Sonorensin, which is predicted to belong to the heterocycloanthracin subfamily of bacteriocins, was found to effectively kill both active and non-multiplying cells of Gram-positive and Gram-negative bacteria.
Nisin is a narrow-spectrum bio-preservative against gram-positive bacteria and their spores. In many cases where both gram-positive and gram-negative bacteria are to be inhibited, other preservatives like e-polylysine or a synthesized one need to be included in the formular too. Sonorensin, which is predicted to belong to the heterocycloanthracin subfamily of bacteriocins, was found to effectively kill both active and non-multiplying cells of Gram-positive and Gram-negative bacteria. Another issue that a preservative system always faces is the antibiotic-resistant issue. Biofilms, which are microbial communities causing serious chronic infections, create environments that enhance antimicrobial resistance. Bacteria within biofilms can be up to a thousand times more resistant to antibiotics than the same bacteria in a planktonic state. Sonorensin can also settle this question by increasing the membrane permeability.
Sonorensin can kill non-multiplying cells of both E. coli and S. aureus. When comparing its antimicrobial activity with nisin, it was noted that sonorensin is as effective as nisin in killing non-multiplying cells of S. aureus and E. coli. It is revealed that sonorensin demonstrated remarkable inhibitory activity against the formation of S. aureus biofilm. The strength is closely related to its concentration.
Tomato sample (1) packaged in untreated LDPE films showed signs of spoilage in contrast to no spoilage in case of tomatoes packaged in sonorensin (2) and nisin (3) coated LDPE films. (A picture quoted from Sonorensin: A new bacteriocin with potential of an anti-biofilm agent and a food biopreservative by Lipsy Chopra, Gurdeep Singh, Kautilya Kumar Jena & Debendra K. Sahoo).
Sonorensin exhibited marked inhibitory activity against the biofilm of Staphylococcus aureus. Fluorescence and electron microscopy suggested that growth inhibition occurred due to increased membrane permeability. The low-density polyethylene film coated with sonorensin was found to effectively control the growth of food spoilage bacteria such as Listeria monocytogenes and S. aureus. The biopreservative effect of the sonorensin-coated film, which shows the growth inhibition of spoilage bacteria in chicken meat and tomato samples, demonstrated the potential of sonorensin as an alternative to current antibiotics/preservatives.
It did not exhibit activity against normal mammalian cells. Sonorensin also brought about the inhibition of biofilm formation. Unlike most antibiotics that target cellular components and are therefore more prone to bacterial resistance, sonorensin acts in the mode of damaging the membrane of the bacteria. As is predicted to be the first bacteriocin of the subfamily of heterocycloanthracin, Sonorensin demonstrated its efficacy as a food bio-preservative. The packaging films activated with sonorensin showed a marked preservative effect on food products. The properties of sonorensin offers a realistic prospect for both food and cosmetic applications.
