Mutagenesis and selection of high efficiency hydrogen-producing mutants by ultraviolet radiation

【Abstract】 Hydrogen is an ideal, clean and sustainable energy source for the future because of its high conversion and nonpolluting nature. Biohydrogen production by dark-fermentation appears to have a great potential to be developed for practical application. However, one limiting factor affecting the development of hydrogen-production industrialization is that the hydrogen-producing capacity of bacteria is lower, so how to increase bacteria’s hydrogen-producing ability will be an urgent issue. In this experiment, 2 mutants, namely UV3 and UV7, were obtained by ultra-violet radiation. They grew and produced hydrogen efficiently on iron-containing medium. The hydrogen evolution of UV3 and UV7 were 2 356.68 ml/L and 2 219.62 ml/L at a glucose concentration of 10 g/L, respectively. With wild parent strain Ethanoligenens sp. ZGX4, the hydrogen evolution was 1 806.02 ml/L under the same conditions. Mutants’ hydrogen-producing capacities were about 29.71% and 22.22% higher than that of wild parent strain ZGX4. The maximum H₂ production rate by mutants UV3 and UV7 were estimated to be 32.57 mmol H₂/g cell h and 31.19 mmol H₂/g cell h, respectively, which were 38.18% and 34.78% higher than the control （23.57 mmol H₂/g cell h）. The abundant products of UV3 and UV7 were ethanol and acetic, which accounted for 95%-98% of total soluble microbial products. In each case, mutant strains UV3 and UV7 evolved hydrogen at a higher rate than the wild type, showing a possible potential for commercial hydrogen production. Another mutant named UV20’ was also gained whose main end metabolites were butyric acid and acetic acid. This would provide researched material for a discussion of metabolic pathways of hydrogen-producing bacteria.更多还原