Temperature and pH Relation to Nutrient Uptake by Immobilized Cells of Pseudomonas aeruginosa

Abstract

Nutrient enrichment of aquatic ecosystem can lead to increase in algae and aquatic plants and the loss of component species and ecosystem function. The aim of this study was to investigate the relationship of temperature and pH to nutrient uptake from nutrient media by immobilized cells of Pseudomonas aeruginosa. The study, which was carried out under shaking flask conditions used sodium alginate, agar-agar and agarose immobilized. The incubation temperatures used for the study were 25°C, 35°C and 45°C while the pH were 6,8 and 10. Just before inoculation and every 24 h, for 120 h, aliquot samples were aseptically withdrawn from each flask for the estimation of phosphate and sulphate concentrations in the media, using standard procedures. The results revealed maximum decreases in phosphate and sulphate concentrations in the media in presence of the immobilized cells occurred at 25°C and 35°C, respectively. In presence of the alginate-immobilized cells, lowest phosphate decreases from the initial concentration of 71.1 mg/L to 50.1 mg/L, 50.6 mg/L and 46.8 mg/L, after 96 h incubation were observed at incubation temperatures of 25°C, 35°C and 45°C, respectively. There was however no significant between phosphate concentrations in the media at the different incubation temperatures in presence of the alginate-immobilized cells. For sulphate uptake, in presence of the alginate-immobilized cells, highest decrease was observed at incubation temperature of 35°C. At this temperature, remarkable decrease was observed from 24 h incubation till the end of incubation. Generally, the study showed optimum pH for sulphate removal by the cells to be 8. At pH 6 and 10, only slight decreases in sulphate levels were observed at the end of incubation in the presence of the immobilized cells. In presence of the alginate-immobilized cells, remarkable increases in sulphate levels were observed throughout the period of incubation. The study was able to give an insight into the phosphate and sulphate uptake efficiency of the immobilized cells of the test bacteria under the experimental conditions used for investigation.