Harnessing Over Ripe Fruits For Isolation And Optimization Of Xylose Utilizing Yeasts And Analysis Of Its Fermentation Products

Abstract

D-xylose nestled within plant hemicelluloses, is primary pentose sugar, comprising the lion's share of all carbohydrates derived from the hydrolysis of renewable plant biomass. Though glucose reigns in natural abundance, the fermentation of D-xylose offers a strategic avenue to bolster the yield of diverse fermented products. Despite their promise, hemicellulose sugars often remain underutilized, despite being more readily obtained from cellulose in higher yields and at a lower cost than glucose. Their conversion potential is vast, spanning the production of xylitol and other valuable chemicals. Among these, ethanol emerges as a frontrunner, holding substantial market potential. While considerable research has been devoted to isolating xylose-fermenting yeasts from various sources, this investigation focuses on isolation and characterization of yeast strains assimilating xylose from a spectrum of fruit samples. The isolates in our investigation were identified as Debaryomyces hansenii and Meyerozyma guilliermondii with 18S rRNA gene sequencing. Optimization investigations were performed to delineate the optimal conditions for yeast growth and fermentation, with pH 4.5, temperature 30°C and 5% substrate concentration yielding the substantial biomass and viable cell counts. Fermentation assays conducted utilizing xylose-enriched media resulted in substantial ethanol yields of 12.56% (S2) and 23.46% (S4), along with xylitol production of 50.85% and 51.05% respectively. HPLC analysis affirmed efficient utilization of more than 99% of the available xylose. Our fermentation studies promise a harvest of various fermented products, each holding potential that would have different applications in the production of bioethanol and xylitol, fostering in the innovation of sustainable bio refinery development.