Potential of Candida glabrata from ragi as a bioethanol producer using selected carbohydrate substrates

Abstract

Abstract. Vincent M, Johnny Q, Adeni DSA, Suhaili N. 2020. Potential of Candida glabrata from ragi as a bioethanol producer using selected carbohydrate substrates. Nusantara Bioscience 12: 1-10. The flexibility and efficiency of fermenting microorganisms to convert substrates to ethanol are important factors in achieving high bioethanol yields during ethanolic fermentation. In this study, Candida glabrata, a common yeast found in fermented food, was evaluated in terms of its capability to produce ethanol using different types of carbohydrates, which included simple saccharides (glucose, maltose, sucrose), polysaccharides (starch and cellulose) and complex carbohydrates (total sago effluent, TSE). Our results indicated that C. glabrata was able to efficiently produce ethanol from glucose at 79.84% TEY (Theoretical Ethanol Yield). The ethanol production from sucrose was low, which was only 6.44% TEY, while no ethanol was produced from maltose. Meanwhile, for complex carbohydrate substrates such as starch and cellulose, ethanol was produced only when supplementary enzymes were introduced. Simultaneous Saccharification and Fermentation (SSF) of starch dosed with amylases resulted in an ethanol yield of 55.08% TEY, whilst SSF of cellulose dosed with cellulases yielded a TEY of 31.41%. When SSF was performed on TSE dosed with amylases and cellulases, the highest ethanol production was recorded within 24 h, with a yield of 23.36% TEY. Lactic acid and acetic acid were found to be at minimal levels throughout the fermentation period, indicating an efficient ethanol conversion. A notable increase in C. glabrata biomass was observed in cultures fed with glucose, starch (with supplementary amylases), and TSE (with supplementary amylases and cellulases). The current study indicates that C. glabrata can be used for bioethanol production from glucose, polysaccharides, and complex starchy lignocellulosic substrates such as TSE via SSF.

Biofilm Formation of Probiotic Saccharomyces cerevisiae var. boulardii on Glass Surface during Beer Bottle Ageing

“…We did not observe residual sugars at the end of the ageing period. In a previous study, Candida glabrata failed to produce ethanol from maltose [58]. Among the volatile acids identified in beer, acetate has the greatest amount quantitatively, comprising 40 to 80% of the total, giving the beer a sour taste.…”

Molecular identification of yeasts from Turkish traditional cheeses: Extracellular enzyme activities and physiological properties important for dairy industry

“…They are also used as a biocontrol agent, as in Metschnikowia pulcherrima and Aureobasidium pullulans (Parafati et al 2015;Settier-Ramírez et al 2021). Conventional and non-conventional yeast strains are also frequently used in the production of bioethanol, heterologous proteins and industrial enzymes (Steensels and Verstrepen 2014;Settier-Ramírez et al 2021;Vincent et al 2021). Stress-resistant yeasts with high osmo-, thermo-and ethanol tolerance are preferred especially in industrial areas involving fermentation processes such as wine and bioethanol production (Balakumar and Arasaratnam 2012).…”