Comparison of Different Nisin Separation and Concentration Methods: Industrial and Cost-Effective Perspectives

Applications of tandem mass spectrometry (MS/MS) in antimicrobial peptides field: Current state and new applications

Antimicrobial peptides (AMPs) constitute a group of small molecular peptides that exhibit a wide range of antimicrobial activity. These peptides are abundantly present in the innate immune system of various organisms. Given the rise of multidrug-resistant bacteria, microbiological studies have identified AMPs as potential natural antibiotics. In the context of antimicrobial resistance across various human pathogens, AMPs hold considerable promise for clinical applications. However, numerous challenges exist in the detection of AMPs, particularly by immunological and molecular biological methods, especially when studying of newly discovered AMPs in proteomics. This review outlines the current status of AMPs research and the strategies employed in their development, considering resent discoveries and methodologies. Subsequently, we focus on the advanced techniques of mass spectrometry for the quantification of AMPs in diverse samples, and analyzes their application, advantages, and limitations. Additionally, we propose suggestions for the future development of tandem mass spectrometry for the detection of AMPs.

Nisin Purification from a Cell-Free Supernatant by Electrodialysis in a Circular Economy Framework

Nisin, an antimicrobial peptide produced by Lactococcus lactis strains, is a promising natural preservative for the food industry and an alternative to antibiotics for the pharmaceutical industry against Gram-positive bacteria. Nisin purification is commonly performed using salting out and chromatographic techniques, which are characterized by their low yields, the use of solvents and the production of large volumes of effluents. In the present work, the purification of nisin from a cell-free supernatant (CFS), after the production of nisin by fermentation on a whey permeate medium, was studied using ammonium sulfate precipitation and electrodialysis (ED) as a promising eco-friendly process for nisin purification. Results showed an increase in nisin precipitation using a 40% ammonium sulfate saturation (ASS) level with a purification fold of 73.8 compared with 34.5 and no purification fold for a 60% and 20% ASS level, respectively. The results regarding nisin purification using ED showed an increase in nisin purification and concentration fold, respectively, of 21.8 and 156 when comparing the final product to the initial CFS. Nisin-specific activity increased from 75.9 ± 4.4 to 1652.7 ± 236.8 AU/mg of protein. These results demonstrated the effectiveness of ED coupled with salting out for nisin purification compared with common techniques. Furthermore, the process was noteworthy for its relevance in a circular economy scheme, as it does not require any solvents and avoids generating polluting effluents. It can be employed for the purification of nisin and the recovery of salts from salting out, facilitating their reuse in a circular economy.

Purification, characterization, and mode of action of Sakacin ZFM225, a novel bacteriocin from Lactobacillus sakei ZFM225

Bacteriocins from lactic acid bacteria (LAB) have attracted widespread attention as a new type of biological preservative due to their safety, high efficiency, and non-toxic characteristics. In this study, we focused on Sakacin ZFM225, a novel bacteriocin produced by Lactobacillus sakei ZFM225, which was isolated from raw milk. It was purified by a strategy including precipitation with 70% ammonium sulfate, cation exchange chromatography and reverse-phase high performance liquid chromatography (RP-HPLC). The predicted molecular weight of Sakacin ZFM225 was 14950.92 Da. Sakacin ZFM225 exhibited resistance to high temperatures, strong activity under acidic conditions, and sensitivity to trypsin and pepsin. Bacteriocins from Lactobacillus sakei mainly inhibited the growth of Listeria monocytogenes. The bacteriocin possessed a broad-spectrum inhibition which could kill many foodborne pathogens such as Pseudomonas aeruginosa, Micrococcus luteus, and Staphylococcus aureus. We further demonstrated that the mode of action of Sakacin ZFM225 was related to the formation of cell membrane porosity, and excluded Lipid Ⅱ as its target. These results suggest that this new bacteriocin has great potential in food industry as a biological preservative and even medical field.