Acetone and Butanol Fermentation

Introduction

The production of acetone and butanol by means of solvent-producing strains of Clostridium spp. was one of the first large-scale industrial fermentation processes to be developed,and during the first part of this century it ranked second in importance only to ethanol fermentation. The reason for the almost total demise of this fermentation in the early 1960s was the inability of the fermentation process to compete economically with the chemical synthesis of solvents. However, interest in the use of renewable resources as feedstocks for the production of chemicals and recent developments in the field of biotechnology have resulted in a renewal of interest in the fermentation route as a possible source of solvent production . Within the last 7 years there has been an escalation in research aimed at obtaining a greater understanding of this complex and interesting fermentation, with the aim of developing a more efficient and competitive fermentation process. Although various aspects of the history and development of acetone-butanol (AB) fermentation have been documented by a number of authors, the information is scattered and incomplete, and there is no comprehensive account of the historical development of AB fermentation. We have reviewed the origin and development of conventional industrial AB fermentation in different parts of the world and discuss the current biochemical, genetic, and process engineering research in relation to the problems and prospects of the re-establishment of a viable industrial AB fermentation process.

HISTORY

Origin of Acetone Butanol Fermentation

The production of butanol in a microbial fermentation was first reported by Pasteur in 1861. During the latter part of the 19th century the production of butanol by anaerobic bacteria was studied by a number of investigators however, it was only in 1905 that Schardinger reported the production of acetone by fermentation. Around the turn of the century a shortage of natural rubber stimulated interest in the possibility of producing synthetic rubber . Among those working on the problem of rubber synthesis was the chemist Chaim Weizmann, who had arrived in Manchester in 1904 from Berlin at the age of 30. He obtained a post under Professor Perkins at Manchester University.In 1910 the firm of Strange and Graham Ltd. in England embarked on a project to make synthetic rubber. They recruited the services of Perkins and Weizmann and subsequently the services of Fernbach and Schoen of the Institute Pasteur. It was decided that the best route for the production of butadiene or isoprene was from butanol or isoamyl alcohol. This initiated an investigation into the possibility of producing the compounds by means of a microbial fermentation. In 1911 Fernbach isolated a culture which was able to ferment potatoes, but not maize starch, to produce butanol. In 1912 Weizmann terminated the connection with Strange and Graham td. but continued his research at Manchester University . He had concluded that the production of butanol or isoamyl alcohol by fermentation was essential for the success of the synthetic rubber process, and although he was not a microbiologist, he set about training himself to become one. Between 1912 and 1914 he isolated and studied a number of cultures, one of which he called BY , which was later named Clostridium acetobutylicum. This organism had a number of unique properties including the ability to use a variety of starchy substances and to produce much better yields of butanol and acetone than did Fernbach's original culture. Meanwhile, Strange and Graham Ltd. continued with their venture and filed an English patent application covering a process that used Fernbach's bacillus. About the middle

of 1913 they began production at a plant at Rainham which produced acetone, in addition to butanol, from potatoes. The Rainham plant was closed after a year and the operations were transferred to a new plant at King's Lynn. The future development of AB fermentation was altered dramatically by the outbreak of the First World War in August 1914. The British army required smokeless powder (cordite) in large amounts for the manufacture of munitions. Acetone was used as the colloidal solvent for nitrocellulose, which was used to manufacture cordite. Before the war acetone was produced from calcium acetate, which was imported in small amounts from Germany, Austria, and the United States. With the advent of the war, most of the supplies were cut off and the limited amount available from the United States was inadequate. Faced with an emergency, the British War Office approached Strange and Graham Ltd. in 1915 and they were contracted to supply acetone to the British government. Some acetone was produced at the plant at King's Lynn, using potatoes as a substrate, but production was relatively inefficient, with an average production of only 970 pounds (ca. 440 kg) per week(61). During this period Weizmann continued working on his own at the University of Manchester and intended publishing his findings as a scientific publication (61). However, the outbreak of war altered this as it was apparent that his work could be of benefit to the British war effort. In response to a request for cooperation from the scientific community, he set about bringing his work to the attention of the authorities, and a confidential demonstration was arranged for the head of the Chemical Department of Nobel's Explosive Company (61, 270). The head of the Chemical Department was impressed with the advantages of the Weizmann process and Weizmann was advised to apply for a patent, which was issued in March 1915 (61, 264). However, an explosion at the company's works prevented any further developments (270). A year later Weizmann was summoned to the British Admiralty and was asked to undertake a project to manufacture acetone (61.270). He agreed, and initial pilot-scale studies were started at the Nicholson Distillery in London; following an interview with Churchill (who was First Lord of the Admiralty), Weizmann was given carte blanche to recruit a team of young scientists to work on the project (94, 270). Weizmann resigned his post at Manchester University in mid-1916, and the group was given facilities in the south of England (94, 270). Further research work was undertaken under his direction at the Lister Institute in London, and larger pilot-scale development work was started at distilleries in London and Greenock (228). The results were so promising that the Admiralty decided to erect a plant for the production of acetone at the Royal Naval Cordite Factory at Poole in Dorset and to adapt six distilleries in Great Britain for the production of acetone by the Weizmann process (61, 270).