近日由于公眾對(duì)細(xì)菌造成污染的說(shuō)法關(guān)注過(guò)多，很容易讓人忽略這樣一個(gè)事實(shí)：如果沒(méi)有有益菌種的存在和作用,，我們的世界將會(huì)變得乏味和缺少食物,；乳酸菌就屬于這一類有益菌種。美國(guó)能源部聯(lián)合基因協(xié)會(huì)(DOE-JGI)和加州大學(xué)戴維斯分校的研究人員們已經(jīng)確定了9種不同的乳酸菌（LAB）的基因序列,，并把這一發(fā)現(xiàn)發(fā)表在10月17日的美國(guó)科學(xué)院院刊(http://www.pnas.org/cgi/content /abstract/0607117103v1)中,。這些微小的乳酸菌基因信息揭示了乳酸菌是如何依靠其不同的基因功能，有效地從其生存的營(yíng)養(yǎng)環(huán)境中攝取碳,、氮元素的,；并反映了其生物合成能力的有限范圍，使其有望得到更多的工業(yè)應(yīng)用,。
乳酸菌在食品和飲料的發(fā)酵生產(chǎn)過(guò)程中起著重要的作用,，每年可帶來(lái)數(shù)百億美元的市場(chǎng)銷售額。乳酸菌通過(guò)發(fā)酵六碳糖（己糖）來(lái)產(chǎn)生乳酸,，相關(guān)產(chǎn)品種類豐富,，包括酒類、臘腸、干酪,、發(fā)酵面包,、腌菜、酸奶,、可可飲料和咖啡等,。
“能源部聯(lián)合基因協(xié)會(huì)對(duì)全面研究乳酸菌的貢獻(xiàn)非常巨大，”這項(xiàng)研究的高級(jí)合作者,、加州大學(xué)戴維斯分校葡萄栽培與釀造學(xué)的助教David Mills說(shuō),，“破解這些發(fā)酵微生物的基因序列將極大地幫助我們了解它們?cè)谑称饭I(yè)中的作用，實(shí)現(xiàn)最優(yōu)化的生產(chǎn)設(shè)計(jì),。舉例來(lái)說(shuō),，更好地了解乳酸菌在干酪成熟中的作用就可以制定出縮短成熟時(shí)間的方案，從而節(jié)約能源,。另外,，乳酸菌還可以用于各種生物產(chǎn)品如右旋糖苷和抗菌劑的商業(yè)化生產(chǎn)，基因序列的信息則可以幫助發(fā)展其在生物能源和其它重要化學(xué)品生產(chǎn)方面的應(yīng)用,。”
這一成果的發(fā)表是乳酸菌基因聯(lián)盟在多年的不懈努力中取得的最高成果,，該聯(lián)盟于2001年成立，由至少12個(gè)學(xué)術(shù)團(tuán)體組成,。能源部聯(lián)合基因協(xié)會(huì)基因科技項(xiàng)目主任Paul Richardson介紹說(shuō),，該聯(lián)盟的研究類目涵蓋了工業(yè)應(yīng)用中的多種重要菌屬，包括乳球菌,、腸球菌,、酒球菌、足球菌、鏈球菌,、明串珠菌和乳桿菌,。“這些不同菌屬的基因序列為研究乳酸菌的糖類代謝和能量轉(zhuǎn)化系統(tǒng)及其演變提供了依據(jù),，這有助于確定在產(chǎn)生某種最終產(chǎn)物的過(guò)程中起關(guān)鍵作用的酶，這些產(chǎn)物包括醋酸,、乳酸,、乙醇和二氧化碳。”
“這項(xiàng)研究揭示了乳酸菌的基因和生物信息的特點(diǎn),，必將給食品,、健康和農(nóng)業(yè)帶來(lái)沖擊，”荷蘭Wageningen食品科學(xué)中心的項(xiàng)目主任,、微生物學(xué)教授Willem M.de Vos說(shuō),，“這是個(gè)壯舉,，他們公布的乳酸菌基因數(shù)據(jù)比現(xiàn)有的多幾倍，這些豐富和可靠的數(shù)據(jù)可以幫助其它研究團(tuán)體更好地了解和提高牛奶,、肉類和酒類發(fā)酵的引發(fā)過(guò)程,，或應(yīng)用于養(yǎng)殖工業(yè)和其它工業(yè)領(lǐng)域。”世界各地的專家對(duì)這些新的生物信息的分析將會(huì)進(jìn)一步完善這些基因數(shù)據(jù),，并提供更多關(guān)于微生物基因的學(xué)說(shuō)，包括基因變異的機(jī)理和水平基因的獲得,。
背景資料：
能源部聯(lián)合基因協(xié)會(huì)（DOE-JGI）是由美國(guó)能源部科學(xué)事務(wù)所資助,，聯(lián)合了來(lái)自能源部的五個(gè)國(guó)家實(shí)驗(yàn)室（Lawrence Berkeley,、Lawrence Livermore、Los Alamos,、 Oak Ridge和 Pacific Northwest）和斯坦福大學(xué)人類基因中心的專家,，通過(guò)對(duì)基因組學(xué)的研究來(lái)完成能源部關(guān)于清潔能源和環(huán)境保護(hù)方面的研究項(xiàng)目。
英文原文：
Genomic Comparison Of Lactic Acid Bacteria Published
With public concerns at a fevered pitch over the bacterial contamination of spinach, it is easy to lose track of how bland and deprived our world would be without the contribution to our food supply of such benign microbial players as lactic acid-producing bacteria. Researchers from the U.S. Department of Energy Joint Genome Institute (DOE JGI) and the University of California, Davis, and their colleagues have characterized the genome sequences of nine different lactic acid-producing bacteria, or LAB, and have published their findings in the October 17 edition of the Proceedings of the National Academy of Sciences .The small LAB genomes encode a diverse repertoire of genes for efficient carbon and nitrogen acquisition from the nutritionally rich environments they inhabit and reflect a limited range of biosynthetic capabilities promising broad industrial applications.
Lactic acid-producing bacteria play a key role in the production of fermented foods and beverages, accounting for tens of billions of dollars in sales annually. Products constituting a fine repast, such as wine, salami, cheese, sourdough bread, pickles, yogurt, cocoa, and coffee are all enhanced by LAB, which ferment six-carbon sugars, or hexoses, to produce lactic acid.
"DOE JGI's contribution to the whole study of lactic acid bacteria is simply immense," said David Mills, Associate Professor, Viticulture & Enology, University of California, Davis, and senior author on the study. "Access to the genome sequences for these fermentative microorganisms will dramatically increase our understanding of their role in industrial food production, leading to more optimized production schemes. For example, a better understanding of the role of lactic acid bacteria in cheese ripening will result in production strategies that reduce ripening time and thereby save energy. Moreover, lactic acid bacteria are used for production of various commercial bioproducts such as dextran and antimicrobials. The availability of these genome sequences will foster development of additional production schemes for biofuels and other important chemicals."
The publication is the culmination of a multiyear effort by the Lactic Acid Bacteria Genome Consortium, a group of at least a dozen academic organizations formed in 2001. Paul Richardson, DOE JGI Genomic Technologies Program head, said that the functional classification embraced a variety of industrially important genera, including Lactococcus, Enterococcus, Oenococcus, Pediococcus, Streptococcus, Leuconostoc, and Lactobacillus species. "The sequence of these diverse species offered a window into the sugar metabolism and energy conversion systems of LAB, and the evolution of these systems, which helped identify key enzymes involved in the production of end products including acetic acid, lactic acid, ethanol, and CO2."
"This work represents a hallmark in the genomic and bioinformatic characterization of lactic acid bacteria that have an impact on food, health, and agriculture," said Willem M. de Vos, Professor of Microbiology and Program Director of the Wageningen Center for Food Sciences in Holland. "In a heroic effort, their publication more than doubles the number of lactic acid bacterial genomes that are publicly available and provides the research community with a wealth of high-quality data that can be used to understand and improve starter cultures for dairy, meat, and wine fermentations; probiotic cultures; and other industrial applications. The extensive bioinformatic analyses by world experts adds to the impact of the genomic data and provides new hypotheses on how microbial genomes evolve by mechanisms of genomic loss and horizontal gene acquisitions."
