Enhanced Biobutanol Production in Batch Simultaneous Saccharification and Fermentation From Agriculture Residues Using Novel Clostridial Fusants

Sarkar Begum

doi:10.32920/ryerson.14660370.v1

Abstract

A novel approach was introduced for the enhancement of biobutanol production in ABE fermenetation. Thermostable Clostridia species were developed through protoplast fusion between mesophilic and thermophilic Clostridial species. Two parental strains of Clostridia species, Clostridium acetobutylicum (ATCC 4259) and Clostridium beijerinckii (ATCC BA101), along with three fused strains, Clostridium acetobutylicum Clostridium thermocellum (CaCt), Clostridium beijerinckii Clostridium thermocellum (CbCt) and Clostridium acetobutylicum Clostridium beijerinckii (CaCb), were examined for biobutanol production using wheat straw as a feed stock in a batch process of simultaneous saccharification and fermentation (SSF). The objective of the study was to use the thermotolerant fused strains to enhance enzymatic activity during the SSF by raising the incubation temperature and thereby eventually increasing biobutanol production. Economic and residence time analysis of SSF found that addition of cellulase increases the cost of fermentation and prolongs biobutanol production cycle. However, results from the current study indicated that the fused strains, at the higher temperature, were able to produce the required enzymes for the saccharification of wheat straw (i.e., endoglucanase, exoglucanase, and b- glucosidase). This will have a major impact on eliminating costs associated with adding enzymes as raw material to the saccharification process. Fused strain CbCt achieved the highest biobutanol production of up to 14.13 g/L (i.e., a yield of 0.29) was reached at 45°C with total sugar consumption of 82%. Enzymatic activity of CbCt was found to be 61.67 FPU (Filter Paper Unit) which was the highest in comparison with other fused strains evaluated in this study. These results indicate a breakthrough for the technological and economical obstacles associated with industrialization of the SSF process.

Highlights

Reductions of fossil fuels and fluctuating prices have revived an interest in the development of renewable fuels such as ethanol and butanol
The aim of the present study is to introduce a novel approach by using an improved microorganism strain, Clostridium fusant, that is formed through protoplast fusion to produce butanol by simultaneous saccharification and fermentation; because of small scale production, butanol did not show toxicity
Batch simultaneous saccharification and fermentation (SSF) were conducted at two different temperatures to produce biobutanol from wheat straw (WS) using

Summary

Introduction

Reductions of fossil fuels and fluctuating prices have revived an interest in the development of renewable fuels such as ethanol and butanol. In the first generation of biofuels, production is achieved by the action of microorganisms and enzymes through the fermentation of starch or cellulose. High oil prices, competing demands between foods and other biofuel sources, and the world food crisis, have ignited interest in algae culture (farming algae) for producing biofuels, using land that is unsuitable for agriculture. These all lead to the interest in the Consolidated Bioprocessing (CBP), which is an alternative processing strategy, where feedstock substrate hydrolysis and biofuel production by fermentation are accomplished in a single process step simultaneously by microorganisms that produce cellulolytic enzymes

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