Yeast cell wall mannan structural features, biological activities, and production strategies

Proteomic insight into the beneficial effect of mannoproteins on Oenococcus oeni in wine malolactic fermentation

Oenococcus oeni is the main species of lactic acid bacteria (LAB) responsible for malolactic fermentation (MLF) in winemaking. MLF development can present difficulties because of the harsh, stressful conditions of wine. Yeast mannoproteins have been described as possible activators of O. oeni and MLF. This study investigated the proteomic response of O. oeni PSU-1 to the presence of yeast mannoproteins in wine like-medium (WLM). In the proteomic analysis, 956 proteins were identified, with 59 differentially expressed proteins (DEPs) when mannoproteins were added. Notably, carbohydrate metabolism and transport were activated, suggesting the use of the mannose oligosaccharides released from mannoproteins. Some of the DEP proteins identified have been associated with mannan recognition in other LAB. However, proteins associated with amino acid metabolism were relatively low in abundance in the presence of mannoproteins, indicating that the amino acid fraction of mannoproteins is not relevant to O. oeni metabolism under the studied conditions. Surprisingly, some stress response proteins, such as ClpP, cold-shock DNA-binding protein, and the citrate transporter MaeP, presented increased abundance. The roles of these proteins in the presence of mannoproteins require further investigation.

The recent advances in vaccine adjuvants

Vaccine adjuvants, as key components in enhancing vaccine immunogenicity, play a vital role in modern vaccinology. This review systematically examines the historical evolution and mechanisms of vaccine adjuvants, with particular emphasis on innovative advancements in aluminum-based adjuvants, emulsion-based adjuvants, and nucleic acid adjuvants (e.g., CpG oligonucleotides). Specifically, aluminum adjuvants enhance immune responses through particle formation/antigen adsorption, inflammatory cascade activation, and T-cell stimulation. Emulsion adjuvants amplify immunogenicity via antigen depot effects and localized inflammation, while nucleic acid adjuvants like CpG oligonucleotides directly activate B cells and dendritic cells to promote Th1-type immune responses and memory T-cell generation. The article further explores the prospective applications of these novel adjuvants in combating emerging pathogens (including influenza and SARS-CoV-2), particularly highlighting their significance in improving vaccine potency and durability. Moreover, this review underscores the critical importance of adjuvant development in next-generation vaccine design and provides theoretical foundations for creating safer, effective adjuvant.

Production of yeast cell wall polysaccharides-β-glucan and chitin by using food waste substrates: Biosynthesis, production, extraction, and purification methods

Food waste causes significant environmental and economic challenges worldwide, prompting many nations to prioritize its reduction and recycling. As a nutrient-rich material containing vitamins, proteins, and carbohydrates, it serves as a promising substrate for the cultivation of single-cell microorganisms like yeast. Yeast cell wall polysaccharides (YCWPs), particularly chitin and β-glucans, offer valuable applications in food, pharmaceuticals, and bioprocessing. This review highlights the biosynthesis, production, extraction, and purification of YCWP cultivated on food waste substrates. Key species including Saccharomyces cerevisiae, Pichia pastoris, and Candida spp. are discussed, with a focus on optimizing chitin and β-glucan yield through mechanical, chemical, and enzymatic extraction methods. In addition, the structural and functional properties of β-glucans and chitin in maintaining cell wall stability are explored, emphasizing their potential as prebiotics, dietary fibers, and biodegradable packaging materials. This review also examines the valorization of food waste in yeast cultivation, presenting a sustainable bioprocessing strategy for transforming waste into valuable bioproducts.

Structural characteristics of Saccharomyces cerevisiae mannoprotein and its immunomodulatory activities on RAW264.7 cells

An enzyme-extracted mannoprotein (SC-MP) from the cell wall of Saccharomyces cerevisiae was investigated for structural characteristics and immunomodulatory effects on RAW264.7. The SC-MP was purified using the diethylaminoethyl (DEAE) cellulose column and gel column to isolate 2 fractions (MP-1 and MP-2), with MP-1 as the dominant fraction (yield, 87.4 %). The results of composition analyses showed that MP-1, which comprises 88.13 % (w/w) sugar and 6.93 % (w/w) protein, had lower protein content than SC-MP (20.89 %, w/w). Monosaccharide analysis showed MP-1 comprises mannose, glucose, and glucosamine in a molar ratio of 97.64:1.46:0.38. The molecule weight of MP-1 was 141 kDa. The MP-1 was further analyzed using GC-MS, NMR to elucidate its structural characteristics, the results showed that the main sugar residue types of MP-1 included T-D-Manp (45.41 mol%), 1,2,6-D-Manp (21.58 mol%), 1,2-D-Manp (19.45 mol%), and 1,6-D-Manp (6.06 mol%), 1,3-D-Manp (3.91 mol%), and a little amount of 1,6-D-Glcp (3.59 mol%). The mannoses polymerized to form mannan and mano-oligosaccharide. Mannan, which has α-1,6-mannan backbone branched with α-1,2-mannan and α-1,3-mannan, connected to protein by N-glycosylation (via asparagine), and mano-oligosaccharide connected to protein by O-glycosylation (via serine or threonine). At 150 μg/mL concentrations, SC-MP and MP-1, which were different in purity, significantly stimulated the secretion of TNF-α and inhibited the secretion of IL-10 of RAW 264.7 cells, and MP-1 showed stronger effects. This study provided a scientific basis for further exploring the applications of yeast mannoprotein.

Yeast mannans promote laxation and specifically modulate microbiota composition in older adults: An open-label pilot study

Yeast mannans (YM) are potential prebiotics that may improve laxation. The aim was to evaluate the effects of YM on gastrointestinal symptoms, with a hypothesis of high tolerance. A secondary aim assessed stool frequency. Fecal microbiota composition (16S rRNA gene amplicon sequencing) and targeted urine metabolites (LC-MS/MS) were explored. An ex vivo simulation of digestion and fermentation (6 donors) compared YM to the reference prebiotic inulin followed by an open-label pilot study, with a 1-week baseline and 2-week intervention of 15 g/d of YM. Ex vivo findings showed increased Bacteroides faecis, B. ovatus, Parabacteroides merdae, P. distasonis, Blautia faecis, and Bifidobacterium spp. in response to YM. Participants (n = 20, 71.4 ± 11.0 y) reported no change with YM for burping, constipation, diarrhea, flatulence/gas, nausea, reflux/heartburn, or rumblings/noise, rated from 0 for none to 3 for severe symptoms. Cramping/pain marginally increased from baseline (0.02 ± 0.01) to intervention (0.05 ± 0.02; P = .046), as did distention/bloating (baseline, 0.07 ± 0.03; intervention week 2, 0.15 ± 0.05; P = .037). This high tolerability was explained by the ex vivo finding that YM induced less gas production than inulin (-45%). Stool frequency trended higher with YM (1.53 ± 0.15 stools/d) compared to baseline (1.35 ± 0.11) (P = .079); participants with ≤1 stools/d (n = 8) showed an increase (0.84 ± 0.14 to 1.19 ± 0.32; P = .016). In vivo compositional changes in fecal microbiota suggest increased B. faecis, B. ovatus, P. merdae, and P. distasonis levels in response to YM. Overall, YM elicited specific microbiota modulation with minimal gastrointestinal symptoms and the potential to increase stool frequency, supporting its prebiotic potential. This trial was registered at clinicaltrials.gov (NCT05939336).

Yeast cell wall derivatives as a potential strategy for modulating oral microbiota and dental plaque biofilm

Introduction

Derivatives from Saccharomyces cerevisiae yeast including yeast extracts and yeast cell walls are sustainable sources of valuable nutrients, including dietary fibers and proteins. Previous studies have shown that certain components from these yeast derivatives can inhibit the growth of harmful intestinal bacteria and promote the growth of beneficial bacteria. However, the effects of yeast derivatives on oral health have not yet been investigated.

Methods

An in vitro oral biofilm model was employed to examine the impacts of yeast derivatives on the oral microbiota and their potential benefits for maintaining oral homeostasis. The model incorporated dental plaque donor material from both healthy and periodontitis diagnosed individuals. Biofilm formation, density, and microbial composition were quantified. Additionally, the production of short-chain fatty acids in the biofilm supernatants was measured.

Results

Yeast extracts had only minor effects on oral biofilm formation. In contrast, yeast cell wall derivatives, which are rich in polysaccharides such as beta-glucans and mannans, significantly reduced the density of the oral biofilms in vitro. This reduction in biofilm density was associated with an overall shift in the bacterial community composition, including an increase in beneficial bacteria and a decrease in the abundance of Tannerella forsythia, an important species involved in bacterial coaggregation and the development and maturation of the oral biofilm. Furthermore, the yeast cell wall derivatives decreased the production of short-chain fatty acids, including acetic and butyric acid. These findings were consistent across both healthy and periodontitis microbiomes.

Conclusion

This study has demonstrated the potential of yeast cell wall derivatives to positively impact oral health by significantly reducing biofilm density, modulating the oral microbial composition, and decreasing the production of short-chain fatty acids. The observed effects highlight the promising applications of these yeast-based compounds as an approach to managing oral diseases. Further research is needed to fully elucidate the mechanisms of action and explore the clinical potential of yeast cell wall derivatives in promoting and maintaining oral health.

Disturbances in cell wall biogenesis as a key factor in the replicative aging of budding yeast

Aging is a multifactorial process that significantly impairs organismal function. Yeast is one of the model organisms used in aging research. Our understanding of the impact of the cell wall on aging remains elusive. Yeast cell wall is a complex and dynamic structure that plays a crucial role in the growth, survival, and aging of Saccharomyces cerevisiae. In this study, we demonstrated for the first time that the deletion of genes involved in cell wall biogenesis leads to significant impact on aging. In this study, we analysed five deletion mutants: crh2Δ, cwp1Δ, flo11Δ, gas1Δ and hsp12Δ. We showed a correlation between Raman spectroscopy signatures assigned to proteins, nucleic acids and RNA and replicative aging. Using Raman spectroscopy, we also revealed that a lack GAS1 gene results in significant changes in the biochemical composition of the cells that may increase sensitivity to environmental stressors. Our data unequivocally indicate that employing yeast as a model in aging research is appropriate, as long as the factors under analysis are not implicated in cell wall biogenesis.

Technologies and practices to improve feed and nutrient utilization by pigs

This review aims to summarize the current practices producers can use to improve feed and nutrient utilization with a focus on providing critical information for use within future life cycle assessments of the swine industry. Nutrient utilization by pigs can be improved by closely meeting the nutrient requirements for maintenance, growth, and reproduction, which reduces nutrient excretion. For example, N excretion can be reduced by 8% and 3.7% for every percentage unit reduction in crude protein for growing pigs and lactating sows, respectively. Similarly, reducing excess trace minerals or replacing inorganic Cu, Zn, and Mn with lower additions of organic sources can reduce excretion by 28% to 42%, 38% to 53%, and 12% to 20%, respectively. Adoption of precision feeding strategies can lower N and P excretion by at least 11%. Ingredient selection and use of feed additives that enhance nutrient digestibility are also an important component in improving feed efficiency and nutrient utilization. The use of exogenous carbohydrase and protease can improve feed efficiency by 1.8%, while phytase can enhance P digestibility by 30% to 50%. At the feed mill, feed efficiency can be improved by 1% for every 100-µm reduction in particle size and by 8% with pelleting. At the farm, management practices such as reducing overfeeding of developing gilts and sows, increasing meal frequency, and minimizing feed wastage can also improve feed utilization. For example, feed wastage is estimated to represent 5% to 6% of total feed disappearance, and feeder type can reduce this by 1% to 10%. Lastly, non-nutritional strategies to improve feed efficiency should be considered, including genetic selection, managing thermal environment, and improving herd health. Current genetic selection results in a reduction in greenhouse gas production by 0.5% to 1.5% per year. Likewise, compared to healthy pigs, disease-challenged pigs have 6.3%, 7.9%, 7.4%, 5.8%, and 5.8% greater climate change potential, soil and water acidification potential, eutrophication potential, cumulative energy demand, and land application requirements, respectively. Currently, the swine industry primarily focuses on feed and management practices that optimize growth and minimize production costs. The challenge to future swine production will be to find emerging technologies that further reduce environmental impacts while still optimizing performance and production costs.

Effects of passion fruit peel (Passiflora edulis) pectin and red yeast (Sporodiobolus pararoseus) cells on growth, immunity, intestinal morphology, gene expression, and gut microbiota in Nile tilapia (Oreochromis niloticus)

This study explores the effects of dietary supplementation with passion fruit peel pectin (Passiflora edulis) and red yeast cell walls (Sporidiobolus pararoseus) on growth performance, immunity, intestinal morphology, gene expression, and gut microbiota of Nile tilapia (Oreochromis niloticus). Nile tilapia with an initial body weight of approximately 15 ± 0.06 g were fed four isonitrogenous (29.09-29.94%), isolipidic (3.01-4.28%), and isoenergetic (4119-4214 Cal/g) diets containing 0 g kg-1 pectin or red yeast cell walls (T1 - Control), 10 g kg-1 pectin (T2), 10 g kg-1 red yeast (T3), and a combination of 10 g kg-1 pectin and 10 g kg-1 red yeast (T4) for 8 weeks. Growth rates and immune responses were assessed at 4 and 8 weeks, while histology, relative immune and antioxidant gene expression, and gut microbiota analysis were conducted after 8 weeks of feeding. The results showed that the combined supplementation (T4) significantly enhanced growth performance metrics, including final weight, weight gain, specific growth rate, and feed conversion ratio, particularly by week 8, compared to T1, T2, and T3 (P < 0.05). Immunological assessments revealed increased lysozyme and peroxidase activities in both skin mucus and serum, with the T4 group showing the most pronounced improvements. Additionally, antioxidant and immune-related gene expression, including glutathione peroxidase (GPX), glutathione reductase (GSR), and interleukin-1 (IL1), were upregulated in the gut, while intestinal morphology exhibited improved villus height and width. Gut microbiota analysis indicated increased alpha and beta diversity, with a notable rise in beneficial phyla such as Actinobacteriota and Firmicutes in the supplemented groups. These findings suggest that the combined use of pectin and red yeast cell walls as prebiotics in aquaculture can enhance the health and growth of Nile tilapia, offering a promising alternative to traditional practices. Further research is needed to determine optimal dosages for maximizing these benefits.

Mannan oligosaccharides as a prebiotic for laying hens: effects on fertility, hatchability, productive performance, and immunity

This experiment examined how adding mannan-oligosaccharides (MOS) to the diet affected fertility, hatching rates, egg production, carcass characteristics, cost-effectiveness, and immune function in laying hens. One hundred and twenty Mandarah chickens (30 hens and 3 roosters per group) were randomly chosen between 34 and 50 wk old and divided into four groups. The first group was the control group, which was given just the basal diet. The basal diet was given to the second, third, and fourth experimental groups along with three different levels of MOS (0.1, 0.2, and 0.5 g/kg diet, respectively). Results found that hens fed MOS at various levels laid eggs at a significantly higher rate, enhanced egg number, egg mass and feed conversion ratio than the control group (P < 0.05). MOS seemed to improve carcass quality. The best results for egg quality (Haugh unit) and testosterone levels were seen with a dose of 0.5 g/kg of MOS compared to the control birds (P < 0.05). All MOS levels led to higher estradiol-17β (E2) levels and better economic efficiency (EE). MOS also improved the hens' immune systems as compared to the control group. Hens-fed MOS had significantly greater levels of antibodies against Influenza viruses (H9N2) and Infectious Bronchitis Virus (P < 0.05). Also, the spleen and thymus gland, both crucial immune system components, were slightly larger (P < 0.05). It's important to note that fertility rates, hatchability, and embryo mortality rates remained similar across all groups. So, our findings suggest that incorporating MOS into the birds' diet enhances their productivity, strengthens their immune system, improves EE, and contributes to the overall health of the hens.

Characterization of the exopolysaccharides produced by the industrial yeast Komagataella phaffii

The yeast Komagataella phaffii has become a popular host strain among biotechnology start-up companies for producing recombinant proteins for food and adult nutrition applications. Komagataella phaffii is a host of choice due to its long history of safe use, open access to protocols and strains, a secretome free of host proteins and proteases, and contract manufacturing organizations with deep knowledge in bioprocess scale-up. However, a recent publication highlighted the abundance of an unknown polysaccharide that accumulates in the supernatant during fermentation. This poses a significant challenge in using K. phaffii as a production host. This polysaccharide leads to difficulties in achieving high purity products and requires specialized and costly downstream processing steps for removal. In this study, we describe the use of the common K. phaffii host strain YB-4290 for production of the bioactive milk protein lactoferrin. Upon purification of lactoferrin using membrane-based separation methods, significant amounts of carbohydrate were copurified with the protein. It was determined that the carbohydrate is mostly composed of mannose residues with minor amounts of glucose and glucosamine. The polysaccharide fraction has an average molecular weight of 50 kDa and consists mainly of mannan, galactomannan, and amylose. In addition, a large fraction of the carbohydrate has an unknown structure likely composed of oligosaccharides. Additional strains were tested in fermentation to further understand the source of the carbohydrates. The commonly used industrial hosts, BG10 and YB-4290, produce a basal level of exopolysaccharide; YB-4290 producing slightly more than BG10. Overexpression of recombinant protein stimulates exopolysaccharide production well above levels produced by the host strains alone. Overall, this study aims to provide a foundation for developing methods to improve the economics of recombinant protein production using K. phaffii as a production host.

ONE-SENTENCE SUMMARY

Overexpression of recombinant protein stimulates the hyperproduction of high-molecular-weight, mannose-based, exopolysaccharides by the industrial yeast Komagataella phaffii.