Short term atmospheric pressure cold plasma treatment: A novel strategy for enhancing the substrate utilization in a thermophile, Geobacillus sp. strain WSUCF1

Thermophilic Exopolysaccharide Films: A Potential Device for Local Antibiotic Delivery

Natural polysaccharides being investigated for use in the field of drug delivery commonly require the addition of sugars or pretreated biomass for fabrication. Geobacillus sp. strain WSUCF1 is a thermophile capable of secreting natural polymers, termed exopolysaccharides (EPSs), cultivated from cost-effective, non-treated lignocellulosic biomass carbon substrates. This preliminary investigation explores the capabilities of a 5% wt/wt amikacin-loaded film constructed from the crude EPS extracted from the strain WSUCF1. Film samples were seen to be non-cytotoxic to human keratinocytes and human skin-tissue fibroblasts, maintaining cell viability, on average, above 85% for keratinocytes over 72-h during a cell viability assay. The drug release profile of a whole film sample revealed a steady release of the antibiotic up to 12 h. The amikacin eluted by the EPS film was seen to be active against Staphylococcus aureus, maintaining above a 91% growth inhibition over a period of 48 h. Overall, this study demonstrates that a 5% amikacin-EPS film, grown from lignocellulosic biomass, can be a viable option for preventing or combating infections in clinical treatment.

Microbial electrosynthesis: carbonaceous electrode materials for CO2 conversion

Microbial electrosynthesis (MES) is a sustainable approach to address greenhouse gas (GHG) emissions using anthropogenic carbon dioxide (CO₂) as a building block to create clean fuels and highly valuable chemicals. The efficiency of MES-based CO₂ conversion is closely related to the performance of electrode material and, in particular, the cathode for which carbonaceous materials are frequently used. Compared to expensive metal electrodes, carbonaceous materials are biocompatible with a high specific surface area, wide range of possible morphologies, and excellent chemical stability, and their use can maximize the growth of bacteria and enhance electron transfer rates. Examples include MES cathodes based on carbon nanotubes, graphene, graphene oxide, graphite, graphite felt, graphitic carbon nitride (g-C₃N₄), activated carbon, carbon felt, carbon dots, carbon fibers, carbon brushes, carbon cloth, reticulated vitreous carbon foam, MXenes, and biochar. Herein, we review the state-of-the-art MES, including thermodynamic and kinetic processes that underpin MES-based CO₂ conversion, as well as the impact of reactor type and configuration, selection of biocompatible electrolytes, product selectivity, and the use of novel methods for stimulating biomass accumulation. Specific emphasis is placed on carbonaceous electrode materials, their 3D bioprinting and surface features, and the use of waste-derived carbon or biochar as an outstanding material for further improving the environmental conditions of CO₂ conversion using carbon-hungry microbes and as a step toward the circular economy. MES would be an outstanding technique to develop rocket fuels and bioderived products using CO₂ in the atmosphere for the Mars mission.

Cold atmospheric plasma treatment improves the γ-aminobutyric acid content of buckwheat seeds providing a new anti-hypertensive functional ingredient

Buckwheat (BW) is rich in γ-aminobutyric acid (GABA), which has great potential as a functional anti-hypertensive food ingredient. This study utilized cold atmospheric plasma (CAP) to promote GABA accumulation in BW during germination. The effect of this approach on GABA enrichment and anti-hypertensive activity of BW along with its processing properties were investigated. The results indicated that CAP stress treatment (50 W for 40 s) of BW seeds followed by germination at 30 °C for 60 h resulted in a GABA content of 2.22 ± 0.06 mg/g, which was a 2.64-fold greater than that of pristine BW. Cracking of the seed coat, faster germination, and the activation of glutamate decarboxylase might be responsible for the GABA enrichment. Compared with pristine BW, the GABA-enriched BW powder showed a greater inhibitory effect on the angiotensin-converting enzyme, an increased degree of pre-gelatinization and elasticity when it was formed into a dough.

Subcellular damages of Colletotrichum asianum and inhibition of mango anthracnose by dielectric barrier discharge plasma

Colletotrichum asianum (C. asianum) is a new pathogenic fungus that causes mango anthracnose. Cold plasma is a novel non-thermal decontamination technology, which has been proven to be effective in controlling postharvest fungus. Herein, dielectric barrier discharge (DBD) plasma was used to treat C. asianum spores in sterile phosphate-buffered saline, the damages in subcellular structures of C. asianum and inhibition of mango anthracnose were evaluated. Results showed that after 9 min treatment, the spore germination rate and spore viability were decreased by 95.48% and 98.82%, respectively, and the subcellular structures were damaged (P < 0.05), leading to spores death. Besides, DBD plasma treatments could control mango anthracnose and maintain mango quality, and the disease incidence and lesion diameter of mango treated for 9 min were decreased by 48.00% and 62.95%, respectively. Therefore DBD plasma inactivated C. asianum spore, providing an alternative technique for preventing and controlling mango anthracnose.

Enhanced bioethanol production using atmospheric cold plasma-assisted detoxification of sugarcane bagasse hydrolysate

The current study used acid hydrolysis of lignocellulosic materials to obtain fermentable sugar for bioethanol production. However, toxic compounds that inhibit fermentation are also produced during the process, which reduces the bioethanol productivity. In this study, atmospheric cold plasma (ACP) was adopted to degrade the toxic compounds within sulfuric acid-hydrolyzed sugarcane bagasse. After ACP treatment, significant decreases in toxic compounds (31% of the formic acid, 45% of the acetic acid, 80% of the hydroxymethylfurfural, and 100% of the furfural) were observed. The toxicity of the hydrolysate was low enough for bioethanol production using Kluyveromyces marxianus. After adopting optimal ACP conditions (200 W power for 25 min), the bioethanol productivity improved from 0.25 to 0.65 g/L/h, which means that ACP could effectively degrade toxic compounds within the hydrolysate, thereby enhancing bioethanol production. Various nitrogen substitute was coordinated with detoxified hydrolysate, and chicken meal group presented the highest bioethanol productivity (0.45 g/L/h).