Biotechnological potential of yeast cell wall: An overview

The yeast cell wall is a complex structure whose main function is to protect the cell from physical and chemical damage, providing it with rigidity. It is composed of a matrix of covalently linked polysaccharides and proteins, including β-glucans, mannoproteins, and chitin, whose proportion can vary according to the yeast species and environmental conditions. The main components of the yeast cell wall have relevant properties that expand the possibilities of use in different industrial sectors, such as pharmaceutical, food, medical, veterinary, and cosmetic. Some applications include bioremediation, enzyme immobilization, animal feed, wine production, and hydrogel production. In the literature it is the description of the cell wall composition of model species like Saccharomyces cerevisiae and Candida albicans, however, it is important to know that this composition can vary according to the species or the culture medium conditions. Thus, understanding the structural composition of different species holds promise as an alternative to expanding the utilization of residual yeast from different bioprocesses. In the context of a circular economy, the conversion of residual yeast into valuable products is an attractive prospect for researchers aiming to develop sustainable technologies. This review provides an overview of yeast cell wall composition and its significance in biotechnological applications, considering prospects to increase the diversification of these compounds in industry.

Production of pyruvic acid with Candida glabrata using self-fermenting spent yeast cell dry powder as a seed nitrogen source

Pyruvic acid is an important organic acid and a key industrial raw material. It is widely used in the chemical, agricultural, and food fields. Candida glabrata is the preferred strain for pyruvic acid production. The waste yeast cell for pyruvic acid fermentation with C. glabrata are rich in protein, amino acid, nucleic acid, and vitamins, as potential and cost-effective nitrogen source raw material. In this study, the potential of C. glabrata to produce pyruvic acid using spent yeast cell dry powder was evaluated. When 30 g/L of spray-dried spent yeast cell powder was used as the seed nitrogen source, a high titer of pyruvic acid was obtained. The pyruvic acid production reached 63.4 g/L with a yield of 0.59 g/g in a 5 L bioreactor. After scale-up to a 50 L bioreactor using the fermented spent yeast cell dry powder as a seed nitrogen source, 65.1 g/L of pyruvic acid was harvested, with a yield of 0.61 g/g. This study proposes a promisingapproach for increasing the pyruvic acid titer and reducing the costs.

Biosorption Potential of Microbial and Residual Biomass of Saccharomyces pastorianus Immobilized in Calcium Alginate Matrix for Pharmaceuticals Removal from Aqueous Solutions

Two types of biosorbents, based on Saccharomyces pastorianus immobilized in calcium alginate, were studied for the removal of pharmaceuticals from aqueous solutions. Synthetized biocomposite materials were characterized chemically and morphologically, both before and after simulated biosorption. Ethacridine lactate (EL) was chosen as a target molecule. The process performance was interpreted as a function of initial solution pH, biosorbent dose, and initial pharmaceutical concentration. The results exhibited that the removal efficiencies were superior to 90% for both biosorbents, at the initial pH value of 4.0 and biosorbent dose of 2 g/L for all EL initial concentrations tested. Freundlich, Temkin, Hill, Redlich-Peterson, Sips, and Toth isotherms were used to describe the experimental results. The kinetic data were analyzed using kinetic models, such as pseudo-first order, pseudo-second order, Elovich, and Avrami, to determine the kinetic parameters and describe the transport mechanisms of EL from aqueous solution onto biosorbents. Among the tested equations, the best fit is ensured by the pseudo-second-order kinetics model for both biosorbents, with the correlation coefficient having values higher than 0.996. The many potential advantages and good biosorptive capacity of Saccharomyces pastorianus biomass immobilized in calcium alginate recommend these types of biocomposite materials for the removal of pharmaceuticals from aqueous solutions.