Investigation of poly(γ-glutamic acid) production via online determination of viscosity and oxygen transfer rate in shake flasks

Meissner, Lena; Arndt, Julia; Palmen, Thomas G.; Jestel, Tim; Mitsunaga, Hitoshi; Fukusaki, Eiichiro; Büchs, Jochen

doi:10.1186/s13036-017-0065-4

Cited by 11 publications

(9 citation statements)

References 48 publications

(60 reference statements)

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“…Because ammonium was used as nitrogen source, γ‐PGA is produced during microbial growth in phase I (Meissner et al, ). In the second phase (II: 18.5–32 hr), the produced γ‐PGA is degraded (Meissner et al, ; Regestein née Meissner et al, ; Wilming et al, ).…”

Section: Resultsmentioning

confidence: 99%

Combined dissolved oxygen tension and online viscosity measurements in shake flask cultivations via infrared fluorescent oxygen‐sensitive nanoparticles

Ladner

Flitsch

Lukacs

et al. 2019

Biotech & Bioengineering

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Oxygen supply is one of the most critical process parameters in aerobic cultivations.To assure sufficient oxygen supply, shake flasks are usually used in combination with orbital shaking machines. In this study, a measurement technique for the dissolved oxygen tension (DOT) in shake flask cultures with viscosity changes is presented. The movement of the shaker table is monitored by means of a Hall effect sensor. For DOT measurements, infrared fluorescent oxygen-sensitive nanoparticles are added to the culture broth. The position of the rotating bulk liquid needs to be determined to assure measurements inside the liquid. The leading edge of the bulk liquid is detected based on the fluorescence signal intensity of the oxygen-sensitive nanoparticles. Furthermore, online information about the viscosity of the culture broth is acquired due to the detection of the position of the leading edge of the bulk liquid relative to the direction of the centrifugal force, as described by Sieben et al. (2019. Sci. Rep., 9, 8335). The DOT measurement is combined with a respiration activity monitoring system which allows for the determination of the oxygen transfer rate (OTR) in eight parallel shake flasks. Based on DOT and OTR, the volumetric oxygen transfer coefficient (k L a) is calculated during cultivation. The new system was successfully applied in cultivations of Escherichia coli, Bacillus licheniformis, and Xanthomonas campestris. K E Y W O R D S dissolved oxygen tension, optical measurement, oxygen-sensitive nanoparticles, RAMOS, shake flask, viscosity

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Section: Resultsmentioning

confidence: 99%

Combined dissolved oxygen tension and online viscosity measurements in shake flask cultivations via infrared fluorescent oxygen‐sensitive nanoparticles

Ladner

Flitsch

Lukacs

et al. 2019

Biotech & Bioengineering

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“…It evaluates the shift in the angular position of the bulk liquid relative to the direction of the centrifugal acceleration. The measurement system is different from the previously used, based on power input measurement (Regestein Née Meissner et al, 2017).…”

Section: Cultivation For On-line Monitoring (Otr and Viscosity Measurmentioning

confidence: 99%

“…Growth was closely monitored by measuring the OTR. Regestein et al have shown that the γ-PGA concentration is closely related to viscosity (Regestein Née Meissner et al, 2017).…”

Section: γ-Pga Production Under Varying Substrate Concentrationsmentioning

confidence: 99%

Comparison of Isomerase and Weimberg Pathway for γ-PGA Production From Xylose by Engineered Bacillus subtilis

Halmschlag

Hoffmann

Hanke

et al. 2020

Front. Bioeng. Biotechnol.

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The production of poly-γ-glutamic acid (γ-PGA), a biopolymer consisting of D-and L-glutamic acid monomers, currently relies on L-glutamate, or citrate as carbon substrates. Here we aimed at using plant biomass-derived substrates such as xylose. γ-PGA producing microorganisms including Bacillus subtilis natively metabolize xylose via the isomerase pathway. The Weimberg pathway, a xylose utilization pathway first described for Caulobacter crescentus, offers a carbon-efficient alternative converting xylose to 2-oxoglutarate without carbon loss. We engineered a recombinant B. subtilis strain that was able to grow on xylose with a growth rate of 0.43 h −1 using a recombinant Weimberg pathway. Although ion-pair reversed-phase LC/MS/MS metabolome analysis revealed lower concentrations of γ-PGA precursors such as 2-oxoglutarate, the γ-PGA titer was increased 6-fold compared to the native xylose isomerase strain. Further metabolome analysis indicates a metabolic bottleneck in the phosphoenolpyruvate-pyruvate-oxaloacetate node causing bi-phasic (diauxic) growth of the recombinant Weimberg strain. Flux balance analysis (FBA) of the γ-PGA producing B. subtilis indicated that a maximal theoretical γ-PGA yield is achieved on D-xylose/ D-glucose mixtures. The results of the B. subtilis strain harboring the Weimberg pathway on such D-xylose/ D-glucose mixtures demonstrate indeed resource efficient, high yield γ-PGA production from biomass-derived substrates.

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“…Probably the mucilage, which already has a fairly high viscosity, may not increase its viscosity even if the c-PGA content is increased. In addition, Regestein Nee Meissner et al reported that even though the amount of c-PGA is important in the viscosity of mucilage, the influence of Mw of c-PGA is greater (Regestein Nee Meissner et al, 2017). By the way, it is known that the Mw of c-PGA can be greatly reduced as the fermentation progresses, thereby reducing viscosities (Feng et al, 2017).…”

Section: Effect Of Added Nitrogen Sourcesmentioning

confidence: 99%

Factors increasing poly-γ-glutamic acid content of cheongguk-jang fermented by Bacillus subtilis 168

Ratha

Jhon

2018

Food Sci Biotechnol

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Cheongguk-jang is a Korean traditional food produced by natural fermentation of boiled soybean. In cheongguk-jang, bacilli are dominant bacteria and produce highly viscous poly-c-glutamic acid (c-PGA), which improves human health functions. The purpose of this experiment was to find maximum production condition for the c-PGA content during fermentation of cheongguk-jang with Bacillus subtilis 168. The most viscous cheonggukjang was produced when soybean was cooked at 121°C for 60 min in the presence of 50%(w/w) added water, followed by fermentation at 40°C for 2 days. Additional conditions for maximum production of c-PGA were the addition of 0.1%(w/w) FeCl 3 Á6H 2 O, 3.0%(w/w) lactose and 3.0%(w/ w) yeast extract as nutrients of inorganic salts, carbon source and nitrogen source, respectively. The three conditions did not show cumulative effect on the c-PGA production and the addition of iron salt induced the most c-PGA (0.97 ± 0.05%(w/w)), which corresponded to 2.7 times of the content in control cheongguk-jang.

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Investigation of poly(γ-glutamic acid) production via online determination of viscosity and oxygen transfer rate in shake flasks

Cited by 11 publications

References 48 publications

Combined dissolved oxygen tension and online viscosity measurements in shake flask cultivations via infrared fluorescent oxygen‐sensitive nanoparticles

Combined dissolved oxygen tension and online viscosity measurements in shake flask cultivations via infrared fluorescent oxygen‐sensitive nanoparticles

Comparison of Isomerase and Weimberg Pathway for γ-PGA Production From Xylose by Engineered Bacillus subtilis

Factors increasing poly-γ-glutamic acid content of cheongguk-jang fermented by Bacillus subtilis 168

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