Length Of Lag Phase Research Articles

Minimizing the Lag Phase of Cupriavidus necator Growth under Autotrophic, Heterotrophic, and Mixotrophic Conditions.

Cupriavidus necator has the unique metabolic capability to grow under heterotrophic, autotrophic, and mixotrophic conditions. In the current work, we examined the effect of growth conditions on the metabolic responses of C. necator. In our lab-scale experiments, autotrophic growth was rapid, with a short lag phase as the exponential growth stage was initiated in 6 to 12 h. The lag phase extended significantly (>22 h) at elevated O2 and CO2 partial pressures, while the duration of the lag phase was independent of the H2 or N2 partial pressure. Under heterotrophic conditions with acetate as the organic substrate, the lag phase length was short (<12 h), but it increased with increasing acetate concentrations. When glucose and glycerol were provided as the organic substrate, the lag phase was consistently long (>12 h) regardless of the examined substrate concentrations (up to 10.0 g/L). In the transition experiments, C. necator cells showed rapid transitions from autotrophic to heterotrophic growth in less than 12 h and vice versa. Our experimental results indicate that C. necator can rapidly grow with both autotrophic and heterotrophic substrates, while the lag time substantially increases with nonacetate organic substrates (e.g., glucose or glycerol), high acetate concentrations, and high O2 and CO2 partial pressures. IMPORTANCE The current work investigated the inhibition of organic and gaseous substrates on the microbial adaption of Cupriavidus necator under several metabolic conditions commonly employed for commercial polyhydroxyalkanoate production. We also proposed a two-stage cultivation system to minimize the lag time required to change over between the heterotrophic, autotrophic, and mixotrophic pathways.

Lysine-Derived Maillard Reaction Products Inhibit the Growth of Salmonella enterica Serotype Typhimurium

An emerging consumer trend to purchase minimally heated and ready-to-eat food products may result in processing methods that do not effectively reduce pathogenic populations. Crude Maillard reaction products (MRPs) are naturally generated compounds that have been shown to display antimicrobial effects against pathogens. Crude MRPs were generated from reducing sugars (fructose (Fru), glucose (Glc), ribose (Rib) or xylose (Xyl)) with lysine and the melanoidin equivalence was measured using an absorbance of 420 nm (Ab420). The relative antimicrobial activity of each MRP was measured by examining both the length of lag phase and maximum growth rate. MRPs were found to significantly shorten the lag phase and decrease the maximum growth rate of S. Typhimurium (p < 0.05). Glucose-lysine MRP (GL MRP) was determined to have the highest relative melanoidin (1.690 ± 0.048 at Ab420) and its efficacy against S. Typhimurium populations was measured at 37 °C and at pH 7.0 and estimated on xylose lysine deoxycholate (XLD) agar. GL MRP significantly reduced S. Typhimurium populations by >1 log CFU/mL at 8 and 24 h after inoculation (p < 0.05). GL MRPs also further decreased S. Typhimurium populations significantly under thermal stress condition (55 °C) compared to optimal (37 °C) by ~1 log CFU/mL (p < 0.05). Overall, GL MRP demonstrated effective antimicrobial activity against S. Typhimurium at 37 °C and 55 °C.

Upgrading ADM1 by Addition of Lag Phase Sub-model to Simulate Acidic Inhibition of Methanogenic Reactor

This study is aimed at improving calculation quality for IWA Anaerobic Digestion Model No.1 (ADM1) to simulate acidic failure of the methane fermentation systems and its performance recovery. The methanogen collected from digestate at a municipal wastewater treatment plant was cultivated in a lab-scale continuous reactor receiving acetate as a sole organic source. By varying the influent concentration during 400 days of operation, 6 datasets of acidification events were obtained to simulate the concentrations of acetate, VSS, pH, and the methane production rate. The ADM1 equipped with either pH sub-model or undissociated acetate sub-model could reproduce the deterioration of reactor performance in the acidic failure but totally failed to simulate the recovery in the subsequent lowered volumetric loading rate. The statistical analysis revealed both ADM1 models had relatively low correlation coefficient (Nash-Sutcliffe model efficiency coefficient (NSE)) of 0.31–0.38 although these were considerably improved from that without parameter calibration (NSE = −0.04). To cope with the mismatch, a lag phase sub-model was developed. The sub-model is composed of the remaining relative activity of the microorganism at which the inhibition peaked, and the half-saturation coefficient to express the specific length of lag phase. By adding the sub-model into the calibrated ADM1, NSE was significantly improved to 0.49–0.53.

Elucidating the kinetics of ammonia inhibition to anaerobic digestion through extended batch experiments and stimulation-inhibition modeling

Ammonia can be accumulated to a level inhibitory to methanogenesis. There are large discrepancies in the reported inhibition thresholds. Through extended batch digestion experiments (up to 110 d) at 6 ammonia concentrations (0.70–13 g N/L), this study discovered sequential occurrence of adaptable and unadaptable inhibition that reveals the discrepancies. Lag phase length representing adaptable inhibition increased exponentially with ammonia concentration. The kinetics of specific biogas yield that reveals unadaptable inhibition was best simulated with the Han & Levenspiel model. The 50% unadaptable inhibition thresholds were 10.7 g N/L with active inoculum and 6.8 g/L with stressed inoculum. The digesters with stressed inoculum had faster adaptation to adaptable inhibition though less resistance to unadaptable inhibition. The inhibition sequence was evidenced by microbial population shifts and confirmed by earlier studies employing short (2–65 d) and long (80–198 d) batch experiments. Distinguishing adaptable from unadaptable inhibition provides precise guidance for mitigating ammonia inhibition.

Availability of the Molecular Switch XylR Controls Phenotypic Heterogeneity and Lag Duration during Escherichia coli Adaptation from Glucose to Xylose.

ABSTRACTThe glucose-xylose metabolic transition is of growing interest as a model to explore cellular adaption since these molecules are the main substrates resulting from the deconstruction of lignocellulosic biomass. Here, we investigated the role of the XylR transcription factor in the length of the lag phases when the bacterium Escherichia coli needs to adapt from glucose- to xylose-based growth. First, a variety of lag times were observed when different strains of E. coli were switched from glucose to xylose. These lag times were shown to be controlled by XylR availability in the cells with no further effect on the growth rate on xylose. XylR titration provoked long lag times demonstrated to result from phenotypic heterogeneity during the switch from glucose to xylose, with a subpopulation unable to resume exponential growth, whereas the other subpopulation grew exponentially on xylose. A stochastic model was then constructed based on the assumption that XylR availability influences the probability of individual cells to switch to xylose growth. The model was used to understand how XylR behaves as a molecular switch determining the bistability set-up. This work shows that the length of lag phases in E. coli is controllable and reinforces the role of stochastic mechanism in cellular adaptation, paving the way for new strategies for the better use of sustainable carbon sources in bioeconomy.

Microbial lag phase can be indicative of, or independent from, cellular stress

Measures of microbial growth, used as indicators of cellular stress, are sometimes quantified at a single time-point. In reality, these measurements are compound representations of length of lag, exponential growth-rate, and other factors. Here, we investigate whether length of lag phase can act as a proxy for stress, using a number of model systems (Aspergillus penicillioides; Bacillus subtilis; Escherichia coli; Eurotium amstelodami, E. echinulatum, E. halophilicum, and E. repens; Mrakia frigida; Saccharomyces cerevisiae; Xerochrysium xerophilum; Xeromyces bisporus) exposed to mechanistically distinct types of cellular stress including low water activity, other solute-induced stresses, and dehydration-rehydration cycles. Lag phase was neither proportional to germination rate for X. bisporus (FRR3443) in glycerol-supplemented media (r2 = 0.012), nor to exponential growth-rates for other microbes. In some cases, growth-rates varied greatly with stressor concentration even when lag remained constant. By contrast, there were strong correlations for B. subtilis in media supplemented with polyethylene-glycol 6000 or 600 (r2 = 0.925 and 0.961), and for other microbial species. We also analysed data from independent studies of food-spoilage fungi under glycerol stress (Aspergillus aculeatinus and A. sclerotiicarbonarius); mesophilic/psychrotolerant bacteria under diverse, solute-induced stresses (Brochothrix thermosphacta, Enterococcus faecalis, Pseudomonas fluorescens, Salmonella typhimurium, Staphylococcus aureus); and fungal enzymes under acid-stress (Terfezia claveryi lipoxygenase and Agaricus bisporus tyrosinase). These datasets also exhibited diversity, with some strong- and moderate correlations between length of lag and exponential growth-rates; and sometimes none. In conclusion, lag phase is not a reliable measure of stress because length of lag and growth-rate inhibition are sometimes highly correlated, and sometimes not at all.

The effect of temperature and moisture on lag phase length of bacterial growth in soil after substrate addition

Microorganisms in soil are commonly limited by available substrate, and removing the limitation will increase activity and growth, with predictable dynamics in growth. The initial phase with a lag period (λ) will usually be followed by exponential growth (also called log phase, with growth rate μ). These two growth phases may be differently affected by environmental conditions, like temperature and moisture. Using glucose addition as a model of a sudden increase in labile C, we studied the effect of temperature (0 °C–30 °C) and soil moisture (10%–35%) on bacterial growth dynamics (estimated using leucine incorporation). Decreasing temperature resulted in decreased μ and increased λ. The latter increased from a minimum around 6 h at 25 °C to >100 h at 0 °C. The square root of μ increased linearly with temperature below Topt according to the Ratkowsky equation, with an apparent Tmin of −11 °C. The square root of 1/λ also increased linearly with temperature (the inverse Ratkowsky equation), with a Tmin of −10 °C. Thus, there was a close correlation between μ and 1/λ, suggesting that the length of λ at different temperatures was entirely determined by the rate of growth after adding glucose. Increasing soil moisture increased μ and decreased λ (at 20 °C), with the latter decreasing from 14 to 21 h at 15% moisture to 8–14 h at 35% moisture. No exponential growth was found within 71 h at 10% moisture. μ after glucose addition was more affected by moisture than λ. The effects of moisture on 1/λ could therefore not be explained solely by changes in μ. Temperature effects on μ and λ after adding substrate could be estimated, including effects of temperature adaptation of the community, using the Ratkowsky equations. Thus, effects on future changes in temperature on both μ and λ can be predicted.

Time Series Genome-Centric Analysis Unveils Bacterial Response to Operational Disturbance in Activated Sludge.

Understanding ecosystem response to disturbances and identifying the most critical traits for the maintenance of ecosystem functioning are important goals for microbial community ecology. In this study, we used 16S rRNA amplicon sequencing and metagenomics to investigate the assembly of bacterial populations in a full-scale municipal activated sludge wastewater treatment plant over a period of 3 years, including a 9-month period of disturbance characterized by short-term plant shutdowns. Following the reconstruction of 173 metagenome-assembled genomes, we assessed the functional potential, the number of rRNA gene operons, and the in situ growth rate of microorganisms present throughout the time series. Operational disturbances caused a significant decrease in bacteria with a single copy of the rRNA (rrn) operon. Despite moderate differences in resource availability, replication rates were distributed uniformly throughout time, with no differences between disturbed and stable periods. We suggest that the length of the growth lag phase, rather than the growth rate, is the primary driver of selection under disturbed conditions. Thus, the system could maintain its function in the face of disturbance by recruiting bacteria with the capacity to rapidly resume growth under unsteady operating conditions.IMPORTANCE Disturbance is a key determinant of community assembly and dynamics in natural and engineered ecosystems. Microbiome response to disturbance is thought to be influenced by bacterial growth traits and life history strategies. In this time series observational study, the response to disturbance of microbial communities in a full-scale activated sludge wastewater treatment plant was assessed by computing specific cellular traits of genomes retrieved from metagenomes. It was found that the genomes observed in disturbed periods have more copies of the rRNA operon than genomes observed in stable periods, whereas the in situ mean relative growth rates of bacteria present during stable and disturbed periods were indistinguishable. From these intriguing observations, we infer that the length of the lag phase might be a growth trait that affects the microbial response to disturbance. Further exploration of this hypothesis could contribute to better understanding of the adaptive response of microbiomes to unsteady environmental conditions.

Optimized pH and Its Control Strategy Lead to Enhanced Itaconic Acid Fermentation by Aspergillus terreus on Glucose Substrate

Biological itaconic acid production can by catalyzed by Aspergillus terreus (a filamentous fungi) where the fermentation medium pH is of prominent importance. Therefore, in this work, we investigated what benefits the different pH regulation options might offer in enhancing the process. The batch itaconic acid fermentation data underwent a kinetic analysis and the pH control alternatives were ranked subsequently. It would appear that the pH-shift strategy (initial adjustment of pH to 3 and its maintenance at 2.5 after 48 h) resulted in the most attractive fermentation pattern and could hence be recommended to achieve itaconic acid production with an improved performance using A. terreus from carbohydrate, such as glucose. Under this condition, the itaconic acid titer potential, the maximal itaconic acid (titer) production rate, the length of lag-phase and itaconic acid yield were 87.32 g/L, 0.22 g/L/h, 56.04 h and 0.35 g/g glucose, respectively.

Undiscovered Mechanism for Pyrogenic Carbonaceous Matter-Mediated Abiotic Transformation of Azo Dyes by Sulfide.

Pyrogenic carbonaceous matter (PCM) catalyzes the transformation of a range of organic pollutants by sulfide in water; however, the mediation mechanisms are not fully understood. In this study, we observed for the first time that the degradation of azo dyes by sulfide initially underwent a lag phase followed by a fast degradation phase. Interestingly, the presence of PCM only reduced the lag phase length of the azo dye decolorization but did not significantly enhance the reaction rate in the fast degradation phase. An analysis of the azo dye reduction and polysulfide formation indicated that PCM facilitated the transformation of sulfide into polysulfides, including disulfide and trisulfide, resulting in fast azo dye reduction. Moreover, the oxygen functional groups of the PCM, especially the quinones, may play an important role in the transformation of sulfide into polysulfides by accelerating the electron transfer. The results of this study provide a better understanding of the PCM-mediated abiotic transformation of organic pollutants by sulfide in anaerobic aqueous environments.

Growth of a common planktonic diatom quantified using solid medium culturing

The ability to grow on solid culture medium is a pre-requisite for a successful microbial genetic model organism. Skeletonema marinoi, a bloom-forming, planktonic marine microalga, is widely used in ecological, evolutionary and population genetics studies. We have tested and confirmed the ability of this common organism to grow on solid culture medium (agar) under experimentally manipulated conditions. We established a protocol for quantifying growth characteristics – length of lag phase, growth rate, maximum biomass yield – on agar medium. The procedure was tested under experimental treatments and the resulting growth changes correlated with those observed in standard liquid culture. The ability to grow on solid medium broadens the use of S. marinoi as a molecular model, where agar is routinely used for various purposes (growth, selection, storage); and the possibility to quantify colony growth opens the way for high throughput, automated, or semi-automated phenotyping solutions.

Lag phase alteration in the modified bovine serum albumin under the inducing and inhibitory effect of vitamin C

Lag phase as the initial stage of protein aggregation has an important role in fibril formation and contributes to pathogenesis of many human diseases. Harsh environments provided by some additives can change the rate and the amounts of protein abnormalities. Here we studied the lag phase as the first stage of fibrillation process of bovine serum albumin (BSA) and determined the effects of potassium sorbate (PS) a widespread industrial preservative and vitamin C as an important antioxidant on these changes. Thioflavin T binding assay, circular dichroism, intrinsic and extrinsic fluorescence spectroscopy, and atomic force microscopy techniques were used for these assessments. Our results indicated that the lag phase of BSA fibrillation was affected under different conditions. The length of lag phase in BSA protein aggregation process was short due to the generation of the advanced glycation end products (AGEs) by PS. In contrast, vitamin C by its antioxidant properties and chaperone ability dramatically prolonged BSA lag phase, preserved BSA structural changes that lead to aggregation, and dramatically decreased formation of AGEs and the amount of fibrillation.

Bacterial prey food characteristics modulate community growth response of freshwater bacterivorous flagellates

AbstractDifferent bacterioplankton species represent different food quality resources for heterotrophic nanoflagellate (HNF) communities, potentially affecting HNF growth, community dynamics and carbon flow to higher trophic levels. However, our knowledge of such dynamics is still very limited. Here, we describe the results of 11 experiments with natural HNF communities from distinct seasonal phases in two freshwater habitats. The HNF communities were released from predation pressure of zooplankton and incubated with 16 distinct ecologically relevant prey bacterial strains from important Betaproteobacteria genera (Limnohabitans, Polynucleobacter, and Methylopumilus) and one Actinobacteria strain from the Luna 2 cluster. We observed remarkable prey‐ and season‐specific variability in community HNF growth parameters, i.e., doubling time, volumetric gross growth efficiency (GGE), and length of lag phase. All strains, except for the actinobacterium, supported rapid HNF population growth with an average doubling time of 10 h and GGE of 29%. Our analysis revealed that 59% of the variability in flagellate GGE data was explained by the length of lag phase after prey amendments. This indicates a considerable “adaptation time,” during which the predator communities undergo compositional shifts toward flagellate bacterivores best adapted to grow on the offered prey. Importantly, the rapid HNF growth detected on various bacteria tightly corresponds to doubling times reported for fast growing bacterioplankton groups. We propose a conceptual model explaining the tight linkages between rapid bacterial community shifts and succeeding HNF community shifts, which optimize prey utilization rates and carbon flow from various bacteria to the microbial food chain.

Kinetic parameters and nitrate, nitrite changes in bioremediation of Toxic Pentaerythritol Tetranitrate (PETN) contaminated soil.

BackgroundCleanup of areas contaminated by explosives is a public health concern. Some explosives can be carcinogenic in humans. Pentaerythritol Tetranitrate (PETN), a powerful explosive with very low water solubility, can be easily transported to ground waters.ObjectiveThis study was conducted to determine the removal efficiencies of PETN from soil by bioremediation, and obtain kinetic parameters of biological process.MethodsThis experimental study was conducted at the Environmental Health Engineering Lab (Isfahan University of Medical Sciences, Isfahan, Iran) in 2015–2016. In the present work, bioremediation of the explosive-polluted soils by PETN in anaerobic-aerobic landfarming method was performed. The influence of seeding and biosurfactant addition on bioremediation was also evaluated. The data were analyzed using Microsoft Excel software.ResultsThe results show that, as the initial concentration of PETN increased, the lag phase was increased and the specific growth rate was increased up to 0.1/day in concentration of 50 mg/kg, and then it was decreased to 0.04/day. Subsequent decreases in specific growth rate can cause substrate inhibition. Seeding causes decrease in lag phase significantly. Biosurfactant addition had little to no impact on the length of lag phase, but biosurfactant plus seeding can increase the growth rate to 0.2/day, however, inhibitory effect of the initial concentration was started in very high concentration of PETN (150 mg/kg).ConclusionBiosurfactant addition and seeding together have an impressive effect on biodegradation of PETN, furthermore seeding can enhance active microbial consortium and biosurfactant can improve the poor aqueous solubility of PETN, therefore making the substrate more accessible.

A Bayesian approach to analyzing phenotype microarray data enables estimation of microbial growth parameters.

Biolog phenotype microarrays (PMs) enable simultaneous, high throughput analysis of cell cultures in different environments. The output is high-density time-course data showing redox curves (approximating growth) for each experimental condition. The software provided with the Omnilog incubator/reader summarizes each time-course as a single datum, so most of the information is not used. However, the time courses can be extremely varied and often contain detailed qualitative (shape of curve) and quantitative (values of parameters) information. We present a novel, Bayesian approach to estimating parameters from Phenotype Microarray data, fitting growth models using Markov Chain Monte Carlo (MCMC) methods to enable high throughput estimation of important information, including length of lag phase, maximal "growth" rate and maximum output. We find that the Baranyi model for microbial growth is useful for fitting Biolog data. Moreover, we introduce a new growth model that allows for diauxic growth with a lag phase, which is particularly useful where Phenotype Microarrays have been applied to cells grown in complex mixtures of substrates, for example in industrial or biotechnological applications, such as worts in brewing. Our approach provides more useful information from Biolog data than existing, competing methods, and allows for valuable comparisons between data series and across different models.

Novel Functions and Regulation of Cryptic Cellobiose Operons in Escherichia coli.

Presence of cellobiose as a sole carbon source induces mutations in the chb and asc operons of Escherichia coli and allows it to grow on cellobiose. We previously engineered these two operons with synthetic constitutive promoters and achieved efficient cellobiose metabolism through adaptive evolution. In this study, we characterized two mutations observed in the efficient cellobiose metabolizing strain: duplication of RBS of ascB gene, (β-glucosidase of asc operon) and nonsense mutation in yebK, (an uncharacterized transcription factor). Mutations in yebK play a dominant role by modulating the length of lag phase, relative to the growth rate of the strain when transferred from a rich medium to minimal cellobiose medium. Mutations in ascB, on the other hand, are specific for cellobiose and help in enhancing the specific growth rate. Taken together, our results show that ascB of the asc operon is controlled by an internal putative promoter in addition to the native cryptic promoter, and the transcription factor yebK helps to remodel the host physiology for cellobiose metabolism. While previous studies characterized the stress-induced mutations that allowed growth on cellobiose, here, we characterize the adaptation-induced mutations that help in enhancing cellobiose metabolic ability. This study will shed new light on the regulatory changes and factors that are needed for the functional coupling of the host physiology to the activated cryptic cellobiose metabolism.

Kinetics and mechanism of the biodegradation of PLA/clay nanocomposites during thermophilic phase of composting process

The degradation mechanism and kinetics of polylactic acid (PLA) nanocomposite films, containing various commercially available native or organo-modified montmorillonites (MMT) prepared by melt blending, were studied under composting conditions in thermophilic phase of process and during abiotic hydrolysis and compared to the pure polymer. Described first order kinetic models were applied on the data from individual experiments by using non-linear regression procedures to calculate parameters characterizing aerobic composting and abiotic hydrolysis, such as carbon mineralization, hydrolysis rate constants and the length of lag phase. The study showed that the addition of nanoclay enhanced the biodegradation of PLA nanocomposites under composting conditions, when compared with pure PLA, particularly by shortening the lag phase at the beginning of the process. Whereas the lag phase of pure PLA was observed within 27days, the onset of CO2 evolution for PLA with native MMT was detected after just 20days, and from 13 to 16days for PLA with organo-modified MMT. Similarly, the hydrolysis rate constants determined tended to be higher for PLA with organo-modified MMT, particularly for the sample PLA-10A with fastest degradation, in comparison with pure PLA. The acceleration of chain scission in PLA with nanoclays was confirmed by determining the resultant rate constants for the hydrolytical chain scission. The critical molecular weight for the hydrolysis of PLA was observed to be higher than the critical molecular weight for onset of PLA mineralization, suggesting that PLA chains must be further shortened so as to be assimilated by microorganisms. In conclusion, MMT fillers do not represent an obstacle to acceptance of the investigated materials in composting facilities.

Collective effects of SNPs on transgenerational inheritance in Caenorhabditis elegans and budding yeast

We studied the collective effects of single nucleotide polymorphisms (SNPs) on transgenerational inheritance in Caenorhabditis elegans recombinant inbred advanced intercross lines (RIAILs) and yeast segregants. We divided the RIAILs and segregants into two groups of high and low minor allele content (MAC). RIAILs with higher MAC needed less generations of benzaldehyde training to gain a stable olfactory imprint and showed a greater change from normal after benzaldehyde training. Yeast segregants with higher MAC showed a more dramatic shortening of the lag phase length after ethanol exposure. The short lag phase as acquired by ethanol training was more dramatically lost after recovery in ethanol free medium for the high MAC group. We also found a preferential association between MAC and traits linked with higher number of additive QTLs. These results suggest a role for the collective effects of SNPs in transgenerational inheritance, and may help explain human variations in disease susceptibility.

Parameters that Affect Macromolecular Self-Assembly of Prion Protein

Amyloidogenesis of prion protein (PrP) is closely associated with the pathobiology of prion diseases. To understand details on formation of PrP amyloids, we investigated various conditions that influence the process in vitro, using full length and truncated recombinant PrP. Disrupted agitation and fluctuated temperature resulted in prolongation of lag phase during PrP amyloid formation. With the same conditions and material for the assay, fluorescence microplate readers of different manufacturers, which are assumed to have incongruent level of mechanical performance, demonstrated variations for the length of lag phase and the level of fluorescence detection. Presence of preformed amyloid seeds accelerated PrP amyloid formation. Similarly, recombinant proteins of different species affected effectual generation of amyloids. This process was also influenced by the concentrations and truncation of recombinant PrP. By investigating several conditions to perform PrP amyloid formation assay, our study addresses the factors that determine how much and how rapidly PrP amyloids are formed.

Application of Central Composite Design to evaluate the antilisterial activity of hydro-alcohol berry extract of Myrtus communis L.

The antimicrobial activity of the hydro-alcohol extract of Myrtus communis L. (ME) berries was investigated against six Listeria monocytogenes strains (2 type strains and 4 isolates). Sub-lethal ME concentrations reduced L. monocytogenes counts by at least 2 log cycles. A Central Composite Design was used to investigate the combined effects of sub-lethal concentrations of ME (0.039–0.195 mL/100 mL), NaCl (0–2.0 g/100 mL) and pH (5.0–7.0) on strains growth. ME affected growth parameters, generally extending lag phase length and reducing maximum growth, sometimes with interactive effects with pH. The highest ME concentrations (0.117–0.195 mL/100 mL) combined with the lowest pH values (5.0–6.0) strongly reduced or even inhibited strains growth.Total phenolic content (TPC) and radical scavenging activity were also determined. ME had a TPC of 5315 ± 20 mg/kg of gallic acid equivalent, and malvidin-3-O-glucoside was the most abundant anthocyanin. In vitro radical scavenging activity, determined by TEAC assay, was stable during 70 days of refrigerated storage.In conclusion, low ME concentrations, combined with salt and pH, were effective in reducing or containing cell growth. This antilisterial effect has interesting perspectives on industrial application; ME hydro-solubility can be considered a useful feature when antilisterial strategies are applied in food formulation.