Isolation and Optimization of Cellulolytic and Xylanolytic Microbes from Nepal and their Utilization for Lignocellulosic Biomass Degradation.

ABSTRACT

Microorganisms harbored by nature and guts of herbivorous animals can degrade different plant related biomass. One of the in-between steps for conversion of lignocellulosic biomass to ethanol entails isolation and identification of microorganisms that could convert pretreated biomass into a suitable form, which could then be fermented into bioethanol. We isolated 36 different microorganisms from hot spring, 6 from ruminant’s (goat) gut, 2 sample from hay spray on the basis of their ability to secrete enzymes that hydrolyzed different plant constituents. Similarly 3 microorganisms were isolated from the rotten wood available around Kathmandu University on the basis of utilization of xylose and glucose. 3 varieties of thermophiles, gut microorganism and microorganism from hay spray that showed the highest cellulolytic and xylanolytic activities by saccharification of cellulose and xylan into their monosaccharide glucose and xylose units respectively were then applied on different biomass (rice straw, corn stover and sugarcane bagasse). Before Saccharification biomass was made accessible for the digestion by enzymes through 3 different pretreatment strategies (3.35% H2SO4, NaOH and H2O2 with 110 substrate chemical ratio) following thermal strategy of steam explosion. Also, different conditions like incubation time, pH and temperature for saccharification were assessed with the highest liberation of reducing sugar at pH 5, temperature of 5̊ C and incubation time of 4 days. Microorganism from rotten wood was able to utilize both xylose and glucose and yielded highest amount (5.567 mg/ml) of bioethanol.