Development, characterization and application of 3D printed adsorbents for in situ recovery of taxadiene from microbial cultivations.

Microbial cell factories are an attractive alternative to produce high-value natural products using sustainable processes. However, product recovery is one of the main challenges to reduce production cost and make these technologies economically interesting. In this work, new resins were formulated to 3D print hydrophobic adsorbents for the recovery of biologics from microbial cultivations. Benzyl methacrylate (BEMA) and butyl methacrylate (BUMA) were selected as functional monomers suitable for the adsorption of hydrophobic compounds. Pore morphology was tailored through the inclusion of pore forming agents (porogens) in the resin. Different porogens and porogen concentrations were evaluated resulting in materials with different porous networks. Sudan 1 and the anticancer drug paclitaxel were employed as model compounds to test the adsorption performance of hydrophobic and terpene molecules onto the developed 3D printed materials. The material with greatest adsorption capacity was obtained using BEMA monomer with 40 % (v/v) porogen (BEMA40). The performance of BEMA40 to recover taxadiene from small-scale (5 mL) Saccharomyces cerevisiae cultivations was tested and compared with commercial Diaion HP-20 beads. Taxadiene titres on BEMA40 (46 ± 2 mg/L) and Diaion HP-20 (54 ± 4 mg/L) were comparable, with no taxadiene detected in the cells and cell-free media, suggesting near 100 % taxadiene partition on the adsorbents. Compared to commercial beads, 3D printed adsorbents can be customized with adjustments in the resin formulation, are well adaptable to diverse bioreactor types, do not clog sampling ports and columns and are easier to handle during post processing. The results of this work demonstrate the potential of 3D printing to fabricate hydrophobic interaction adsorbent materials and their application in the recovery of biological products.

In situ recovery of taxadiene using solid adsorption in cultivations with Saccharomyces cerevisiae.

In this study, an engineered strain of Saccharomyces cerevisiae was used to produce taxadiene, a precursor in the biosynthetic pathway of the anticancer drug paclitaxel. Taxadiene was recovered in situ with the polymeric adsorbent Diaion © HP-20. Here we tested two bioreactor configurations and adsorbent concentrations to maximize the production and recovery of taxadiene. An external recovery configuration (ERC) was performed with the integration of an expanded bed adsorption column, whereas the internal recovery configuration (IRC) consisted in dispersed beads inside the bioreactor vessel. Taxadiene titers recovered in IRC were higher to ERC by 3.4 and 3.5 fold by using 3% and 12% (w/v) adsorbent concentration respectively. On the other hand, cell growth kinetics were faster in ERC which represents an advantage in productivity (mg of taxadiene/L*h). High resin bead concentration (12% w/v) improved the partition of taxadiene onto the beads up to 98%. This result represents an advantage over previous studies using a 3% resin concentration where the partition of taxadiene on the beads was around 50%. This work highlights the potential of in situ product recovery to improve product partition, reduce processing steps and promote cell growth. Nevertheless, a careful design of bioreactor configuration and process conditions is critical.

Chained structure of directed graphs with applications to social and transportation networks.

The need to determine the structure of a graph arises in many applications. This paper studies directed graphs and defines the notions of ℓ -chained and { ℓ , k } -chained directed graphs. These notions reveal structural properties of directed graphs that shed light on how the nodes of the graph are connected. Applications include city planning, information transmission, and disease propagation. We also discuss the notion of in-center and out-center vertices of a directed graph, which are vertices at the center of the graph. Computed examples provide illustrations, among which is the investigation of a bus network for a city.

Scorepochs: A Computer-Aided Scoring Tool for Resting-State M/EEG Epochs.

M/EEG resting-state analysis often requires the definition of the epoch length and the criteria in order to select which epochs to include in the subsequent steps. However, the effects of epoch selection remain scarcely investigated and the procedure used to (visually) inspect, label, and remove bad epochs is often not documented, thereby hindering the reproducibility of the reported results. In this study, we present Scorepochs, a simple and freely available tool for the automatic scoring of resting-state M/EEG epochs that aims to provide an objective method to aid M/EEG experts during the epoch selection procedure. We tested our approach on a freely available EEG dataset containing recordings from 109 subjects using the BCI2000 64 channel system.

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.