Quantificational Analysis Of Luminescence Based On LuxAB-marked Strain And Its Application In Detection Of Cadmium Toxicity

The thesis discussed the quantificational analysis of luminescence based on luxAB-marked strain and its application in detection of cadmium toxicity. The content included three major parts: the foundation of quantificational analysis of luminescence, the comparison of luminescence performance in different harbored strain and the application in detection of cadmium toxicity. The results were listed as following:1. Quantificational analysis of luminescence based on luxAB-marked strain was investigated using Escherichia coli (pHN102). The marked strain showed a typical luminescence response profile, which features a peak that decreases rapidly. A maximum light intensity was observed in the presence of≥1 % decanal concentration. The optimal temperature and pH for light intensity were 35 °C and 6, respectively. There was significant correlation between the Light intensity and the amount of cells. The maximum light intensity was observed in the late log-growth phase. The treatment of re-suspending in the fresh medium can enhance the light intensity dramatically.2. Two marked strains E. aerogenes NTG-01 (pHN102) and P. putida X4 (pHN102) were gained by using triparental conjugation, and the differences in luminescence performance were compared among the three marked strains. The results showed that the light intensity of the two marked soil bacteria was stronger than that of E. coli, but the effect of light intensity improved by re-suspending treatment was less. The evidence may reflect the high tolerance to stress condition for soil bacteria. The optimal condition for light intensity of NTG-01 (pHN102) and X4 (pHN102) were 35°C and pH 4-8, which is inconsistent with the optimal grow condition (28 °C) for them. It concludes that the light intensity is not only determined by the metabolism activity of marked strain but also by the activity of luciferase.3. Experimental conditions in detection of Cadmium toxicity were investigated using Escherichia coli (pHN102). The proper contact time needed for testing between strain and Cadmium sample was 30 min. The stability of light intensity under the condition of nonnutritive state could be improved by re-suspending in fresh medium. There was a significant linear relationship between relative light intensity and cadmium concentration. EC50 values of cadmium in LB medium, M9 medium and water were 4.27 mmol/L, 34.8 mmol/L and 62 μmol/L, respectively, which suggest that cadmium in water is far more toxic than that in LB medium and M9 medium.4. The bio-toxicity of cadmium under different conditions was investigated using Pseudomonas putida X4 (pHN102). The toxicity of cadmium in different organic acid...