Arsenic metabolism in technical biogas plants: possible consequences for resident microbiota and downstream units.

The metal(loid) and in particular the Arsenic (As) burden of thirteen agricultural biogas plants and two sewage sludge digesters were investigated together with the corresponding microbial consortia. The latter were characterized by ARISA (automated ribosomal intergenetic spacer analysis) and next generation sequencing. The consortia were found to cluster according to digester type rather than substrate or metal(loid) composition.

Isolation and purification of recombinant proteins, antibodies and plasmid DNA with hydroxyapatite chromatography.

Hydroxyapatite and related stationary phases increasingly play a role in the downstream processing of high-value biological materials, such as recombinant proteins, therapeutic antibodies and pharmaceutical-grade plasmid DNA. Chromatographic hydroxyapatite is an inorganic, ceramic material identical in composition, if not in structure, to calcium phosphate found in human bones and teeth. The interaction of hydroxyapatite with biomacromolecules is complex and highly dynamic, which can make predicting performance difficult, but also allows the design of very selective isolation processes.

Antibody purification by affinity chromatography based on small molecule affinity ligands identified by SPR-based screening of chemical microarrays.

Libraries of small molecules were searched for Fc-fragment selective binders to a recombinant human antibody ("MDJ8″, IgG(1)-subtype, κ-light chain) via SPR-based screening of chemical microarrays. Identified hit structures were immobilised on NHS-activated Sepharose for the determination of MDJ8 binding and selectivity versus typical proteineous impurities represented by the spend cell culture supernatant. Columns were packed and the most promising ligands further characterized in terms of binding constants, binding kinetics, as well as dynamic and equilibrium binding capacities.

Use of azobenzene amino acids as photo-responsive conformational switches to regulate antibody-antigen interaction.

In an attempt to exploit the large geometry changes associated with azobenzene photo-isomerization for the modulation of antibody-antigen interaction, we introduced in the backbone of the FLAG peptide (DYKDDDDK), an azobenzene unit to photo-modulate its conformational states and consequently its interaction with the monoclonal anti-FLAG-tag antibody M1. The FLAG-tag system is an established technique for purifying and detecting the corresponding fusion proteins. In this context, conflicting evidence has been presented regarding the necessity of calcium for stable binding.

Screening of a human antibody phage display library against a peptide antigen using stimuli-responsive bioconjugates.

A synthetic antibody phage library (ETH-2) was screened against the MUC-1 peptide. Two standard methods were used, namely screening on immunotubes coated with the peptide antigen and on streptavidin-coated paramagnetic particles together with a biotinylated MUC-1 peptide. The results were compared with those obtained using a novel approach based on a stimuli-responsive bioconjugate of avidin and poly-(N-isopropylacrylamide), also in combination with the biotinylated peptide.

Strategy for the isolation of native dehydrogenases with potential for biosensor development from the organism Hyphomicrobium zavarzinii ZV580.

Dehydrogenases are interesting candidates for the development of electrochemical biosensors. Most dehydrogenases are characterised by a comparatively broad substrate spectrum, yet highly specific enzymes exist as well. A specific formaldehyde dehydrogenase has, e.

Extraction of haemoglobin from human blood by affinity precipitation using a haptoglobin-based stimuli-responsive affinity macroligand.

Affinity precipitation was compared to affinity chromatography and batch adsorption as the final purification step in a protocol for the isolation of haemoglobin from human blood. Haptoglobin was the affinity ligand. The first steps on the process were realized by traditional methods (lyses of red blood cells followed by ammonium sulphate precipitation).

Use of the avidin (imino)biotin system as a general approach to affinity precipitation.

Biospecific interactions are used in many capturing and bioseparation steps. A typical situation is the coupling of a biospecific ligand to a chromatographic stationary phase for affinity chromatography. This approach has two possible drawbacks.

A fast method for the quantification of methylamine in fermentation broths by gas chromatography.

The objective of this study was to develop a method for the quantitative analysis of the methylamine concentration in fermentation broths of Hyphomicrobium zavarzinii ZV 580 cultures. For this purpose an established method for the quantification of free amino acids in such matrices was adapted and validated. The detection limit was 10 microM, the calibration curve showed good linearity (R2=0.

Development of a fed-batch process for the production of a dye-linked formaldehyde dehydrogenase in Hyphomicrobium zavarzinii ZV 580.

The dye-linked formaldehyde dehydrogenase (dlFalDH) from Hyphomicrobium zavarzinii ZV 580 processes formaldehyde in a highly selective manner and without need for NAD(P). The enzyme thus has considerable potential for technical applications if the difficulties associated with its efficient production can be resolved. In this contribution, a fed-batch bioprocess is developed, which improves both the biomass production of H.

Integration of bacteria capture via filtration and in situ lysis for recovery of plasmid DNA under industry-compatible conditions.

Combining capture and lysis of the bacteria with partial purification of the plasmid DNA is beneficial for the design of efficient plasmid production processes at larger scale. Such an approach is possible when the bacteria are captured by filtration. Taking industrial requirements into account, however, such a capture requires complex filtration mixtures containing retentive additives such as bentonite and polycations.

Theory and practical understanding of the migration behavior of proteins and peptides in CE and related techniques.

CEC is defined as an analytical method, where the analytes are separated on a chromatographic column in the presence of an applied voltage. The separation of charged analytes in CEC is complex, since chromatographic interaction, electroosmosis and electrophoresis contribute to the experimentally observed behavior. The putative contribution of effects such as surface electrodiffusion has been suggested.

Affinity precipitation an option for early capture in bioprocessing.

Affinity precipitation is a bioseparation technique where the affinity ligand is coupled to a stimuliresponsive polymer. Stimuli-responsive polymers show abrupt, yet reversible, phase transition (precipitation) in response to a small change in an environmental parameter. The corresponding ligand conjugates can be used to co-precipitate and thereby capture and isolate target molecules from complex solutions such as culture supernatants and cell lysates.

Purification of RT-PCR competent poly(A) mRNA from crude cell lysate by affinity precipitation.

Stimuli-responsive bioconjugates consisting of avidin covalently linked to poly(N-isopropylacrylamide) were used for the recovery of poly(A) mRNA hybridized to biotinylated poly(dT)-tags from crude cell lysates (Jurkat cells) by affinity precipitation. The bioconjugates are soluble in cold water but precipitate readily once a critical solution temperature (33 degrees C in pure water) is surpassed. The process is fully reversible and shows the expected dependencies on the composition of the aqueous solution and the bioconjugate chemistry.

Design and characterization of stimuli-responsive FLAG-tag analogues and the illumination-induced modulation of their interaction with antibody 4E11.

An azobenzene group containing beta-amino acid N-Fmoc-4-aminomethyl phenylazobenzoic acid was synthesized and with the exception of the C-terminal amino acid residue was substituted by solid-phase peptide synthesis into all positions of the FLAG sequence (DYKDDDDK), an octapeptide capable of specific interaction with the monoclonal antibody 4E11. The trans state of the beta-amino acid was thermodynamically more stable than the cis state. However, the molecule could be switched into the cis conformation by illumination at 340 nm.

Capture of bacteria from fermentation broth by body feed filtration: a solved problem?

The direct capture of bacteria produced in high cell density fermentation by filtration is not possible once the milliliter-scale has been surpassed. Filtration in the presence of a filter aid (body feed filtration) constitutes a putative and scalable alternative, but only if conditions proposed by industry for large-scale filtration processes, namely, flow rates (for aqueous solutions) in the range of 500-1,500 L/(m(2) x h) and a filter aid concentration of View Article and Find Full Text PDF

Proposal for a better integration of bacterial lysis into the production of plasmid DNA at large scale.

The paper addresses the question of how to achieve bacterial lysis in large-scale plasmid DNA production processes, where conventional alkaline lysis may become awkward to handle. Bacteria were grown in shaker flasks and a bioreactor. Suboptimal growth conditions were found advantageous for stable plasmid production at high copy numbers (up to 25mg/L could be achieved).

Protein purification by affinity precipitation.

Developing the most efficient strategy for the purification of a (recombinant) protein especially at large scale remains a challenge. A typical problem of the downstream process of mammalian cell products is, for instance, the early capture of the highly diluted product from the complex process stream. Affinity precipitation has been suggested in this context.

Continuous annular chromatography.

The principle of continuous annular chromatography (CAC) has been known for several decades. CAC is a continuous chromatographic mode, which lends itself to the separation of multi-component mixtures as well as of bi-component ones. In CAC, the mobile and stationary phases move in a crosscurrent fashion, which allows transformation of the typical one-dimensional batch column separation into a continuous two-dimensional one.

DNA purification by triple-helix affinity precipitation.

Recent advances in DNA-based medicine (gene therapy, genetic vaccination) have intensified the necessity for pharmaceutical-grade plasmid DNA purification at comparatively large scales. In this contribution triple-helix affinity precipitation is introduced for this purpose. A short, single-stranded oligonucleotide sequence (namely (CTT)(7)), which is capable of recognizing a complementary sequence in the double-stranded target (plasmid) DNA, is linked to a thermoresponsive N-isopropylacrylamide oligomer to form a so-called affinity macroligand (AML).