%0 Journal Article
%T Screening of a low alcohol dehydrogenase activity mutant of Rhizopus oryzae and the regulation of Zr2+ and Mg2+<br>米根霉乙醇脱氢酶突变株的筛选及其锌镁离子的调控研究
%A PAN Li-jun
%A FU Ping
%A ZHENG Zhi
%A LUO Shui-zhong
%A JIANG Shao-tong
%A <br>潘丽军
%A 付萍
%A 郑志
%A 罗水忠
%A 姜绍通
%J 微生物学报
%D 2006
%I 
%X Ethanol is the main by-product in the fermentation broth of Rhizopus oryzae As3.3461 for the production of high-optical purity L-lactic acid.Alcohol Dehydrogenase(ADH) is the branch pathway enzyme that catalyzes the transformation of ethanol from pyruvate in Rhizopus oryzae,which decreases the conversion rate of glucose to L-lactic acid.Thus,screening the mutants with lower ADH activity may increase lactate production dramatically.In present study,Rhizopus oryzae As3.3461 was mutated with N-methyl-N'-nitro-N-nitrosoguanidine(NTG), and 21 mutants which showed lower ADH activity were isolated with selective medium of Yeast-Peptone-Dextrose(YPD) containing 0.6% allyl alcohol(V/V).Compared with other mutants,the 12~(th) mutant strain(named as HBF-12) shows the highest conversion rate of L-lactic acid.By contrast with Rhizopus oryzae As3.3461,the parent strain,the ethanol production and the ADH activity of HBF-12 decrease 73.6% and 76%,respectively.Whereas,the L-lactic acid production and the LDH activity of HBF-12 increase 41.2% and 19.6% than those of the parent strain,respectively.The activities of ADH and LDH of HBF-12 were regulated by Zn~(2 )and Mg~(2 ),but showed opposite effects.Added with Zn~(2 ) to the concentration of 0.01% improves the ADH activity dramatically,but inhibits the activity of LDH.By contraries,added with Mg~(2 ) improves the LDH activity markedly,but inhibits the ADH activity slightly.In fermentation experiment,the addition of Zn~(2 ) and Mg~(2 ) show different effects on the accumulation of ethanol,L-lactic acid and the biomass in mutant HBF-12.When improve the concentration of Zn~(2 ),the accumulation of L-lactic acid and the biomass show the decreased trend,but the production of ethanol show positive effect.With the improvement of the concentration of Mg~(2 ),the production of lactic acid and biomass increase markedly,but no effect on the production of ethanol.When ferment under the concentrations of Zn~(2 ) 0.01% and Mg~(2 ) 0.04% in fermentation medium,the lactate production of HBF-12 reached the highest level,96.21g/L.
%K Rhizopus oryzae
%K Alcohol dehydrogenase
%K Lactate dehydrogenase
%K Zn~(2 )
%K Mg~(2 )<br>米根霉
%K 乙醇脱氢酶
%K 乳酸脱氢酶
%K 锌离子
%K 镁离子
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=90BA3D13E7F3BC869AC96FB3DA594E3FE34FBF7B8BC0E591&jid=A3C6BA55AB623B90FA9104CFFC826F3C&aid=3E445718B50CEAAB&yid=37904DC365DD7266&vid=D997634CFE9B6321&iid=E158A972A605785F&sid=CD26609C367AC9C8&eid=C7461453A367FC85&journal_id=0001-6209&journal_name=微生物学报&referenced_num=0&reference_num=14