Industrial-scale fermentation process development

For the production of natural products on an industrial scale, fermentation processes are often preferable in comparison to chemical processes. In biosynthesis processes, natural products may be generated efficiently and cleanly via enzymatic catalysis 185). Thus, the development of synthesis approaches similar to their biosynthesis is one of the main objectives of the synthesis community. To pursue this goal, Yokoyama and co-workers developed a bio-similar three-step synthesis of optically active clavicipitic acid (175) 186), which was isolated from natural sources as an isomeric mixture (Scheme 4.10) 187). 

NPI-0052 is currently manufactured under cGMP through a robust saline fermentation process by S. tropica strain NPS21184. It was quite an effort to find the proper contract manufacturing organisations (CMOs) that would accept and adapt our saline fermentation process, developed in laboratory fermenters, to their industrial-scale production fermenters and also have the proper containment facility to handle the downstream processing (DSP) of the highly potent NPI-0052. 

Until World War 1 acetone was manufactured commercially by the dry distillation of calcium acetate from lime and pyroligneous acid (wood distillate) (9). During the war processes for acetic acid from acetylene and by fermentation supplanted the pyroligneous acid (10). In turn these methods were displaced by the process developed for the bacterial fermentation of carbohydrates (cornstarch and molasses) to acetone and alcohols (11). At one time Pubhcker Industries, Commercial Solvents, and National Distillers had combined biofermentation capacity of 22,700 metric tons of acetone per year. Biofermentation became noncompetitive around 1960 because of the economics of scale of the isopropyl alcohol dehydrogenation and cumene hydroperoxide processes. 

The most widespread biological application of three-phase fluidization at a commercial scale is in wastewater treatment. Several large scale applications exist for fermentation processes, as well, and, recently, applications in cell culture have been developed. Each of these areas have particular features that make three-phase fluidization particularly well-suited for them Wastewater Treatment. As can be seen in Tables 14a to 14d, numerous examples of the application of three-phase fluidization to waste-water treatment exist. Laboratory studies in the 1970 s were followed by large scale commercial units in the early 1980 s, with aerobic applications preceding anaerobic systems (Heijnen et al., 1989). The technique is well accepted as a viable tool for wastewater treatment for municipal sewage, food process waste streams, and other industrial effluents. Though pure cultures known to degrade a particular waste component are occasionally used (Sreekrishnan et al., 1991 Austermann-Haun et al., 1994 Lazarova et al., 1994), most applications use a mixed culture enriched from a similar waste stream or treatment facility or no inoculation at all (Sanz and Fdez-Polanco, 1990). 

As a matter of fact, most of the processes currently developed to generate biochemicals out of biomass involve fermentation of starch originating from corn, wheat, or rice, for example. The various chemicals obtainable from theses processes and their end applications are listed in Table 10.3. A lot of these fermented biochemicals, however, are not yet economically competitive compared with their petrochemical equivalent, essentially due to the large capital investment in equipment and land needed to implement the fermentation process on an industrial scale. An additional disadvantage of this route is that it competes with feedstock needed by the food industry. More research to reduce the costs of fermentation technology is needed. 

A brilliant example for the industrial-scale application of plant cell fermentation is the new process for the production of the anticancer drug paclitaxel developed by Bristol-Myers Squibb (see Figure 15.1). It starts with clusters of paclitaxel producing cells from the needles of the Chinese yew, T. chinensis, and was introduced in 2002. The API is isolated from the fermentation broth and is purified by chromatography and crystallization. The new process substitutes the previously used semisynthetic route. It started with lO-deacetylbaccatin(III), a compound that contains most of the structural complexity of paclitaxel and can be extracted from leaves and twigs of the European yew, T. baccata. The chemical process to convert 10-deacetylbaccatin(III) to paclitaxel is complex. It includes 11 synthetic steps and has a modest yield. 

A new method for the preparation of soy sauce has been developed. The new scaled-up method divides the moromi process into two processes autolysis and fermentation. Because of the utilization of high temperatures, the new process permits the production of a NaCl free autolyzate from koji. Division of the fermentation process into two separated processes permit better control of lactic acid fermentation and alcohol fermentation processed which used to require great skill. The new scale-up procedure for soy sauce production yields a product in half the time required by the traditional (conventional) method and still produces a soy sauce with high levels of the desirable Bavor component, glutamic acid. Utilization of this protocol by the soy sauce producing industry should have significant economic impact to bo producers and consumers. 

Weizmann discovered a process to produce butyl alcohol and acetone from the bacterium Clostridium acetobutylicum in 1914. With England s urgent demand for acetone, Winston Churchill (1874-1965) enlisted Weizmann to develop the Weizmann process for acetone production on an industrial scale. Large industrial plants were established in Canada, India, and the United States to provide the allies with acetone for munitions. Weizmann, who is considered the father of industrial fermentation, obtained significant status from his war contributions and used this to further his political mission of establishing a Jewish homeland. Weizmann was a leader of the Zionist movement and campaigned aggressively until the nation of Israel was established in 1948. He was the first president of Israel. 

A variety of bacterial species have been used for almost 40 years in the large-scale fermentative production of amino acids for industrial uses. The Corynebacteria have been most widely used in this application as a result of their propensity to overproduce and excrete very high concentrations of amino acids under specific process conditions and their early development for monosodium glutamate production. However, other organisms including E. coli have also been successfully used in the production of amino acids such as phenylalanine. 

The final process fermentation development standardised parameters such as temperature exposure, operating parameters, cleaning and passivation to overcome the corrosive effect of saline fermentation and was performed in 500-1500 L industrial-scale stainless steel fermenters. This, together with careful design of the timing and method for introducing the resin to the production fermenter, resulted in production titres of 250-300 mg/L in 500-1500 L industrial fermenters. 

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