition of exogenous riboflavin increased P. guilliermondii resistance to both Cr (III) and Cr (VI). Electrophoretic protein profiles revealed the induction and/or suppression of several proteins in response to toxic Cr (VI) levels.
authors.affiliation: Institute of Cell Biology, National Academy of Science of Ukraine, Dragomanov Str. 14/16, 79005 Lviv, Ukraine
authors.forename: Helena
authors.initials: H
authors.lastname: Ksheminska
authors.forename: Anita
authors.initials: A
authors.lastname: Jaglarz
authors.forename: Daria
authors.initials: D
authors.lastname: Fedorovych
authors.forename: Lyubov
authors.initials: L
authors.lastname: Babyak
authors.forename: Dmytro
authors.initials: D
authors.lastname: Yanovych
authors.forename: Pawel
authors.initials: P
authors.lastname: Kaszycki
authors.forename: Henryk
authors.initials: H
authors.lastname: Koloczek
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects*; D001673:Biodegradation, Environmental / Q000187:drug effects; D002857:Chromium / Q000378:metabolism / Q000633:toxicity*; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000096:biosynthesis; D016296:Mutagenesis; D009154:Mutation; D010843:Pichia / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D012256:Riboflavin / Q000096:biosynthesis / Q000494:pharmacology*
chemical_list: D005656:Fungal Proteins; D002857:Chromium; D012256:Riboflavin