The last few years have seen a dramatic increase in the price of fuel leading to various nations trying to find the alternatives to the fuel addiction. Biofuels are considered renewable and sustainable in contrast to the majority of liquid and gas fuels we use today. Biofuels are basically solid, liquid or gaseous fuels obtained from relatively recently lifeless or living biological materials. Biofuel in the form of ethanol have been seen as one of the most attractive source of biofuel to replace or supplement existing fuel demands.
The technology to produce alcohol from sugars is through the process of fermentation, whereby microorganisms such as yeasts and certain species of bacteria have the ability to convert sugar through their metabolism to form alcohol as their main fermentation products.
The chemical reaction is shown below:
C6H12O6 2C2H5OH + 2CO2
In the fermentation of sugar to alcohol, economic factors play the most crucial roles. The requirement is higher production at less cost. Therefore, agronomic residues such as corn stover (corn cobs and stalks), sugarcane waste, wheat, or rice straw, forestry a paper mill wastes, and dedicated energy crops are the major biomass resources considered for the production of fuel ethanol. Most bio-ethanol in India is produced from the molasses left over from the refining of sugar from sugarcane.
Molasses is a thick by-product from the processing of the sugar beet or sugar cane into sugar. Molasses (waste from sugarcane industry) is the commonly used raw material for production of alcohol in most distilleries because of low cost and easy availability. Utilization of molasses for the production of ethanol in India will not only provide value-addition to the byproduct, it can also ensure better price stability and price realization of molasses for the sugar mills. This will improve the viability of the sugar mills, which will in turn benefit cane growers.
Though ethanol is widely accepted as biofuel, there are several constraints in large scale production of ethanol. The ethanol production is not very cost effective. This is due to inefficient methods of production and conversion technologies available. Further the microbial strains used for industrial fermentation are less fermentation stress tolerant. The viability and fermentation efficiency of strains considerably reduces at high glucose and ethanol stress and hence the number of fermentation batches required to produce a fixed amount of alcohol is high which considerably adds to production cost.
In view of the above facts, the objectives of the present study were:
Isolation of high ethanol and glucose tolerant strains from molasses, since it is a rich source of nutrients and has high concentration of sugars.
Characterization of the identified strains.
Examination of the fermentation efficiency of the isolated strains.
2. REVIEW OF LITERATURE
Surging fuel prices have shifted the world’s attention towards biofuel development. Biofuels are defined as solid, liquid or gaseous fuels obtained from relatively recently lifeless or living biological materials and are different from fossil fuels, which are derived from long dead biological material.(www.asiaing.com). Agricultural products such as corn, soybeans, wheat sugar beet, sugar cane and sorghum among many others have been commonly used for biofuel production.
2.1. Types of biofuels
2.1.1. First generation biofuels
First-generation biofuels are biofuels made from sugar, starch, vegetable oil, or animal fats using conventional technology. The basic feedstocks for the production of first generation biofuels are often seeds or grains such as wheat, which yields starch that is fermented into bioethanol, or sunflower seeds, which are pressed to yield vegetable oil that, can be used in...