Abstract
Ketogulonicigenium vulgare, though grows poorly when mono-cultured, has been widely used in the industrial production of the precursor of vitamin C with the coculture of Bacillus megaterium. Various efforts have been made to clarify the synergic pattern of this artificial microbial community and to improve the growth and production ability of K. vulgare, but there is still no sound explanation. In previous research, we found that the addition of reduced glutathione into K. vulgare monoculture could significantly improve its growth and productivity. By performing SEM and TEM, we observed that after adding GSH into K. vulgare monoculture, cells became about 4–6 folds elongated, and formed intracytoplasmic membranes (ICM). To explore the molecular mechanism and provide insights into the investigation of the synergic pattern of the co-culture system, we conducted a comparative iTRAQ-2-D-LC-MS/MS-based proteomic analysis of K. vulgare grown under reduced glutathione. Principal component analysis of proteomic data showed that after the addition of glutathione, proteins for thiamin/thiamin pyrophosphate (TPP) transport, glutathione transport and the maintenance of membrane integrity, together with several membrane-bound dehydrogenases had significant up-regulation. Besides, several proteins participating in the pentose phosphate pathway and tricarboxylic acid cycle were also up-regulated. Additionally, proteins combating intracellular reactive oxygen species were also up-regulated, which similarly occurred in K. vulgare when the co-cultured B. megaterium cells lysed from our former research results. This study reveals the demand for transmembrane transport of substrates, especially thiamin, and the demand for antioxidant protection of K. vulgare.
Highlights
L-Ascorbic acid (L-AA), known as vitamin C, has been widely used in pharmaceutical, food and cosmetic industries mainly for its antioxidant property [1,2]
The fermentation process consists of one step of conversion from Dsorbitol to L-sorbose by Gluconobacter oxydans [6], followed by another step of converting L-sorbose to 2-keto-gulonic acid (2KGA), the precursor of vitamin C, by a mixed culture system of Ketogulonicigenium vulgare and Bacillus megaterium [6,7,8]
In our previous study on the metabolic cooperation of K. vulgare and B. megaterium by spatially cultivating them on a solid agar plate [20], we have found that K. vulgare had the ability of secreting amino acids to the environment, suggesting K. vulgare itself may have a high-efficiency amino acid transport system
Summary
L-Ascorbic acid (L-AA), known as vitamin C, has been widely used in pharmaceutical, food and cosmetic industries mainly for its antioxidant property [1,2]. In China, a two-step microbial fermentation process was developed [4] and has been successfully used for industrial production of vitamin C [5]. The fermentation process consists of one step of conversion from Dsorbitol to L-sorbose by Gluconobacter oxydans [6], followed by another step of converting L-sorbose to 2-keto-gulonic acid (2KGA), the precursor of vitamin C, by a mixed culture system of Ketogulonicigenium vulgare and Bacillus megaterium [6,7,8]. The 2-KGA producing bacteria K. vulgare which grows poorly when cultivated alone even on rich media [9], can grow better and carry out the conversion with the coculture of B. megaterium with high efficiency [8]. In spite of obvious advantages over monoculture of K. vulgare, the mixed culture has relatively higher cost for fermentation and contamination issue caused by the B. megaterium spore [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
