| Hydrogen is one of the new energy resources, which is efficient, clean and renewable. Recent years, biohydrogen technology from anaerobic fermentation attracts extensive attention, because of its low energy consumption, good stability,high efficient, etc.There are many means to improve the efficiency of microbial anaerobic hydrogen production. The preliminary study shows that the static magnetic field can improve the efficiency of anaerobic fermentation biohydrogen by Enterobacter aerogenes and Enterobacter cloacae, but the effect of magnetic field on the hydrogen production by Bacillus sp. has not been reported.In this study, 7 strains were screened from the self-made anaerobic bioreactor with magnetic field by plate scribing method and the 7 strains were sequenced by 16S rDNA sequence analysis technology. Then the hydrogen production of 7 strains from glucose were tested at the initial pH of 7, and the strain BH01 displayed the best hydrogen production efficient.And optimising the anaerobic hydrogen production conditions of strain BH01 under mesophilic (37±1℃),discussing the effect of magnetic fields on its hydrogen production with the intensity of OmT, 4mT, 54mT and 65mT. The mechanism of the effect of magnetic fields on the anaerobic fermentation hydrogen production from glucose of strain BH01 was explored, and the following conclusions were drawn:(1) 7 strains were isolated from the reactor and they are all identified as Bacillus by 16S rDNA sequencing analysis technology. Strain BH01 was gram-positive bacteria on the basis of further physiological and biochemical experiments. Besides,methyl red and indol test results were positive,tyrosine hydrolysis test result was positive and D-mannitol produce acid test result was negative. Based on the physiological and biochemical experiment results,the strain BH01 was preliminary identified as bacillus cereus.(2) The maximum hydrogen production rate of Bacillus cereus was 0.88 mol hydrogen at the initial pH value of 8, the amount of vaseline (v/v) was 8% and the initial glucose concentration was 10 g/L/mol glucose, when the temperature was 37±1℃.(3) The magnetic field can accelerate the process of biohydrogen with magnetic field intensity of 4mT and 54mT,and improve the effeciency of hydrogen production.When the magnetic field intensity was 54mT, the time to start hydrogen production 5 hours ahead of time compared with OmT. And the duration of hydrogen production reduced by a quarter. The yield and effeciency of hydrogen production was 2.58 and 9.27 times of that no magnetic field, respectively. Intensity of 4mT, although the hydrogen production process lasted 24h, but also ahead of time 5 hours the time to start hydrogen production, and the yield and effeciency of hydrogen production was 1.87 and 3.11 times of that no magnetic field.(4) The magnetic field has no significant effect on the growth and reproduction of Bacillus BH01, but it can significantly improve the activity of dehydrogenase.When the magnetic field intensity was 54mT, the activity of dehydrogenase was 0.011 g / L · h-1 at the highest hydrogen production rate, and improved by 44.74% and 19.57%, respectively, compared with the non-magnetic and intensity of 4mT.(5) The anaerobic fermentation hydrogen type of Bacillus BH01 was the ethanol-type fermentation. Mgnetic field has not changed the type, and the main liquid products still were acetic acid and ethanol with the proportion of total products more than 80%; External magnetic field will reduce the total yield of fermented liquid end products.When the magnetic field intensity was 4mT, 54mT and 65mT, the total yield of liquid fermentation products reduced by 15.20%、18.86%、66.31%,respectively. |
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