title: Effect of yeast pretreatment on the characteristics of yeast-modified electrodes as mediated amperometric biosensors for lactic acid.
abstract: Carbon paste electrode modified with baker' and wine yeast Saccharomyces cerevisiae (a source of flavocytochrome b(2)) were investigated as amperometric biosensors for L-lactic acid. Before immobilization on the electrode surface, yeast cells were pretreated with various electrolytes, alcohols and weak organic acids. Electrode responses to L-lactic acid were tested in the presence of various mediators (potassium ferricyanide, phenazine methosulfate, 2,6-dichlorophenolindophenol sodium salt hydrate, 1,2-naphthoquinone-4-sulfonic acid sodium salt). The highest (144+/-7 nA per 0.2 mM L-lactic acid) and the most stable responses were obtained after yeast pretreatment with 30% ethanol using potassium ferricyanide as a mediator. Different electrode sensitivities with mediator phenazine methosulphate probably reflected diverse changes in yeast membrane (and/or cell wall).
authors.affiliation: Institute of Chemistry, Gostauto 9, LT-01108, Vilnius, Lithuania. rasa.garjonyte@chi.lt
authors.forename: R
authors.initials: R
authors.lastname: Garjonyte
authors.forename: V
authors.initials: V
authors.lastname: Melvydas
authors.forename: A
authors.initials: A
authors.lastname: Malinauskas
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004563:Electrochemistry; D004566:Electrodes; D004800:Enzymes, Immobilized; D005292:Ferricyanides; D042844:L-Lactate Dehydrogenase (Cytochrome) / Q000378:metabolism; D019344:Lactic Acid / Q000032:analysis*; D008773:Methylphenazonium Methosulfate; D012441:Saccharomyces cerevisiae; D015002:Yeast, Dried
chemical_list: D004800:Enzymes, Immobilized; D005292:Ferricyanides; D008773:Methylphenazonium Methosulfate; D019344:Lactic Acid; D042844:L-Lactate Dehydrogenase (Cytochrome); C028033:potassium ferricyanide