Functional and bioinformatics analysis of an exopolysaccharide-related gene ( epsN ) from Lactobacillus kefiranofaciens
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ORIGINAL PAPER
Functional and bioinformatics analysis of an exopolysaccharide‑related gene (epsN) from Lactobacillus kefiranofaciens ZW3 Jingrui Wang1 · Wei Tang1 · Yongna Zheng1 · Zhuqing Xing1 · Yanping Wang1
Received: 8 October 2015 / Revised: 20 March 2016 / Accepted: 29 March 2016 © Springer-Verlag Berlin Heidelberg 2016
Abstract A novel lactic acid bacteria strain Lactobacillus kefiranofaciens ZW3 exhibited the characteristics of high production of exopolysaccharide (EPS). The epsN gene, located in the eps gene cluster of this strain, is associated with EPS biosynthesis. Bioinformatics analysis of this gene was performed. The conserved domain analysis showed that the EpsN protein contained MATE-Wzx-like domains. Then the epsN gene was amplified to construct the recombinant expression vector pMG36e-epsN. The results showed that the EPS yields of the recombinants were significantly improved. By determining the yields of EPS and intracellular polysaccharide, it was considered that epsN gene could play its Wzx flippase role in the EPS biosynthesis. This is the first time to prove the effect of EpsN on L. kefiranofaciens EPS biosynthesis and further prove its functional property. Keywords Lactobacillus kefiranofaciens · Exopolysaccharide · Bioinformatics analysis · Wzydependent · Flippase
Introduction Lactic acid bacteria (LAB) are kinds of the safe and edible microorganism with a generally recognized as safe (GRAS) Communicated by Erko Stackebrandt. * Yanping Wang [email protected] 1
Key Laboratory of Food Nutrition and Safety, College of Food Engineering and Biotechnology, Ministry of Education, Tianjin University of Science and Technology, Tianjin 300457, China
status in natural environment. They are also the members of the agricultural beneficial microorganisms and plant growth-promoting bacteria (Esteban-Torres et al. 2014; Liu et al. 2014). They have played a unique advantage in agriculture products cultivation. With the deepening of studies in antipathogenic fungi properties, adsorption of heavy metals and pesticide residues of LAB, more and more studies were focused on producing plant products with reduced use of pesticides and chemical fertilizers. Besides, modern food industries and researchers have been working toward the identification of valuable food bio-additives to meet the needs of nutrition as well as for healthful benefits of consumers. To meet consumer demand, the use of natural polymers in dairy products has attracted keen interest using microorganisms that are capable of producing EPS with improved quality and quantity. Therefore, the biosynthesis of EPS by microorganisms, as well as their excretion out of the cell, with improved properties has become an important focus for researchers (Black et al. 2012; Li et al. 2015). Bacterial EPS, when used in fermented food products, imparts unique physical features such as stabilizing, emulsifying, thickening and gelling characteristics (Anita et al. 2007; Sun et al. 2014). Fermented milk products and their related dairy LAB have been fou
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