Nitrate and nitrite reduction by liquid membrane-encapsulated whole cells
| Autor: | Norman N. Li, Raam R. Mohan |
|---|---|
| Rok vydání: | 1975 |
| Předmět: |
Nitrite Reductases
Cell Survival Bioengineering Applied Microbiology and Biotechnology Chloride Catalysis chemistry.chemical_compound Nitrate Reductases Methods medicine NADH NADPH Oxidoreductases Nitrite Paracoccus denitrificans Chromatography Aqueous two-phase system Substrate (chemistry) Membranes Artificial Selective catalytic reduction Mercury Hydrogen-Ion Concentration Permeation Kinetics Membrane chemistry Biotechnology medicine.drug |
| Zdroj: | Biotechnology and Bioengineering. 17:1137-1156 |
| ISSN: | 1097-0290 0006-3592 |
| DOI: | 10.1002/bit.260170805 |
| Popis: | Purified enzymes and cell-free homogenates encapsulated by liquid-surfactant membrane have been shown to retain their catalytic activity (see previously published literature). This paper describes the preparation and properties of liquid-surfactant membrane-encapsulated whole cells of Micrococcus denitrificansATCC 21909. Batch and continuous studies with this model system have demonstrated that encapsulated viable cells reduce nitrates and retain their catalytic activity over anextended period of time. In batch operation, the reactivity of the encapsulated whole cells has been investigated under a variety of experimental conditions. The system is capable of reducing NO3− or NO2−. Data obtained indicate that encapsulated live cells have a broad pH and temperature optimum range. The encapsulated cells remain viable and do not “escape” into the external aqueous phase, even after five days of constant stirring with nitrate-containing simulated wastewater. Pulsed substrate addition experiments have demonstrated that the encapsulated cells also effectively reduce NO2− with no significant reduction in activity, even after 5.5 days of incubation at 30°C. The membrane selectivity for ion transfer has been achieved by incorporating oil-soluble ion exchangers in the membrane. Because of the protection of the liquid membranes, the catalytic reduction of NO2− by the encapsulated whole cells is not inhibited by 1 × 10−4M mercuric chloride, which is otherwise extremely toxic to the cells, when present in the external aqueous phase. Continuous reduction of 20 ppm of NO2− by liquid membrane-encapsulated whole cells has been demonstrated in a constantly stirred reactor over a test period of about one week. In this paper we will discuss the reduction of NO3−and NO2− by the liquid membrane-encapsulated whole cells of M. denitrificansATCC 21909 mainly in batch runs undera variety of experimental conditions, such as cell and substrate concentrations, product and inhibitor permeation, pH and temperature, effect of oil-soluble ion exchangers on the substrate diffusion, etc. |
| Databáze: | OpenAIRE |
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