Acetate-mediated pH-stat fed-batch cultivation of transconjugant Enterobacter sp. BL-2S over-expressing glmS gene for excretive production of microbial polyglucosamine PGB-1

Son, Mi-Kyung; Hong, Su Hyung; Lee, Yong-Hyun

doi:10.1007/s10295-007-0258-9

Cited by 7 publications

(4 citation statements)

References 21 publications

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“…Therefore, this culturing technique is used to overcome the Crabtree effect 22 . Fed-batch strategies include constant dissolved oxygen value feeding (DO-stat) 23 – 27 , constant specific growth rate feeding (μ-stat) 25 , 28 , constant pH feeding (pH–stat) 20 , 29 , 30 , and constant carbon source concentration feeding 31 . Besides the Crabtree effect, oxygen in short supply is another obstacle in aerobic culture.…”

Section: Introductionmentioning

confidence: 99%

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Dissolved-oxygen feedback control fermentation for enhancing β-carotene in engineered Yarrowia lipolytica

Shan

Liu

et al. 2020

Sci Rep

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The DO-stat fed-batch fermentation was carried out to explore the volumetric productivity of β-carotene in engineered Yarrowia lipolytica C11 strain. Using DO-stat fed-batch fermentation, we achieved 94 g/L biomass and 2.01 g/L β-carotene. Both biomass and β-carotene were about 1.28-fold higher than that in fed-batch fermentation. The ATP, NADP+/NADPH, and gene expression levels of tHMG, GGS1, carRA, and carB were promoted as compared to that in fed-batch fermentation. As for as the kinetic parameters in DO-stat fed-batch fermentation, μm′, Yx/s′, and Yp/s′ was 0.527, 0.353, and 0.158, respectively. The μm′ was elevated 4.66-fold than that in fed-batch fermentation. These data illustrate that more dissolved oxygen increased the biomass. The Yx/s′ and Yp/s′ were increased 1.15 and 22.57-fold, which suggest that the DO-stat fed-batch fermentation reduced the Crabtree effect and improved the utilization rate of glucose. Therefore, DO-stat fed-batch fermentation is a promising strategy in the industrialized production of β-carotene.

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Section: Introductionmentioning

confidence: 99%

“…growth rate feeding (μ-stat) 25,28 , constant pH feeding (pH-stat) 20,29,30 , and constant carbon source concentration feeding 31 . Besides the Crabtree effect, oxygen in short supply is another obstacle in aerobic culture.…”

mentioning

confidence: 99%

Dissolved-oxygen feedback control fermentation for enhancing β-carotene in engineered Yarrowia lipolytica

Shan

Liu

et al. 2020

Sci Rep

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“…Son et al hypothesized that the genes associated with the hexosamine pathway ( glmU , glmS , and glmM ) are essential for the production of microbial polyglucosamine PGB-1 in Enterobacter sp. BL-2, and they introduced additional glmS copies (as a pBBR1MCS-2-based plasmid) into the BL-2 strain by conjugation to strengthen the pathway [9,35]. The resulting BL-2S strain produced a 1.5-fold more PGB-1 compared than the wild-type BL-2 strain.…”

Section: Discussionmentioning

confidence: 99%

Biosynthetic Pathway and Genes of Chitin/Chitosan-Like Bioflocculant in the Genus Citrobacter

Takeo

Kimura²,

Mayilraj

et al. 2018

Polymers

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Chitin/chitosan, one of the most abundant polysaccharides in nature, is industrially produced as a powder or flake form from the exoskeletons of crustaceans such as crabs and shrimps. Intriguingly, many bacterial strains in the genus Citrobacter secrete a soluble chitin/chitosan-like polysaccharide into the culture medium during growth in acetate. Because this polysaccharide shows strong flocculation activity for suspended solids in water, it can be used as a bioflocculant (BF). The BF synthetic pathway of C. freundii IFO 13545 is expected from known bacterial metabolic pathways to be as follows: acetate is metabolized in the TCA cycle and the glyoxylate shunt via acetyl-CoA. Next, fructose 6-phosphate is generated from the intermediates of the TCA cycle through gluconeogenesis and enters into the hexosamine synthetic pathway to form UDP-N-acetylglucosamine, which is used as a direct precursor to extend the BF polysaccharide chain. We conducted the draft genome sequencing of IFO 13545 and identified all of the candidate genes corresponding to the enzymes in this pathway in the 5420-kb genome sequence. Disruption of the genes encoding acetyl-CoA synthetase and isocitrate lyase by homologous recombination resulted in little or no growth on acetate, indicating that the cell growth depends on acetate assimilation via the glyoxylate shunt. Disruption of the gene encoding glucosamine 6-phosphate synthase, a key enzyme for the hexosamine synthetic pathway, caused a significant decrease in flocculation activity, demonstrating that this pathway is primarily used for the BF biosynthesis. A gene cluster necessary for the polymerization and secretion of BF, named bfpABCD, was also identified for the first time. In addition, quantitative RT-PCR analysis of several key genes in the expected pathway was conducted to know their expression in acetate assimilation and BF biosynthesis. Based on the data obtained in this study, an overview of the BF synthetic pathway is discussed.

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“…BL-4, and genetically-engineered Enterobacter sp. BL-2S, resulting in the production of 1.53 g l -1 of the BF PGB-1 2) , 4.86 g l -1 of crude PGB-2 3) , and 1.15 g l -1 PGB-1 6) , respectively. To produce the BF04 of strain TKF04 at commercial levels, some fermentation companies have attempted to scale up production, but this has been unsuccessful because the TKF04 strain is unstable during BF production; fl occulation activity (FA) is sometimes reduced or lost during cultivation.…”

Section: Introductionmentioning

confidence: 99%

Effects of Organic Acids and Amino Acids on the Flocculation Activity of Chitosan-Like Bioflocculant-Producing <i>Citrobacter freundii </i>IFO 13545

Kimura

Inoue

Nagayama

et al. 2014

Japanese J. Wat. Treat. Biol.

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Citrobacter freundii IFO 13545 produces a chitosan-like bioflocculant (BF) from acetate. The effects of other organic acids (citrate, fumarate, malate, glyoxylate, succinate, and oxaloacetate) as carbon sources on the growth and flocculation activity (FA) of the cultures were investigated. Citrate, fumarate, malate, succinate, or oxaloacetate supported the growth of IFO 13545 as a sole carbon source, but any FA was not detected during the growth on these organic acids. Glyoxylate did not serve as a carbon source. These organic acids were tested for a possibility as auxiliary carbon sources by adding each organic acid to a basal medium including 10 g l-1 acetate (AM). However, with the exception of malate, they all negatively affected FA at 1 g l-1 in AM. As a supply of amino acids, the effect of casamino acids on FA was also investigated. Unexpectedly, casamino acids considerably reduced FA at a concentration of 1 g l-1 in AM, although it improved the growth greatly. To determine which constituents caused FA reduction, the effects of individual amino acids were evaluated. Valine and tryptophan were found to strongly repress FA, even at low concentrations (≥10 mg l-1). Furthermore, to select complex organic nutrients suitable for BF production media, the effects exerted by yeast extract, peptone, and tryptone on FA were also investigated. Intriguingly, yeast extract and tryptone negatively affected FA, even at a concentration of 1 g l-1 , although peptone did not have significant effect at the same concentration. These results demonstrate that ubiquitous organic acids, amino acids, and complex organic nutrients can significantly affect the FA of IFO 13545 even at low concentrations.

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Acetate-mediated pH-stat fed-batch cultivation of transconjugant Enterobacter sp. BL-2S over-expressing glmS gene for excretive production of microbial polyglucosamine PGB-1

Cited by 7 publications

References 21 publications

Dissolved-oxygen feedback control fermentation for enhancing β-carotene in engineered Yarrowia lipolytica

Dissolved-oxygen feedback control fermentation for enhancing β-carotene in engineered Yarrowia lipolytica

Biosynthetic Pathway and Genes of Chitin/Chitosan-Like Bioflocculant in the Genus Citrobacter

Effects of Organic Acids and Amino Acids on the Flocculation Activity of Chitosan-Like Bioflocculant-Producing <i>Citrobacter freundii </i>IFO 13545

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