Design And Synthesis Of Fluorescent Probes And Their Recognization For Microthrix Parvicella

The sludge bulking is one of the worldwide problems frequently occurred inwastewater treamtment plants, which is mainly associated with filamentousbacteria. Microthrix parvicella is one of the dominant filamentous bacteria inwinter and spring and its excessive growth is the main reason of sludge bulking.Therefore, how to find a useful, fast and accurate way to detect and quantifythe Microthrix parvicella, judge the trend of excessive breeding earlier, andcontrol the ludge bulking effectively is of great importance for theimprovement of the process’s stability.At present there is relatively few methods to qualitatively and quantitativelyresearch Microthrix parvicella in situ condition. Traditional methods forMicrothrix parvicella identification are mainly used microscope and sludgesedimentation index (SVI). Though the method is simple and quick, they couldlead to an imprecise result. In addition quantitative analysis has certainhysteresis. Compared with the traditional identification methods, modernmolecular biotechnology has a higher sensitivity, specificity and sampleveracity for the detection of Microthrix parvicella. With nucleic acids (DNA orRNA) as identifying targets, however, several disadvantages are pointed out,such as more operation rules and high technique required. In addition, thedifficulty in quantifying the hybridization intensity remains a barrier toovercome in molecular biotechnology application.As a safe and useful fluorescent labeling, fluorescent probes technology areapplied due to its advantages, such as quick detection, less sample,radiation-free, et al. By contrasting, analyzing the molecular structure of thelipids with more hydrophobic long chains, and considering the stronglyhydrophobic property of the Microthrix parvicella, we design and synthesize aseries of carbazole cyanine dyes, which was modified by hexadecylene longchain, and has hydrophobic property. The dyes’ absorbtion are in the range of440-500nm and molar extinction coefficients are2.56×104-4.00×104. Theirfluorescence emission, quantum yields and Stokes shifts are in the range of570-630nm,0.15-0.23and80-130nm in different solvents, respectively. The experimental results of the recognization for Microthrix parvicella inactivated sludge in situ condition showed that the fluorescent probes couldspecifically recognize Microthrix parvicella in short time (5-20min). So asimple, fast and accurate method is supplied for Microthrix parvicella analysis.In addition, on the basis of these results, we study the fluorescent signal andthe quantitative relationship of Microthrix parvicella expression.The targets of our method of recognization for Microthrix parvicella are onthe extracellular surface but not in nucleic acid inside the cell, which couldavoid the destruction of probe to the hyphae cell structure. The method solvedthe problem of the shortcomings of the low cell penetration rate. So thefluorescent probes are specific, simple and convenient, and could be used as arapid and efficient detection method for recognizing Microthrix parvicella.