Cell wall polysaccharides released during the alcoholic fermentation by Schizosaccharomyces pombe and S. japonicus: quantification and characterization

The pre­sent work demon­strates that yeasts be­long­ing to the Schizosac­cha­romyces genus re­lease a high quan­tity of poly­sac­cha­rides of cell wall ori­gin start­ing from the on­set of the al­co­holic fer­men­ta­tion. By the end of the al­co­holic fer­men­ta­tion, all of the Schizosac­cha­romyces yeast strains re­leased a quan­tity of poly­sac­cha­rides ap­prox­i­mately 3–7 times higher than that re­leased by a com­mer­cial Sac­cha­romyces cere­visiae yeast strain un­der the same fer­men­ta­tive con­di­tions of syn­thetic juice. A higher con­tent of poly­sac­cha­ride was found in me­dia fer­mented by Schizosac­cha­romyces japon­i­cus with re­spect to that of Schizosac­cha­romyces pombe. Some of the strains eval­u­ated were also able to pro­duce high lev­els of pyru­vic acid, which has been shown to be an im­por­tant com­pound for color sta­bil­ity of wine. The pres­ence of strains with dif­fer­ent malic acid con­sump­tion pat­terns along with high poly­sac­cha­ride re­lease would en­able pro­duc­tion of nat­u­rally mod­i­fied wines with en­hanced mouth feel and re­duced acid­ity. The chem­i­cal analy­sis of the re­leased poly­sac­cha­rides demon­strated di­ver­gence be­tween the two yeast species S. pombe and S. japon­i­cus. A dif­fer­ent man­nose/​galac­tose ra­tio and a dif­fer­ent per­cent­age of pro­teins was ob­served on the poly­sac­cha­rides re­leased by S. pombe as com­pared to S. japon­i­cus. Analy­sis of the pro­teins re­leased in the me­dia re­vealed the pres­ence of a gly­co­pro­tein with a mol­e­c­u­lar size around 32–33 kDa only for the species S. japon­i­cus. Mass spec­trom­e­try analy­sis of car­bo­hy­drate moi­eties showed sim­i­lar pro­por­tions among the N-gly­can chains re­leased in the me­dia by both yeast species but dif­fer­ences be­tween the two species were also ob­served. These ob­ser­va­tions sug­gest a pos­si­ble role of rapid MALDI-TOF screen­ing of N-gly­cans com­po­si­tional fin­ger­print as a tax­o­nomic tool for this genus. Poly­sac­cha­rides re­lease in the me­dia, in par­tic­u­lar galac­tomanno­pro­teins in sig­nif­i­cant amounts, could make these yeasts par­tic­u­larly in­ter­est­ing also for the in­dus­trial pro­duc­tion of ex­oge­nous poly­sac­cha­ride prepa­ra­tions.