Logistic modeling to predict minimum inhibitory concentration of olive leaf extract against Listeria monocytogenes

Authors: DU, RENJI - Northeast Forestry University; QU, YUEJUN - Heilongjiang Academy Of Agricultural Sciences; ZHAO, MIN - Northeast Forestry University; Liu, Yanhong; Qi, Phoebe; SUN, XINGBIN - Northeast Forestry University

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2022
Publication Date: 1/28/2022
Citation: Du, R., Qu, Y., Zhao, M., Liu, Y., Qi, P.X., Sun, X. 2022. Logistic modeling to predict minimum inhibitory concentration of olive leaf extract against Listeria monocytogenes. PLoS ONE. https://doi.org/10.1371/journal.pone.0263359.
DOI: https://doi.org/10.1371/journal.pone.0263359

Interpretive Summary: Foodborne pathogenic bacteria, including Listeria monocytogenes are a serious public health concern. Consumers favor more natural antimicrobial agents to control pathogens in food. Olive leaf extract (OLE) derived from leaves of olive trees, has been used in traditional medicine for its health benefits, and it has potential application as a natural antimicrobial agent used as a food additive or incorporated into food packaging materials. There is a need to know the lowest effective concentration of OLE so that the cost of the food product can remain low and to avoid undesirable changes in taste with use of high amounts of OLE. In this study, the minimal inhibitory concentration (MIC), which is the lowest concentration of an antimicrobial agent that prevents growth of a bacterium, was determined for OLE against L. monocytogenes using what is known as the asymptotic deceleration point (PDA) in a logistic model (LM) and referred to as MIC-PDA. The accuracy of the MIC-PDA was evaluated by a growth inhibition assay against L. monocytogenes. The MIC-PDA approximated the MIC of OLE and agreed reasonably with the data obtained from inhibition assays. Knowledge of an effective and adequate MIC value is critical for the viable and broad applications of OLE by the food industry to control pathogens.

Technical Abstract: The main objective of this study was to predict a minimum inhibitory concentration (MIC) of olive leaf extract (OLE) against L. monocytogenes F2365 by utilizing the asymptotic deceleration point (PDA) in a logistic model (LM), namely MIC-PDA. The experimental data obtained from the inhibitory rate (IR) versus OLE concentration against L. monocytogenes were sufficiently fitted (R2 = 0.88957). Five significant critical points were derived by taking the derivatives of the LM function: the inflection point (PI), the maximum acceleration point (PAM), the maximum deceleration point (PDM), the absolute acceleration point (PAA), and the asymptotic deceleration point (PDA). The PDA ([OLE] = 37.055 mg/mL) was employed to approximate the MIC-PDA. This MIC value was decreased by over 42% compared to the MIC of 64.0 mg/mL by the conventional 2-fold dilution method (i.e., MIC-2fold). The accuracy of MIC-PDA was evaluated by an in vitro L. monocytogenes growth inhibition assay.