Toward optimal use of biomass as carbon source for chemical bioproduction.

Biomass is widely identified as a promising, renewable replacement for fossil feedstocks in the production of energy, fuels, and chemicals. However, the sustainable supply of biomass is limited. Economic and ecological criteria support prioritization of biomass as a carbon source for organic chemicals; however, utilization for energy currently dominates. Therefore, to optimize the use of available biomass feedstock, biorefining development must focus on high carbon efficiencies and enabling the conversion of all biomass fractions, including lignin and fermentation-derived CO2. Additionally, novel technological platforms should allow the incorporation of nontraditional, currently underutilized carbon feedstocks (e.g. manure) into biorefining processes. To this end, funneling of waste feedstocks to a single product (e.g. methane) and subsequent conversion to chemicals is a promising approach.

Solid-state co-culture fermentation of simulated food waste with filamentous fungi for production of bio-pigments.

The use of waste stream residues as feedstock for material production simultaneously helps reduce dependence on fossil-based resources and to shift toward a circular economy. This study explores the conversion of food waste into valuable chemicals, namely, bio-pigments. Here, a simulated food waste feedstock was converted into pigments via solid-state fermentation with the filamentous fungus Talaromyces albobiverticillius (NRRL 2120). Pigments including monascorubrin, rubropunctatin, and 7-(2-hydroxyethyl)-monascorubramine were identified as products of the fermentation via ultra-performance liquid chromatography coupled with quadrupole-time-of-flight electrospray ionization mass spectrometry. Pigments were obtained at concentrations of 32.5, 20.9, and 22.4 AU/gram dry substrate for pigments absorbing at 400, 475, and 500 nm, respectively. Pigment production was further enhanced by co-culturing T. albobiverticillius with Trichoderma reesei (NRRL 3652), and ultimately yielded 63.8, 35.6, and 43.6 AU/gds at the same respective wavelengths. This represents the highest reported production of pigments via solid-state fermentation of a non-supplemented waste stream feedstock. KEY POINTS: • Simulated food waste underwent solid-state fermentation via filamentous fungi. • Bio-pigments were obtained from fermentation of the simulated food waste. • Co-culturing multiple fungal species substantially improved pigment production.

Use of filamentous fungi as biocatalysts in the oxidation of 5-(hydroxymethyl)furfural (HMF).

The objective of this study was to explore the use of filamentous fungi as oxidative biocatalysts. To that end, filamentous fungal whole-cells, comprising five different species were employed in the oxidation of 5-(hydroxymethyl)furfural (HMF). Two species (A. niger and T. reesei), which demonstrated superior HMF conversion and product accumulation, were further evaluated for growth on alternative substrates (e.g. pentoses) as well as for use in a chemo-biocatalytic reaction system. Concerning the latter, the two whole-cell biocatalysts were coupled with laccase/TEMPO in a one-pot reaction designed to enable catalysis of the three oxidative steps necessary to convert HMF into 2,5-furandicarboxylic acid (FDCA), a compound with immense potential in the production of sustainable and eco-friendly polymers. Ultimately, the optimal one-pot chemo-biocatalytic cascade system, comprising 1 g/L T. reesei whole cells coupled with 2.5 mM laccase and 20 mol% TEMPO, achieved a molar yield of 88% after 80 h.

Vortex- and Centrifugation-Free Extraction of HIV-1 RNA.

BACKGROUND AND OBJECTIVE: HIV viral load measurements play a critical role in monitoring disease progression in those who are on antiretroviral treatment. In order to obtain an accurate measurement, rapid sample preparation techniques are required. There is an unmet need for HIV extraction instruments in resource-limited settings, where HIV prevalence is high. Therefore, the objective of our study was to develop a three-dimensional (3D) microfluidic system to extract HIV-1 RNA with minimal electricity and without complex laboratory instruments. METHODS: A 3D microfluidic system was designed in which magnetic beads bound with nucleic acids move through immiscible oil-water interfaces to separate HIV-1 RNA from the sample. Polymerase chain reaction (PCR) amplification was used to quantify the total amount of HIV-1 RNA extracted as we optimized the system through chip design, bead type, carry-over volume, carrier RNA concentration, and elution buffer temperature. Additionally, the extraction efficiency of the 3D microfluidic system was evaluated by comparing with a Qiagen EZ1 Advanced XL instrument using 20 HIV-1-positive plasma samples. RESULTS: Our method has near-perfect (100%) extraction efficiency in spiked serum samples with as little as 50 copies/mL starting sample. Furthermore, we report carry-over volumes of 0.31% ± 0.006% of total sample volume. Using the EZ1 Advanced XL as a gold standard, the average percentage HIV-1 RNA extracted using the microchip was observed to be 65.4% ± 24.6%. CONCLUSIONS: From a clinical perspective, the success of our method opens up its possible use in diagnostic tests for HIV in the remote areas where access to vortexes and centrifuges is not available. Here we present a proof-of-concept device which, with further development, could be used for sample preparation at the point of care.

Feasibility of recording high frequency oscillations with tripolar concentric ring electrodes during pentylenetetrazole-induced seizures in rats.

As epilepsy remains a refractory condition in about 30% of patients with complex partial seizures, electrical stimulation of the brain has recently shown potential for additive seizure control therapy. Previously, we applied noninvasive transcranial focal stimulation via novel tripolar concentric ring electrodes (TCREs) on the scalp of rats after inducing seizures with pentylenetetrazole (PTZ). We developed a close-loop system to detect seizures and automatically trigger the stimulation and evaluated its effect on the electrographic activity recorded by TCREs in rats. In our previous work the detectors of seizure onset were based on seizure-induced changes in signal power in the frequency range up to 100 Hz, while in this preliminary study we assess the feasibility of recording high frequency oscillations (HFOs) in the range up to 300 Hz noninvasively with scalp TCREs during PTZ-induced seizures. Grand average power spectral density estimate and generalized likelihood ratio tests were used to compare power of electrographic activity at different stages of seizure development in a group of rats (n= 8). The results suggest that TCREs have the ability to record HFOs from the scalp as well as that scalp-recorded HFOs can potentially be used as features for seizure onset detection.