Microbial catalysts

The same holds true for potentials there is a standardized method, which is to report them versus the standard hydrogen electrode (SHE) or normal hydrogen electrode (NHE) [2, 36]. Furthermore, cell potentials are only relevant when the external resistance is also noted. 

Microbial electrocatalysis relies on microorganisms as catalysts for reactions occurring at electrodes. The microorganisms involved are able to transport electrons in and out of the cell, a process known as extracellular electron transfer (EET), and can catalyze both oxidation and reduction reactions [80, 81]. Their catalytic properties have been confirmed by the fact that they are able to lower the overpotentials (lower energy loss) at both anodes [82] and cathodes [56, 69], giving an increased performance of the system. Nevertheless, they cannot be considered as true catalysts since part of the substrate/electron donor is consumed for growth. 

So far, most research has been done on biological anodes, cathodes being mainly abiotic and of minor interest. In the last few years, researchers have realized that the (bio)cathode still remains one of the weakest points of this technology this has led to a steep increase in the scope of possible electrode materials and cathode reactions, both chemical and biological. 

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Olson, G. Microbial catalyst for desulfurization of fossil fuels. Patent No. US6124130. 2000, Sep. 26. 

Microbial biocatalytic systems, 76 398 Microbial biocontrol agents, 73 347-348 foliar application of, 73 349 phytotoxin production and, 73 351 problems associated with, 73 348-349 shelf life and storage of, 73 350 Microbial biomass, 26 471 474 substrates for, 26 473-474 Microbial catalysts, rapid screening of, 76 405... 

Microcat (meaning microbial catalysts) products constitute a bioremediation technology used on wastewaters, sludges, and soils. Microcat products include specialized microbial cultures, nutrients, and surfactants to remediate organic contaminants such as petroleum hydrocarbons. The products used in site remediation include ... 

The development of microbial catalyst remains a highly vibrant, challenging, and rapidly expanding part of the symposium, and we expect that it will continue to play an important role in future years. 

These significant barriers are largely responsible for the lack of substantial commercial impact of enzyme and microbial catalysts on the chemicaIs-related industries. High fructose corn syrup and amino... 

Denitrification [the conversion of NOs to N2(ag>] is a common reaction catalyzed by many bacteria and proceeds rapidly. However, it appears that microbial catalysts are unable to catalyze the reverse of the denitrification reaction (Ngca, ) — NOs ). 

Four billion pounds of adipic acid are produced each year using petroleum-based feedstocks, carcinogenic benzene as starting material, and extreme reaction conditions. Nitrous oxide, which plays a role in ozone layer depletion, is emitted as a byproduct. As an alternative to the currently employed synthetic methcdology, a two-step synthesis of adipic acid from D-glucose has been developed which eliminates each of these problems. A microbial catalyst was created which possesses a novel biosynthetic pathway that synthesizes cis, cis-muconic acid from D-glucose. This pathway does not occur in nature but has been created in a strain of Escherichia colL Cis, cw-muconic acid is exported to the culture supernatant, where it is hydrogenated under mild conditions to yield adipic acid. 

Before it will be practical to consider using a microbial catalyst to manufacture adipic acid, significant challenges must be addressed. To improve catalyst stability and increase the percent conversion of D-glucose into product, further development of the microbial catalyst will be needed. The scale of the reaction also requires adjustment from laboratory shake flasks to fermentation tanks, which would then be readily scaled to industrial production. Future efforts will focus on these challenges. 

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