Abstract
Formaldehyde (FA) is a highly reactive compound with a toxic effect on all organisms due to non-specific interactions with proteins and nucleic acids. This substance is a hazardous air pollutant, and prolonged exposure to FA may cause serious health effects. This chapter describes approaches for detection and eliminating FA in several real and model sources. The cells of the thermotolerant methylotrophic yeast Hansenula (Ogatae) polymorpha as well as FA-oxidizing enzymes isolated from these cells were employed as catalytic elements in the development of enzymatic methods for FA detection by analytical kits and biosensors as well as for degradation in bioreactors. Recombinant yeast strains, originating from NCYC 495 and CBS 4732 H. polymorpha strains resistent to elevated concentrations of FA in the medium and overproducing a homologous NAD-and glutathione-dependent formaldehyde dehydrogenase (FdDH), were constructed. Optimal cultivation conditions for the highest yield of FdDH as well as formaldehyde reductase (FR) were found. Alcohol oxidase (AOX) was isolated from the mutant strain H. polymorpha C-105 (gcrl catX) which is defective in glucose repression of AOX synthesis and lacks catalase. Simple schemes for FdDH, FR and AOX isolation and chromatographic purification from the recombinant overproducers were proposed and the physico-chemical and catalytic properties of the purified enzymes were studied. Enzymatic methods and analytical kits for FA assay based on glutathione-dependent FdDH and AOX were developed. The purified FdDH and AOX preparations, as well as yeast cells overproducing these enzymes, were used for the construction of FA-selective enzyme-based and microbial electrochemical biosensors. A laboratory prototype of a FA analyzer with a catalytic chemosensing element and a simple low-cost FA-sensitive biosensor for semi-quantitative FA detection were developed. The latter sensor is based on a change in the color of a solution that contains a mixture of AOX, horseradish peroxidase and a chromogen, after exposure to airborne FA. The reliability of the proposed analytical approaches was tested on model solutions and on real samples of FA-containing industrial products, vaccines and wastes. A strong cross-correlation was found between FA content values obtained by the developed methods and routinely used chemical ones. The enzyme preparations and the yeast cells overproducing the corresponding enzymes were used for construction of FA-selective electrochemical biosensors. The purified enzymes and the recombinant and mutant cells served as the catalytic units in cartridges for FA removal from indoor air and from water solutions. Experimental data confirm the possibility of exploiting the developed bioreactors based on crude preparations of AOX or methylotrophic yeast cells, for effective FA oxidation (up to 99.9%) controlled by a coupled FdDH-based biosensor.
Original language | English |
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Title of host publication | Formaldehyde |
Subtitle of host publication | Synthesis, Applications and Potential Health Effects |
Publisher | Nova Science Publishers, Inc. |
Pages | 117-142 |
Number of pages | 26 |
ISBN (Electronic) | 9781634824262 |
ISBN (Print) | 9781634824125 |
State | Published - 1 Apr 2015 |
Keywords
- air-lift bioreactor
- biodegradation
- biosensor
- chemosensor
- enzymatic assay
- formaldehyde