Bacterial xylose isomerases from the mammal gut Bacteroidetes cluster function in Saccharomyces cerevisiae for effective xylose fermentation

Microbial Cell Factories

Research

Anli Geng¹  Bingyin Peng¹  Tingting Liu²  Shuangcheng Huang² 

[1] School of Life Sciences and Chemical Technology, Ngee Ann Polytechnic, Singapore, Singapore;School of Life Sciences and Chemical Technology, Ngee Ann Polytechnic, Singapore, Singapore;School of Chemical Engineering and Pharmacy, Key Laboratory for Green Chemical Process of Ministry of Education, Wuhan Institute of Technology, 430073, Wuhan, Peoples Republic of China;

关键词: Xylose isomerase;    Bacteroidetes;    Alistipes;    Bacteroides;    Mammal gut;    Microbe;    Adaptive evolution;    Saccharomyces cerevisiae;    Xylose fermentation;    Cellulosic ethanol;   

DOI  :  10.1186/s12934-015-0253-1

 received in 2014-12-31, accepted in 2015-05-06,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundXylose isomerase (XI) catalyzes the conversion of xylose to xylulose, which is the key step for anaerobic ethanolic fermentation of xylose. Very few bacterial XIs can function actively in Saccharomyces cerevisiae. Here, we illustrate a group of XIs that would function for xylose fermentation in S. cerevisiae through phylogenetic analysis, recombinant yeast strain construction, and xylose fermentation.ResultsPhylogenetic analysis of deposited XI sequences showed that XI evolutionary relationship was highly consistent with the bacterial taxonomic orders and quite a few functional XIs in S. cerevisiae were clustered with XIs from mammal gut Bacteroidetes group. An XI from Bacteroides valgutus in this cluster was actively expressed in S. cerevisiae with an activity comparable to the fungal XI from Piromyces sp. Two XI genes were isolated from the environmental metagenome and they were clustered with XIs from environmental Bacteroidetes group. These two XIs could not be expressed in yeast with activity. With the XI from B. valgutus expressed in S. cerevisiae, background yeast strains were optimized by pentose metabolizing pathway enhancement and adaptive evolution in xylose medium. Afterwards, more XIs from the mammal gut Bacteroidetes group, including those from B. vulgatus, Tannerella sp. 6_1_58FAA_CT1, Paraprevotella xylaniphila and Alistipes sp. HGB5, were individually transformed into S. cerevisiae. The known functional XI from Orpinomyces sp. ukk1, a mammal gut fungus, was used as the control. All the resulting recombinant yeast strains were able to ferment xylose. The respiration-deficient strains harboring B. vulgatus and Alistipes sp. HGB5 XI genes respectively obtained specific xylose consumption rate of 0.662 and 0.704 g xylose gcdw−1 h−1, and ethanol specific productivity of 0.277 and 0.283 g ethanol gcdw−1 h−1, much comparable to those obtained by the control strain carrying Orpinomyces sp. ukk1 XI gene.ConclusionsThis study demonstrated that XIs clustered in the mammal gut Bacteroidetes group were able to be expressed functionally in S. cerevisiae and background strain anaerobic adaptive evolution in xylose medium is essential for the screening of functional XIs. The methods outlined in this paper are instructive for the identification of novel XIs that are functional in S. cerevisiae.

【 授权许可】

Unknown   
© Peng et al.; licensee BioMed Central. 2015. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.