Fermentation, bioproducts

The separation of cells from the culture media or fermentation broth is the first step in a bioproduct recovery sequence. Whereas centrifugation is common for recombinant bacterial cells (see Centrifugal separation), the final removal of CHO cells utilizes sterile-filtration techniques. Safety concerns with respect to contamination of the product with CHO cells were addressed by confirming the absence of cells in the product, and their relative noninfectivity with respect to immune competent rodents injected with a large number of CHO cells. 

Approximately 89 million metric t of organic chemicals and lubricants, the majority of which are fossil based, are produced annually in the United States. The development of new industrial bioproducts, for production in standalone facilities or biorefineries, has the potential to reduce our dependence on imported oil and improve energy security. Advances in biotechnology are enabling the optimization of feedstock composition and agronomic characteristics and the development of new and improved fermentation organisms for conversion of biomass to new end products or intermediates. This article reviews recent biotechnology efforts to develop new industrial bioproducts and improve renewable feedstocks and key market opportunities. 

Index Entries Bioproducts thermoplastics fermentation solvents platform chemicals. 

In recent years, BASF AG, Ludwigshafen, and Omnigene Bioproducts, Cambridge, MA, USA, have developed a novel fermentation process for preparation of D-pantothenate with Bacillus [8]. Bacillus subtilis is inherently capable of producing... 

Biotechnological transformation is powerful tool to effectively utilize a broad variety of plant oils, with the aim to modify their structure for the production of new lipid-based materials with demanded properties and functions. One method of plant oil transformation is based on the direct utilization by microorganisms. Employed oils can be converted to aimed compounds by submerged cultivation or oils, and/or oleaginous plant materials can be utilized during solid state fermentation to useful bioproducts enriched with demanded microbial products. Another biotransformation technique covers the enzymatic modification of oil components to structured lipids with biological properties. 

Bioproducts Enriched with Arachidonic Acid (AA) Solid-state fermentations were also employed to improve the market for fungal AA-rich bioproducts. Screening of many fungi has resulted in selection of Mortierella... 

Certik, M., Slavikova, L., and Lai, M. H. 2003a. Preparation of bioproducts enriched with polyunsaturated fatty acids based on solid state fermentations. Hanoi Proceedings of the 8th Asean Food Conference (pp. 654-658). 

The isolation and purification of fermentation products is often collectively referred to as downstream processing. The early part of the separation of a bioproduct is the primary recovery process, whereas the elements further downstream may include purification, concentration, and formulation. The overall goal of downstream processing and formulation is to recover the product of interest cost effectively at high yield, purity, and concentration, and in a form that is stable, safe, and easy to use in a target application. 

Purification of bioproducts from fermentation, although necessary, comes with a major drawback. Biological compounds evolved in an environment of complex components are adapted to be most stable in these conditions. Highly pure forms of bioproducts have a tendency towards lower chemical and physical stability. For instance, proteases are prone to autolysis in the absence of impurities that inhibit degradation. This is one of the major... 

The ability of proteins to transfer from an aqueous solution to a reversed micelle=icontaining organic phase, and be subsequently recovered in a second aqueous phase, was first established by the group of Luisi (2,3). It has since been suggested by van t Riet and Dekker (4, 5) and Goklen and Hatton (6 -9 ) that this phenomenon be exploited in the recovery, separation and concentration of bioproducts from complex aqueous mixtures. In the past three years, significant progress has been made in this direction, and it has been established that these solvents can be selective in the separation of binary and ternary protein mixtures (7f9 ) and in the recovery of an extracellular alkaline protease from a clarified fermentation broth (1 0). It has also been demonstrated that the process can be operated on a continuous basis (5). 

Table 1 Some bioproducts produced by fermentation and downstream processing steps used in their recovery and purification...

Some bioproducts are derived from fermentation by living organisms but immobilized enzymes can also catalyze a biotransformation. If the product is extracellular, then the initial steps of recovery include removal of the cells and other particulate matters from the broth. If the product is intracellular, it would be necessary to lyse the cells to release the product into the broth. The cell debris is then separated before the product is recovered from the broth. In certain cases, proteins produced as IBs need to be solubilized and the proteins renatured before further recovery steps. In the case of biotransformed products, the immobilized cells or enzymes and their support need to be removed initially. 

Processes for the bioproduction of ethanol from cellulosic materials have been studied extensively. Some of the process steps are specialized and beyond the scope of this chapter. However, there are many recent review articles dealing with some specific subjects. Basically, the processes consist of a number of steps. They are availability and collection of raw feedstock [20], size reduction, pretreatment, fractionation of biomass components, enzyme production [21, 22], saccharification, enzyme recycle [23, 24], pentose fermentation, improvement of pentose-fermenting biocatalyst, overcoming of product inhibition, overcoming inhibition by substrate-derived inhibitors, ethanol recovery [25], steam generation and recycling [26], waste treatment, and by-product utilization. 

This book covers several of the emerging areas of separations in biotechnology and is not intended to be a comprehensive handbook. It includes recent advances and latest developments in techniques and operations used for bioproduct recovery in biotechnology and applied to fermentation systems as well as mathematical analysis and modeling of such operations. The topics have been arranged in three sections beginning with product release from the cell and recovery from the bioreactor. This section is followed by one on broader separation and concentration processes, and the final section is on purification operations. The operations covered in these last two sections can be used at a number of different stages in the downstream process. 

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