Semi-continuous fumaric acid production by Rhizopus arrhizus immobilized in polyurethane sponge

Fumaric acid: fermentative production, applications and future perspectives

The rising prices of petroleum-based chemicals and the growing apprehension about food safety and dairy supplements have reignited interest in fermentation process to produce fumaric acid. This article reviews the main issues associated with industrial production of fumaric acid. Different approaches such as strain modulation, morphological control, selection of substrate and fermentative separation have been addressed and discussed followed by their potential towards production of fumaric acid at industrial scale is highlighted. The employment of biodegradable wastes as substrates for the microorganisms involved in fumaric acid synthesis has opened an economic and green route for production of the later on a commercial scale. Additionally, the commercial potential and technological approaches to the augmented fumaric acid derivatives have been discussed. Conclusion of the current review reveals future possibilities for microbial fumaric acid synthesis.

Enhanced l-Malic Acid Production by Aspergillus oryzae DSM 1863 Using Repeated-Batch Cultivation

l-Malic acid is a C4-dicarboxylic acid and a potential key building block for a bio-based economy. At present, malic acid is synthesized petrochemically and its major market is the food and beverages industry. In future, malic acid might also serve as a building block for biopolymers or even replace the commodity chemical maleic anhydride. For a sustainable production of l-malic acid from renewable resources, the microbial synthesis by the mold Aspergillus oryzae is one possible route. As CO₂ fixation is involved in the biosynthesis, high yields are possible, and at the same time greenhouse gases can be reduced. In order to enhance the production potential of the wild-type strain Aspergillus oryzae DSM 1863, process characteristics were studied in shake flasks, comparing batch, fed-batch, and repeated-batch cultivations. In the batch process, a prolonged cultivation time led to malic acid consumption. Keeping carbon source concentration on a high level by pulsed feeding could prolong cell viability and cultivation time, however, did not result in significant higher product levels. In contrast, continuous malic acid production could be achieved over six exchange cycles and a total fermentation time of 19 days in repeated-batch cultivations. Up to 178 g/L l-malic acid was produced. The maximum productivity (0.90 ± 0.05 g/L/h) achieved in the repeated-batch cultivation had more than doubled than that achieved in the batch process and also the average productivity (0.42 ± 0.03 g/L/h for five exchange cycles and 16 days) was increased considerably. Further repeated-batch experiments confirmed a positive effect of regular calcium carbonate additions on pH stability and malic acid synthesis. Besides calcium carbonate, nitrogen supplementation proved to be essential for the prolonged malic acid production in repeated-batch. As prolonged malic acid production was only observed in cultivations with product removal, product inhibition seems to be the major limiting factor for malic acid production by the wild-type strain. This study provides a systematic comparison of different process strategies under consideration of major influencing factors and thereby delivers important insights into natural l-malic acid production.

Bioenergy from dairy manure: technologies, challenges and opportunities

Dairy manure (DM) is a kind of cheap cellulosic biomass resource which includes lignocellulose and mineral nutrients. Random stacks not only leads damage to the environment, but also results in waste of natural resources. The traditional ways to use DM include returning it to the soil or acting as a fertilizer, which could reduce environmental pollution to some extent. However, the resource utilization rate is not high and socio-economic performance is not utilized. To expand the application of DM, more and more attention has been paid to explore its potential as bioenergy or bio-chemicals production. This article presented a comprehensive review of different types of bioenergy production from DM and provided a general overview for bioenergy production. Importantly, this paper discussed potentials of DM as candidate feedstocks not only for biogas, bioethanol, biohydrogen, microbial fuel cell, lactic acid, and fumaric acid production by microbial technology, but also for bio-oil and biochar production through apyrolysis process. Additionally, the use of manure for replacing freshwater or nutrients for algae cultivation and cellulase production were also discussed. Overall, DM could be a novel suitable material for future biorefinery. Importantly, considerable efforts and further extensive research on overcoming technical bottlenecks like pretreatment, the effective release of fermentable sugars, the absence of robust organisms for fermentation, energy balance, and life cycle assessment should be needed to develop a comprehensive biorefinery model.

Mahua flowers (Madhuca sp.) utilization as a carbon-rich natural substrate for the cost-effective bench-scale production of fumaric acid

Fumaric acid is a multi-functional bio-based organic acid that is extensively used as a building block compound in chemical synthesis, food preservative and as therapeutics. The substrates required for the production are the sugars that account for 50–60% of the total process economics. The present work explores the utilization of Mahua flowers as a cheaper carbon source and low cost production medium for cost-effective fumaric acid production using Rhizopus oryzae. Various process parameters for fumaric acid production and desired fungal morphology were investigated, including Mahua flower extract concentration, fermentation temperature, fermentation pH and agitation speed. The highest concentration of the product, fumaric acid obtained in shake flask was 23.5 ± 0.9 g/L at optimized conditions of 100 g/L of Mahua flower extract medium, pH 6, 30 ℃ temperature and shaking speed of 200 rpm in 72 h. The pellet morphology resulted in higher production than mycelial clumps. Bench-scale production in stirred tank reactor resulted in 24.1 ± 1.0 g/L of fumaric acid production at an aeration rate of 1 vvm, agitation at 200 rpm and temperature of 30 ℃. The results obtained were comparable to fermentation with pure glucose. The present study evidently reveals the feasibility of carbon-rich, low cost, abundantly available natural substrate for cost-effective fumaric acid production.

Fumaric acid production using renewable resources from biodiesel and cane sugar production processes

The microbial production of fumaric acid by Rhizopus arrhizus NRRL 2582 has been evaluated using soybean cake from biodiesel production processes and very high polarity (VHP) sugar from sugarcane mills. Soybean cake was converted into a nutrient-rich hydrolysate via a two-stage bioprocess involving crude enzyme production via solid state fermentations (SSF) of either Aspergillus oryzae or R. arrhizus cultivated on soybean cake followed by enzymatic hydrolysis of soybean cake. The soybean cake hydrolysate produced using crude enzymes derived via SSF of R. arrhizus was supplemented with VHP sugar and evaluated using different initial free amino nitrogen (FAN) concentrations (100, 200, and 400 mg/L) in fed-batch cultures for fumaric acid production. The highest fumaric acid concentration (27.3 g/L) and yield (0.7 g/g of total consumed sugars) were achieved when the initial FAN concentration was 200 mg/L. The combination of VHP sugar with soybean cake hydrolysate derived from crude enzymes produced by SSF of A. oryzae at 200 mg/L initial FAN concentration led to the production of 40 g/L fumaric acid with a yield of 0.86 g/g of total consumed sugars. The utilization of sugarcane molasses led to low fumaric acid production by R. arrhizus, probably due to the presence of various minerals and phenolic compounds. The promising results achieved through the valorization of VHP sugar and soybean cake suggest that a focused study on molasses pretreatment could lead to enhanced fumaric acid production.

Production of fumaric acid by immobilized Rhizopus arrhizus RH 7-13-9# on loofah fiber in a stirred-tank reactor

Fumaric acid is an important building-block chemical. The production of fumaric acid by fermentation is possible. Loofah fiber is a natural, biodegradable, renewable polymer material with highly sophisticated and pore structure. This work investigated a new immobilization method using loofah fiber as carrier to produce fumaric acid in a stirred-tank reactor. Compared with other carriers, loofah fiber was proven to be efficiently and successfully used in the reactor. After the optimization process, 20g addition of loofah fiber and 400rpm agitation speed were chosen as the most suitable process conditions. 30.3g/L fumaric acid in the broth as well as 19.16g fumaric acid in the precipitation of solid was achieved, while the yield from glucose reached 0.211g/g. Three batches of fermentation using the same loofah fiber carrier were conducted successfully, which meant it provided a new method to produce fumaric acid in a stirred-tank reactor.

Pull-in urea cycle for the production of fumaric acid in Escherichia coli

Fumaric acid (FA) is an important raw material in the chemical and pharmaceutical industries. In this work, Escherichia coli was metabolically engineered for the production of FA. The fumA, fumB, fumC, and frdABCD genes were deleted to cut off the downstream pathway of FA. In addition, the iclR and arcA genes were also deleted to activate the glyoxylate shunt and to reinforce the oxidative Krebs cycle. To increase the FA yield, this base strain was further engineered to be pulled in the urea cycle by overexpressing the native carAB, argI, and heterologous rocF genes. The metabolites and the proteins of the Krebs cycle and the urea cycle were analyzed to confirm that the induced urea cycle improved the FA accumulation. With the induced urea cycle, the resulting strain ABCDIA-RAC was able to produce 11.38 mmol/L of FA from 83.33 mmol/L of glucose in a flask culture during 24 h of incubation.

Direct fungal fermentation of lignocellulosic biomass into itaconic, fumaric, and malic acids: current and future prospects

Various economic and environmental sustainability concerns as well as consumer preference for bio-based products from natural sources have paved the way for the development and expansion of biorefining technologies. These involve the conversion of renewable biomass feedstock to fuels and chemicals using biological systems as alternatives to petroleum-based products. Filamentous fungi possess an expansive portfolio of products including the multifunctional organic acids itaconic, fumaric, and malic acids that have wide-ranging current applications and potentially addressable markets as platform chemicals. However, current bioprocessing technologies for the production of these compounds are mostly based on submerged fermentation, which necessitates physicochemical pretreatment and hydrolysis of lignocellulose biomass to soluble fermentable sugars in liquid media. This review will focus on current research work on fungal production of itaconic, fumaric, and malic acids and perspectives on the potential application of solid-state fungal cultivation techniques for the consolidated hydrolysis and organic acid fermentation of lignocellulosic biomass.

Production of fumaric acid by immobilized Rhizopus arrhizus on net

An immobilization method using net was developed for fumaric acid fermentation by Rhizopus arrhizus RH-07-13. The large surface of the net immobilized enough filamentous mycelia which produced fumaric acid rapidly. Net size and spore concentration were optimized to enhance fermentation performance and 150cm(2) of net size, 0.5×10(6)per ml of spore concentration were selected finally. Compared to free-cell fermentation, fumaric acid production was flat (32.03 vs. 31.23g/L) but fermentation time reduced 83.3% (24 vs. 144h).

Production of fumaric acid by fermentation

Fermentative fumaric acid production from renewable resources may become competitive with petrochemical production. This will require very efficient processes. So far, using Rhizopus strains, the best fermentations reported have achieved a fumaric acid titer of 126 g/L with a productivity of 1.38 g L(-1) h(-1) and a yield on glucose of 0.97 g/g. This requires pH control, aeration, and carbonate/CO(2) supply. Limitations of the used strains are their pH tolerance, morphology, accessibility for genetic engineering, and partly, versatility to alternative carbon sources. Understanding of the mechanism and energetics of fumaric acid export by Rhizopus strains will be a success factor for metabolic engineering of other hosts for fumaric acid production. So far, metabolic engineering has been described for Escherichia coli and Saccharomyces cerevisiae.

Fumaric acid production by fermentation

The potential of fumaric acid as a raw material in the polymer industry and the increment of cost of petroleum-based fumaric acid raises interest in fermentation processes for production of this compound from renewable resources. Although the chemical process yields 112% w/w fumaric acid from maleic anhydride and the fermentation process yields only 85% w/w from glucose, the latter raw material is three times cheaper. Besides, the fermentation fixes CO₂. Production of fumaric acid by Rhizopus species and the involved metabolic pathways are reviewed. Submerged fermentation systems coupled with product recovery techniques seem to have achieved economically attractive yields and productivities. Future prospects for improvement of fumaric acid production include metabolic engineering approaches to achieve low pH fermentations.

Enhanced separation of filamentous fungi by ultrasonic field: possible usage in repeated batch processes

Usage of ultrasonic field-based filters in retention of filamentous fungal cells was assessed using Rhizopus arrhizus NRRL 1526 as a model organism. Effects of operating conditions, such as power input, harvest pump flow rate, run time and stop time, on the system's separation efficiency (SE) were evaluated by modulating the variables according to a Central Composite Design (CCD). The standard pump with which the ultrasonic filter was equipped was shown to be unsuitable and was, therefore, substituted for with a prime rate reverse pump that made possible separation and recycle of the mycelial biomass. The operating conditions were optimised (run time, 300 s; stop time, 3 s; power input, 6 W; harvest pump flow rate, 4 l per day) and a repeated batch process (three batches for a total of 192 h) was performed during which the SE was maintained always higher than 88%.

Study of an enzyme membrane reactor with immobilized fumarase for production of L-malic acid

The conversion of fumaric acid into L-malic acid by fumarase immobilized in a membrane reactor was analyzed experimentally. The enzyme was entrapped in asymmetric capillary membranes made of polysulfone. The performance of the reactor was evaluated in terms of conversion degree, reaction rate, and stability. The influence of operating conditions, such as amount of immobilized enzyme, substrate concentration, residence time, and axial flow rate, were investigated. The kinetic parameters K(m), V(max), and k(+2) were also measured. The stability of the immobilized enzyme was very good, showing no activity decay during more than 2 weeks of continuous operation.

Production of multifunctional organic acids from renewable resources

Recently, the microbial production of multifunctional organic acid has received interest due to their increased use in the food industry and their potential as raw materials for the manufacture of biodegradable polymers. Certain species of microorganisms produce significant quantities of organic acids in high yields under specific cultivation conditions from biomass-derived carbohydrates. The accumulation of some acids, such as fumaric, malic and succinic acid, are believed to involve CO2-fixation which gives high yields of products. The application of special fermentation techniques and the methods for downstream processing of products are described. Techniques such as simultaneous fermentation and product recovery and downstream processing are likely to occupy an important role in the reduction of production costs. Finally, some aspects of process design and current industrial production processes are discussed.