The effects of microbial lignocellulose pretreatments on xylooligosaccharide production

Abstract

gases. The processing and utilization of lignocellulosic substrate is complex, differing in many aspects from crop-based ethanol production. One important requirement is an efficient microorganism able to ferment a variety of sugars (pentoses and hexoses) as well as to tolerate stress conditions. The study aims to extend the range of sources from which ethanol may be made beyond sugar cane bagasse which is used for the preparation of pulp and paper. Therefore, one fungal strain isolated from pulp and paper mill effluent identified as Cryptococcus albidus by 18S rDNA, internal transcribed spacer (ITS) together with Saccharomyces cerevisiae was used for the production of ethanol. The cellulose, lignin and xylan-degrading potency of fungus was evaluated by the production of sugar and enzymes, endoglucanase, exoglucanase, lignin peroxidase, manganese peroxidase, laccase, glucose oxidase and xylanase. The optimization of process parameters like pH, temperature, carbon and nitrogen source, phosphorus, agitation, inoculum size and duration using Taguchi approach indicated increase in 2-fold sugar production by fungus. The sugar cane bagasse treated by fungus subsequently treated by S. cerevisiae indicated the production of ethanol (36 g/L). The fermentation process was further improved by Taguchi approach where carbon, nitrogen, temperature, osmotic tolerance, inorganic compounds, stirring and pH were used. The result of the study indicated an increase in 1.5-fold production of ethanol. The method was tested in 15-L sequential bioreactor in which sugar cane bagasse was initially degraded by fungus and subsequently fermented by yeast for the production of ethanol for scale up of the method for huge production of bioethanol from sugar cane bagasse.Various non-edible tree-borne oils such as Azadirachta indica, Madhuca longifolia, Pongamia pinnata and Jatropha curcas are available in India but oil yields are insufficient to meet the energy demands. Biotechnology could contribute to yield improvement strategies. Genetic analysis and mapping in species with a view to identify quantitative trait loci (QTLs) for useful characteristics and marker assisted selection (MAS) breeding strategies can be used to jumpstart genetic improvement of jatropha for seed yield characteristics. Interspecific and intergeneric crosses and techniques in tissue culture such as in vitro fertilization and somatic hybridization can be employed. Tissue culture can induce variability in plant tissues through somaclonal variation and micropropagation can be useful for the multiplication and distribution of suitable planting material. The present study will focus on the percentage yield from Jatropha and determination of the specific activity of biodiesel derived from the same plant. We have successfully extracted 26.185% of seed oil from Jatropha with a specific gravity of 0.821. The consumption of diesel is much higher than petrol consumption, which creates great potential for biodiesel production in India, without the risk of competing with the food mar...