Xanthan production in a plunging jet reactor

Zaidi, Ahmed; Ghosh, Purnendu; Schumpe, Adrian; Deckwer, Wolf‐Dieter

doi:10.1007/bf00172721

Cited by 24 publications

(7 citation statements)

References 7 publications

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“…Interestingly, higher OD600 values, growth rates, minimum DO saturations and equal GFP fluorescence intensities were obtained in the ELR in relation to the STR. This is in agreement with studies of the early loop reactors from the 1980's and 90's which reported that the circulation pump and the ejector in ejector-type loop reactors did not affect microbial growth [13,21,22]. However, the release of GFP into the growth media was higher in the ELR compared to STR, thus indicating higher cell perforation due to shear stress.…”

Section: Discussionsupporting

confidence: 90%

“…For this type of reaction, an alternative to the STR concept, in which mixing and dispersing is achieved by a liquid jet generated by an ejector, is widely used and applied in industry. It has been shown that these so called Venturi or ejector loop reactors (ELR) favour higher mass transfer rates compared to the STR at comparable power inputs . Loop reactors with liquid jets in downflow mode especially feature favourable mass transfer characteristics .…”

Section: Introductionmentioning

confidence: 99%

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The ejector loop reactor: Application for microbial fermentation and comparison with a stirred‐tank bioreactor

Ughetti

Jussen

Riedlberger

2018

Engineering in Life Sciences

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Ejector loop reactors (ELR) are successfully used in industrial chemical processes for gas/liquid reactions. They achieve higher mass transfer rates compared to the stirred‐tank reactor (STR) at comparable specific power input. Insufficient oxygen transport and shear stress induced growth inhibition are limiting parameters during microbial fermentation. Due to its better mass transfer characteristics, the ELR was expected to have beneficial effects on biomass and recombinant protein production. One concern, however, was whether the ELR's shear stress characteristics would have a negative effect. This study evaluated the suitability of using the Buss‐Loop® Reactor (BLR), one of the most advanced ELR technologies, as a bioreactor. The well‐studied STR was used as a reference. A lab scale BLR was adapted for microbial fermentation. Mass transfer rates and specific power inputs were within the same order of magnitude in the ELR and the reference STR. Maximum kLa values of 207 and 205 h−1 at power inputs of 6.9 and 9.7 W/L were measured in the ELR and STR, respectively. During batch fermentation of Escherichia coli K12 MG1655, maximum cell densities were higher in the ELR (OD600 of 22) than in the STR (OD600 of 18). Green fluorescence protein (GFP) production with pGS1 was comparable; however, more GFP was released into the media in the ELR. This indicates higher cell disruption compared to the STR. Despite this drawback of the first prototype, our work clearly demonstrates the potential of the ELR as a system for microbial fermentations.

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Section: Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

The ejector loop reactor: Application for microbial fermentation and comparison with a stirred‐tank bioreactor

Ughetti

Jussen

Riedlberger

2018

Engineering in Life Sciences

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“…Another important aspect that cannot be overlooked is whether a disposables-based approach may affect the overall yield of the process. The unit operations that may be affected by a switch to disposables operation are the fermentation, where a stirred tank has to be replaced by a plunging jet (Zaidi et al, 1991) or an airlift reactor, and the chromatography step, where the column may be replaced by a column prepacked with cheaper media or by multiple batch adsorption/desorption steps. The microfiltration, and periplasmic release steps are not expected to be affected as they remain intrinsically the same as in the conventional process.…”

Section: Sensitivity Analysismentioning

confidence: 99%

Economic comparison between conventional and disposables‐based technology for the production of biopharmaceuticals

Novais

Titchener‐Hooker

Hoare

2001

Biotech & Bioengineering

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Time to market, cost effectiveness, and flexibility are key issues in today's biopharmaceutical market. Bioprocessing plants based on fully disposable, presterilized, and prevalidated components appear as an attractive alternative to conventional stainless steel plants, potentially allowing for shorter implementation times, smaller initial investments, and increased flexibility. To evaluate the economic case of such an alternative it was necessary to develop an appropriate costing model which allows an economic comparison between conventional and disposables-based engineering to be made. The production of an antibody fragment from an E. coli fermentation was used to provide a case study for both routes. The conventional bioprocessing option was costed through available models, which were then modified to account for the intrinsic differences observed in a disposables-based option. The outcome of the analysis indicates that the capital investment required for a disposables-based option is substantially reduced at less than 60% of that for a conventional option. The disposables-based running costs were evaluated as being 70% higher than those of the conventional equivalent. Despite this higher value, the net present value (NPV) of the disposables-based plant is positive and within 25% of that for the conventional plant. Sensitivity analysis performed on key variables indicated the robustness of the economic analysis presented. In particular a 9-month reduction in time to market arising from the adoption of a disposables-based approach, results in a NPV which is identical to that of the conventional option. Finally, the effect of any possible loss in yield resulting from the use of disposables was also examined. This had only a limited impact on the NPV: for example, a 50% lower yield in the disposable chromatography step results in a 10% reduction of the disposable NPV. The results provide the necessary framework for the economic comparison of disposables and conventional bioprocessing technologies.

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“…Consequently, conventional xanthan gum fermentation has low xanthan concentration (usually below 3% wt/v) and low productivity (usually below 0.5 g/(L·h). There have been many attempts to increase xanthan productivity and to lower energy costs by using new agitation designs (Funahashi et al, 1987; Galindo and Nienow, 1992, 1993; Herbst et al, 1992; Nakajima et al, 1990; Nienow, 1984; Peters et al, 1992; Tecante and Choplin, 1993) and new types of bioreactors (Herbst et al, 1989; Kawase and Tsujimura, 1994; Kessler et al, 1993; Long et al, 1988; Misra and Barnett, 1987; Pons et al, 1989; Suh et al, 1991; Zaidi et al, 1991). Fermentation with water‐in‐oil emulsion (Ju and Zhao, 1993; Schumpe et al, 1991) and cell immobilization using porous Celite beads (Robinson and Wang, 1988), which reduces broth viscosity and improves aeration and oxygen transfer, have also been studied.…”

Section: Introductionmentioning

confidence: 99%

Xanthan Gum Fermentation by Xanthomonas campestris Immobilized in a Novel Centrifugal Fibrous-Bed Bioreactor

Yang

Min

1996

Biotechnol. Prog.

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Current industrial fermentations in conventional stirred-tank fermentors for production of xanthan gum and other polysaccharides are energy-intensive and costly, mainly because the high broth viscosity causes agitation and aeration to be difficult and limits the final product concentration and productivity. In this work, a novel, centrifugal, packed-bed reactor (CPBR) was developed for viscous xanthan gum fermentation. Xanthomonas campestris cells were immobilized in a rotating fibrous matrix by natural attachment to the fiber surfaces. The mixing and aeration problems were overcome by continuously pumping and circulating the medium broth through the rotating fibrous matrix to ensure intimate contact of gas and liquid with the cells and to separate the xanthan polymer from the cells. Almost all of the cells were immobilized on the fiber surfaces as was indicated by the absence of suspended cells in the fermentation broth. Thus, cell-free xanthan broth was obtained, with ∼85% xanthan yield from glucose. The bioreactor was operated in repeated batch mode to study the feasibility and performance of long-term xanthan gum production using the immobilized cells in the fibrous bed. Consistent xanthan production rate and gum quality were obtained for eight consecutive batches studied during a total operation period of over 3 weeks. The volumetric xanthan productivity achieved in the reactor was ∼1 g/(L‚h) based on the total liquid volume and ∼3 g/(L‚h) based on the fibrous-bed volume. In contrast, conventional batch fermentation in a stirred-tank reactor (STR) with free cells usually has a productivity of only 0.5 g/(L‚h) or lower. The high productivity in CPBR was attributed to the relatively high cell density, ∼7 g/L, in the reactor. The specific xanthan productivity was lower in CPBR than in STR, however. This was because of the relatively low cell viability (∼60%) and limitation in oxygen transfer in CPBR, which can be improved by increasing the medium recirculation rate and the rotational speed of the fibrous matrix.

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Xanthan production in a plunging jet reactor

Cited by 24 publications

References 7 publications

The ejector loop reactor: Application for microbial fermentation and comparison with a stirred‐tank bioreactor

The ejector loop reactor: Application for microbial fermentation and comparison with a stirred‐tank bioreactor

Economic comparison between conventional and disposables‐based technology for the production of biopharmaceuticals

Xanthan Gum Fermentation by Xanthomonas campestris Immobilized in a Novel Centrifugal Fibrous-Bed Bioreactor

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