title: RNA-Seq reveals transcriptomic interactions of Bacillus subtilis natto and Bifidobacterium animalis subsp. lactis in whole soybean solid-state co-fermentation.
abstract: Bifidobacteria are anaerobes and are difficult to culture in conventional fermentation system. It was observed that Bacillus subtilis natto enhanced growth of Bifidobacterium animalis subsp. lactis v9 by about 3-fold in a whole soybean solid-state co-fermentation, in a non-anaerobic condition. For the purpose of understanding the metabolic interactions between Bif. animalis subsp. lactis v9 and Ba. subtilis natto, the transcriptome of Bif. animalis subsp. lactis v9 and Ba. subtilis natto was analyzed in single and mixed cultures using RNA-Seq. Compared with the single culture, 459 genes of Bif. animalis subsp. lactis v9 were up regulated and 21 were down regulated in the mixed culture with Ba. subtilis natto, with more than 2-fold difference. Predictive metagenomic analyses suggested that Ba. subtilis natto up regulated transport functions, complex carbohydrates and amino acid metabolism, DNA repair, oxydative stress-related functions, and cell growth of Bif. animalis subsp. lactis v9. In the mixed culture with Bif. animalis subsp. lactis v9, only 3 transcripts of Ba. subtilis natto were over-expressed and 3115 were under-expressed with more than 2-fold difference. The highest down-regulated genes were those involved in carbohydrate and amino acid metabolism. The data presented here demonstrated a parasitic-like interaction regulated at the transcription level, between Ba. subtilis natto and Bif. animalis subsp. lactis in the mixed culture. The over-expression of genes involved in substrate uptake and metabolism in Bif. animalis subsp. lactis in the mixed culture nevertheless, led to its higher cell concentration in the nutrient rich whole soybean medium.
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, People's Republic of China.
authors.forename: Hai Kuan
authors.initials: HK
authors.lastname: Wang
authors.affiliation: Department of Microbiology, National University of Singapore, Singapore.
authors.forename: Yi Kai
authors.initials: YK
authors.lastname: Ng
authors.affiliation: Department of Microbiology, National University of Singapore, Singapore.
authors.forename: Eileen
authors.initials: E
authors.lastname: Koh
authors.affiliation: Department of Microbiology, National University of Singapore, Singapore.
authors.forename: Lina
authors.initials: L
authors.lastname: Yao
authors.affiliation: Department of Microbiology, National University of Singapore, Singapore.
authors.forename: Ang Sze
authors.initials: AS
authors.lastname: Chien
authors.affiliation: Department of Microbiology, National University of Singapore, Singapore.
authors.forename: Hui Xin
authors.initials: HX
authors.lastname: Lin
authors.affiliation: Department of Microbiology, National University of Singapore, Singapore. Electronic address: yuan_kun_lee@nuhs.edu.sg.
authors.forename: Yuan Kun
authors.initials: YK
authors.lastname: Lee
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism*; D001644:Bifidobacterium / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D015536:Down-Regulation; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D059014:High-Throughput Nucleotide Sequencing; D056265:Microbial Interactions; D017423:Sequence Analysis, RNA; D013025:Glycine max / Q000378:metabolism; D059467:Transcriptome; D015854:Up-Regulation / Q000235:genetics
keywords: Bacillus subtilis natto; Bifidobacterium animalis subsp. lactis; Co-fermentation; RNA-Seq; Whole soybean