Wang Xiaoyi, Jin Bo
School of Earth and Environmental Sciences, The University of Adelaide, SA 5005, Australia.
J Biosci Bioeng. 2009 Feb;107(2):138-44. doi: 10.1016/j.jbiosc.2008.10.012.
This work sought to optimize fermentation parameters in a batch process for hydrogen production from molasses by a newly isolated Clostridium butyricum W5. Hydrogen yield and production rate, bacterial biomass and volatile fatty acids, including acetic, lactic and butyric acids, were measured. Key fermentation operation parameters, including concentration of carbon and nitrogen sources, growth temperature and pH, and inoculum size were investigated. The best results in terms of hydrogen yield and productivity were obtained under the conditions of 100 g/L molasses, 1.2 g/L NH4NO3, 39 degrees C at pH 6.5 with initial cell concentration of 9x10(4) cell/ml. Maximum hydrogen yield was 1.85 mol hydrogen/mol hexose, corresponding to a hydrogen production rate of 17.38 mmol/h/L. Experimental data showed that the acetic/butyric acid ratio remained relatively stable with an increase in molasses concentration, while the unfavoured product, lactic acid, portion increased. No solvent (ethanol, butanol and acetone) was detected during the fermentation. Propionic acid was measured at a very low level in the hydrogen fermentation. Statistical analysis showed that hydrogen yield increased exponentially with the increase in cell growth, and that there was no correlation between the hydrogen yield and ratio of acetic acid to butyric acid.
本研究旨在优化新分离的丁酸梭菌W5在分批培养过程中利用糖蜜生产氢气的发酵参数。测定了氢气产量和产率、细菌生物量以及挥发性脂肪酸（包括乙酸、乳酸和丁酸）。研究了关键发酵操作参数，包括碳源和氮源浓度、生长温度、pH值以及接种量。在糖蜜浓度为100 g/L、硝酸铵浓度为1.2 g/L、温度为39℃、pH值为6.5且初始细胞浓度为9×10⁴ 个细胞/ml的条件下，获得了氢气产量和生产率方面的最佳结果。最大氢气产量为1.85 mol氢气/mol己糖，相应的氢气产率为17.38 mmol/h/L。实验数据表明，随着糖蜜浓度的增加，乙酸/丁酸比例保持相对稳定，而不利产物乳酸的比例增加。发酵过程中未检测到溶剂（乙醇、丁醇和丙酮）。在氢气发酵过程中检测到丙酸的含量非常低。统计分析表明，氢气产量随着细胞生长的增加呈指数增长，并且氢气产量与乙酸和丁酸的比例之间没有相关性。
