Succinic Acid: How is it obtained?

Succinic acid can be obtained through chemical synthesis.

The succinic acid has long been obtained via petrochemical processes from fossil resources. Among the most common methods, we find catalytic hydrogenation, the oxidation of maleic acid or maleic anhydride, as well as electrolytic reduction. For example, the oxidation of butane or benzene allows the formation of maleic anhydride, which is then hydrogenated to obtain succinic acid, with a global production of about 30,000 tonnes per year.

However, the fluctuations in oil prices and the environmental issues associated with the depletion of fossil resources have led to the search for sustainable alternatives. In response to these challenges, the focus is on the production of succinic acid from renewable resources, such as biomass.

A closer look at the production of succinic acid through biochemical synthesis.

The biochemical synthesis of succinic acid relies on a fermentation process, taking advantage of the Krebs cycle, which is a fundamental cellular mechanism. This process involves various microorganisms, among which are Actinobacillus succinogenes, Mannheimia succiniciproducens, as well as modified strains of Escherichia coli, to convert substrates into succinic acid.

The production of succinic acid through fermentation is influenced by several factors, such as the type of substrate used and environmental conditions, including pH and temperature, which directly affect the production yield. Notable advancements in the genetic modification of microorganisms have also significantly increased these yields. For example, Corynebacterium glutamicum S071 has demonstrated a production of 152.2 g/L of succinic acid under optimised anaerobic conditions.

A recent advancement in the biosynthesis of succinic acid is the use of yeasts, such as Saccharomyces cerevisiae. Compared to bacteria, yeasts exhibit better tolerance to low pH, utilise transporters to extract succinic acid from cells, and produce fewer unwanted by-products. Furthermore, these yeasts use cellular compartments to optimise production, notably via the reductive pathway of the Krebs cycle.

Various metabolic pathways, such as the reductive branches of the Krebs cycle and the glyoxylate cycle, play a fundamental role in the biosynthesis of succinic acid. These pathways are mediated by key enzymes, including phosphoenolpyruvate carboxylase, pyruvate carboxylase, and acetyl-CoA carboxylase. Optimising these processes, coupled with the selection of new microbial strains and the reduction of substrate costs, represents a promising approach for a more environmentally friendly production of succinic acid that can be used in cosmetics.

What should we take away from the methods of obtaining succinic acid?

Here are the key points to remember about the production of succinic acid:

Diversity of Methods: Succinic acid can be obtained either through chemical processes from fossil resources, or by microbial fermentation methods.
Traditional chemical processes: Although chemical synthesis is well established, it has environmental drawbacks, particularly related to fossil resources.
Biotechnological Advances: Microbial fermentation, particularly through the use of yeasts, proves to be a more sustainable and eco-friendly solution with increased yields.
Optimisation of Strains: Current research is focused on enhancing microbial strains to increase the efficiency of processes and reduce costs.
Reduced environmental impact: The use of renewable substrates, such as biomass, contributes to a more environmentally friendly production.