Bioprocesses barriers

There are several barriers to the successful control of bioprocesses due to particular circumstances that are related to their characteristics the complexities of microbial metabolisms, the nonlinearity of microbial reactions, the frequent use of batch and fed-batch operations, and the limited availability of sterihzable online sensors for important process variables such as cell and product concentrations. Furthermore, it is difficult to construct mathematical models that can predict the entire range of batch or fed-batch operations that many fermentation processes require. 

The greatest amount of work on scale-up of bioprocesses relevant to plants has been with cell suspension cultures. The potential for chemicals production and for biomass generation, from large scale plant suspension cultures has indeed been recognized for some time (8-10). Many factors remain to be resolved, however, as evidenced by the fact that only one process during the past 25 years has reached commercialization (5). Some of the barriers to successful commercialization are associated with ... 

When used in biotechnology, the first part of a FIA system (see Figure 22-4) is a filtration probe [28-32]. A cell-free sample is drawn from the bioprocess unit (eg, a fermenter) via this probe. Thus, these probes are sterile barriers between the bioprocess and the analysis system, protecting the bioprocess from infections and the analysis system from clogging by cells. Only a few FIA applications utilizing cell-containing samples are known [33]. In those cases, cells and medium are separated inside the FIA system. 

Harris, S. and Shuler, M.L. (2003). Growth of endothelial cells on microfabricated silicon nitride membranes for an in vitro model of the blood-brain barrier. Biotechnol. Bioprocess Eng. 8 246. 

The primary economic barrier to commercialization may not be the fermentation but rather the separation of 2,3-BD from the media. It does not separate well by distillation, and chemical conversion of 2,3-BD in the broth and subsequent distillation are costly (Afschar et al. 1993). Other separation techniques that have been examined include salting out (Afschar et al. 1993) and countercurrent steam stripping (Garg and Jain 1995). Continued fermentation and downstream improvements and a change in the economics of petrochemicals may at some future date make 2,3-BD production from a bioprocess economically attractive. 

As an alternative to chemical conversion, bioconversirai offers superior chemo-, regio-, and enantioselectivity, using nontoxic biocatalysts at ambient temperature and pressure while producing biodegradable waste (Thomas et al. 2002). However, biocatalysis requires the availability of a specific enzyme for each individual reaction. The same is true for FDCA, where indeed the lack of suitable enzymes was long considered the major technical barrier for the development of an efficient bioprocess (Werpy et al. 2004). 

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