| The versatile metabolism of Ketogulonigenium vulgare and different companion mechanism of Bacillus strains are two topic researches in industrial production of vitamin C.In present study,the properties of vitamin C productional strains and diverse metabolic pathways were analysized based on comparative genomics and metabolomics,which will provide the help to further guide the engineering transformation.K.vulgare has been widely used in vitamin C two steps fermentation and requires companion strain for optimal growth.The complete genome of K.vulgare Hbe602 was deciphered to understand the symbiosis mechanism and the versatile metabolism.Besides,the growth state of K.vulgare was observed when five carbohydrates(D-sorbitol,L-sorbose,D-glucose,D-fructose and D-mannitol)were used as carbon source.The growth of K.vulgare increased by 40.72% and 62.97%respectively when cultured on D-mannitol and D-sorbitol than on L-sorbose.Combined genomics and metabolomics analysis indicated that TCA cycle,amino acids and nucleotides were significantly up-regulated when K.vulgare was cultured on the D-mannitol and D-sorbitol,which facilitated better growth.Bacillus thuringiensis and Bacillus endophyticus both acted as the companion bacteria,which cooperated with K.vulgare in vitamin C two-step fermentation.B.thuringiensis Bc601 consists of one chromosome and six circular plasmids.The genes in plasmids are mainly encoding transposases,transcriptional regulators,recombinases,type VII secretion proteins and cell surface proteins.Besides,B.thuringiensis Bc601 also encodes thiamine biosynthesis protein,ATPase and flagellar biosynthesis protein on plasmids for nutrients synthesis.B.endophyticus Hbe603 consists of one chromosome and eight circular plasmids,which has the highest similarity with that of Bacillus megaterium.Genome-based functional studies revealed the specific capability in transcription regulation,membrane transportation,extracellular proteins and nutrients synthesis.In particular,it has specific pathways for vitamin B12 synthesis and sorbitol metabolism.By culturing the two species with K.vulgare orthogonally on agar plate,only B.thuringiensis could swarm to K.vulgare.Swarming motility reflects different companion mechanisms of two Bacillus species,and may be connected with the ability of respond to the external environment and nutrients biosynthesis.For the ability of response to the external environment,B.thuringiensis Bc601 has more two-component system,sporulation coat and peptidoglycan biosynthesis related proteins than B.endophyticus Hbe603.For the ability of nutrients biosynthesis,B.endophyticus Hbe603 has more alpha-galactosidase,glutathione and inositol phosphate metabolism,and amino acid degradation related proteins than B.thuringiensis Bc601. |
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