Evaluation of rice husk as a substrate for the growth of Lactobacillus species
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Abstract
The most produced and consumed cereal is Rice (Oryza sativa). Rice husk is composed of 11% hemicellulose with xylan being the main sugar subunit. Xylan is the most abundant carbohydrate in lignocellulosic biomass the precursor of Xylooligosaccharides (XOS), used as prebiotics. Toxic products and activity of pathogenic bacteria are decreased by xylooligosaccharides which enables the growth of probiotic bacteria. The present study was aimed to study the by-products of rice cultivation as a substrate for the growth of Lactobacillus species. The collected rice husk was weighed and dried in Hot Air Oven. After hot air drying the sample was weighed again and measured the dry weight. A two-step auto-hydrolysis method was used. The liquor contained xylooligosaccharides which were refined by filtration. The non-digestible oligosaccharides XOS were predominant in acid extract when sulfuric acid was 2% (w/w), temperature and time were 100°C and 0.5 hours respectively. The prebiotic efficacy of XOS was checked with Lactobacillus strains grown in MRS broth for in-vitro evaluation. The OD600 was high with the liquor extract of rice husk instead of other sugar. This study shows xylan from agriculture waste produces XOS, an emerging prebiotic with a promising low-cost strategy of production.
Keywords: Fermentation; Lactobacillus; Probiotics; Rice Husk; Substrate