Replacing conventional decontamination of hatching eggs with a natural defense strategy based on antimicrobial, volatile pyrazines

Revolutionizing poultry hygiene: advanced electrostatic and cold fog disinfection strategies combat Mycoplasma gallisepticum in hatching eggs

The incidence of chronic respiratory disease (CRD) due to Mycoplasma gallisepticum (MG) contamination in hatching eggs poses a serious threat to poultry health and hatchability. Implementing effective sanitization methods while safeguarding the hatching potential of embryos is crucial. This study aimed to explore novel techniques for sanitizing hatching-fertile eggs to prevent and manage MG-associated CRD. The primary objective was to assess the efficacy of acidic electrochemically stimulated water (ECS), focusing on MG disinfection. Additionally, the study investigated 2 application methods, 1) electrostatic disinfection (ED) and 2) cold fog (CF) disinfection, to evaluate their bactericidal effects against MG-contaminated eggs. Deliberately infected MG strains were used for the experimental design, which compared the disinfection efficacy of ECS with its acidic properties. The comparison involved ED, which applies an electrostatic charge to water particles, and CF disinfection, a cold mist technique. Both methods aimed to target MG without compromising egg-hatching potential. The results indicated a significant (p < 0.05) reduction in colony-forming units per milliliter (CFU/mL). However, both application methods demonstrated distinct bactericidal effects. Eggs treated with electrostatic disinfection showed a significant (p < 0.001) reduction in embryonic mortality during incubation (10%) compared to control untreated eggs (18%). Similarly, the CF method exhibited a significant (p < 0.001) decrease in embryonic mortality (13%). The ECS potential in reducing embryonic mortality within the pH range of 2.5 to 6.5 was noted. Both the ED and CF methods show promise for preventing MG-induced hatchery infection while maintaining egg-hatching potential. This study presents innovative techniques to control MG in hatching eggs, contributing to improved poultry health and reduced CRD incidence.

The effect of avian eggshell membrane structure on microbial penetration: A simulation study

Avian eggshells exhibit excellent antimicrobial properties. In this study, we conducted simulation experiments to explore the defense mechanisms of eggshell membranes with regards to their physical features. We developed a mathematical model for the movement of microorganisms and estimated their penetration ratio into eggshell membranes based on several factors, including membrane thickness, microbial size, directional drift, and attachment probability to membrane fibers. These results not only suggest that an eggshell membrane with multiple layers and low porosity indicates high antimicrobial performance, but also imply that the fibrous network structure of the membrane might contribute to effective defense. Our simulation results aligned with experimental findings, specifically in measuring the penetration time of Escherichia coli through the eggshell membrane. We briefly discuss the significance and limitations of this pilot study, as well as the potential for these results, to serve as a foundation for the development of antimicrobial materials.

Thermal/Redox-triggered release of pyrazinic functional molecules by coordination polymers with luminescence monitoring ability

Storage of volatile active molecules, along with the prolongation of their specific functions, requires the use of regulatable carriers. Pyrazine derivatives are highly volatile compounds with a broad application owing to their flavoring, pharmaceutical, antimicrobial, antiseptic, and insecticidal properties. In this study, pyrazines were stored by coordinating them with cuprous iodide to easily generate a series of luminescent coordination polymer (CP)-based carriers. The CPs could respond to thermal-redox stimuli and manipulate pyrazine release by breaking the labile Cu-N bonds when triggered by the two stimuli. Moreover, the release process could be visualized by decreased luminescence caused by the gradual decomposition of CP structures. The loading efficiencies ranged from 31% to 38%, and the controlled release behaviors accord with the zero-order kinetics. This work is the first to prove that CPs could function as dual stimuli-mediated delivery systems, which hold the potential to control the release and strengthen the usability of functional molecules.

Effects of Sanitizers on Microbiological Control of Hatching Eggshells and Poultry Health during Embryogenesis and Early Stages after Hatching in the Last Decade

Simple Summary

Poultry systems, especially conventional comprehensive production systems to meet the global demand for eggs and meat, are constantly challenged by pathogens, requiring intense sanitary practices. Operations, including the sanitization of hatching eggs, can employ synthetic chemical sanitizers as well as natural plant extracts to minimize the microbial challenge. As the application of formaldehyde sanitizer in hatching eggs cannot be justified in terms of safety for embryonic and human health, studies are underway to assist the industry in adopting new alternative sanitizers. This review aims to evaluate the effects of different sanitizers on the microbiological quality of hatching eggshells and poultry health during embryogenesis and early stages after hatching.

Abstract

The sanitization of hatching eggs is the backbone of the hygienic–sanitary management of eggs on farms and extends to the hatchery. Poultry production gains depend on the benefits of sanitizers. Obtaining the maximum yield from incubation free of toxic sanitizers is a trend in poultry farming, closely following the concerns imposed through scientific research. The toxic characteristics of formaldehyde, the primary sanitizer for hatching eggs, are disappointing, but it is a cheap, practical and widely used antimicrobial. To overcome this shortcoming, multiple synthetic and natural chemical sanitizers have been, and continue to be, tested on hatching eggs. This review aims to evaluate the effects of different sanitizers on the microbiological quality of hatching eggshells and poultry health during embryogenesis and early stages after hatching.

Trade-off for survival: Microbiome response to chemical exposure combines activation of intrinsic resistances and adapted metabolic activity

The environmental microbiota is increasingly exposed to chemical pollution. While the emergence of multi-resistant pathogens is recognized as a global challenge, our understanding of antimicrobial resistance (AMR) development from native microbiomes and the risks associated with chemical exposure is limited. By implementing a lichen asa bioindicatororganism and model for a native microbiome, we systematically examined responses towards antimicrobials (colistin, tetracycline, glyphosate, and alkylpyrazine). Despite an unexpectedly high resilience, we identified potential evolutionary consequences of chemical exposure in terms of composition and functioning of native bacterial communities. Major shifts in bacterial composition were observed due to replacement of naturally abundant taxa; e.g. Chthoniobacterales by Pseudomonadales. A general response, which comprised activation of intrinsic resistance and parallel reduction of metabolic activity at RNA and protein levels was deciphered by a multi-omics approach. Targeted analyses of key taxa based on metagenome-assembled genomes reflected these responses but also revealed diversified strategies of their players. Chemical-specific responses were also observed, e.g., glyphosate enriched bacterial r-strategists and activated distinct ARGs. Our work demonstrates that the high resilience of the native microbiota toward antimicrobial exposure is not only explained by the presence of antibiotic resistance genes but also adapted metabolic activity as a trade-off for survival. Moreover, our results highlight the importance of native microbiomes as important but so far neglected AMR reservoirs. We expect that this phenomenon is representative for a wide range of environmental microbiota exposed to chemicals that potentially contribute to the emergence of antibiotic-resistant bacteria from natural environments.

Endophytic Bacteria and Essential Oil from Origanum vulgare ssp. vulgare Share Some VOCs with an Antibacterial Activity

Medicinal aromatic plants’ essential oils (EOs) are mixtures of volatile compounds showing antimicrobial activity, which could be exploited to face the emerging problem of multi-drug resistance. Their chemical composition can depend on the interactions between the plant and its endophytic microbiota, which is known to synthesize volatile organic compounds (VOCs). However, it is still not clear whether those volatile metabolites can contribute to the composition of the aroma profile of plants’ EOs. The aims of this study were to characterize medicinal plant O. vulgare ssp. vulgare bacterial endophyte VOCs, evaluating their ability to antagonize the growth of opportunistic human pathogens belonging to the Burkholderia cepacia complex (Bcc) and compare them with O. vulgare EO composition. Many of the tested endophytic strains showed (i) a bactericidal and/or bacteriostatic activity against most of Bcc strains and (ii) the production of VOCs with widely recognized antimicrobial properties, such as dimethyl disulfide, dimethyl trisulfide, and monoterpenes. Moreover, these monoterpenes were also detected in the EOs extracted from the same O. vulgare plants from which endophytes were isolated. Obtained results suggest that endophytes could also play a role in the antibacterial properties of O. vulgare ssp. vulgare and, potentially, in determining its aromatic composition.

Antioxidant, Antidiabetic, and Antibacterial Potentials and Chemical Composition of Salvia officinalis and Mentha suaveolens Grown Wild in Morocco

This work evaluated in vitro antioxidant, antidiabetic, and antibacterial properties of Salvia officinalis (S. officinalis) and Mentha suaveolens (M. suaveolens) essential oils (EO). The EOs were extracted, and their chemical composition was determined using GC-MS analysis. The in vitro antioxidant, antidiabetic, and antibacterial activities of S. officinalis and M. suaveolens EO were shown to be remarkable. Furthermore, S. officinalis EO demonstrated better antioxidant findings (using DPPH, ABTS, and FRAP test) than M. suaveolens EO (p < 0.5). There were no significant differences in the inhibitory effects of the EOs on α-amylase and α-glucosidase activities in the antidiabetic assays. All of the examined bacterial strains (10 different strains), with the exception of P. aeruginosa, demonstrated significant sensitivity to the tested EOs, with M. suaveolens EO exhibiting better activity than S. officinalis EO. Thus, the research indicated that EO from these two medicinal plants has considerable potential for application in the formulation of antibacterial, antioxidant, and antidiabetic pharmaceuticals. However, more research studies are required to interpret the pharmacologic action of the studied EOs and their principal constituents and to confirm their safety.

A multifunctional study of naturally occurring pyrazines in biological systems; formation mechanisms, metabolism, food applications and functional properties

Natural pyrazines, mainly methyl- or ethyl-substituted forms, are commonly applied as flavor ingredients in raw and roasted food. Meanwhile alkylpyrazines are used as food preservatives due to their effective antimicrobial action. These natural pyrazines are widely distributed in several biological systems such as plants, animals, and insects; each with respective physiological role. Besides, pyrazines are formed in food via thermal treatment and fermentation. This review presents the most comprehensive overview of pyrazines with correlation to their chemical structures and different applications with emphasis on their food applications. The major part deals with pyrazines generated in thermally treated food, reaction mechanisms highlighting factors and optimum conditions affecting their production. Additionally, the several metabolic reactions mediating for pyrazines metabolism in humans and excretion via the kidney are discussed and on context to their effects. Lastly, a review of the different techniques applied for pyrazines isolation, detection and quantitation is presented. The study provides future considerations and direction of research on this important dietary component and their applications. Pyrazines multifunctional chemistry is of value to the food sector, by presenting the best practices for their production whilst the detrimental effects are minimized.

Fusaricidins, Polymyxins and Volatiles Produced by Paenibacillus polymyxa Strains DSM 32871 and M1

Paenibacilli are efficient producers of potent agents against bacterial and fungal pathogens, which are of great interest both for therapeutic applications in medicine as well as in agrobiotechnology. Lipopeptides produced by such organisms play a major role in their potential to inactivate pathogens. In this work we investigated two lipopeptide complexes, the fusaricidins and the polymyxins, produced by Paenibacillus polymyxa strains DSM 32871 and M1 by MALDI-TOF mass spectrometry. The fusaricidins show potent antifungal activities and are distinguished by an unusual variability. For strain DSM 32871 we identified numerous yet unknown variants mass spectrometrically. DSM 32871 produces polymyxins of type E (colistins), while M1 forms polymyxins P. For both strains, novel but not yet completely characterized polymyxin species were detected, which possibly are glycosylated. These compounds may be of interest therapeutically, because polymyxins have gained increasing attention as last-resort antibiotics against multiresistant pathogenic Gram-negative bacteria. In addition, the volatilomes of DSM 32781 and M1 were investigated with a GC–MS approach using different cultivation media. Production of volatile organic compounds (VOCs) was strain and medium dependent. In particular, strain M1 manifested as an efficient VOC-producer that exhibited formation of 25 volatiles in total. A characteristic feature of Paenibacilli is the formation of volatile pyrazine derivatives.

The efficacy of pulsed ultraviolet light processing for table and hatching eggs

In the United States, every year an average of 287.1 eggs are consumed per person, and over 14.1 billion eggs are set in hatchery incubators to produce chicks destined for the egg and meat bird industries. By reducing the microbial load on eggs, food-borne-associated outbreaks can be reduced while good chick health is maintained. Pulsed ultraviolet (PUV) light system delivers an energy-intense broad spectrum (100-1,100 nm) pulse derived from a xenon flashlamp. In recent years, PUV light has been shown to reduce microbial pathogens on the surface of shell eggs by using a static PUV light system. In this study, shell eggs were surface inoculated with Escherichia coli or Enterococcus faecium and treated with PUV light using a modified egg candling conveyor that provided complete rotation of eggs under a flashlamp. Pulsed UV light treatment inactivated both microbial strains, with greater energy resulting in a greater germicidal response (P < 0.05). Treatments of 1.0, 2.4, 3.1, and 4.9 J/cm2 resulted in microbial reductions (Log10 CFU/cm2) of 3.83, 4.26, 4.28, and 4.62 for E. coli and 2.04, 3.12, 3.11, and 3.82 for E. faecium, respectively. This study also evaluated the effects of PUV light treatment of hatching eggs (commercial Leghorn hybrids) on both embryo and chick growth parameters. Using the same system, 4 replicates of 125 fertile eggs per rep were treated with 0 (control), 4.9, 24.4, or 48.8 J/cm2 of PUV light. After processing, eggs were placed in a commercial incubator under normal incubation conditions. There was no significant effect of the PUV light treatment on percent fertility, hatchability, or hatch (P > 0.05). Furthermore, there were no significant effects on posthatch observations, including livability and average bird weight at hatch or at 42 d of age (P > 0.05). In conclusion, this study supports the application of PUV light as an effective antimicrobial intervention for both table and hatching eggs.

Antimicrobial-specific response from resistance gene carriers studied in a natural, highly diverse microbiome

BACKGROUND

Antimicrobial resistance (AMR) is a major threat to public health. Microorganisms equipped with AMR genes are suggested to have partially emerged from natural habitats; however, this hypothesis remains inconclusive so far. To understand the consequences of the introduction of exogenic antimicrobials into natural environments, we exposed lichen thalli of Peltigera polydactylon, which represent defined, highly diverse miniature ecosystems, to clinical (colistin, tetracycline), and non-clinical (glyphosate, alkylpyrazine) antimicrobials. We studied microbiome responses by analysing DNA- and RNA-based amplicon libraries and metagenomic datasets.

RESULTS

The analyzed samples consisted of the thallus-forming fungus that is associated with cyanobacteria as well as other diverse and abundant bacterial communities (up to 108 16S rRNA gene copies ng-1 DNA) dominated by Alphaproteobacteria and Bacteroidetes. Moreover, the natural resistome of this meta-community encompassed 728 AMR genes spanning 30 antimicrobial classes. Following 10 days of exposure to the selected antimicrobials at four different concentrations (full therapeutic dosage and a gradient of sub-therapeutic dosages), we observed statistically significant, antimicrobial-specific shifts in the structure and function but not in bacterial abundances within the microbiota. We observed a relatively lower response after the exposure to the non-clinical compared to the clinical antimicrobial compounds. Furthermore, we observed specific bacterial responders, e.g., Pseudomonas and Burkholderia to clinical antimicrobials. Interestingly, the main positive responders naturally occur in low proportions in the lichen holobiont. Moreover, metagenomic recovery of the responders' genomes suggested that they are all naturally equipped with specific genetic repertoires that allow them to thrive and bloom when exposed to antimicrobials. Of the responders, Sphingomonas, Pseudomonas, and Methylobacterium showed the highest potential.

CONCLUSIONS

Antimicrobial exposure resulted in a microbial dysbiosis due to a bloom of naturally low abundant taxa (positive responders) with specific AMR features. Overall, this study provides mechanistic insights into community-level responses of a native microbiota to antimicrobials and suggests novel strategies for AMR prediction and management. Video Abstract.

Volatile Organic Compounds From Lysobacter capsici AZ78 as Potential Candidates for Biological Control of Soilborne Plant Pathogens

The genus Lysobacter includes several bacterial species which show potential for being used in biological control of plant diseases. It was shown recently that several Lysobacter type strains produce volatile organic compounds (VOCs) which controlled the growth of Phytophthora infestans in vitro when the bacteria were grown on a protein rich medium. In the present study, Lysobacter capsici AZ78 (AZ78) has been tested for its potential to produce VOCs that may contribute to the bioactivity against soilborne plant pathogens. To this end, split Petri dish assays of bacterial cultures have been combined with GC-MS measurements with the aim to reveal the identity of the VOCs which inhibit the growth of Pythium ultimum Rhizoctonia solani, and Sclerotinia minor. While AZ78 completely suppressed the growth of P. ultimum and S. minor, the growth of R. solani was still reduced significantly. The GC-MS analysis revealed 22 VOCs to be produced by AZ78, the majority of which were (putatively) identified as mono- and dialkylated methoxypyrazines. Based on additional cultivation and GC-MS experiments, 2,5-dimethylpyrazine, 2-ethyl-3-methoxypyrazine and 2-isopropyl-3-methoxypyrazine were selected as presumable bioactive compounds. Further bioassays employing indirect exposure to standard solutions (1–10 mg per Petri dish) of the synthetic compounds via the gas phase, revealed that each of these pyrazines was able to suppress the growth of the pathogens under investigation. The results of this study highlight the possible future implementation of pyrazine derivatives in the control of soilborne plant diseases and further support the biocontrol potential of L. capsici AZ78.

Alternative sanitizers to paraformaldehyde for incubation of fertile eggs

The aim of this study was to evaluate an ethanolic extract of propolis and clove essential oil as a substitute for paraformaldehyde for the sanitation of fertile eggs. In total, 1,800 hatching eggs (from 40-week-old CPK [Pesadão Vermelho] breeder hens) were randomly distributed among the treatments (grain alcohol, clove essential oil, ethanolic extract of propolis, and paraformaldehyde). Spraying was the application method for all treatments except for paraformaldehyde, for which fumigation was used. The experimental design was a randomized block design with 4 treatments. Analysis of the incubation parameters was based on 6 replications per treatment. The egg weight loss was lower in the eggs treated with ethanolic extract of propolis (8.59 ± 3.34%) than in the eggs treated with grain alcohol (13.40 ± 2.87%), clove essential oil (12.96 ± 3.33%), and paraformaldehyde (13.05 ± 3.24%). The hatchability of the fertile eggs (51.39 ± 5.81%) and the hatchability of the set eggs (44.74 ± 6.79%) were negatively affected by the application of ethanolic extract of propolis. Late mortality of eggs treated was higher than early mortality in the grain alcohol (12.14 ± 4.72%; 2.86 ± 3.30%), clove essential oil (4.60 ± 5.95%; 3.03 ± 3.50%), and ethanolic extract of propolis (36.63 ± 6.60%, 11.98 ± 4.30%) treatments. The eggs treated with clove essential oil (67.90 ± 1.87%), paraformaldehyde (67.80 ± 1.85%), or grain alcohol (67.50 ± 1.92%) presented chick yields as expected. However, due to the high yield of eggs treated with ethanolic extract of propolis (69.25 ± 1.68%), its application at the concentration used in the present research is not recommended. Clove essential oil, when sprayed on fertile eggs as a sanitizing agent, did not differ from paraformaldehyde in relation to hatchery performance parameters.

Biological activities associated with the volatile compound 2,5-bis(1-methylethyl)-pyrazine

Pyrazines are 1,4-diazabenzene-based volatile organic compounds and known for their broad-spectrum antimicrobial activity. In the present study, we assessed the antimicrobial activity of 2,5-bis(1-methylethyl)-pyrazine, produced by Paenibacillus sp. AD87 during co-culture with Burkholderia sp. AD24. In addition, we were using transcriptional reporter assays in E. coli and mammalian cells to decipher the possible mode of action. Bacterial and mammalian luciferase reporter strains were deployed to elucidate antimicrobial and toxicological effects of 2,5-bis(1-methylethyl)-pyrazine. At high levels of exposure, 2,5-bis(1-methylethyl)-pyrazine exerted strong DNA damage response. At lower concentrations, cell-wall damage response was observed. The activity was corroborated by a general toxicity reporter assay in E. coli ΔampD, defective in peptidoglycan turnover. The maximum E. coli cell-wall stress activity was measured at a concentration close to the onset of the mammalian cytotoxicity, while other adverse outcome pathways, such as the activation of aryl hydrocarbon and estrogenic receptor, the p53 tumour suppressor and the oxidative stress-related Nrf2 transcription factor, were induced at elevated concentrations compared to the response of mammalian cells. Because of its broad-spectrum antimicrobial activity at lower concentrations and the relatively low mammalian toxicity, 2,5-bis(1-methylethyl)-pyrazine is a potential bio-based fumigant with possible applications in food industry, agriculture or logistics.

Novel Strategies for Soil-Borne Diseases: Exploiting the Microbiome and Volatile-Based Mechanisms Toward Controlling Meloidogyne-Based Disease Complexes

Under more intensified cropping conditions agriculture will face increasing incidences of soil-borne plant pests and pathogens, leading to increasingly higher yield losses world-wide. Soil-borne disease complexes, in particular, are especially difficult to control. In order to better understand soil-borne Meloidogyne-based disease complexes, we studied the volatile-based control mechanism of associated bacteria as well as the rhizospheric microbiome on Ugandan tomato plants presenting different levels of root-galling damage, using a multiphasic approach. The experimental design was based on representative samplings of healthy and infected tomato plants from two field locations in Uganda, to establish species collections and DNA libraries. Root galling symptoms on tomato resulted from a multispecies infection of root-knot nematodes (Meloidogyne spp.). Results revealed that 16.5% of the bacterial strain collection produced nematicidal volatile organic compounds (nVOC) active against Meloidogyne. Using SPME GC-MS, diverse VOC were identified, including sulfuric compounds, alkenes and one pyrazine. Around 28% of the bacterial strains were also antagonistic toward at least one fungal pathogen of the disease complex. However, antagonistic interactions appear highly specific. Nematicidal antagonists included Pseudomonas, Comamonas, and Variovorax and fungicidal antagonists belonged to Bacillus, which interestingly, were primarily recovered from healthy roots, while nematode antagonists were prominent in the rhizosphere and roots of diseased roots. In summary, all antagonists comprised up to 6.4% of the tomato root microbiota. In general, the microbiota of healthy and diseased root endospheres differed significantly in alpha and quantitative beta diversity indices. Bacteria-derived volatiles appear to provide a remarkable, yet wholly unexploited, potential to control Meloidogyne-based soil-borne disease complexes. The highly specific observed antagonism indicates that a combination of volatiles or VOC-producing bacteria are necessary to counter the range of pathogens involved in such complexes.

A novel, nature-based alternative for photobioreactor decontaminations

Large-scale microalgae cultivations are increasingly used for the production of animal feed, nutritional supplements and various high-value bioproducts. Due to the process size and other limitations, contaminations of microalgae fermentations with other photoautotrophic microorganism are frequently observed. In the present study, we explored the applicability of 5-isobutyl-2,3-dimethylpyrazine for the removal of contaminating microalgae from industrial photobioreactors. In order to select a representative microbial population for susceptibility experiments, reactor samples were obtained from a multi-stage cultivation process. Assignments of 18S rRNA gene fragment amplicons indicated that Haematococcus, Chlorella, and Scenedesmus were the three most frequently occurring microalgae genera in the selected reactors. Following the isolation of representative algae cultures, susceptibility tests were conducted with the antimicrobial pyrazine. It was demonstrated that all isolated contaminants are highly susceptible to the bioactive compound. The highest tolerance towards the alkylpyrazine was observed with Scenedesmus vacuolatus; solutions with 1.66% (v/v) of the active compound were required for its deactivation. Further tests with the vaporized pyrazine showed consistent reductions in the viability of treated microalgae. This pilot study provides evidence for the applicability of a novel, nature-based alternative for bioreactor decontaminations.

First evaluation of alkylpyrazine application as a novel method to decrease microbial contaminations in processed meat products

Every year about 20% of the globally produced meat gets lost due to microbial spoilage. Nevertheless, the demand for processed meat is constantly rising and producers are searching for novel strategies to reduce microbial contaminations in their products. In the present study, we evaluated the applicability of alkylpyrazines as antimicrobial agents. These fragrant molecules naturally occur in different vegetables, fruits, roasted nut and meat. Several pyrazine derivatives are readily added to processed products for flavoring purposes in the food industry. To evaluate their potential for application, two derivatives were tested for their antimicrobial activity against meat-associated bacterial contaminants and chicken meat as a whole. Isolates assigned to Carnobacteriaceae, Enterobacteriaceae, Listeriaceae, and Moraxellaceae were substantially inhibited in the pilot tests. Moreover, treatments of pyrazine-susceptible isolates resulted in 4-log reductions in bacterial cell counts. The effect was more pronounced when the model contaminants were exposed to higher concentrations of 5-isobutyl-2,3-dimethylpyrazine. In a first small-scale application with processed chicken meat, it was demonstrated that the antimicrobial effects of 2-isobutyl-3-methylpyrazine can be improved by additionally lowering the water activity on the meat surface when maltodextrin is used as a carrier substance. At low pyrazine dosages, the number of viable bacteria was decreased up to 95% in comparison to the corresponding controls. A complementary imaging method that was developed to assess the efficacy on the product, reinforced the applicability of this two-component system.