Microbial scalability

Transgenic plant systems have the potential to produce recombinant proteins on a commodity scale (Kusnadi et al., 1997) due to the low cost of growing plants and because scale-up of production simply requires sewing seeds over a greater field area. As such they offer almost unlimited scalability (Giddings, 2001). It is estimated by Kusnadi et al. (1997) that transgenic plants can produce pharmaceutical proteins at between 10 and 50-fold lower cost than microbial fermentation systems, and 1,000 times lower than mammalian cell culture systems (Hood et al., 2002). 

Extrusion is a simple and low-cost process of encapsulation with core-shell architecture, which is able to preserve probiotic cell viability, owing to the limited use of harmful solvents and the small stresses exerted on microbial cells. However, its use on large scale is limited by the slow process of capsule fabrication. In contrast, owing to its easier scalability, fluid-bed coating is more widely used in the encapsulation of probiotic cells. 

Zhuang, L., Feng, C.H., Zhou, S.G., Li, Y.T., and Wang, Y.Q. (2010) Comparison of membrane- and cloth-cathode assembly for scalable microbial fuel cells construction, performance and cost. Process Biochem., 45 (6), 929-934. 

Zhuang L, Zheng Y, Zhou S, Yuan Y, Yuan H, Chen Y. Scalable microbial fuel cell (MFC) stack for continuous real wastewater treatment. Bioresour Technol 2012 106 82-88. 

Microbial fuel cell scalability and apphcations in robotics... 

In conclusion, both plant cell/tissue and microbial systems offer tremendous advantages as scalable alkaloid production platforms. Moreover, because the characteristics and metabolic capacities of plant cell/tissue and microbial systems are inherently different, they can serve as complementary unit operations in order to solve the long-standing problem of robust alkaloid production. However, better understanding of regulatory mechanisms and refinement for robust cellular and metabolic engineering of plant ceUs/tissues will further provide an impetus to popular use of plant cell technology in industry. 

Zhuang, L., Zhou, S., Wang, Y, Liu, C. Geng, S. Membrane-less cloth cathode assembly (CCA) for scalable microbial fuel-cells. Biosens. Bioelectron. 24 (2009), pp. 3652-3656. 

Even though these special application examples demonstrate the scalability of the technology, and although airlift reactors have long been used for shear-sensitive cell-culture applications, the CSTR design has become the standard for microbial and mammalian cell suspension culture. Its design is versatile, and cultivations can be scaled from the laboratory to pilot scale and to up to 300 m in fully contained sterile fermenters. 

Zuo, Y., Cheng, S., and Logan, B.E. (2008) Ion exchange membrane cathodes for scalable microbial fuel cells. Environmental Science Technology,... 

Electrodes are one of the most critical factors governing the performance and cost of MFCs. The physicochemical properties of electrodes (e.g. surface area, electric conductivity, and chemical stability) determine the microbial attachment affinity, electron transfer efficiency, electrode ohmic resistance and the surface reaction rate. Electrodes constitute a major cost in the construction of MFCs, and determine whether the MFC is cost-effective and scalable technology, especially for wastewater treatment. The long-term stability of MFC performance is largely dependent on the durability of elec-frode maferials. 

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