2019 Publications

// Corynebacterium glutamicum //Lactose-utilization // Medium optimization // Ethanol production // Here we present a novel microbial platform specifically designed to generate useful compounds from dairy waste. An efficient process for producing ethanol from DWP, based on C. glutamicum, was demonstrated. The results obtained clearly show a great potential for this newly developed platform for producing value-added chemicals from dairy waste.

// Butanol // Clostridia // ABE fermentation // Lignocellulosic biomass // Mixed sugars // Exploratory data analysis // This approach provides different insights and information as a guide to a more successful fermentation of lignocellulosic sugars to butanol as a key to more competitive butanol production processes for biofuel applications in the future.

// Corynebacterium glutamicum // Mini Pilot Plant // genome reduction // heterologous protein secretion // quantitative microbial phenotyping // In this study, a novel workflow for repeated low-volume sampling of BioLector-based cultivation setups is presented.

// BioLector // E. coli // fed-batch // high-throughput // online monitoring // In this study, a glucose-containing polymer matrix was used to manufacture polymer rings that were placed at the bottom of a 48-well microtiter plate. Thereby, the liquid content of the well became accessible for optical measurement by the BioLector device.

// Glucose binding protein // Micro cultivation // Online glucose measurement // Sensor beads // Venus // mTurquoise2 // A FRET-based glucose sensor was used to quantify D-glucose consumption in microtiter plate based cultivations. This is the first method reported for online quantification of D-glucose in microtiter plate based cultivations.

The effect of L-PA on C. glutamicum (either added to the culture medium or synthesized de novo) under different conditions of osmotic pressure by physiological and RNAseq experiments is characterized. Evidence that YggB may be involved in export of L-PA and ProP in its import into the C. glutamicum cell is provided.

The polymer-based fed-batch microtiter plate represents a sophisticated and cost efficient system to mimic typical industrial fed-batch conditions in small-scale. Thus, a more reliable strain screening and early process development can be performed. A systematical scale-down with low expenditure of work, time and money is possible.

The analysis of the C. glutamicum genome in combination with systematic reduction of the heterologous xylXABCD operon revealed that the hitherto unknown and endogenous dehydrogenase KsaD (Cg0535) can also oxidize α-ketoglutarate semialdehyde to the tricarboxylic acid cycle intermediate α-ketoglutarate, the final enzymatic step of the Weimberg pathway.

A workfow for 32-fold parallelized microscale cultivation of protein secreting Corynebacterium glutamicum in microtiter plates incorporating online monitoring, pH control and feeding was developed and validated.

A robust workfow for A. giganteus was developed, allowing for reproducible microscale cultivation withonline monitoring, where calcium chloride is an useful alternative to microparticle enhanced cultivation in order tocontrol the morphology. Independent of the cultivation volume, comparable phenotypes were observed in microtiterplates and in lab-scale bioreactor.

Cultivations were done directly using shredded wheat straw as raw substrate in a submerged manner, proving the ability of the equipment to run accurate cultivations on such complex material with some advantages compared to the current flask cultures method (i.e. more conditions screened, less amount of substrate needed, better activities).

Strain engineering in the laboratory often does not consider process requirements in larger-scale bioreactors. Systems and synthetic biology can be applied to design microbial strains that allow reliable and robust production on a large scale. Commercial microbial platforms should be selected and developed based on their relevance to final process goals.

Culture contamination, end-product toxicity, and energy efficient product recovery are long-standing bioprocess challenges. The solution - a high-pressure fermentation strategy, coupled with in situ extraction using the abundant and renewable solvent supercritical carbon dioxide (scCO2), which is also known for its broad microbial lethality.