Concatenating Bacteriocins as an antibiotic alternative for ruminants and aquaculture
Eva Balan-Gutiérrez1, Samira Sarih1, Silvia Torrecillas1, Mahmoud Eltholth2, Ismail A.Odetokun3, Jennifer Cole4, Elena Garcia-Fruitós1* and Anna Arís1*
1Institute of Agrifood Research and Technology, Caldes de Montbui, Spain
2Department of Biological Sciences, Royal Holloway University of London, UK
3Department of Veterinary Public Health and Preventive Medicine, University of Ilorin,
Nigeria
4Department of Geography, Royal Holloway University of London, UK
*Equally contributed
Endangering both human and animal health, AMR bacteria can be transmitted across the animal–human interface, between species, and bidirectionally among humans, animals, and the environment. Thus, regions that rely on mixed farming systems—such as those found in many low- and middle-income countries (LMICs)—are particularly vulnerable to AMR. In this context, this study focuses on identifying antimicrobial alternatives to treat infections caused by Streptococcus agalactiae and Staphylococcus aureus, pathogens that affect both tilapia farming and ruminant production systems in Nigeria.
As the bacterial resistome continues to expand and spread, multiple alternatives to conventional antibiotics are under investigation, with a strong focus on antimicrobial peptides. Among these, bacteriocins are ribosomally synthesized peptides produced by bacteria that shape microbial community dynamics. Owing to their natural biological role, bacteriocins display broad antibacterial activity, a lower probability of resistance development, and limited toxicity to mammalian cells, making them promising candidates for the treatment of multidrug-resistant infections. In this research, four bacteriocins -Enterocin P, Aureocin 53, Sakacin P, and Pediocin A- were investigated. These peptides were engineered into concatemers composed of repeated units of the native bacteriocin (EntPx4, AurA53x4, PedPA1x4, SakPx4), thereby enhancing stability, antimicrobial activity, and production efficiency. Recombinant expression was achieved using Escherichia coli and Lactococcus lactis as production hosts. The engineered bacteriocins were evaluated against Staphylococcus aureus -including both methicillin-resistant (S. aureus, MRSA) and methicillin-sensitive (S. aureus, MSSA)-, as well as Streptococcus agalactiae (S. agalactiae). All constructs exhibited bacteriostatic and bactericidal activity. However, derivatives of Enterocin P and Aureocin 53 showed the strongest antimicrobial effects against these Gram-positive pathogens, with minimum inhibitory concentrations (MICs) ranging from 1.25 μM to 2.5 μM. Notably, their combined application resulted in enhanced efficacy, demonstrating a clear additive interaction against S. agalactiae and S. aureus. These findings concluded that the combined use of Aureocin 53 and Enterocin P concatemers has significant therapeutic potential as an alternative to conventional antibiotics for the control of S. aureus and S. agalactiae infections. Ongoing work is focused on in vivo validation in ruminants and in tilapia aquaculture to assess the realfield applicability.
