Bioprocess methanol production from methane.

甲烷直接氧化制甲醇是一种极具吸引力的工艺，而目前的工艺是将甲烷通过水蒸气转化为合成气的能量密集型工艺。甲烷单加氧酶(MMO)催化甲烷一步氧化制甲醇。但由于MMO的不稳定性，不能用于甲醇合成。因此，我们尝试用甲烷菌从甲烷中生产甲醇。甲基乐辛菌OB3b是一种甲烷营养细菌，含有MMO，催化甲烷羟化为甲醇。当甲烷被氧化时，生成的甲醇随后被同一细菌中含有的甲醇脱氢酶氧化。为了防止甲醇的进一步氧化，细胞悬浮液用环丙醇处理，环丙醇是一种不可逆的甲醇脱氢酶抑制剂，导致细胞外甲醇积累。这项研究的目的是增加甲醇产量，提高…的甲醇产率由于甲醇浓度的增加抑制了MMO的合成，所以在甲醇浓度约为6 mm时终止了MMO的间歇式合成。为了延长甲醇的积累时间，本研究采用了半连续过程。采用标准的50ml超滤池作为半连续反应器。将含有环丙醇处理的细胞悬浮液和甲酸钠的磷酸盐缓冲液引入装有超滤器(Diaflo SuperFilter YM-100，Amcon，Inc.)的超滤池中。将超滤细胞在30ﾟC下孵育5分钟，用气密注射器将甲烷注入超滤细胞内，启动反应。在30ﾟC孵育90min后，反应混合物用氮气压力过滤，从细胞悬浮液中分离出生成的甲醇。甲醇的合成重复5次，固定速率为3.17mumol h^&lt；-1；甲醇总产量为36.1摩尔，约为相同条件下间歇反应甲醇产量的两倍。较少

Direct oxidation of methane to methanol is a highly attractive process compared to the current process consisting of energy intensive conversion of methane by steam into synthesis gas. Methane monooxygenase (MMO) catalyzes single-step oxidation of methane to methanol. But MMO could not be used in methanol synthesis, because of instability. Thus methanol production from methane was tried with methanotroph. Methylosinus trichosporium OB3b, a methanotrophic bacterium, contains MMO and catalyzes hydroxylation of methane to methanol.When the methane is oxidized, produced methanol is subsequently oxidized by methanol dehydrogenase containing in the same bacterium. To prevent further oxidation of methanol, the cell suspension was treated by cyclopropanol, which was found to be an irreversible inhibitor for methanol dehydrogenase by the previous study, leading to extracellular methanol accumulation. The purpose of this research is to increase methanol production and to improve methanol yield a … More nd the efficiency.The batch type of methanol synthesis by M.trichosporium OB3b is terminated at c.a.6 mM of methanol, because MMO is inhibited by increasing methanol concentration. For prolonged methanol accumulation, a semicontinuous process was carried out in this study. A standard 50 ml ultrafiltration (UF) cell was used as semicontinuous reactor. The solution containing cyclopropanol treated cell suspension and sodium formate in phosphate buffer was introduced in to the UF cell attached with ultrafilter (Diaflo ultrafilter YM-100, Amicon, Inc.). The UF cell was incubated for 5 min at 30ﾟC,and the reaction was initiated by injecting methane into the UF cell with a gas-tight syringe. After incubation at 30ﾟC for 90 min, the reaction mixture was filtrated by nitrogen pressure, leading to separate a produced methanol from cell suspension. The methanol synthesis was repeated five times and stationary rate was 3.17 mumol h^<-1>mg^<-1>. The total produced methanol was 36.1 mumol, which is about twice amount of methanol produced by batch reaction under the same condition. Less