Cell wall of yeast

Many microorganisms produce enzymes that lyse the cell wall of yeast. The most extensive work has been done with the lytic system from Arthrobacter sp., Cytophaga sp., Oerskovia, Bacillus circulans, Rhizopus, Tri-choderma, Penicillium, Pellicularia sp., Rhizoctonia, and Streptomyces sp. (3-9). 

In the more abundant a chitin the chains in alternate sheets have opposite orientations,101102 possibly a result of hairpin folds in the strands. Native chitin exists as microfibrils of 7.25 nm diameter. These contain a 2.8-nm core consisting of 15-30 chitin chains surrounded by a sheath of 27-kDa protein subunits. The microfibrils pack in a hexagonal array, but the structure is not completely regular. Several proteins are present some of the glucosamine units of the polysaccharide are not acetylated and the chitin core is often calcified.103 The commercial product chitosan is a product of alkaline deacetylation of chitin but it also occurs naturally in some fungi.102 Chitin is also present in cell walls of yeasts and other fungi. It is covalently bonded to a P-l,3-linked glycan which may, in turn, be linked to a mannoprotein (see Section D,2)97... 

N-linked glycan is pictured in Fig. 4-17. Like many others, it has a number of sialic acid residues at the nonreducing ends and also contains N-acetyllactos-amine units. The major component of the cell walls of yeast (S. cerevisiae) is a mannoprotein that carries long N-linked oligosaccharides with highly branched outer chains of over 100 mannose residues170 (see also Section C,3). 

Free silver ions are the active components of antimicrobial silvers, and it has been shown that as little as one part per million of elemental silver in solution is an effective antimicrobial. Materials such as polymers, charcoal, and hydrocolloids when formulated with silver not only aid wound management and healing but also regulate its release into the wound environment and surrounding tissues. Silver ions kill micro-organisms by inhibiting cellular respiration and cellular function. " It is known that their mode of action is exerted by binding cysteine residues on the cell walls of yeasts such as C. albicans thereby... 

Cell walls of yeasts contain mannans in which the main a-l,6-linked chain carries short branches of one to three mannose units joined in a-1,2, a-1,3, and sometimes a-1,6 linkages. These are covalently linked to proteins. A p-l,4-linked mannan forms microfibrils in the cell wall of some algae such as Acetabu-laria (Fig. 1-11) which do not make cellulose. ... 

The retention of anthocyanins and pyruvic anthocyanin derivatives by the cell walls of yeasts used in the fermentation of red wines. 

The comparison between the two chain pairs is also consistent with the physical properties. Paramylon and amylose are known for their gel forming properties and their carbon reserve function in p1 ants.(13,69) Although (l- -3)-3-D-glucan also plays a structural rFTe when it occurs in the cell walls of yeast( ), it is probably more of a matrix substance than anything else. The ability to form multiple helices probably accounts for unusual solubility phenomena such as retrogradation( ) and irreversible gel formation on heating. (13)... 

Chitin, the precursor of chitosan, is a nitrogen containing polysaccharide and is second most abundant biopolymer after cellulose. It is widely distributed in the shells of crustaceans such as crabs, shrimps, lobsters, prawns, squilla, etc., as well as in the exoskeleton of marine zoo-plankton, including coral, jellyfish, and squid pens. About 20-40% chitin is present the exoskeleton of these animals. It is also present in smaller quantities in insects such as butter flies ladybugs, and the cell walls of yeast, mushrooms, and other fungi [Fig. 19.4]. However, since the crustacean shells [crabs, shrimps, lobsters, etc.] are waste products of food industry, these are commercially employed for the production of chitin and chitosan [1, 4, 18], It is believed that at least 10 gigaton of chitin is synthesized and degraded and it is also estimated that over 150,000 tons of chitin is available for commercial use annually. 

Definition Polysaccharides derived from cell walls of yeast... 

The preparations are featured with combining probiotics and prebiotics (mannans and glucans on cell walls of yeast Saccharomyces cerevisiae), and phytobiotics of the medicinal plants - Echinacea purpurea and holy thistle. Echinacea has immunomodulatory properties. Echinacea preparations exhibit antibacterial, antiviral and antifungal properties. When intaking the Echinacea preparations at metabolic disorders, at the impact of different chemical compounds of toxic nature, contained in the feed (heavy metals, pesticides, insecticides, fungicides), a stimulation of the immune system has been observed. 

Extracellular e/u/n-j3-l,6-D>glucanase was produced in high concentration when Bacillus circulans was grown on yeast cell walls (see also p. 368). This enzyme was separated from the e/idb-jS-l,3-D-glucanase by gel filtration, and was then purified by ion-exchange chromatography. The enzyme exhibited maximal activity at pH 5.5 but, in contrast to the crude culture fluid, had only a limited action on the cell walls of yeast or Schizosaccharomyces pombe. 

Johnson, E. A., ViUa, T. G., Lewis, M. J., Phaff, H. J. Lysis of cell wall of yeast Phaffia rho-dozyme by a lytic complex from Bacillus circulans WL-12. J Appl Biochem 1979, 1, 272-282. 

Kreger, D. R. Observations on cell walls of yeasts and some other fungi by X-ray diffraction and solubdity tests. Biochim Biophys Acta 1954,13,1-9. 

Yeast cells are considered to be one of the most extensive model eukaryotic systems for various fields of fife sciences. The cell walls of yeasts are interesting to study due to their sensitivity toward different biological functions. 

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