Flexible material formulations for 3D printing of ordered porous beds with applications in bioprocess engineering.

BACKGROUND: 3D printing is revolutioning many industrial sectors and has the potential to enhance also the biotechnology and bioprocessing fields. Here, we propose a new flexible material formulation to 3D print support matrices with complex, perfectly ordered morphology and with tuneable properties to suit a range of applications in bioprocess engineering. FINDINGS: Supports were fabricated using functional monomers as the key ingredients, enabling matrices with bespoke chemistry, such as charged groups, chemical moieties for further functionalization, and hydrophobic/hydrophilic groups. Other ingredients, e.g. crosslinkers and porogens, can be employed to fabricate supports with diverse characteristics of their porous network, providing an opportunity to further regulate the mechanical and mass transfer properties of the supports. Through this approach, we fabricated and demonstrated the operation of Schoen gyroid columns with (I) positive and negative charges for ion exchange chromatography, (II) enzyme bioreactors with immobilized trypsin to catalyse hydrolysis, and (III) bacterial biofilm bioreactors for fuel desulphurization. CONCLUSIONS: This study demonstrates a simple, cost-effective, and flexible fabrication of customized 3D printed supports for different biotechnology and bioengineering applications.

New Nanostructured Carbon Coating Inhibits Bacterial Growth, but Does Not Influence on Animal Cells.

An electrospark technology has been developed for obtaining a colloidal solution containing nanosized amorphous carbon. The advantages of the technology are its low cost and high performance. The colloidal solution of nanosized carbon is highly stable. The coatings on its basis are nanostructured. They are characterized by high adhesion and hydrophobicity. It was found that the propagation of microorganisms on nanosized carbon coatings is significantly hindered. At the same time, eukaryotic animal cells grow and develop on nanosized carbon coatings, as well as on the nitinol medical alloy. The use of a colloidal solution as available, cheap and non-toxic nanomaterial for the creation of antibacterial coatings to prevent biofilm formation seems to be very promising for modern medicine, pharmaceutical and food industries.

Degradation of chlorophenols in aqueous media using UV XeBr excilamp in a flow-through reactor.

2-Chlorophenol (2-CP), 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) at initial concentrations of 10, 20, 50 and 100mg l(-1) were degraded in aqueous media by direct UV photolysis using dielectric barrier discharge XeBr( *) excilamp (283nm) in a flow-through photoreactor. The pseudo-first order rate constants were highest and half-life times were lowest for 4-CP. The rates of photolysis under the experimental conditions increased in the order: 2-CP<2,4-DCP<4-CP. The intermediates of photolysis were identified by GC-MS and HPLC. The evolution of hydroquinone and p-benzoquinone as major intermediates of 4-CP photolysis was monitored.

The detection of antibacterial actions of whole herb tinctures using luminescent Escherichia coli.

Two whole cell Escherichia coli luminescent biosensors were used to determine the antibacterial actions of 16 herbal tinctures. These bioassays can detect genotoxic (strain DPD2794) and general oxidative stress (DE135) events when challenged with antibacterial substances. Many of the herbal tinctures were active against these Gram-negative bacteria, affecting their metabolism without, in some cases, arresting cell growth or causing cell death. Antibacterial activity ranged from undetectable for Curcuma longa, Cinnamomum zeylanicum and Apium graveolens to highly effective against both E. coli strains in the case of Rosmarinus officinalis. Some of the results were unexpected. Althaea officinalis affected microbial metabolism in spite of the lack of literature precedent, and Cinnamomum zeylanicum did not appear to be antimicrobial, as claimed in some literature. It is concluded that studies using luminescent bacterial biosensors can provide important new insights into the potency and modes of the lethal and sub-lethal antibacterial action of whole herbs, and thereby provide crucial evidence for efficacy demanded by modern science and medicine.

A new short-term toxicity assay using Aspergillus awamori with recombinant aequorin gene.

BACKGROUND: Most currently available short-term toxicity assays are based on bacterial cells. Therefore there is a need for novel eukaryotic microbial bioassays that will be relevant to higher eukaryotes such as animals and plants. Ca2+ is a universal intracellular signalling molecule found in all organisms from prokaryotes to highly specialized animal cells. In fungi calcium has been demonstrated to be involved in control of many important processes. The recombinant aequorin gene from the jellyfish Aequorea victoria responsible for the expression of the Ca2+-sensitive aequorin photoprotein has been cloned in the filamentous fungus Aspergillus awamori. This has allowed real life monitoring of [Ca2+]c changes in living fungal cells. When subjected to different physico-chemical stimuli fungal cells respond by transiently changing the concentration of free Ca2+ in the cytosol ([Ca2+]c) and the pattern of these changes (Ca2+ signature) is specific to each particular stimulus. Therefore it was interesting to investigate whether different environmental toxicants would be able to affect the pattern of [Ca2+]c changes in a reproducible and dose dependant manner. RESULTS: Toxicity bioassay has been developed to monitor changes [Ca2+]c of the recombinant fungus in the presence of toxicants representing heavy metals--Cr6+ and Zn2+ and a phenolic polar narcotic -3,5-DCP. The fungus responds to toxicants by a decrease in the amplitude of [Ca2+]c response to 5 mM external CaCl2 and an increase in Ca2+ final resting levels and recovery time. CONCLUSION: A novel toxicity bioassay utilizing eukaryotic cells has been developed based on filamentous fungi transformed with the recombinant aequorin gene. A range of parameters characterising changes in [Ca2+]c has been identified, e.g. Amplitude, Length of Transient, Final Resting Level and Recovery Time. These parameters can be used to determine the toxicity of a range of chemicals to eukaryotic cells in a 96-well microtitre plate method.

Congruence in the performance of model nitrifying activated sludge plants located in Germany, Scotland and Spain.

A laboratory model nitrifying activated sludge plant treating OECD synthetic sewage was designed and constructed by each of three laboratories in Germany, Scotland and Spain in order to produce a sludge inoculum for 5 rapid toxicity bioassays. The plants were run for 3 years and produced sludge for the microbially based bioassays Vibrio fischeri bioluminescence, ATP luminescence and respiration, and, nitrification and enzyme inhibition. Although the initial sludge inoculum for the plants differed, as did some of the running conditions such as temperature regime, the sludge produced within the different countries had similar characteristics with respect to sludge age, total suspended solids and volatile suspended solids. Nitrification was generally maintained over the 3-year period although there were occasions when the process was inconsistent. Nitrification recovery was afforded by reseeding with a nitrifying sludge from a local wastewater treatment works (WWTW) or imposition of starvation conditions for a period of time. The sludge produced was used to carry out toxicity testing and results compared well with those using sludge from a WWTW. Overall, the use of sludge generated in the laboratory could be used for toxicity testing negating the need to resort to the use of natural WWTW sludge, which may contain a range of toxic substances due to uncontrolled industrial and domestic inputs and an unbalanced microbial consortium.

Hormesis responses of free and immobilized light-emitting bacteria.

The stimulatory effect of sublethal or low concentrations of toxic chemicals on organismal metabolism, referred to as hormesis, has been found to be common in the widely used Vibrio fischeri luminescence bioassay. In addition to the "normal" type alpha, we have demonstrated type beta and, possibly, type gamma, dose-response curves in free and immobilized V. fischeri bioassays developed. Understanding and utilizing data from hormesis responses are necessary in determining the toxicity of chemicals, singly or in complex mixtures, to natural biota without imposing excessive penalties to dischargers. At the same time, care must be taken not to relax environmental standards. This can only arise by fully investigating and understanding the role of hormesis in toxicity data used for risk assessment.

An ATP luminescence method for direct toxicity assessment of pollutants impacting on the activated sewage sludge process.

An ATP luminescence method was used to determine the toxicity of three reference toxicants to two sources of domestic activated sludge, and an activated sludge from a laboratory model plant. Repeatability in the ATP test was demonstrated for Cr (as K2Cr2O7), Zn (as ZnSO4 x 7H2O), and 3,5-dichlorophenol (3,5-DCP) using each source of activated sludge. The three sources of sludge showed sensitivity to Cr and 3,5-DCP, and insensitivity to Zn using the ATP luminescence method. Sludge source did not appear to effect test response. The toxic response to 3,5-DCP in model and domestic activated sludge was shown to be dependent on sludge solid concentration (measured as total suspended solids, gTSS(-1). It is recommended that a standard solids concentration is used during toxicity evaluation.