title: Comparative transcriptome analysis reveals different molecular mechanisms of Bacillus coagulans 2-6 response to sodium lactate and calcium lactate during lactic acid production.
abstract: Lactate production is enhanced by adding calcium carbonate or sodium hydroxide during fermentation. However, Bacillus coagulans 2-6 can produce more than 180 g/L L-lactic acid when calcium lactate is accumulated, but less than 120 g/L L-lactic acid when sodium lactate is formed. The molecular mechanisms by which B. coagulans responds to calcium lactate and sodium lactate remain unclear. In this study, comparative transcriptomic methods based on high-throughput RNA sequencing were applied to study gene expression changes in B. coagulans 2-6 cultured in non-stress, sodium lactate stress and calcium lactate stress conditions. Gene expression profiling identified 712 and 1213 significantly regulated genes in response to calcium lactate stress and sodium lactate stress, respectively. Gene ontology assignments of the differentially expressed genes were performed. KEGG pathway enrichment analysis revealed that 'ATP-binding cassette transporters' were significantly affected by calcium lactate stress, and 'amino sugar and nucleotide sugar metabolism' was significantly affected by sodium lactate stress. It was also found that lactate fermentation was less affected by calcium lactate stress than by sodium lactate stress. Sodium lactate stress had negative effect on the expression of 'glycolysis/gluconeogenesis' genes but positive effect on the expression of 'citrate cycle (TCA cycle)' genes. However, calcium lactate stress had positive influence on the expression of 'glycolysis/gluconeogenesis' genes and had minor influence on 'citrate cycle (TCA cycle)' genes. Thus, our findings offer new insights into the responses of B. coagulans to different lactate stresses. Notably, our RNA-seq dataset constitute a robust database for investigating the functions of genes induced by lactate stress in the future and identify potential targets for genetic engineering to further improve L-lactic acid production by B. coagulans.
authors: College of Pharmacy, Binzhou Medical University, Yantai, People's Republic of China.
authors: Jiayang
authors: J
authors: Qin
authors: College of Pharmacy, Binzhou Medical University, Yantai, People's Republic of China.
authors: Xiuwen
authors: X
authors: Wang
authors: College of Pharmacy, Binzhou Medical University, Yantai, People's Republic of China.
authors: Landong
authors: L
authors: Wang
authors: College of Pharmacy, Binzhou Medical University, Yantai, People's Republic of China.
authors: Beibei
authors: B
authors: Zhu
authors: College of Pharmacy, Binzhou Medical University, Yantai, People's Republic of China.
authors: Xiaohua
authors: X
authors: Zhang
authors: College of Pharmacy, Binzhou Medical University, Yantai, People's Republic of China.
authors: Qingshou
authors: Q
authors: Yao
authors: State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China.
authors: Ping
authors: P
authors: Xu
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D001407:Bacillus / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D017610:Calcium Compounds / Q000378:metabolism*; D005285:Fermentation; D020869:Gene Expression Profiling / Q000379:methods*; D015964:Gene Expression Regulation, Bacterial; D007773:Lactates / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D015398:Signal Transduction; D019354:Sodium Lactate / Q000378:metabolism*; D059467:Transcriptome
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D017610:Calcium Compounds; D007773:Lactates; C110051:calcium lactate; D019344:Lactic Acid; D019354:Sodium Lactate