β-Glucans from Yeast—Immunomodulators from Novel Waste Resources

Abstract

β-glucans are a large class of complex polysaccharides with bioactive properties, including immune modulation. Natural sources of these compounds include yeast, oats, barley, mushrooms, and algae. Yeast is abundant in various processes, including fermentation, and they are often discarded as waste products. The production of biomolecules from waste resources is a growing trend worldwide with novel waste resources being constantly identified. Yeast-derived β-glucans may assist the host’s defence against infections by influencing neutrophil and macrophage inflammatory and antibacterial activities. β-glucans were long regarded as an essential anti-cancer therapy and were licensed in Japan as immune-adjuvant therapy for cancer in 1980 and new mechanisms of action of these molecules are constantly emerging. This paper outlines yeast β-glucans’ immune-modulatory and anti-cancer effects, production and extraction, and their availability in waste streams.

Response of broiler breeder pullets when fed hydrolyzed whole yeast from placement to 22 wk of age

“…It is worth noting that all other studies have utilized hydrolyzed yeast as feed additives under an ad libitum feed regime in layer and broiler chickens ( Salinas-Chavira et al, 2018 ; Walker et al, 2018 ; Pahlavanzadeh et al, 2021 ; Gunun et al, 2022 ; Kiarie et al, 2022 ; Maina et al, 2022 ; Alagbe et al, 2023 ; De Cloet et al, 2023 ). The initial drop can be attributed to 2 possibilities: the suboptimal analyzed protein-to-energy ratio for the HY group (a 12% difference between the 2 diets) ( Gous et al, 2018 ; Aftab, 2019 ) and the fact that the birds were already challenged due to feed restriction for both treatment groups and the incorporation of HY, which is a rich source of β-glucans and mannans ( Maina et al, 2022 ; Thomas et al, 2022 ), may potentially have affected the immune system ( Volman et al, 2008 ). Arguably, a fraction of nutrients that would ordinarily be channeled to growth and maintenance was transferred to immune protein production, as possibly indicated by the high splenic mass in pullets fed HY ( Bi et al, 2022 ; Cao et al, 2023 ).…”

Beta-Glucan as a Soluble Dietary Fiber Source: Origins, Biosynthesis, Extraction, Purification, Structural Characteristics, Bioavailability, Biofunctional Attributes, Industrial Utilization, and Global Trade

“…It has been demonstrated that Dectin-1 specifically recognizes a particular structural configuration of glucans, particularly β-glucans, with a minimum of seven glucan monomers in the backbone and one side chain branch. This recognition triggers downstream signaling that results in immune responses such as phagocytosis, respiratory burst, microbial cell destruction, and the secretion of cytokines [ 69 ].…”

Polysaccharides—Naturally Occurring Immune Modulators

“…For example, starch, cellulose, and pectin are prevalent in plant tissue [ 30 , 31 ]. Yeast and Mushrooms are abundant in β-glucan polysaccharides [ 32 , 33 ]. Agar, carrageenan, and laminarin are some examples of marine polysaccharides.…”

“…The human immune system has two branches: the innate immune system, which produces a non-specific inflammatory response in response to the instant identification of foreign material; and the adaptive immune system, which conducts highly specific antigen responses and maintains a long-term memory [ 32 ].…”