Cell disruption of S. cerevisiae by scalable high-intensity ultrasound

Potential use of yeast protein in terms of biorefinery, functionality, and sustainability in food industry

A growing demand for sustainable, alternative protein sources that are nutrient-dense, such as microorganisms, and insects, has gradually evolved. When paired with effective processing techniques, yeast cells contain substantial substances that could supply the population's needs for food, medicine, and fuel. This review article explores the potential of yeast proteins as a sustainable and viable alternative to animal and plant-based protein sources. It highlights the various yeast protein extraction methods including both mechanical and non-mechanical methods. The application of nanoparticles is one example of the fast-evolving technology used to damage microbial cells. SiO2 or Al2O3 nanoparticles break yeast cell walls and disrupt membranes, releasing intracellular bioactive compounds. Succinylation of yeast protein during extraction can increase yeast protein extraction rate, lower RNA concentration, raise yeast protein solubility, increase amino acid content, and improve yeast protein emulsification and foaming capabilities. Combining physical and enzymatic extraction methods generates the most representative pool of mannose proteins from yeast cell walls. Ethanol or isoelectric precipitation purifies mannose proteins. Mannoproteins can be used as foamy replacement for animal-derived components like egg whites due to their emulsification, stability, and foaming capabilities. Yeast bioactive peptide was separated by ultrafiltration after enzymatic hydrolysis of yeast protein and has shown hypoglycemic, hypotensive, and oxidative action in vitro studies. Additionally, the review delves into the physicochemical properties and stability of yeast-derived peptides as well as their applications in the food industry. The article infers that yeast proteins are among the promising sources of sustainable protein, with a wide range of potential applications in the food industry.

The Evolution of Sonochemistry: From the Beginnings to Novel Applications

Sonochemistry is the use of ultrasonic waves in an aqueous medium, to generate acoustic cavitation. In this context, sonochemistry emerged as a focal point over the past few decades, starting as a manageable process such as a cleaning technique. Now, it is found in a wide range of applications across various chemical, physical, and biological processes, creating opportunities for analysis between these processes. Sonochemistry is a powerful and eco-friendly technique often called "green chemistry" for less energy use, toxic reagents, and residues generation. It is increasing the number of applications achieved through the ultrasonic irradiation (USI) method. Sonochemistry has been established as a sustainable and cost-effective alternative compared to traditional industrial methods. It promotes scientific and social well-being, offering non-destructive advantages, including rapid processes, improved process efficiency, enhanced product quality, and, in some cases, the retention of key product characteristics. This versatile technology has significantly contributed to the food industry, materials technology, environmental remediation, and biological research. This review is created with enthusiasm and focus on shedding light on the manifold applications of sonochemistry. It delves into this technique's evolution and current applications in cleaning, environmental remediation, microfluidic, biological, and medical fields. The purpose is to show the physicochemical effects and characteristics of acoustic cavitation in different processes across various fields and to demonstrate the extending application reach of sonochemistry. Also to provide insights into the prospects of this versatile technique and demonstrating that sonochemistry is an adapting system able to generate more efficient products or processes.

Yeast β-Glucans as Fish Immunomodulators: A Review

Simple Summary

The β-glucan obtained from yeast—a very important molecule for fish production—activates the immune system of fish by different mechanisms and induces protection against pathogens. However, most previous related studies have focused on the use of commercial β-glucan from the yeast Saccharomyces cerevisiae to understand the activation pathways. Experimental β-glucans extracted from other yeasts show other interesting biological activities even at lower doses. This review article analyzes the current information and suggests perspectives on yeast β-glucans.

Abstract

Administration of immunostimulants in fish is a preventive method to combat infections. A wide variety of these biological molecules exist, among which one of the yeast wall compounds stands out for its different biological activities. The β-glucan that forms the structural part of yeast is capable of generating immune activity in fish by cell receptor recognition. The most frequently used β-glucans for the study of mechanisms of action are those of commercial origin, with doses recommended by the manufacturer. Nevertheless, their immune activity is inefficient in some fish species, and increasing the dose may show adverse effects, including immunosuppression. Conversely, experimental β-glucans from other yeast species show different activities, such as antibacterial, antioxidant, healing, and stress tolerance properties. Therefore, this review analyses the most recent scientific reports on the use of yeast β-glucans in freshwater and marine fish.

Immune-enhancing effects of polysaccharide extract of by-products of Korean liquor fermented by Saccharomyces cerevisiae

To increase the value of yeast-fermented Korean liquor by-products, we obtained crude polysaccharide (CPS) fractions via ultrasound-assisted extraction and stepwise-gradient ethanol precipitation and investigated their functionality. Nitric oxide production in RAW 264.7 cells was increased following treatment with the CPSs derived from extract. Analysis of the monosaccharide and amino acid composition of the CPS fractions using HPLC revealed that the polysaccharides were mainly composed of glucose (57.2%), mannose (22.6%), and galactose (17.6%), and no amino acids were detected. In addition, a higher concentration of ethanol solvent for fractionation yielded polysaccharides with lower molecular weights (<15 kDa). CPS 3 and 4 fractions increased the production of TNF-α (15 and 17-fold, respectively) and IL-6 (20 and 18-fold, respectively) and iNOS (65 and 35-fold, respectively) expression at concentration 12.5 μg/mL compared with levels in non-treated RAW 264.7 cells. Especially, CPS 4 at 200 and 400 μg/mL significantly increased the proliferation of mouse spleen cells by 126% and 153%, respectively. These results indicated that CPS 4 enhanced the proliferation of mouse spleen cells in vivo, indicating its immune-enhancing effects. Therefore, this research can contribute to the development of eco-friendly extraction techniques and immune-enhancing materials.

Giving superabsorbent polymers a second life as pressure-sensitive adhesives

An estimated 6.3 billion metric tons of post-consumer polymer waste has been produced, with the majority (79%) in landfills or the environment. Recycling methods that utilize these waste polymers could attenuate their environmental impact. For many polymers, recycling via mechanical processes is not feasible and these materials are destined for landfills or incineration. One salient example is the superabsorbent material used in diapers and feminine hygiene products, which contain crosslinked sodium polyacrylates. Here we report an open-loop recycling method for these materials that involves (i) decrosslinking via hydrolysis, (ii) an optional chain-shortening via sonication, and (iii) functionalizing via Fischer esterification. The resulting materials exhibit low-to-medium storage and loss moduli, and as such, are applicable as general-purpose adhesives. A life cycle assessment demonstrates that the adhesives synthesized via this approach outcompete the same materials derived from petroleum feedstocks on nearly every metric, including carbon dioxide emissions and cumulative energy demand.

Self-Assembled Regenerated Silk Fibroin Microsphere-Embedded Fe3O4 Magnetic Nanoparticles for Immobilization of Zymolyase

Cytoplasm of Saccharomyces cerevisiae yeast cells contains a significant amount of desired intracellular products for both industrial utility and academic research. To recover intracellular compounds, it is necessary to break the yeast cells with high efficiency, which, under certain circumstances, requires the use of the lytic enzyme zymolyase to completely digest the cell walls. A promising strategy for zymolyase immobilization on silk fibroin (SF) was developed. SF/Fe3O4 magnetic microspheres (MMs) were constructed by solvent (ethanol)-induced self-assembly of SF surrounding Fe3O4 magnetic nanoparticles (MNs), which were synthesized by a coprecipitation method. Zymolyase was covalently bonded on the surface of the SF/Fe3O4 MMs by a photochemical cross-linking method to produce robust biocatalysts of zymolyase/SF/Fe3O4. The chemical, magnetic, and morphological properties of the MM supports and the immobilized zymolyase were investigated. Enzymolysis results demonstrated that the immobilized zymolyase showed good activity and stability for digesting yeast cell walls, and the biocatalyst can be readily recycled through convenient magnetic separation for reuse. At the optimum pH = 7.5, the immobilized zymolyase maintained 84% of the activity of the free zymolyase and retained 41% of its initial activity after four times of reuse. At unfavorable acidic pH = 4, the immobilized zymolyase retained 81% of its initial activity, while the free zymolyase showed no significant activity. Consequently, the SF/Fe3O4 MMs exhibit superior performance in terms of immobilizing enzymes, which have a good prospect in the biological application.

Effects of cavitation on different microorganisms: The current understanding of the mechanisms taking place behind the phenomenon. A review and proposals for further research

A sudden decrease in pressure triggers the formation of vapour and gas bubbles inside a liquid medium (also called cavitation). This leads to many (key) engineering problems: material loss, noise, and vibration of hydraulic machinery. On the other hand, cavitation is a potentially useful phenomenon: the extreme conditions are increasingly used for a wide variety of applications such as surface cleaning, enhanced chemistry, and wastewater treatment (bacteria eradication and virus inactivation). Despite this significant progress, a large gap persists between the understanding of the mechanisms that contribute to the effects of cavitation and its application. Although engineers are already commercializing devices that employ cavitation, we are still not able to answer the fundamental question: What precisely are the mechanisms how bubbles can clean, disinfect, kill bacteria and enhance chemical activity? The present paper is a thorough review of the recent (from 2005 onward) work done in the fields of cavitation-assisted microorganism's destruction and aims to serve as a foundation to build on in the next years.

Enhanced lipid extraction from oleaginous yeast biomass using ultrasound assisted extraction: A greener and scalable process

Soaring demand for alternative fuels has been gaining wide interest due to depletion of conventional fuel, increasing petroleum prices and greenhouse gas emissions. Biodiesel, an alternative fuel, derived from oleaginous microbes has been promising because of short incubation time and easy to scale up. Oleaginous yeast Trichosporon sp. is capable of utilizing glycerol and agro-residues for enhanced lipid synthesis. Lipid extraction from Trichosporon sp. biomass showed highest lipid content with ultrasonic assisted extraction (43 ± 0.33%, w/w) coupled with process parameters than the conventional Soxhlet (30 ± 0.28%, w/w) and Binary solvent [choloroform:methanol, (2:1, v/v)] methods (36 ± 0.38%, w/w), respectively. The standardized process parameters of ultrasonic assisted extraction coupled with chloroform/methanol solvent system resulted 95-97% of conversion efficiency in 20 min at 30 °C with a frequency of 50 Hz and 2800 W power, respectively. Enzymatic transesterification of yeast biomass lipid obtained 85% of fatty acid methyl esters that are predominant with oleic acid methyl ester followed by palmitic and stearic acid methyl esters, respectively. These results substantiate that the ultrasonic assisted extraction is a potential green extraction technique that had reduced time, energy and solvent consumption without compromising on lipid quality. Deploying this green extraction technique could make the biodiesel production process inexpensive and eco-friendly.

A review on acoustic methods of algal growth control by ultrasonication through existing and novel emerging technologies

The uncontrolled proliferation of algae and algal blooms due to excessive nutrient loading in natural and industrial water bodies is a major issue for water quality maintenance. It reduces usability of the water, imposes hazardous effects of algal toxins released from algal blooms, and creates nuisance in the operation of several industrial water units. Among several existing water treatment methods to diminish the post-algae growth effects, ultrasonication has emerged as an environmentally safe technology that does not involve any use of algaecide. The interaction of several parameters, including climatic and environmental conditions with algae growth rate, have been reviewed in this article. The effects of different acoustic operating conditions for inhibition of algae growth have also been discussed. Concern about high energy consumption led other technologies to be integrated with ultrasonication. It has enhanced the process efficiency and reduced the energy consumption as reported in some long-term field investigations and patent proposals. Several issues that require further research for making this technology widely applicable or to install an effective system design have been highlighted in this article.