Enhanced 2-keto-l-gulonic acid production by a mixed culture of Ketogulonicigenium vulgare and Bacillus megaterium using three-stage temperature control strategy

Abstract

As a key precursor of vitamin C, 2-keto-L-gulonic acid (2-KLG) was mainly produced from L-sorbose by mixed fermentation of Ketogulonicigenium vulgare and a helper strain (Bacillus spp.) with a low conversion rate for decades. The aim of this study was to enhance the 2-KLG production by co-culturing K. vulgare and Bacillus megaterium using three-stage temperature control (TSTC) strategy. By investigating the temperature effect on the 2-KLG fermentation, the optimum temperatures for the growths of K. vulgare and B. megaterium were 32 °C and 29 °C, respectively, while the optimum temperature for 2-KLG production was 35 °C. We developed a TSTC process: the temperature was kept at 32 °C during the first 16 h of fermentation, then decreased to 29 °C for the following 14 h, and maintained at 35 °C to the end of fermentation. By using this new process, the productivity and yield of 2-KLG from L-sorbose were obtained at 2.19 ± 0.19 g/L/h and 92.91 ± 1.02 g/L in 20-L fermentors for 5 batches, respectively, which were 22.35% and 6.02% higher than that of the control treatment (the single temperature of 29 °C). The increased cell density of K. vulgare during the exponential phase and the enhanced SDH activity (increased by 25.18% at 36 h, 17.14% at 44 h) in the production stage might be the reasons for enhanced 2-KLG conversion rate and yield. Our results demonstrated the feasibility of the TSTC strategy for 2-KLG production.

Siderophores of Bacillus pumilus promote 2‐keto‐L‐gulonic acid production in a vitamin C microbial fermentation system

“…Colony-forming units per milliliter (CFU/ml) was measured in the counting medium to determine the colonies number of B.p. 2-KLG concentration in K.v monoculture and K.v-B.p coculture fermentation systems was sampled every 3 h to determine by iodometry [3,28]. In a glass tube, 2 ml of fermentation broth and 2 ml of 7 mol/L H 2 SO 4 were added separately.…”

“…Vitamin C (Vc), as an essential water‐soluble nutrient, has been widely used for a long time for its antioxidant properties [1]. At present, a two‐step fermentation process to produce 2‐keto‐ l ‐gulonic acid (2‐KLG, the precursor of Vc) has been adopted by almost all of the main Vc producers and has achieved great economic benefits [2–5]. In the second step of fermentation, Ketogulonigenium vulgare and some of Bacillus strains composed of microbial consortia have been widely used.…”

Enhancing plant growth promoting rhizobacterial activities through consortium exposure: A review

“…Omics (Transcriptomics, trans proteomics, and metabolomics) tool that illuminates the understanding of the interaction between microorganisms in the consortium and provides precious information about functional diversity of consortium in their gene expression levels and also their metabolites profiling that helps to design and decipher the interaction of natural microbial consortium (Jia et al, 2016;Manzoni et al, 2016). Profiling of proteins and metabolites helps to artificially assemble and understand the interaction between Ketogulonicigenium vulgare and Bacillus megaterium that produce 2-keto-gluconic acid, in this interaction B. megaterium helps K. vulgare to resist reactive oxygen stress, and B. megaterium also provide necessary nutrients, like purine for the growth of K. vulgare for the production of 2-keto-gluconic acid (Wushensky et al, 2018;Yang et al, 2020).…”

“…Profiling of proteins and metabolites helps to artificially assemble and understand the interaction between Ketogulonicigenium vulgare and Bacillus megaterium that produce 2-keto-gluconic acid, in this interaction B. megaterium helps K. vulgare to resist reactive oxygen stress, and B . megaterium also provide necessary nutrients, like purine for the growth of K. vulgare for the production of 2-keto-gluconic acid ( Wushensky et al, 2018 ; Yang et al, 2020 ).…”

Artificial microbial consortia for bioproduction processes

“…Many approaches exist for further enhancing 2‐KGA yield. These include, for example, the implementation of a three‐stage temperature control strategy to fulfill the needs of growth and sporulation of Bacillus megaterium , growth and metabolism of K. vulgare and the enzyme activity of the L‐sorbitol dehydrogenase as there are different temperature optima [ 60 ] or the regulation of cell growth of B. megaterium with lysozyme for release of intracellular components for increased 2‐KGA production by K. vulgare [ 61 ].…”