title: Comparative transcriptome analysis reveals that lactose acts as an inducer and provides proper carbon sources for enhancing exopolysaccharide yield in the deep-sea bacterium Zunongwangia profunda SM-A87.
abstract: Many marine bacteria secrete exopolysaccharides (EPSs) that have important ecological and physiological functions. Numerous nutritional and environmental factors influence bacterial EPS production. However, the regulatory mechanisms of EPS production are poorly understood. The deep-sea Bacteroidetes bacterium Zunongwangia profunda SM-A87 can produce high quantities of EPS, and its EPS production is enhanced significantly by lactose. Here, we studied the reasons behind the significant advantage that lactose has over other carbon sources in EPS production in SM-A87. RNA-seq technologies were used to study lactose-regulated genes in SM-A87. The expression level of genes within the EPS gene cluster was up-regulated when lactose was added. Supplement of lactose also influenced the expression of genes located outside the EPS gene cluster that are also involved in EPS biosynthesis. The major glycosyl components of SM-A87 EPS are mannose, glucose and galactose. Genomic metabolic pathway analyses showed that the EPS precursor GDP-mannose can be synthesized from glucose, while the precursor UDP-glucose must be synthesized from galactose. Lactose can provide glucose and galactose simultaneously and prevent glucose inhibition. Lactose can also greatly stimulate the growth of SM-A87. Taken together, lactose acts not only as an inducer but also as a carbohydrate source for EPS production. This research broadens our knowledge of the regulation of EPS production in marine bacteria.
authors: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China; Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors: Qi-Long
authors: QL
authors: Qin
authors: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China; Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors: Yi
authors: Y
authors: Li
authors: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China; Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors: Mei-Ling
authors: ML
authors: Sun
authors: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China; Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors: Jin-Cheng
authors: JC
authors: Rong
authors: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China; Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors: Sheng-Bo
authors: SB
authors: Liu
authors: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China; Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors: Xiu-Lan
authors: XL
authors: Chen
authors: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China; Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors: Hai-Nan
authors: HN
authors: Su
authors: Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors: Bai-Cheng
authors: BC
authors: Zhou
authors: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China; Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors: Bin-Bin
authors: BB
authors: Xie
authors: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China; Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors: Yu-Zhong
authors: YZ
authors: Zhang
authors: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China; Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
authors: Xi-Ying
authors: XY
authors: Zhang
mesh_terms: D003470:Culture Media / Q000737:chemistry; D041965:Flavobacteriaceae / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D020869:Gene Expression Profiling; D007785:Lactose / Q000378:metabolism / Q000494:pharmacology*; D005810:Multigene Family / Q000235:genetics; D011135:Polysaccharides, Bacterial / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D003470:Culture Media; D011135:Polysaccharides, Bacterial; D007785:Lactose