Enzymes, microbial immobilized

Georgiou D, Hatiras J, Aivasidis A (2005) Microbial immobilization in a two stage fixed bed reactor pilot plant for onsite anaerobic decolorization of textile wastewater. Enzyme Microb Technol 37 597-605... 

Bahar, T. and Gelebi, S.S., Performance of immobilized glucoamylase in a magnetically stabilized fluidized bed reactor (MSFBR), Enzyme Microbial Tech., 26 (2000) 28-33. 

The basic hydrodynamic equations are the Navier-Stokes equations [51]. These equations are listed in their general form in Appendix C. The combination of these equations, for example, with Darcy s law, the fluid flow in crossflow filtration in tubular or capillary membranes can be described [52]. In most cases of enzyme or microbial membrane reactors where enzymes are immobilized within the membrane matrix or in a thin layer at the matrix/shell interface or the live cells are inoculated into the shell, a cake layer is not formed on the membrane surface. The concentration-polarization layer can exist but this layer does not alter the value of the convective velocity. Several studies have modeled the convective-flow profiles in a hollow-fiber and/or flat-sheet membranes [11, 35, 44, 53-56]. Bruining [44] gives a general description of flows and pressures for enzyme membrane reactor. Three main modes... 

Addition of microorganisms and enzymes stimulates the biodegradation of xenobiotics in soils. Most efforts have been directed toward the use of bacterial inocula grown in large fermenters for the bioremediation of soils contaminated with PCP. Also, microbial immobilization on bark chips or their encapsulation in polyurethane or alginate, enhances their PCP-degrading ability as well as their resistance to PCP toxicity. 

Konovalova VV, Dmytrenko GM, Nigmatullin RR, Bryk MT, and Gvozdyak PL Chromium(Vl) reduction in a membrane bioreactor with immobilized Pseudomonas cells. Enzyme Microbial Technol, 2003 33(7) 899-907. 

Archambault J (1991) Large-scale (20-L) culture of surface-immobilized Catharanthus ro-seus cells. Enzyme Microbial Technol 13 882-892. 

I. Chibata and T. Tosa Industrial applications of immobilized enzymes and immobilized microbial cells. Applied Biochemistry and Bioengineering 1 (1976) 329-357. 

One of the approaches to prepare more superior catalysts for application purpose is immobilization of enzymes. Over the past 10 years, the immobilization of enzyme has been the subject of increased Interest, and many papers on potential applications of immobilized enzymes and microbial cells have been published. However, practical industrial systems using immobilized enzymes and immobilized microbial cells have been very limited. 

The first volume of a new series entitled Applied Biochemistry and Bioengineering deals with the principles of immobilized enzymes, which, among other topics, are also discussed in one of the latest volumes of Methods in Enzymology . Recent reviews have covered the uses of immobilized enzymes and immobilized microbial cells in industry, the design of immobilized-enzyme flow reactors, the properties of immobilized enzymes, the reactions used to immobilize enzymes, and the uses of immobilized enzymes in clinical diagnosis, detoxification, and therapy, etc. and of immobilized microbial cells. 

Norouzian, D., A. Akbarzadeh, D. Nouri-Inanlou, B. Farahmand, M. Saleh, F. Sheikh-ul-Eslam, J. Vaez, Biotransformation of alcohols to aldehydes by immobilized cells of Saccharomyces cerevisiae PTCC5080, Enzyme Microbial Technol., 33(2-3), p. 150, 2003. 

For measurement by electrochemical methods, probes have to be developed. For example, knowledge of the magnitude of the frictional forces between the solids and the gas-liquid mixture is very important for design of bioreactors. The growth of biomass on solid surfaces may be sensitive to shear stress. In fluidized bed bioreactors the suspended carriers are used for microbial immobilization or enzyme encapsulation. The knowledge of shear stress is important because some micro-organisms and cells attached to microcarriers are sensitive to excessive friction. The aim is to develop and verify a fast and inexpensive method for measuring the frictional forces in multiphase reactors beds. 

P.B. Poulsen, European and American trends in the industrial application of immobilized biocatalysts, Enzym. Microbial Technol. 3 (1981) 271-273. 

C. Mateo, I.M. Palomo, G. Femandez-Lorente, l.M. Guisan, R. Fernandez-Lafuente, Improvement of enzyme activity, stability and selectivity via immobilization techniques, Enzym. Microbial Technol. 40 (2007) 1451-1463. 

Because enzymes can be intraceUularly associated with cell membranes, whole microbial cells, viable or nonviable, can be used to exploit the activity of one or more types of enzyme and cofactor regeneration, eg, alcohol production from sugar with yeast cells. Viable cells may be further stabilized by entrapment in aqueous gel beads or attached to the surface of spherical particles. Otherwise cells are usually homogenized and cross-linked with glutaraldehyde [111-30-8] to form an insoluble yet penetrable matrix. This is the method upon which the principal industrial appHcations of immobilized enzymes is based. 

The above two processes employ isolated enzymes - penicillin G acylase and thermolysin, respectively - and the key to their success was an efficient production of the enzyme. In the past this was often an insurmountable obstacle to commercialization, but the advent of recombinant DNA technology has changed this situation dramatically. Using this workhorse of modern biotechnology most enzymes can be expressed in a suitable microbial host, which enables their efficient production. As with chemical catalysts another key to success often is the development of a suitable immobilization method, which allows for efficient recovery and recycling of the biocatalyst. 

All soil metabolic proce.sses are driven by enzymes. The main sources of enzymes in soil are roots, animals, and microorganisms the last are considered to be the most important (49). Once enzymes are produced and excreted from microbial cells or from root cells, they face harsh conditions most may be rapidly decomposed by organisms (50), part may be adsorbed onto soil organomineral colloids and possibly protected against microbial degradation (51), and a minor portion may stand active in soil solution (52). The fraction of extracellular enzyme activity of soil, which is not denaturated and/or inactivated through interactions with soil fabric (51), is called naturally stabilized or immobilized. Moreover, it has been hypothesized that immobilized enzymes have a peculiar behavior, for they might not require cofactors for their catalysis. 

Guo, X.-L., Deng, G., Xu, J. and Wang, M.-X. (2006) Immobilization of Rhodococcus sp. AJ270 in alginate capsules and its application in enantioselective biotransformation of ira/i.s-2-methyl-3- phenyl-oxiranecarbonitrile and amide. Enzyme and Microbial Technology, 39, 1-5. 

Dias, A.C.P, Cabral, J.M.S. and Pinheiro, H.M. (1994) Sterol side-chain cleavage with immobilized Mycobacterium cells in water-immiscible organic solvents. Enzyme and Microbial Technology, 16, 708-714. 

In general, biomolecules such as proteins and enzymes display sophisticated recognition abilities but their commercial viability is often hampered by their fragile structure and lack of long term stability under processing conditions [69]. These problems can be partially overcome by immobilization of the biomolecules on various supports, which provide enhanced stability, repetitive and continuous use, potential modulation of catalytic properties, and prevention of microbial contaminations. Sol-gel and synthetic polymer-based routes for biomolecule encapsulation have been studied extensively and are now well established [70-72]. Current research is also concerned with improving the stability of the immobilized biomolecules, notably enzymes, to increase the scope for exploitation in various... 

---