Platform chemical microbial production

Succinic acid is a potential platform chemical that is expected to be commercialised in a few years. Although the production capacity of petrochemically derived succinic acid is on the scale of 15 000 tonnes per year (Zeikus etal., 1999), the production capacity of succinic acid derivatives is over 270 000 tonnes per year (Willke and Vorlop, 2004). Fermentative production of succinic acid could offer a viable route to bulk chemical production. Figure 4.4 presents potential routes for chemical production from succinic acid (McKinlay et al., 2007). Another advantage of succinic acid microbial production is the simultaneous requirement for CO2 consumption, which reduces the emission of the most important greenhouse gas and makes fermentative succinic acid production a process of significantly low environmental impact. 

The xylose produced via enzymatic hydrolysis of the hemicellulose fraction could be converted via microbial fermentation into xylitol (which has been listed by the US Department of Energy among the top 12 value-added platform chemicals) for the production of a range of chemicals, including xylaric acid, propylene glycol, ethylene glycol and a mixture of hydroxyl-furans and polyesters (Werpy and Petersen, 2004). 

As discussed in detail in Chapter 1 [1], the chemical-catalytic approach to biomass valorization is poised to come to the fore of biorefinery operations due to its advantages over microbial and thermochemical processing of lignocellulosic feedstocks. Below, we consider three mainstream platform chemicals, collectively referred to as furanics, that are derived from the acid-catalyzed dehydration of carbohydrates. The first, 5-(hydroxymethyl)furfural, or HMF 1, is an icon of the biorefinery movement. With derivatives that branch out over multiple product manifolds, HMF is a recognized commercial opportunity for whoever can manage to produce it economically, and approaches towards the realization of this aim will be discussed. 

Zeng, A.P. and Sabra, W. (2011) Microbial production of diols as platform chemicals recent progresses. Curr. Opin. Biotechnol, 22, 749 -757. 

Hydroxypropionic acid (3-HP) is a valuable platform chemical that can be produced from glucose or glycerol by biological processes. This chapter provides an overview and the current status of microbial 3-HP production. It also describes various constraints of microbial 3-HP production and possible solutions. Finally, economic outlook and future prospects of biological 3-HP production are discussed. 

Recently, microbial production of SA from renewable biomass has been recognized as a potential alternative for SA production by the US Department of Energy and other groups [6-8]. Production of SA from renewable biomass can be environmentally advantageous, as CO2 is assimilated during SA fermentation, and can alleviate our dependence on fossil resources. Hence, SA is becoming a forerunner in biorefinery platform chemicals. Among the various... 

Microbial Life on Green Biomass and Their Use for Production of Platform Chemicals... 

Very recently, lactones have received increasing attention as potential renewable platform chemicals. Perhaps the most prominent bio-based hydroxy fatty acids lactic acid, whose cyclic ester of two lactate molecules serves precursor for the synthesis of bio-based polymers. Fermentative production of hydroxyl-carboxylic acids from agro-industrial waste is an alternative to the synthesis from dwindling fossil resources (Fiichtenbusch et al. 2000). The enzymatic machinery for the production of polyhydroxyalkanoates (PHA) in bacteria offers catalytic pathways for the production of these lactone precursors (Efe et al. 2008). Recent examples include the microbial synthesis of y-butyrolactone and y-valerolactone. Particularly y-valerolactone is of importance and ranks among the top key components of the biomass-based economy. Microbial processes thus offer the perspective of a sustainable fermentative production of optically pure renewable lactones. 

FIGURE 6.4 3-Hydroxy-propionic add (3-HP) can serve as the platform chemical for the synthesis of many chemicals. Adapted from Dishisha, T. 2013. Microbial Production of Bio-Based Chemical A Biorefinery Perspective. Available at https //lup.lub.lu.se/search/pubKcation/3738373. 

Succinic and malic acids are listed among the top 15 platform chemical opportunities to be produced from biorefinery carbohydrates by the US Department of Energy (DoE Werpy et al., 2004 Bozell and Petersen, 2010). Succinic acid is traditionally produced by the catalytic hydrogenation of petrochemical maleic acid or anhydride (de Jong et al., 2012). Its market value potential has been projected as 245 x 10 tons per year, while an additional market size of 25 X10 tons per year is expected for succinic acid-derived polymers (Bozell and Petersen, 2010). Therefore biosuccinic acid production from microbial processes is anticipated to increase progressively in the near future. 

In this chapter, three kinds of multistep BIA production systems are reviewed (shown in Table 1.2). These microbial systems should open a new field in which microbial cells can be given the ability for low-cost production of many diverse alkaloids. The bacterial platform for BIA fermentation has been established, but further applications face problems. Further metabolic engineering (such as optimization and modification of the pathway) may overcome the productivity of alkaloids and enhance the field of applications for microbial alkaloid fermentation. The widespread application may lead to further progress with microbial systems for use in the pharmaceutical industry, which needs a diverse chemical library to develop more advanced tools for chemical therapy. 

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