Fermentable Bio-Ethanol Using Bakers and Palmwine Yeasts: Indices of Bioavailability of Carbohydrate and Sugar from Fungal Treated Rice Husk

Authors: Ezeonu, Chukwuma Stephen, Onwurah, Ikechukwu Noel Emmanuel

Abstract:

Pure strains of Aspergillus fumigatus (AF), aspergillus niger (AN), aspergillus oryzae (AO), trichophyton mentagrophyte (TM), trichophyton rubrum (TR) and Trichophyton soudanense (TS) were isolated from decomposing rice husk. Freshly processed rice husk in Mandle’s medium were heat pre-treated using an autoclave at 121oC for 20 minutes. The isolated fungi as monoculture and di-culture combinations were inoculated into each of the pre-treated rice husk with the exception of two controls. Seven days hydrolysis was followed by estimation of carbohydrate, reducing sugar and non-reducing sugar. Fungal treated rice husks were left to ferment for 7 days with introduction of both baker’s and palm wine yeast. The result obtained in the work gave the highest carbohydrate (20.53 ± 2.73 %) from rice husks treated with TS + TR di-culture. The highest soluble reducing sugar (2.66 ± 0.14 %) was obtained from rice husk treated with TM. The highest soluble nonreducing sugar (18.08 ± 2.61 %) was from AF. The introduction of yeasts from palm wine gave the highest bio-ethanol (12.82 ± 0.39 %) from AO. The highest bio-ethanol (6.60 ± 0.10 %) from baker's yeast fermentation was in AO + TS treated rice husk. There was increased availability of sugar and moderate yield of bio-ethanol, especially from palm wine yeast.

Keywords: fungi, rice husk, carbohydrate, reducing sugar, non-reducing sugar, ethanol, fermentation