本文主要研究内容
作者毛江川（2019）在《啤酒酵母二氧化硫和乙醛产生机制初探》一文中研究指出：啤酒工业中,啤酒风味老化一直是亟待解决的问题。啤酒酵母是啤酒酿造的灵魂,在发酵过程中代谢产生啤酒中主要的风味物质。其中,SO2是最有效的抗氧化物质和风味稳定剂,而乙醛是与老化直接相关且含量最高的醛类物质,通常乙醛含量的增多也伴随着其他老化醛类物质的增多。研究表明SO2和乙醛之间存在着一定的关系,提高菌株产SO2能力的同时,乙醛含量也相应增加,这限制了该菌株在啤酒工业中的应用。此外,SO2是酵母SO42-还原途径的中间代谢产物,乙醛是酒精代谢中的关键物质,两者都与胞内能量代谢相关。因此,研究SO2和乙醛的产生机制以及相关性尤为重要,为选育优良的抗老化啤酒酵母提供理论基础和重要的指导意义。论文证明了啤酒酵母中SO2和乙醛的产生存在着一定的正相关性,并从基因表达水平上分析啤酒酵母SO2和乙醛产量差异的内在原因,研究发现丝氨酸和MET5基因对两者产量有重要的影响,主要研究结果如下所示:（1）SO2和乙醛产量的相关性分析:选择高产SO2和乙醛啤酒酵母M41（Saccharomyces pastorianus）及其诱变菌D-A-14（低产SO2和乙醛）为出发菌株,分别添加与硫代谢相关的蛋氨酸、半胱氨酸及苏氨酸于麦汁来分析氨基酸对两者产量的变化。尽管三种氨基酸对两者产量的作用效果不同,但Pearson相关性分析表明两者产量存在着正相关性（r=0.502,P<0.01）。（2）表型差异菌株的转录组学分析:从代谢途径上分析可得,菌株M41和D-A-14之间主要的差异包括糖代谢（糖酵解和糖异生）、蛋白质和氨基酸代谢（含硫氨基酸合成途径）。高产SO2菌株M41中SO42-还原途径通量显著下调,其中MET5基因（0.35倍）表达水平的下调可能引起SO32-还原酶活性下降,导致胞内更少的SO2被还原利用;而超过80%糖代谢差异基因表达上调则暗示着乙醛产量的提高。此外,丝氨酸胞内代谢流向同时影响胞内乙醛和含硫氨基酸代谢,从而可能影响两菌株SO2和乙醛的产生能力。（3）丝氨酸对啤酒酵母SO2和乙醛产量的作用:适量丝氨酸促进两菌株SO2和乙醛的产量,但对两者产量的调节水平不同。原本丝氨酸流向硫代谢通量较小的菌株M41中,添加200mg·L-1丝氨酸后SO42-还原途径通量增强,SO2产量提高至原来1.90倍,而乙醛含量基本不变,显著增强了发酵液的抗老化能力。而丝氨酸流向糖代谢的通量较小的菌株D-A-14中,添加丝氨酸后胞内PDC1和PDC5基因表达量分别上调2.43和2.41倍,促进其乙醛和乙醇产量;而丝氨酸对该菌株SO42-还原途径的影响甚小。（4）MET5基因对啤酒酵母产SO2和乙醛的影响:敲除菌株D-A-14中MET5基因后,SO2含量增加至5.42 mg·L-1,提高幅度为52.7%,但乙醛产量也相应增加。qRT-PCR结果表明敲除MET5基因菌株D7中SO42-还原途径通量显著下调,MET5基因表达水平下调至原来的0.31倍;与乙醛合成相关PDC5基因表达水平却显著上调了4.20倍,可能促使胞内更多乙醛的产生。此外,本研究表明两菌株中MET5基因氨基酸序列的差异对SO32-还原酶的活性也有着一定的影响。
Abstract
pi jiu gong ye zhong ,pi jiu feng wei lao hua yi zhi shi ji dai jie jue de wen ti 。pi jiu jiao mu shi pi jiu niang zao de ling hun ,zai fa jiao guo cheng zhong dai xie chan sheng pi jiu zhong zhu yao de feng wei wu zhi 。ji zhong ,SO2shi zui you xiao de kang yang hua wu zhi he feng wei wen ding ji ,er yi quan shi yu lao hua zhi jie xiang guan ju han liang zui gao de quan lei wu zhi ,tong chang yi quan han liang de zeng duo ye ban sui zhao ji ta lao hua quan lei wu zhi de zeng duo 。yan jiu biao ming SO2he yi quan zhi jian cun zai zhao yi ding de guan ji ,di gao jun zhu chan SO2neng li de tong shi ,yi quan han liang ye xiang ying zeng jia ,zhe xian zhi le gai jun zhu zai pi jiu gong ye zhong de ying yong 。ci wai ,SO2shi jiao mu SO42-hai yuan tu jing de zhong jian dai xie chan wu ,yi quan shi jiu jing dai xie zhong de guan jian wu zhi ,liang zhe dou yu bao nei neng liang dai xie xiang guan 。yin ci ,yan jiu SO2he yi quan de chan sheng ji zhi yi ji xiang guan xing you wei chong yao ,wei shua yo you liang de kang lao hua pi jiu jiao mu di gong li lun ji chu he chong yao de zhi dao yi yi 。lun wen zheng ming le pi jiu jiao mu zhong SO2he yi quan de chan sheng cun zai zhao yi ding de zheng xiang guan xing ,bing cong ji yin biao da shui ping shang fen xi pi jiu jiao mu SO2he yi quan chan liang cha yi de nei zai yuan yin ,yan jiu fa xian si an suan he MET5ji yin dui liang zhe chan liang you chong yao de ying xiang ,zhu yao yan jiu jie guo ru xia suo shi :（1）SO2he yi quan chan liang de xiang guan xing fen xi :shua ze gao chan SO2he yi quan pi jiu jiao mu M41（Saccharomyces pastorianus）ji ji you bian jun D-A-14（di chan SO2he yi quan ）wei chu fa jun zhu ,fen bie tian jia yu liu dai xie xiang guan de dan an suan 、ban guang an suan ji su an suan yu mai zhi lai fen xi an ji suan dui liang zhe chan liang de bian hua 。jin guan san chong an ji suan dui liang zhe chan liang de zuo yong xiao guo bu tong ,dan Pearsonxiang guan xing fen xi biao ming liang zhe chan liang cun zai zhao zheng xiang guan xing （r=0.502,P<0.01）。（2）biao xing cha yi jun zhu de zhuai lu zu xue fen xi :cong dai xie tu jing shang fen xi ke de ,jun zhu M41he D-A-14zhi jian zhu yao de cha yi bao gua tang dai xie （tang jiao jie he tang yi sheng ）、dan bai zhi he an ji suan dai xie （han liu an ji suan ge cheng tu jing ）。gao chan SO2jun zhu M41zhong SO42-hai yuan tu jing tong liang xian zhe xia diao ,ji zhong MET5ji yin （0.35bei ）biao da shui ping de xia diao ke neng yin qi SO32-hai yuan mei huo xing xia jiang ,dao zhi bao nei geng shao de SO2bei hai yuan li yong ;er chao guo 80%tang dai xie cha yi ji yin biao da shang diao ze an shi zhao yi quan chan liang de di gao 。ci wai ,si an suan bao nei dai xie liu xiang tong shi ying xiang bao nei yi quan he han liu an ji suan dai xie ,cong er ke neng ying xiang liang jun zhu SO2he yi quan de chan sheng neng li 。（3）si an suan dui pi jiu jiao mu SO2he yi quan chan liang de zuo yong :kuo liang si an suan cu jin liang jun zhu SO2he yi quan de chan liang ,dan dui liang zhe chan liang de diao jie shui ping bu tong 。yuan ben si an suan liu xiang liu dai xie tong liang jiao xiao de jun zhu M41zhong ,tian jia 200mg·L-1si an suan hou SO42-hai yuan tu jing tong liang zeng jiang ,SO2chan liang di gao zhi yuan lai 1.90bei ,er yi quan han liang ji ben bu bian ,xian zhe zeng jiang le fa jiao ye de kang lao hua neng li 。er si an suan liu xiang tang dai xie de tong liang jiao xiao de jun zhu D-A-14zhong ,tian jia si an suan hou bao nei PDC1he PDC5ji yin biao da liang fen bie shang diao 2.43he 2.41bei ,cu jin ji yi quan he yi chun chan liang ;er si an suan dui gai jun zhu SO42-hai yuan tu jing de ying xiang shen xiao 。（4）MET5ji yin dui pi jiu jiao mu chan SO2he yi quan de ying xiang :qiao chu jun zhu D-A-14zhong MET5ji yin hou ,SO2han liang zeng jia zhi 5.42 mg·L-1,di gao fu du wei 52.7%,dan yi quan chan liang ye xiang ying zeng jia 。qRT-PCRjie guo biao ming qiao chu MET5ji yin jun zhu D7zhong SO42-hai yuan tu jing tong liang xian zhe xia diao ,MET5ji yin biao da shui ping xia diao zhi yuan lai de 0.31bei ;yu yi quan ge cheng xiang guan PDC5ji yin biao da shui ping que xian zhe shang diao le 4.20bei ,ke neng cu shi bao nei geng duo yi quan de chan sheng 。ci wai ,ben yan jiu biao ming liang jun zhu zhong MET5ji yin an ji suan xu lie de cha yi dui SO32-hai yuan mei de huo xing ye you zhao yi ding de ying xiang 。
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论文详细介绍
论文作者分别是来自江南大学的毛江川，发表于刊物江南大学2019-10-21论文，是一篇关于啤酒酵母论文,乙醛论文,丝氨酸论文,基因论文,风味稳定性论文,江南大学2019-10-21论文的文章。本文可供学术参考使用，各位学者可以免费参考阅读下载，文章观点不代表本站观点，资料来自江南大学2019-10-21论文网站，若本站收录的文献无意侵犯了您的著作版权，请联系我们删除。