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Papers by Detlef Goelling

Applied and Environmental Microbiology, 1988

The Streptococcus lactis gene coding for alpha-acetolactate decarboxylase (ADC) was cloned in Esc... more The Streptococcus lactis gene coding for alpha-acetolactate decarboxylase (ADC) was cloned in Escherichia coli. Subsequent subcloning in E. coli showed that the ADC gene was located within a 1.3-kilobase DNA fragment. The ADC gene was controlled by its own promoter. Gas chromatography showed that S. lactis and the transformed E. coli strains produced the two optical isomers of acetoin in different ratios.

L'invention concerne des souches Lactobacillus ou bien des cellules Lactobacillus (bacteries ... more L'invention concerne des souches Lactobacillus ou bien des cellules Lactobacillus (bacteries de l'acide lactique) sechees par vaporisation ainsi que leurs utilisations, en particulier pour des compositions pharmaceutiques et/ou dietetiques pour le traitement et la prophylaxie d'infections a Helicobacter pylori chez l'homme et l'animal.

Engineering in Life Sciences, 2017

Saccharomyces cerevisiae is a popular expression system for recombinant proteins. In most cases, ... more Saccharomyces cerevisiae is a popular expression system for recombinant proteins. In most cases, production processes are performed as carbon-limited fed-batch cultures to avoid aerobic ethanol formation. Especially for constitutive expression systems, the specific product formation rate depends on the specific growth rate. The development of optimal feeding strategies strongly depends on laboratory-scale cultivations, which are time and resource consuming, especially when continuous experiments are carried out. It is therefore beneficial for accelerated process development to look at alternatives. In this study, S. cerevisiae AH22 secreting a heterologous endo-polygalacturonase (EPG) was characterized in microwell plates with an enzyme-based fed-batch medium. Through variation of the glucose release rate, different growth profiles were established and the impact on EPG secretion was analyzed. Product formation rates of 200-400 U (g x h) −1 were determined. As a reference, bioreactor experiments using the change-stat cultivation technique were performed. The growth-dependent product formation was analyzed over dilution rates of D = 0.01-0.35 with smooth change of D at a rate of 0.003 h −2. EPG production was found to be comparable with a q p of 400 U (g x h) −1 at D = 0.27 h −1. The presented results indicate that parallel miniaturized fed-batch cultures can be applied to determine product formation profiles of putative production strains. With further automation and parallelization of the concept, strain characterization can be performed in shorter time.

Journal of laboratory automation, Jan 26, 2015

In this study, a slow-responding chemo-optical sensor for dissolved oxygen (DO) integrated into a... more In this study, a slow-responding chemo-optical sensor for dissolved oxygen (DO) integrated into a 96-well plate was developed. The slow response time ensures that the measured oxygen value does not change much during plate transport to the microplate reader. The sensor therefore permits at-line DO measurement of microbial cultures. Moreover, it eliminates the necessity of individual optical measurement systems for each culture plate, as many plates can be measured successively. Combined with the 96-well format, this increases the experimental throughput enormously. The novel sensor plate (Slow OxoPlate) consists of fluorophores suspended in a polymer matrix that were placed into u-bottom 96-well plates. Response time was measured using sodium sulfite, and a t90 value of 9.7 min was recorded. For application, DO values were then measured in Escherichia coli and Saccharomyces cerevisiae cultures grown under fed-batch-like conditions. Depending on the DO sensor's response time, dif...

Journal of Dairy Research, 2003

A new method for characterization of acid production by dairy starter cultures is presented. Micr... more A new method for characterization of acid production by dairy starter cultures is presented. Microplates with integrated optical pH sensors are developed. Two fluorophores, a pH-sensitive and a pH-insensitive one are immobilised at the bottom of a polystyrene 96-well microtitre plate. The pH-insensitive fluorophore serves as an internal reference and makes calibration unnecessary. The sensor measures pH accurately in optically well-defined media. Particles and fluorophores contained in the bulk medium disturbed the measurements. Despite these disturbances it was possible to clearly sense differences in inoculum type and in inoculum sizes of cultures of Lactococcus lactis and of Streptococcus thermophilus at 30 and 37°C. Besides a pH-related signal there is information about other changes during milk fermentation. The cultivation results were compared with those from the established CINAC-method. From this comparison it can be concluded that the new method can be used reliably to cha...

Applied Biocatalysis: From Fundamental Science to Industrial Applications, 2016

Applied and Environmental Microbiology, 1988

TheStreptococcus lactis gene coding fora-acetolactate decarboxylase (ADC)was cloned inEscherichia... more TheStreptococcus lactis gene coding fora-acetolactate decarboxylase (ADC)was cloned inEscherichia coli. Subsequent subcloning inE.coli showed thattheADC gene was located within a 1.3-kilobase DNA fragment. TheADC gene was controlled byits own promotor.Gaschromatography showedthatS.lactis andthe transformed E.coli strains produced thetwooptical isomers ofacetoin indifferent ratios. Diacetyl (2,3-butanedione), one ofthemajorcompounds

Applied and Environmental Microbiology, 1988

The Streptococcus lactis gene coding for alpha-acetolactate decarboxylase (ADC) was cloned in Esc... more The Streptococcus lactis gene coding for alpha-acetolactate decarboxylase (ADC) was cloned in Escherichia coli. Subsequent subcloning in E. coli showed that the ADC gene was located within a 1.3-kilobase DNA fragment. The ADC gene was controlled by its own promoter. Gas chromatography showed that S. lactis and the transformed E. coli strains produced the two optical isomers of acetoin in different ratios.

L'invention concerne des souches Lactobacillus ou bien des cellules Lactobacillus (bacteries ... more L'invention concerne des souches Lactobacillus ou bien des cellules Lactobacillus (bacteries de l'acide lactique) sechees par vaporisation ainsi que leurs utilisations, en particulier pour des compositions pharmaceutiques et/ou dietetiques pour le traitement et la prophylaxie d'infections a Helicobacter pylori chez l'homme et l'animal.

Engineering in Life Sciences, 2017

Saccharomyces cerevisiae is a popular expression system for recombinant proteins. In most cases, ... more Saccharomyces cerevisiae is a popular expression system for recombinant proteins. In most cases, production processes are performed as carbon-limited fed-batch cultures to avoid aerobic ethanol formation. Especially for constitutive expression systems, the specific product formation rate depends on the specific growth rate. The development of optimal feeding strategies strongly depends on laboratory-scale cultivations, which are time and resource consuming, especially when continuous experiments are carried out. It is therefore beneficial for accelerated process development to look at alternatives. In this study, S. cerevisiae AH22 secreting a heterologous endo-polygalacturonase (EPG) was characterized in microwell plates with an enzyme-based fed-batch medium. Through variation of the glucose release rate, different growth profiles were established and the impact on EPG secretion was analyzed. Product formation rates of 200-400 U (g x h) −1 were determined. As a reference, bioreactor experiments using the change-stat cultivation technique were performed. The growth-dependent product formation was analyzed over dilution rates of D = 0.01-0.35 with smooth change of D at a rate of 0.003 h −2. EPG production was found to be comparable with a q p of 400 U (g x h) −1 at D = 0.27 h −1. The presented results indicate that parallel miniaturized fed-batch cultures can be applied to determine product formation profiles of putative production strains. With further automation and parallelization of the concept, strain characterization can be performed in shorter time.

Journal of laboratory automation, Jan 26, 2015

In this study, a slow-responding chemo-optical sensor for dissolved oxygen (DO) integrated into a... more In this study, a slow-responding chemo-optical sensor for dissolved oxygen (DO) integrated into a 96-well plate was developed. The slow response time ensures that the measured oxygen value does not change much during plate transport to the microplate reader. The sensor therefore permits at-line DO measurement of microbial cultures. Moreover, it eliminates the necessity of individual optical measurement systems for each culture plate, as many plates can be measured successively. Combined with the 96-well format, this increases the experimental throughput enormously. The novel sensor plate (Slow OxoPlate) consists of fluorophores suspended in a polymer matrix that were placed into u-bottom 96-well plates. Response time was measured using sodium sulfite, and a t90 value of 9.7 min was recorded. For application, DO values were then measured in Escherichia coli and Saccharomyces cerevisiae cultures grown under fed-batch-like conditions. Depending on the DO sensor's response time, dif...

Journal of Dairy Research, 2003

A new method for characterization of acid production by dairy starter cultures is presented. Micr... more A new method for characterization of acid production by dairy starter cultures is presented. Microplates with integrated optical pH sensors are developed. Two fluorophores, a pH-sensitive and a pH-insensitive one are immobilised at the bottom of a polystyrene 96-well microtitre plate. The pH-insensitive fluorophore serves as an internal reference and makes calibration unnecessary. The sensor measures pH accurately in optically well-defined media. Particles and fluorophores contained in the bulk medium disturbed the measurements. Despite these disturbances it was possible to clearly sense differences in inoculum type and in inoculum sizes of cultures of Lactococcus lactis and of Streptococcus thermophilus at 30 and 37°C. Besides a pH-related signal there is information about other changes during milk fermentation. The cultivation results were compared with those from the established CINAC-method. From this comparison it can be concluded that the new method can be used reliably to cha...

Applied Biocatalysis: From Fundamental Science to Industrial Applications, 2016

Applied and Environmental Microbiology, 1988

TheStreptococcus lactis gene coding fora-acetolactate decarboxylase (ADC)was cloned inEscherichia... more TheStreptococcus lactis gene coding fora-acetolactate decarboxylase (ADC)was cloned inEscherichia coli. Subsequent subcloning inE.coli showed thattheADC gene was located within a 1.3-kilobase DNA fragment. TheADC gene was controlled byits own promotor.Gaschromatography showedthatS.lactis andthe transformed E.coli strains produced thetwooptical isomers ofacetoin indifferent ratios. Diacetyl (2,3-butanedione), one ofthemajorcompounds