# \(\beta\)-Glucans from Yeast--Immunomodulators from Novel Waste Resources
###### Abstract  
\(\beta\)-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 \(\beta\)-glucans may assist the host's defence against infections by influencing neutrophil and macrophage inflammatory and antibacterial activities. \(\beta\)-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 \(\beta\)-glucans' immune-modulatory and anti-cancer effects, production and extraction, and their availability in waste streams.  
\(\beta\)-glucans; yeast; bioactive properties; anti-cancer; immune-modulation 2022125208. [[https://doi.org/10.3390/app12105208](https://doi.org/10.3390/app12105208)]([https://doi.org/10.3390/app12105208](https://doi.org/10.3390/app12105208))  
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system. Therapeutic effects include anti-inflammatory, anti-cancer, and anti-infective properties [5]. Recognition by immune cells is not exclusively linked to branching but to the length of the polysaccharide polymer and its tertiary structure as well [8; 13].  
Other influences on final conformational structure aside from the originating source include extraction procedure and growth or culture conditions [14]. Herein lies the hurdle of the clinical translation of \(\beta\)-glucans. There are substantial structural variances between \(\beta\)- glucans, including those originating from the same source. These variances include the chain length of the backbone and branching, type of branching, and 3D conformational structure, which can display a random, single helix, or triple helical structure [15]. Thus, research groups are reporting differences in activity which can be seen in an abundance of in-vitro and in-vivo tests and clinical trials registered for the use of \(\beta\)-glucans. \(\beta\)-glucans have been extensively studied in infectious illnesses and tumour immunology.  
Yeast cells are an abundant source of \(\beta\)-glucans and are well documented for their biological activity in both humans and animals [5; 16]. _Saccharomyces cerevisiae_ (_S. cerevisiae_), or baker's yeasts, are the most often utilised in winemaking and brewing [17; 18; 19]. Usually, \(\beta\)-glucans are found in residues and byproducts from these applications. One-third to one-half of the yeast's cell wall is made up of \(\beta\) 1,3-glucan, whereas \(\beta\) 1,6-glucan makes up 10% to 15% of the polysaccharide in the cell wall [20]. This branched structure is a known bioactive that is often discarded as a waste byproduct.  
This review will focus on yeast \(\beta\)-glucans, their production from waste streams, and their vast effect on the immune system which can reduce infection, as well as target cancerous cells. This review also discusses the benefits of administering \(\beta\)-glucans from yeast to livestock to prevent infection and replace antibiotics and concludes with methods of extraction, which are fundamental to activity.