Improved fermentation efficiency of S. cerevisiae by changing glycolytic metabolic pathways with plasma agitation

How to Survive at Point Nemo? Fischer-Tropsch, Artificial Photosynthesis, and Plasma Catalysis for Sustainable Energy at Isolated Habitats

Inhospitable, inaccessible, and extremely remote alike the famed pole of inaccessibility, aka Point Nemo, the isolated locations in deserts, at sea, or in outer space are difficult for humans to settle, let alone to thrive in. Yet, they present a unique set of opportunities for science, economy, and geopolitics that are difficult to ignore. One of the critical challenges for settlers is the stable supply of energy both to sustain a reasonable quality of life, as well as to take advantage of the local opportunities presented by the remote environment, e.g., abundance of a particular resource. The possible solutions to this challenge are heavily constrained by the difficulty and prohibitive cost of transportation to and from such a habitat (e.g., a lunar or Martian base). In this essay, the advantages and possible challenges of integrating Fischer-Tropsch, artificial photosynthesis, and plasma catalysis into a robust, scalable, and efficient self-contained system for energy harvesting, storage, and utilization are explored.

Enhanced Antimicrobial Activity through Synergistic Effects of Cold Atmospheric Plasma and Plant Secondary Metabolites: Opportunities and Challenges

The emergence of antibiotic resistant microorganisms possesses a great threat to human health and the environment. Considering the exponential increase in the spread of antibiotic resistant microorganisms, it would be prudent to consider the use of alternative antimicrobial agents or therapies. Only a sustainable, sustained, determined, and coordinated international effort will provide the solutions needed for the future. Plant secondary metabolites show bactericidal and bacteriostatic activity similar to that of conventional antibiotics. However, to effectively eliminate infection, secondary metabolites may need to be activated by heat treatment or combined with other therapies. Cold atmospheric plasma therapy is yet another novel approach that has proven antimicrobial effects. In this review, we explore the physiochemical mechanisms that may give rise to the improved antimicrobial activity of secondary metabolites when combined with cold atmospheric plasma therapy.

Andrographolide Induces ROS-Mediated Cytotoxicity, Lipid Peroxidation, and Compromised Cell Integrity in Saccharomyces cerevisiae

Andrographolide, a bioactive compound found in Andrographis paniculata, has gained significant attention for its potential therapeutic properties. Despite its promising benefits, the understanding of its side effects and underlying mechanisms remains limited. Here, we investigated the impact of andrographolide in Saccharomyces cerevisiae and observed that andrographolide induced cytotoxicity, particularly when oxidative phosphorylation was active. Furthermore, andrographolide affected various cellular processes, including vacuole fragmentation, endoplasmic reticulum stress, lipid droplet accumulation, reactive oxygen species levels, and compromised cell integrity. Moreover, we unexpectedly observed that andrographolide induced the precipitation of biomolecules secreted from yeast cells, adding an additional source of stress. Overall, this study provides insights into the cellular effects and potential mechanisms of andrographolide in yeast, shedding light on its side effects and underlying cytotoxicity pathways.

Nonthermal Plasma Effects on Fungi: Applications, Fungal Responses, and Future Perspectives

The kingdom of Fungi is rich in species that live in various environments and exhibit different lifestyles. Many are beneficial and indispensable for the environment and industries, but some can threaten plants, animals, and humans as pathogens. Various strategies have been applied to eliminate fungal pathogens by relying on chemical and nonchemical antifungal agents and tools. Nonthermal plasma (NTP) is a potential tool to inactivate pathogenic and food-contaminating fungi and genetically improve fungal strains used in industry as enzyme and metabolite producers. The NTP mode of action is due to many highly reactive species and their interactions with biological molecules. The interaction of the NTP with living cells is believed to be synergistic yet not well understood. This review aims to summarize the current NTP designs, applications, and challenges that involve fungi, as well as provide brief descriptions of underlying mechanisms employed by fungi in interactions with the NTP components.

Response surface optimization of microalgae microbial fuel cell (MMFC) enhanced by yeast immobilization for bioelectricity production

In this work, suspended and immobilized Saccharomyces cerevisiae yeast in alginate was utilized as a biocatalyst to interact with different concentrations of tofu wastewater for microalgae microbial fuel cell (MMFC) application. Operating conditions are one of the factors that impact the MMFC's performance, thus they must be optimized. The response surface approach was used to optimize operating conditions, which involved CCD-randomized by five levels of two variables. With an average voltage of 0.13 V, power density of 13.94 mW·m^-2, and current density of 102.20 mA·m^-2, bioelectricity output produced more suspended yeast than immobilized yeast. The average voltage of MMFC with immobilized yeast was 0.123 V, the power density was 11.25 mW·m^-2, and the current density was 91.82 mA·m^-2. Immobilized yeast, on the other hand, led in faster stabilization of the resulted electrical output. When compared to suspension yeast, immobilized yeast removed more COD. The best conditions were reached with a yeast concentration of 10.89% w/v and a wastewater concentration of 56.94%, resulting in a power density and COD removal of 11.25 mW·m^-2 and 31.82%, respectively. The effect of yeast and wastewater concentrations on power density and COD removal revealed that the model was well supported by experimental results.

Interaction of air cold plasma with Saccharomyces cerevisiae in the multi-scale microenvironment for improved ethanol yield

In this study, the long-acting mechanism of reactive species was investigated for enhanced ethanol production of Saccharomyces cerevisiae. The results indicated that short-lifetime active species from gas phase plasma dissolved into various liquid microenvironments with different media (water, buffer, medium, and cells), forming different types and amounts of reactive species in multi-scale microenvironments, such as extracellular reactive nitrogen species, endocellular reactive oxygen and nitrogen species. The sustained elevation of cytoplasm calcium concentration with treatment time depended on the activated calcium channels of Cch1p/Mid1p in cell membrane and Yvc1p in vacuole membrane by these species. Accordingly, the Ca²⁺ increase promoted the H⁺-ATPase expression. Consequently, 75.6% ATP hydrolysis induced about 5 fold NADH increase compared with the control. Ultimately, the bioethanol yield increased by 34.2% compared to the control. These results promote the development of atmospheric cold plasma as a promising bio-process enhancement technology for improved target product yields of microbes in fermentation industry.

Combinations of emerging technologies with fermentation: Interaction effects for detoxification of mycotoxins?

Consumption of foods containing mycotoxins, as crucial groups of naturally occurring toxic agents, could pose significant health risks. While the extensive scientific literature indicates that prevention of contamination by toxigenic fungi is one of the best ways to reduce mycotoxins, detoxifying strategies are useful for improving the safety of food products. Nowadays, the food and pharmaceutical industries are using the concept of combined technologies to enhance the product yield by implementing emerging techniques, such as ultrasound, ohmic heating, moderate electric field (MEF), pulsed electric field (PEF) and high-pressure processing, during the fermentation process. While the application of emerging technologies in improving the fermentation process is well explained in this literature, there is a lack of scientific texts discussing the possibility of mycotoxin degradation through the interaction effects of emerging technologies and fermentation. Therefore, this study was undertaken to provide deep insight into applying emerging processing technologies in fermentation, mechanisms and the prospects of innovative combinations of physical and biological techniques for mycotoxins' detoxification. Among various emerging technologies, ultrasound, ohmic heating, MEF, PEF, and cold plasma have shown significant positive effects on fermentation and mycotoxins detoxification, highlighting the possibility of interactions from such combinations to degrade mycotoxins in foods.

Prussian blue analogue nanoenzymes mitigate oxidative stress and boost bio-fermentation

Oxidative stress in cells caused by the accumulation of reactive oxygen species (ROS) is a common cause of cell function degeneration, cell death and various diseases. Efficient, robust and inexpensive nanoparticles (nanoenzymes) capable of scavenging/detoxifying ROS even in harsh environments are attracting strong interest. Prussian blue analogues (PBAs), a prominent group of metalorganic nanoparticles (NPs) with the same cyanometalate structure as the traditional and commonly used Prussian blue (PB), have long been envisaged to mimic enzyme activities for ROS scavenging. However, their biological toxicity, especially potential effects on living beings during practical application, has not yet been fully investigated. Here we reveal the enzyme-like activity of FeCo-PBA NPs, and for the first time investigate the effects of FeCo-PBA on cell viability and growth. We elucidate the effect of the nanoenzyme on the ethanol-production efficacy of a typical model organism, the engineered industrial strain Saccharomyces cerevisiae. We further demonstrate that FeCo-PBA NPs have almost no cytotoxicity on the cells over a broad dosage range (0-100 μg mL^-1), while clearly boosting the yeast fermentation efficiency by mitigating oxidative stress. Atmospheric pressure cold plasma (APCP) pretreatment is used as a multifunctional environmental stress produced by the plasma reactive species. While the plasma enhances the cellular uptake of NPs, FeCo-PBA NPs protect the cells from the oxidative stress induced by both the plasma and the fermentation processes. This synergistic effect leads to higher secondary metabolite yields and energy production. Collectively, this study confirms the positive effects of PBA nanoparticles in living cells through ROS scavenging, thus potentially opening new ways to control the cellular machinery in future nano-biotechnology and nano-biomedical applications.