Fumaric acid carbon sources

To optimize the culture medium for fumaric acid production, we investigated the effects of rice bran concentrations and various carbon sources. When rice bran was used as a nitrogen source, the effects of additional elements (phosphate, magnesium, zinc, and iron) on fumaric acid production were also investigated. The medium previously reported by Zhou et al. (11) was used as the basal medium. Fermentations were performed in 250-mL Erlenmeyer flasks containing 100 mL of medium. 

Fig. 2. Effect of different carbon sources on fumaric acid production. The culture conditions were as follows 250-mL flask containing 100 mL of medium at 35°C, 200 rpm for 3 d 50 g/L of initial carbon source 5 g/L of rice bran 15 g/L of CaC03 0.6 g/L of KH2P04 0.5 g/L of MgS04-7H20 0.0179 g/L of ZnS04-7H20 0.498 mg/L of FeS04-7H20. ...

Batch fermentations were carried out using rice bran and glucose as nitrogen and carbon sources, respectively. Figure 4 shows the profile of fumaric acid production in a 2.5-L jar fermentor. The fumaric acid concentration reached 25.3 g/L. The yield (fumaric acid produced/glucose consumed) and the productivity were 52% and 0.21 g/(L-h), respectively. For the following experiment, the fungal culture broth was used as a medium for the bioconversion of fumaric acid into succinic acid. 

The photochemical carboxylation of pyruvic acid by this process is endergonic by about AG° = 11.5 kcal mol and represents a true uphill photosynthetic pathway. The carbon dioxide fixation product can then act as the source substrate for subsequent biocatalyzed transformations. For example, photogenerated malic acid can act as the source substrate for aspartic acid (Figure 35). In this case, malic acid is dehydrated by fumarase (Fum) and the intermediate fumaric acid is aminated in the presence of aspartase (Asp) to give aspartic acid. 

Succinic acid can also be generated from fumarate [100] or citrate [101] in the presence of a readily metabolizable carbon source to serve as the hydrogen donor. When citrate is the hydrogen acceptor, it is split into oxaloacetate and acetate by citrate lyase. Oxaloacetate is in turn converted into succinate [102]. The rate of conversion and yield of succinate from fumarate can be enhanced by the amplification of genes that synthesize fumarate reductase [103, 104]. Table 1 shows the fermentation results reported by Wang et al. [104]. In addition, succinic acid can be generated from glucose with mixed culture fermentation, in which fumarate produced by a Rhizopus culture is converted into succinate by a bacterial culture [105]. 

In the first step of the reaction Rhizopus cells were grown in a medium containing 10% glucose as the only carbon source at 32 C for 8 d. After this time the glucose is used up and 36% of it has been converted into fumaric acid. The second reaction step involves E. coli cells. They are seeded into the fungus medium (containing fumaric acid), 3.6 x 10s cells per mL and cultivated for another 5 d. 

Direct proof that this reductive TCA pathway participates in fumaric acid production came from C NMR experiments using [1- C] and [U- C] glucose as a carbon source for R. oryzae (Kenealy et al., 1986). The unexpectedly high fumaric acid molar yields can thus be explained in terms of pyruvate carboxylation as the initial reaction of a reductive TCA pathway (Figure 15.1). 

Evidence for the carbon dioxide fixation mechanism for fumaric acid production came from two sources. Osmani and Scrutton (1985) discovered that R. oryzae... 

There are several examples describing the production of multiple compounds from biomass, or its derived components (Table 9.2). Dairy manure is a type of biomass that contains 12% hemicellulose, 22% cellulose, and 18% crude protein, representing a lai e potential source of carbohydrates as a carbon source and proteins as a nitrc en source. This substrate is uniquely adaptable and advant eous for animal manure refineries. The Rhizopus oryzae ATCC 20344 cell factory produced fumaric acid and chitin fiom the dairy manure. A liquid/ solid separation was used to obtain a nitrc en-rich liquid stream for fungal growth and subsequent chitin accumulation, while the manure s solid stream, which primarily consisted of carbohydrates in the form of cellulose and hemicellulose, could be converted by various pretreatment methods into monosaccharides for fumaric acid production. 

Propionic acid bacteria can use citrate as a carbon source. In the presence of lactate the utilization of citrate is suppressed (Hietaranta and Antila, 1954). Propionibacteria can oxidize acetate and propionate. The oxidation is intensified in the presence of thiamine, Mg and ions displaying synergistic actions (Quastel and Webley, 1942). In the absence of thiamine Mg and stimulate the oxidation of succinate, fumarate, lactate, ethanol, propanol, and glucose. It has been suggested (Quastel and Webley, 1942) that enhanced the effect of Mg by increasing the permeability to the latter. 

An influence of carbon sources on the growth of P. sizovae and biosynthesis of agroclavine-I and epoxyagroclavine-I, as well as the activity of key enzymes of the Krebs cycle, the pentose phosphate pathway and glyoxalate cycle were studied (Kozlovsky and Vepritskaya, 1987). The best alkaloid productivity was observed with mannitol and fumaric acid as the carbon sources. A combination of sorbitol with fumaric acid stimulated epoxyagroclavine-I synthesis. A high alkaloid production was accompanied by high activity of the pentose phosphate cycle and low activity of the Krebs cycle. 

Foster and Waksman (1938) supplied ethanol as the only carbon source and found that 70% was converted to fumaric acid. Using glucose, transient accumulation of ethanol is often observed, and apparently this might later be converted into fumaric acid. Glycerol, another potential side-product of fumaric acid fermentation, can also serve as carbon source for formation of fumaric acid (Moon et al. 2004). 

TABLE 8.2 Literature Summary on Fumaric Acid Production From Different Waste Carbon Sources... 

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