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In VALORISH, scientists combine microbial biotechnology and computational modelling to produce valuable compounds such as nisin. By using nutrients derived from fish processing by-products, the project demonstrates how marine residues can support circular biomanufacturing. Read more.
Harnessing Microbial Power for the Circular Bioeconomy
Microorganisms are biochemical factories capable of producing a wide range of valuable compounds. Among these are bacteriocins, antimicrobial peptides produced by bacteria, as part of their immune reactions or defence mechanisms, which may enhance their ability to compete for space and resources. These molecules have attracted significant interest for their applications in food safety, biotechnology, and sustainable biomanufacturing (Darbandi et al., 2022).
In the VALORISH project, bacteriocins are part of a broader portfolio of high-value bioproducts. By combining biotechnology, computational modelling, and circular resource use, VALORISH aims to transform underutilised fish processing by-products into valuable compounds that support the transition towards a sustainable blue bioeconomy.
What Are Bacteriocins?
Bacteria live in crowded environments where many different microorganisms compete for the same nutrients and space. To survive, some bacteria produce special molecules called bacteriocins, small antimicrobial proteins or peptides that act like highly precise biological weapons against rival microbes.
You can think of bacteriocins as targeted missiles rather than carpet bombing. While many conventional antibiotics kill a wide range of bacteria, bacteriocins usually act against closely related species, allowing the producing bacteria to eliminate competitors without disturbing the entire microbial community.
Bacteriocins are produced through the normal protein-making machinery of the cell (they are ribosomally synthesised peptides that are often further modified after translation). Once released, they attack susceptible bacteria in several ways. One of the most common mechanisms is damaging the cell membrane, the protective barrier that surrounds a bacterial cell. Bacterocins damage the cell membrane by creating tiny pores causing essential molecules and ions leak out of the cell, and then the bacterium loses its internal balance, and it quickly dies. Other bacteriocins interfere with vital processes such as cell wall construction or key metabolic reactions, effectively preventing the bacterium from growing or maintaining its structure. Other bacteriocins interfere with the formation of the bacterial cell wall. Without a properly built cell wall, bacteria cannot grow or divide and eventually collapse. Another mechanism of bacteriocins is by acting inside the cell with vital processes such as DNA replication, RNA production, or protein synthesis (Banerjee et al. 2022).
Because bacteriocins are both powerful and highly selective, they have attracted increasing interest in biotechnology and food science. They can be used as natural preservatives, helping control harmful bacteria in food without affecting beneficial microbes.
Nisin A: A Widely Used Antimicrobial Peptide
One of the most well-known bacteriocins is nisin A, produced by the lactic acid bacterium Lactococcus lactis. Nisin has been widely used for decades as a natural food preservative due to its effectiveness against important foodborne pathogens such as Listeria monocytogenes and Clostridium botulinum (Setiarto et al., 2023). These bacteria are responsible for some of the most serious food safety incidents. For example, a prolonged Listeria monocytogenes outbreak affected several European countries—including Germany, the Netherlands, Belgium, Finland, Italy, and the United Kingdom—resulting in 73 confirmed infections and 14 deaths, with ready-to-eat fish products identified as a likely source.
Because it is both safe and highly effective, nisin has been approved by food safety authorities in many countries. In particular, Nisin (E 234) is currently an authorised food additive in the EU under Annex II of Regulation (EC) 1333/2008 for use in several food categories. Its proven value is one of the main reasons why nisin A is part of the VALORISH portfolio of high-value bioproducts.
Modelling Microbial Metabolism for Bioproduction
Producing valuable molecules such as nisin A efficiently is not simply a matter of growing bacteria in a tank. Scientists first need to identify which microbial strains are best suited for the job, those capable of converting nutrients into the desired compound as efficiently as possible.
To do this, the VALORISH project uses advanced computational tools called genome-scale metabolic models (GEMs). These models act like a digital blueprint of a microorganism’s metabolism, mapping the metabolic reactions known to occur in the organism based on its genome. You can think of a GEM as a metabolic map or GPS for the cell. It connects genes, enzymes, and biochemical pathways, showing how nutrients move through the cell and are transformed into energy, biomass, or useful products such as nisin. With this digital model, researchers can run simulations to see how a bacterium behaves under different conditions, for example, when it grows on different nutrient sources or when environmental conditions change. Simulations are used to identify the most efficient metabolic routes. For example, just as a GPS calculates the fastest route to a destination, GEM simulations help us to find the metabolic pathways that allow the cell to reach a desired product (such as nisin) using the most efficient use of nutrients and resources.
From Fish By-Products to High-Value Compounds
A central goal of VALORISH is to demonstrate how fish processing by-products can serve as sustainable feedstocks for high-value bioproducts production.
Fish protein hydrolysates (FPH), derived from underutilised fish residues, contain a rich mixture of amino acids and nutrients that can support microbial growth. By using these substrates as fermentation media, VALORISH explores new ways to convert marine side streams into valuable biochemical products. The integration of metabolic modelling and circular feedstocks allows researchers to evaluate whether bacterial strains can efficiently produce compounds such as nisin A using FPH-derived substrates.
This approach contributes to:
- Reducing waste in the seafood industry
- Creating new value chains for marine resources
- Supporting the development of circular and sustainable biorefineries
Through this work, VALORISH contributes to advancing sustainable biotechnology solutions that transform biological resources into high-value products, supporting Europe’s growing bio-based economy.
References
Banerjee, S., Kanaujia, A., Malik, S., & Sharma, S. (2022). Bacteriocins: Potential usage and mechanism of action. International Journal of Recent Scientific Research, 9(8),7897-7906
Darbandi, A., Asadi, A., Mahdizade Ari, M., Ohadi, E., Talebi, M., Halaj Zadeh, M., Darb Emamie, A., Ghanavati, R., & Kakanj, M. (2021). Bacteriocins: Properties and potential use as antimicrobials. Journal of Clinical Laboratory Analysis, 36(1), e24093. https://doi.org/10.1002/jcla.24093
Setiarto, R. H. B., Anshory, L., & Wardana, A. A. (2023). Biosynthesis of nisin, antimicrobial mechanism and its applications as a food preservation: A review. IOP Conference Series: Earth and Environmental Science, 1169(1), 012105. https://doi.org/10.1088/1755-1315/1169/1/012105