为寻找一株专一性更强的乙醇氧化菌（Methylobacterium sp.），确立最佳微生物固定化方法，最终建立微生物乙醇检测体系，采用有利于微生物细胞生长的PVA-海藻酸盐溶胶-凝胶包埋法，对筛选、分离得到的乙醇氧化菌进行固定化，将其制备成固定化小球。考查了海藻酸钠、氯化钙等固定化添加剂浓度对固定化微生物细胞成球难易和活性的影响。研究了固定化颗粒机械强度和通透性。在乙醇菌的不同固定化条件下进行了实验比较，得出最佳固定化方法：10%聚乙烯醇、1.5%海藻酸钠、4%CaCl2、4%硼酸溶液固定化微生物细胞，其活性最高、机械强度较强。固定化小球与溶解氧电极组合成乙醇微生物传感体系，用于乙醇检测。考查了温度、pH值、盐离子浓度、菌种保存时间等因素对该传感体系的影响。用该体系测得乙醇线性响应范围为0.002%~0.2%(V/V)，RSD为6.3%。实验证明该体系适合于微量乙醇检测，具有精密度高、重现性良好、无毒害、响应快、方便及成本低的特点。

The determination of ethanol content finds fairly wide applications in different fields, such as clinical, pharmaceutical, liquor, beverage and fermentation industries. An accurate determination of the concentration of ethanol is of great significance for the control of production targets during the fermentation process and the quality assurance for children's drinks. The method of microbial sensor for the ethanol determination is a simple, rapid, accurate, inexpensive and tracking detection method. This study is to find a strain of ethanol-oxidizing bacteria (Methylobacterium sp.) with greater specificity, to determine the best method for the microbial immobilization, and finally to construct a micro-alcohol test system by combining immobilized cell with dissolved oxygen electrode, as a simple, non-toxic method, which can be used for the determination of micro-samples. The selected ethanol-oxidizing bacteria is immobilized with the PVA-alginate sol-gel entrapment method, which is conducive to the growth of microbial cells. The immobilized small balls with good air permeability and high mechanical strength are prepared, which can be repeatedly used and easily be unloaded. The mechanical strength and the permeability of immobilized particles are studied. Optimized conditions of immobilization are determined by comparing different methods and materials. The best result is: 10% polyvinyl alcohol, 1.5% sea alginic acid sodium, 4% CaCl2, and 4% boric acid solution. Effects of the sensing system are tested, including temperature, pH, salt ion concentration, retention time and so on. The linear response to the ethanol of this system is 0.002%~0.2% (V/V), with relative standard deviation of 6.3%. It is shown that the system is suitable for detection of trace ethanol, with advantages including high-precision, nontoxic, fast-response, convenient, low-cost and good reproducibility.