Fundamental Research on Application of Genetic Recombination Technique Wastewater Treatment

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In this research, several investigation were made on the microorganisms and their enzymes which utilize environmental micropollutants as source of cell carbon and energy and/or degrade them. As the compounds of investigation, 2-chloroacrylic acid (CAA) and an azo dye were respectively selected as halogenated and recalcitrant organic compounds among environmentally important micropollutants. The research results for these two organic compounds are as follows:Three species of microorganisms which could utilize 2-chloroacrylic acid as a source of cell carbon and energy, were isolated from various soil samples of different origins. These three microorganisms were confirmed to be Pseudmonas. The characteristics of the dehalogenase of one of these three microorganisms was investigated through a purification of the extracted liquid. The result indicated that the molecular weight of the enzyme was about 50,000 and that the enzymatic activity was relatively high for the similar halogenated orga … More nic compounds with three or less C. With a cloning technique, the dehalogenase gene was introduced into E.coli, and a clonal culture was successfully obtained. (This part of research was carried out under the guidance of Prof. Kenji SODA of the Institute for Chemical Research in Kyoto University.)The microorganisms degradation capability of recalcitrant organic compounds, azo dye, was investigated using Reactive Red B. Also, various environmental conditions for decolourisation were evaluated. Eleven species of microorganisms were isolated from the bacterial culture which was acclimated for a long period of time with an artificial wastewater containing the azo dye and glucose. All eleven species were Gram-negative, and most of them were bacillus. These species showed different decolourisation capability, which positively related to the glucose utilization capability. The experiments using the acclimated and isolated cultures indicated that the decolourisation rate was faster under lower ORP condition, and that easily biodegradable substrates (e.g., glucose and sugar) must exist as energy source. These results suggested that the decolourisation process was carried out through co-metabolism with reductive transformation, and that these microorganisms could effectively decolourise other azo dyes than Reactive Red B. Less