Citric Acid Production by Aspergillus niger Using Solid-State Fermentation of Agricultural Processing Coproducts

Abstract

The ability of Aspergillus niger strains to support citric acid production using solid-state fermentation of agricultural processing coproducts was examined in this review. Citric acid has been shown to have a number of commercial applications in the food and beverage industries. The A. niger strains capable of elevated citric acid production are known to contain genetic mutations that stimulate overproduction of the organic acid likely involving citric acid cycle reactions. The agricultural processing coproducts previously examined for their ability to support citric acid production by A. niger solid-state fermentation include fruit processing wastes, sugarcane bagasse, starch vegetable processing wastes and cereal grain processing coproducts. A comparison of citric acid production by A. niger strains using solid-state fermentation demonstrated that certain agricultural processing coproducts were more effective in supporting a high level of acid synthesis. In particular, fruit processing wastes, such as apple pomace, banana peels, grape pomace and orange peels, supported high levels of citric acid by the fungal strains following solid-state fermentation. On the other hand, processing coproducts of cereal grains, such as brans and ethanol processing coproducts, supported low levels of citric acid production by the A. niger strains using solid-state fermentation. It appeared that the cereal processing coproducts provided less available sugar content to support citric acid production by the fungal strains. It was concluded that the level of citric acid produced by the A. niger strains during solid-state fermentation was dependent on the sugar content of the agricultural processing coproduct utilized.

Optimization of Medium Constituents for the Production of Citric Acid from Waste Glycerol Using the Central Composite Rotatable Design of Experiments

“…Unfortunately, they increase production costs due to their high price [ 22 ]. In order to reduce the cost of citric acid production, cheap carbon sources are sought that can be used by Aspergillus niger (e.g., apple pomace, sweet potato hydrolysates, sugar cane cake, pineapple pomace) [ 49 , 50 , 51 ].…”

Citric Acid: Properties, Microbial Production, and Applications in Industries

“…The activity of hexokinase is strongly inhibited by trehalose-6-phosphate. To increase the efficiency of citric acid biosynthesis, the gene tpsA, responsible for the expression of trehalose-6-phosphate synthase, was blocked [ 53 , 54 ].…”

“…The search for citric acid biosynthesis substrates involving Aspergillus niger has been the subject of extensive research [ 54 , 123 , 132 , 133 , 134 , 135 , 136 , 137 , 138 , 139 , 140 , 141 ]. High-purity substrates such as sucrose, glucose, fructose, and maltose can be utilized in citric acid production.…”

“…From a health quality perspective, citric acid, when used as a food additive, has been approved as generally recognized as safe (GRAS) by the FAO/WHO Expert Committee on Food Additives, and its Acceptable Daily Intake (ADI) does not require limitation [ 54 ]. Derivatives of citric acid, such as calcium citrate, iron citrate, manganese citrate, potassium citrate, sodium citrate, diammonium citrate, isopropyl citrate, and stearyl citrate, have also received GRAS status as food additives [ 13 ].…”

Industrial enzyme production in Bangladesh: current landscape, scope, and challenges

“…The use of purified proteases has been made for the clarification of beer since 1911, whereas pectinases have previously been employed for wine and juice clarification. The global production of citric acid exceeded one million tons in 2023 and is anticipated to reach $3.2 billion (West, 2023). The incorporation of microbial proteases in detergents is a great achievement in Enzymology.…”