Functional Characterization of a Novel Heat-stable Recombinant LCI

Background and Objective: Foodborne pathogens represent a substantial threat to
living organisms. Therefore, techniques for prolonging food shelf life while ensuring
food its quality are imperative practices that must be adopted. Bacteriocins are broadly
addressed as preservatives. This study generally characterized LCI peptide as a β-
structure antimicrobial peptide and a novel alternative for extending food shelf life.
Material and Methods: The antimicrobial activity of recombinant LCI was assessed
against selected Gram-positive and Gram-negative bacterial strains. Temperature, pH
and bile salt concentration stability of the antimicrobial peptide were studied.
Furthermore, the effect of the peptide on the bacterial membrane was assessed.
Results and Conclusion: The study demonstrated that this novel LCI recombinant
bacteriocin included antimicrobial characteristics with wide-spectrum activity against
Gram-positive and Gram-negative bacteria. The minimum inhibitory concentrations
(MICs) were 50 μg.ml-1 for Micrococcus (M.) luteus ATCC 6633, Staphylococcus (S.)
aureus ATCC 6538 and Bacillus (B.) subtilis ATCC 6633 and 100 μg.ml-1 for Gram-
negative bacteria when assessed against Escherichia (E.) coli ATCC 8739, Salmonella
(S.) typhimurium ATCC 13311 and Vibrio (V.) parahaemolyticus. Time-kill kinetics
demonstrated a bactericidal mechanism of action, showing increased antimicrobial
efficacy when reported with acetic acid. Membrane permeabilization assessments
indicated that LCI created pores in bacterial membranes in a dose-dependent fashion.
The peptide stability assessments revealed its heat resistance up to 100 °C for 15 min,
while preserving activity in aqueous solutions within pH range of 3–11 and bile salt
concentration of 0–2%. These characteristics indicate that LCI may be a viable
candidate for antimicrobial uses, especially when used in combination with organic
acids.