Production of 2,3-Butanediol from Sucrose by Klebsiella pneumoniae NRRL B199 in Batch and Fed-Batch Reactors

In batch mode, Klebsiella pneumoniae growth and 2,3-butanediol/acetoin formation are increasingly inhibited by initial sucrose concentrations (S0) over 60 g/L. At non inhibitory conditions, a maximum sucrose consumption rate of 1,5 g/L/h was measured. With S0=204 g/L however, this rate decreased to 0.15 g/L/h. K. pneumoniae fermented 204 g/L sucrose to produce 84.3 g/L of a mixture 2,3-butanediol/acetoin with a yield of 0.41 g/g and a productivity of 1.06 g/L/h. Higher oxygen transfer rates improved the overall process rate but the product yield was reduced. Avoiding substrate inhibition, by performing the fermentation in fed-batch mode, a final 2,3-butanediol/acetoin concentration of 80.0 g/L was achieved. In this case, a productivity of 2.63 g/L/h and a product yield of 0.37 g/g were calculated.

Download Full-text

Regio- and Stereoselective Fungal Oxyfunctionalisation of Limonenes

Zeitschrift für Naturforschung C ◽

10.1515/znc-2005-5-615 ◽

2005 ◽

Vol 60 (5-6) ◽

pp. 459-466 ◽

Cited By ~ 9

Author(s):

Rüdiger Kaspera ◽

Ulrich Krings ◽

Michael Pescheck ◽

Dieter Sell ◽

Jens Schrader ◽

...

Keyword(s):

Optical Purity ◽

Product Yield ◽

Careful Selection ◽

Fed Batch ◽

Batch Mode ◽

Theoretical Yield ◽

Pleurotus Sapidus ◽

Terminal Oxidation ◽

By Products ◽

Selection Of

Selective transformations of limonene by asco- and basidiomycetes were investigated. On the shake flask scale, Penicillium citrinum hydrated R-(+)-limonene to α-terpineol [83% regioselectivity (rs), more than 80 mg 1-1 product yield], and Gongronella butleri catalysed the terminal oxidation to yield perillyl alcohol (60% rs, 16 mg 1-1). On the laboratory bioreactor scale, Penicillium digitatum produced a peak concentration of 506 mg α-terpineol 1-1 in the fed-batch mode, equivalent to a theoretical yield of 67%, and no volatile by-products were found. Fusarium proliferatum transformed R-(+)-limonene enantiospecifically to cis-(+)- carveol (98.6% ee, more than 35 mg 1-1 product yield) and S-(-)-limonene predominantly to trans-(-)-carveol (96.3% ee). Pleurotus sapidus selectively dehydrogenised the accumulating trans-(-)-carveol to the corresponding enantiopure R-(-)-carvone. The results show that a careful selection of strain and bioprocess parameters may improve both the yield and the optical purity of a desired product.

Download Full-text

Screening for optimal protease producing Bacillus licheniformis strains with polymer-based controlled-release fed-batch microtiter plates

Microbial Cell Factories ◽

10.1186/s12934-021-01541-2 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Tobias Habicher ◽

Tobias Klein ◽

Jacqueline Becker ◽

Andreas Daub ◽

Jochen Büchs

Keyword(s):

Controlled Release ◽

Bacillus Licheniformis ◽

Protease Activity ◽

Microtiter Plate ◽

Fed Batch ◽

Batch Mode ◽

Screening Process ◽

Microtiter Plates ◽

Batch Fermenter ◽

Production Conditions

Abstract Background Substrate-limited fed-batch conditions have the favorable effect of preventing overflow metabolism, catabolite repression, oxygen limitation or inhibition caused by elevated substrate or osmotic concentrations. Due to these favorable effects, fed-batch mode is predominantly used in industrial production processes. In contrast, screening processes are usually performed in microtiter plates operated in batch mode. This leads to a different physiological state of the production organism in early screening and can misguide the selection of potential production strains. To close the gap between screening and production conditions, new techniques to enable fed-batch mode in microtiter plates have been described. One of these systems is the ready-to-use and disposable polymer-based controlled-release fed-batch microtiter plate (fed-batch MTP). In this work, the fed-batch MTP was applied to establish a glucose-limited fed-batch screening procedure for industrially relevant protease producing Bacillus licheniformis strains. Results To achieve equal initial growth conditions for different clones with the fed-batch MTP, a two-step batch preculture procedure was developed. Based on this preculture procedure, the standard deviation of the protease activity of glucose-limited fed-batch main culture cultivations in the fed-batch MTP was ± 10%. The determination of the number of replicates revealed that a minimum of 6 parallel cultivations were necessary to identify clones with a statistically significant increased or decreased protease activity. The developed glucose-limited fed-batch screening procedure was applied to 13 industrially-relevant clones from two B. licheniformis strain lineages. It was found that 12 out of 13 clones (92%) were classified similarly as in a lab-scale fed-batch fermenter process operated under glucose-limited conditions. When the microtiter plate screening process was performed in batch mode, only 5 out of 13 clones (38%) were classified similarly as in the lab-scale fed-batch fermenter process. Conclusion The glucose-limited fed-batch screening process outperformed the usual batch screening process in terms of the predictability of the clone performance under glucose-limited fed-batch fermenter conditions. These results highlight that the implementation of glucose-limited fed-batch conditions already in microtiter plate scale is crucial to increase the precision of identifying improved protease producing B. licheniformis strains. Hence, the fed-batch MTP represents an efficient high-throughput screening tool that aims at closing the gap between screening and production conditions.

Download Full-text

Daphnetin Ameliorates Corticosterone-Induced Depressive-Like Behavior and Oxidative Stress in Mice Via Nuclear Factor Erythroid 2-Related Factor/Heme Oxygenase-1 Pathway

Current Topics in Nutraceutical Research ◽

10.37290/ctnr2641-452x.19:470-476 ◽

2021 ◽

Vol 19 (4) ◽

pp. 470-476

Author(s):

Chao Liu ◽

Chao Liang ◽

Jie Huang

Keyword(s):

Oxidative Stress ◽

Consumption Rate ◽

Tail Suspension Test ◽

Protein Carbonyl ◽

Heme Oxygenase 1 ◽

Related Factor ◽

Sucrose Consumption ◽

Markers Of Oxidative Stress ◽

Swimming Test ◽

And Oxidative Stress

We have investigated the effect of daphnetin on depressive-like behavior and oxidative stress caused by corticosterone in mice. To this end, we have analyzed the effect of corticosterone alone and combination of corticosterone and daphnetin on three behavioral indices of depressive-like behavior - sucrose consumption rate, forced swimming test, and tail suspension test as well as biochemical markers of oxidative stress - malondialdehyde, nitrite, protein carbonyl, nonprotein sulfhydryl and glutathione contents as well as hippocampal cell apoptosis. The results support the conclusion that daphnetin diminished corticosterone induced depressive like behavior and oxidative stress by activating Nrf2/HO-1 pathway.

Download Full-text