Chang I S, Kim B H, Shin P K
Environment Research Center, Korea Institute of Science and Technology, Seoul, Korea.
Appl Environ Microbiol. 1997 Jan;63(1):1-6. doi: 10.1128/aem.63.1.1-6.1997.
Lactic acid bacteria isolated from an industrial-scale ethanol fermentation process were used to evaluate sulfite as a bacterial-contamination control agent in a cell-recycled continuous ethanol fermentation process. The viabilities of bacteria were decreased by sulfite at concentrations of 100 to 400 mg liter-1, while sulfite at the same concentrations did not change the viability of the Saccharomyces cerevisiae strain used in this process. Sulfite was effective only in the presence of oxygen. Bacteria showed differences in their susceptibilities to sulfite. Facultatively heterofermentative Lactobacillus casei 4-3 was more susceptible than was obligatory heterofermentative Lactobacillus fermentum 7-1. The former showed higher enzyme activities involved in the production and consumption of hydrogen peroxide than did the latter. The viability of L. fermentum 7-1 could be selectively controlled by hydrogen peroxide at concentrations of 1 to 10 mM. Based on these findings, it is hypothesized that the sulfur trioxide radical anions formed by peroxidase in the presence of hydrogen peroxide are responsible for the control of contaminating bacteria. Sulfite did not kill the yeast strain, which has catalase to degrade hydrogen peroxide. A cell-recycled continuous ethanol fermentation process was run successfully with sulfite treatments.
从工业规模乙醇发酵过程中分离出的乳酸菌，被用于评估亚硫酸盐在细胞循环连续乙醇发酵过程中作为细菌污染控制剂的效果。浓度为100至400毫克/升的亚硫酸盐可降低细菌的活力，而相同浓度的亚硫酸盐不会改变该过程中所用酿酒酵母菌株的活力。亚硫酸盐仅在有氧存在时有效。不同细菌对亚硫酸盐的敏感性存在差异。兼性异发酵干酪乳杆菌4-3比专性异发酵发酵乳杆菌7-1更敏感。前者参与过氧化氢产生和消耗的酶活性高于后者。浓度为1至10毫摩尔的过氧化氢可选择性地控制发酵乳杆菌7-1的活力。基于这些发现，推测在过氧化氢存在下过氧化物酶形成的三氧化硫自由基阴离子负责控制污染细菌。亚硫酸盐不会杀死具有过氧化氢酶可降解过氧化氢的酵母菌株。经亚硫酸盐处理后，细胞循环连续乙醇发酵过程成功运行。
