This variation in primary sequences may account for different functions attributed to plant defensins including antibacterial activity, zinc tolerance, proteinase and α-amylase inhibitory activity, ion channel blocking activity [4] as well as pollen tube growth arrest, burst and sperm discharge [5].
We hope that this will serve as an up-to-date reference for researchers to develop polymyxin analogues with better antibacterial activity and less adaptable bacterial tolerance.
This review mainly aims to discuss advances in unraveling the mechanisms of antibacterial activity of polymyxins and bacterial tolerance together with the description of polymyxin structure, synthesis, and structural modification.
Previously, we found that two lactobacilli strains, Lactobacillus salivarius CICC 23174 and Lactobacillus plantarum CGMCC 1.557, have probiotic properties, such as acid and bile tolerance, adhesion capacity, and antibacterial activity (data not published).
Expression of an enzyme able to citrullinate peptidylarginine has been demonstrated in the oral organism Porphyromonas gingivalis [ 39], which provides a mechanism by which antibacterial antibodies cross-react with endogenous citrullinated proteins and initiate loss of tolerance.
Bacterial biofilms are a significant problem in clinical settings owing to their increased tolerance towards conventionally prescribed antibiotics and their propensity for selection of further antibacterial resistance.
There are no reports of a direct antibacterial action of glucocorticosteroids; nevertheless, an impact on bacterial functions that promote persistence and tolerance to antibiotics might impinge on the efficacy of therapy.
Host tolerance is one of the issues that must be considered when evaluating natural antibacterial agents [ 54].
Antibacterial biocides and metals can co-select for antibiotic resistance when bacteria harbour resistance or tolerance genes towards both types of compounds.
