左圖為白蟻,，右上圖為原蟲,，右下圖為細菌Pseudotrichonympha grassii在細胞內(nèi)的照片
據(jù)11月13日的《科學(xué)》雜志報道說，用于消化木材的生物化學(xué)能力即神秘又在加工生物燃料上有著很高的需求,?？茖W(xué)家們?nèi)缃衩枥L了一種成為白蟻以消化木材作為其唯一食物來源基礎(chǔ)的復(fù)雜的寄生蟲體內(nèi)含有寄生蟲的關(guān)系。
許多共生性微生物居住在白蟻的腸道內(nèi)協(xié)助白蟻消化木材,。其中的一種是原蟲,，它本身又是細菌Pseudotrichonympha grassii 的一個宿主。Yuichi Hongoh及其同僚對P. grassii 的完整的基因組進行了序列測定,。他們報道說,， 其獨特的基因組序列披露了該種細菌能夠固定大氣中的氮,，再循環(huán)廢棄物中的氮并為它們自己以及它們的原蟲宿主制造氨基酸的能力。（生物谷Bioon.com）
生物谷推薦原始出處：
Science 14 November 2008: 1108-1109.
Genome of an Endosymbiont Coupling N2 Fixation to Cellulolysis Within Protist Cells in Termite Gut
Yuichi Hongoh,1* Vineet K. Sharma,2,3* Tulika Prakash,2,3 Satoko Noda,1 Hidehiro Toh,2,3Todd D. Taylor,2,3 Toshiaki Kudo,1 Yoshiyuki Sakaki,2Atsushi Toyoda,2,4Masahira Hattori,2,5Moriya Ohkuma1
Termites harbor diverse symbiotic gut microorganisms, the majority of which are as yet uncultivable and their interrelationships unclear. Here, we present the complete genome sequence of the uncultured Bacteroidales endosymbiont of the cellulolytic protist Pseudotrichonympha grassii, which accounts for 70% of the bacterial cells in the gut of the termite Coptotermes formosanus. Functional annotation of the chromosome (1,114,206 base pairs) unveiled its ability to fix dinitrogen and recycle putative host nitrogen wastes for biosynthesis of diverse amino acids and cofactors, and import glucose and xylose as energy and carbon sources. Thus, nitrogen fixation and cellulolysis are coupled within the protist's cells. This highly evolved symbiotic system probably underlies the ability of the worldwide pest termites Coptotermes to use wood as their sole food.
1 Ecomolecular Biorecycling Science Research Team, RIKEN Advanced Science Institute, Saitama 351-0198, Japan.
2 RIKEN Genomic Sciences Center, Kanagawa 230-0045, Japan.
3 MetaSystems Research Team, RIKEN Advanced Science Institute, Kanagawa 230-0045, Japan.
4 Comparative Genomics Laboratory, National Institute of Genetics, Shizuoka 411-8540, Japan.
5 Department of Computational Biology, Graduate School of Frontier Sciences, University of Tokyo, Chiba 277-8561, Japan.
