人腸道微生物群落所起的有用作用之一是,，提供人類基因組中所缺的消化酶,。例如,，來自在整個演化過程中一直是人類飲食構(gòu)成部分的陸地植物的多糖，就是在腸道中被碳水化合物活性酶（CAZymes）分解的,，它們當(dāng)中很多都是來自類桿菌的具有高度特異性的酶,。然而，人們對幫助消化可食性海藻如紫菜,、海白菜和裙帶菜（常見于日本菜）的腸道酶卻知之甚少,。
現(xiàn)在，能夠消化來自紫菜類紅海藻的硫酸多糖的碳水化合物活性酶已在海洋類桿菌分離菌種中被發(fā)現(xiàn),。出乎意料的是,，基因組數(shù)據(jù)挖掘顯示，這種酶存在于日本人的腸道細(xì)菌中,，但在美國人的腸道細(xì)菌中卻沒有,。
這表明，最近（這里說的“最近”是從演化意義上來講的）發(fā)生了從一種來自海洋環(huán)境的類桿菌向日本人腸道細(xì)菌"Bacteroides plebeius"的基因轉(zhuǎn)移,。紫菜傳統(tǒng)上用于壽司中,，這表明，接觸未滅菌的食物,，在帶有不同碳水化合物活性酶的腸道細(xì)菌在體內(nèi)積累中是一個普遍因素,。(生物谷Bioon.com)
生物谷推薦原文出處：
Nature 464, 908-912 (8 April 2010) | doi:10.1038/nature08937
Transfer of carbohydrate-active enzymes from marine bacteria to Japanese gut microbiota
Jan-Hendrik Hehemann1,2,3, Ga?lle Correc1,2, Tristan Barbeyron1,2, William Helbert1,2, Mirjam Czjzek1,2 & Gurvan Michel1,2
1 Université Pierre et Marie Curie, Paris 6,
2 Centre National de la Recherche Scientifique, Végétaux marins et Biomolécules UMR 7139, Station Biologique de Roscoff, Roscoff F 29682, France
3 Present address: Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, British Columbia V8W 3PG, Canada.
Gut microbes supply the human body with energy from dietary polysaccharides through carbohydrate active enzymes, or CAZymes1, which are absent in the human genome. These enzymes target polysaccharides from terrestrial plants that dominated diet throughout human evolution2. The array of CAZymes in gut microbes is highly diverse, exemplified by the human gut symbiont Bacteroides thetaiotaomicron 3, which contains 261 glycoside hydrolases and polysaccharide lyases, as well as 208 homologues of susC and susD-genes coding for two outer membrane proteins involved in starch utilization1, 4. A fundamental question that, to our knowledge, has yet to be addressed is how this diversity evolved by acquiring new genes from microbes living outside the gut. Here we characterize the first porphyranases from a member of the marine Bacteroidetes, Zobellia galactanivorans, active on the sulphated polysaccharide porphyran from marine red algae of the genus Porphyra. Furthermore, we show that genes coding for these porphyranases, agarases and associated proteins have been transferred to the gut bacterium Bacteroides plebeius isolated from Japanese individuals5. Our comparative gut metagenome analyses show that porphyranases and agarases are frequent in the Japanese population6 and that they are absent in metagenome data7 from North American individuals. Seaweeds make an important contribution to the daily diet in Japan (14.2?g per person per day)8, and Porphyra spp. (nori) is the most important nutritional seaweed, traditionally used to prepare sushi9, 10. This indicates that seaweeds with associated marine bacteria may have been the route by which these novel CAZymes were acquired in human gut bacteria, and that contact with non-sterile food may be a general factor in CAZyme diversity in human gut microbes.
