Effect of glucose on poly-γ-glutamic acid metabolism in Bacillus licheniformis

Yu, Wencheng; Chen, Zhen; Ye, Hong; Liu, Peize; Li, Zhipeng; Wang, Qianqian; Li, Qingbiao; Yan, Shan; Zhong, Chuan‐Jian; He, Ning

doi:10.1186/s12934-017-0642-8

Cited by 29 publications

(15 citation statements)

References 49 publications

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“…Thus, mutations may occur in the genes encoding the enzymes for the lactose, mannose and galactose metabolism pathways. It was reported that glucose can affect the γ-PGA synthetic enzyme system and catabolite control protein A (CcpA) [34]. CcpA possesses several functions, such as control of lactose transport, β-galactosidase activity, and glycolysis [35], CcpA represses the TCA cycle and activates the EMP pathway when glucose is present in the medium [36].…”

Section: Effect Of Carbon Sources On γ-Pga Production By B Siamensismentioning

confidence: 99%

High-level production of poly-γ-glutamic acid from untreated molasses by Bacillus siamensis IR10

et al. 2020

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Background: Poly-γ-glutamic acid (γ-PGA) is a promising biopolymer and has been applied in many fields. Bacillus siamensis SB1001 was a newly isolated poly-γ-glutamic acid producer with sucrose as its optimal carbon source. To improve the utilization of carbon source, and then molasses can be effectively used for γ-PGA production, 60 cobalt gamma rays was used to mutate the genes of B. siamensis SB1001. Results: Bacillus siamensis IR10 was screened for the production of γ-PGA from untreated molasses. In batch fermentation, 17.86 ± 0.97 g/L γ-PGA was obtained after 15 h, which is 52.51% higher than that of its parent strain. Fed-batch fermentation was performed to further improve the yield of γ-PGA with untreated molasses, yielding 41.40 ± 2.01 g/L of γ-PGA with a productivity of 1.73 ± 0.08 g/L/h. An average γ-PGA productivity of 1.85 g/L/h was achieved in the repeated fed-batch fermentation. This is the first report of such a high γ-PGA productivity. The analysis of the enzyme activities showed that they were affected by the carbon sources, enhanced ICDH and GDH, and decreased ODHC, which are important for γ-PGA production. Conclusion: These results suggest that untreated molasses can be used for economical and industrial-scale production of γ-PGA by B. siamensis IR10.

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Section: Effect Of Carbon Sources On γ-Pga Production By B Siamensismentioning

confidence: 99%

High-level production of poly-γ-glutamic acid from untreated molasses by Bacillus siamensis IR10

et al. 2020

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“…In contrast, in B. licheniformis , the carbon metabolism regulatory proteins CcpA and CcpN and the nitrogen metabolism regulatory protein NrgB played core roles in the transition between the metabolism of the polysaccharide and γ-PGA. CcpA and CcpN could co-enhance glycolysis and suppress the carbon flux in the TCA cycle, consequently slowing the synthesis of γ-PGA; simultaneously, CcpN could cut off the carbon flux from glycerol metabolism and further reduce the γ-PGA production [ 37 ]. The synthesis of γ-PGA was also influenced by NrgB, which could transform the major nitrogen metabolic flux between NH 4 + and glutamate, facilitate ammonium utilization and promote glutamine synthesis; these effects are all beneficial for γ-PGA synthesis [ 37 ].…”

Section: Resultsmentioning

confidence: 99%

“…CcpA and CcpN could co-enhance glycolysis and suppress the carbon flux in the TCA cycle, consequently slowing the synthesis of γ-PGA; simultaneously, CcpN could cut off the carbon flux from glycerol metabolism and further reduce the γ-PGA production [ 37 ]. The synthesis of γ-PGA was also influenced by NrgB, which could transform the major nitrogen metabolic flux between NH 4 + and glutamate, facilitate ammonium utilization and promote glutamine synthesis; these effects are all beneficial for γ-PGA synthesis [ 37 ]. Our results also showed that overexpressing epsB could reduce the expression of CcpA and CcpN while increasing the expression of NrgB, all of which improved the γ-PGA synthesis (Fig.…”

Section: Resultsmentioning

confidence: 99%

Increasing the bioflocculant production and identifying the effect of overexpressing epsB on the synthesis of polysaccharide and γ-PGA in Bacillus licheniformis

et al. 2017

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BackgroundPolysaccharides and poly-γ-glutamic acid (γ-PGA) are biomacromolecules that have been reported as bioflocculants, and they exhibit high flocculating activity in many industrial applications. Bacillus licheniformis CGMCC 2876 can produce polysaccharide and γ-PGA bioflocculants under different culture conditions. Several key genes are involved in the metabolic pathway of polysaccharides in B. licheniformis, but the impacts of the regulation of these genes on the production of polysaccharide bioflocculants have not been illustrated completely. To increase the bioflocculant production and identify the correlation between the synthesis of polysaccharides and γ-PGA in B. licheniformis, a few key genes were investigated to explore their influence on the synthesis of the bioflocculants.ResultsOverexpressing epsB from the eps gene cluster not only improved the bioflocculant crude yield by 13.98% but also enhanced the flocculating activity by 117.92%. The composition of the bioflocculant from the epsB recombinant strain was 28.95% total sugar, 3.464% protein and 44.03% γ-PGA, while in the original strain, these components represented 53.67%, 3.246% and 34.13%, respectively. In combination with an analysis of the transcriptional levels of several key genes involved in γ-PGA synthesis in B. licheniformis, we inferred that epsB played a key role in the synthesis of both polysaccharide and γ-PGA. The bioflocculant production of the epsB recombinant strain was further evaluated during batch fermentation in a 2 L fermenter; the flocculating activity reached 9612.75 U/mL, and the bioflocculant yield reached 10.26 g/L after 72 h, representing increases of 224% and 36.62%, respectively, compared with the original strain. Moreover, we found that the tandem expression of phosphoglucomutase (pgcA) and UTP-glucose-1-phosphate uridylyltransferase (gtaB1) could enhance the crude yield of the bioflocculant by 20.77% and that the overexpression of epsA could enhance the bioflocculant yield by 23.70% compared with the original strain.ConclusionsThis study provides a new method to greatly increase the bioflocculant production in B. licheniformis, and it demonstrates the correlation between the biosynthesis of polysaccharide and γ-PGA during EPS fermentation by regulating the expression of EpsB.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-017-0775-9) contains supplementary material, which is available to authorized users.

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“…When a rapid-acting carbon source (glucose) is present in a fermentation system, the utilization priority of the rapid-acting carbon source is higher than that of the inducer, causing the inducer (another sugar or alcohol)-related genes to be inhibited by the CcpA protein and subjecting the expression system to the CCR effect ( Jankovic and Brückner, 2007 ; Moreno et al., 2010 ). When a delayed carbon source is present in a fermentation system, the inducer (sugar or alcohol) is the fast-acting carbon source, and the related metabolic utilization genes involved are activated by the CcpA protein, thereby causing the expression system to be subjected to the CCA effect ( Yu et al., 2017 ). Sugar/alcohol-inducible promoters usually contain a classical CRE site in the core region ( Heravi et al., 2011 ; Ren et al., 2010 ), which makes the regulation of the CcpA protein particularly important for the promoter.…”

Section: Discussionmentioning

confidence: 99%

A new CcpA binding site plays a bidirectional role in carbon catabolism in Bacillus licheniformis

Xiao

Zhang

et al. 2021

iScience

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Summary Bacillus licheniformis is widely used to produce various valuable products, such as food enzymes, industrial chemicals, and biocides. The carbon catabolite regulation process in the utilization of raw materials is crucial to maximizing the efficiency of this microbial cell factory. The current understanding of the molecular mechanism of this regulation is based on limited motif patterns in protein-DNA recognition, where the typical catabolite-responsive element (CRE) motif is “TGWNANCGNTNWCA”. Here, CRE Tre is identified and characterized as a new CRE. It consists of two palindrome arms of 6 nucleotides (AGCTTT/AAAGCT) and an intermediate spacer. CRE Tre is involved in bidirectional regulation in a glucose stress environment. When AGCTTT appears in the 5′ end, the regulatory element exhibits a carbon catabolite activation effect, while AAAGCT in the 5′ end corresponds to carbon catabolite repression. Further investigation indicated a wide occurrence of CRE Tre in the genome of B. licheniformis .

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Effect of glucose on poly-γ-glutamic acid metabolism in Bacillus licheniformis

Cited by 29 publications

References 49 publications

High-level production of poly-γ-glutamic acid from untreated molasses by Bacillus siamensis IR10

High-level production of poly-γ-glutamic acid from untreated molasses by Bacillus siamensis IR10

Increasing the bioflocculant production and identifying the effect of overexpressing epsB on the synthesis of polysaccharide and γ-PGA in Bacillus licheniformis

A new CcpA binding site plays a bidirectional role in carbon catabolism in Bacillus licheniformis

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