RESUMEN

Biofilms are a critical factor for food safety, causing important economic losses. Among the novel strategies for controlling biofilms, essential oils (EOs) can represent an environmentally friendly approach, able to act both on early and mature stages of biofilm formation. This review reports the anti-biofilm mechanisms of action of EOs against five pathogenic bacterial species known for their biofilm-forming ability. These mechanisms include disturbing the expression of genes related to quorum sensing (QS), motility, adhesion, and virulence. Biofilms and QS are interconnected processes, and EOs interfere with the communication system (e.g. regulating the expression of agrBDCA, luxR, luxS, and pqsA genes), thus influencing biofilm formation. In addition, QS is an important mechanism that regulates gene expression related to bacterial survival, virulence, and pathogenicity. Similarly, EOs also influence the expression of many virulence genes. Moreover, EOs exert their effects modulating the genes associated with bacterial adhesion and motility, for example those involved in curli (csg), fimbriae (fim, lpf), and flagella (fla, fli, flh, and mot) production, as well as the ica genes responsible for synthetizing polysaccharide intercellular adhesin. This review provides a comprehensive framework on the topic for a better understanding of EOs biofilm mechanisms of action.

RESUMEN

Here, we report for the first time on the mechanisms of action of the essential oil of Ruta graveolens (REO) against the plant pathogen Colletotrichum gloeosporioides. In particular, the presence of REO drastically affected the morphology of hyphae by inducing changes in the cytoplasmic membrane, such as depolarization and changes in the fatty acid profile where straight-chain fatty acids (SCFAs) increased by up to 92.1%. In addition, REO induced changes in fungal metabolism and triggered apoptosis-like responses to cell death, such as DNA fragmentation and the accumulation of reactive oxygen species (ROS). The production of essential enzymes involved in fungal metabolism, such as acid phosphatase, ß-galactosidase, ß-glucosidase, and N-acetyl-ß-glucosaminidase, was significantly reduced in the presence of REO. In addition, C. gloeosporioides activated naphthol-As-BI phosphohydrolase as a mechanism of response to REO stress. The data obtained here have shown that the essential oil of Ruta graveolens has a strong antifungal effect on C. gloeosporioides. Therefore, it has the potential to be used as a surface disinfectant and as a viable replacement for fungicides commonly used to treat anthracnose in the postharvest testing phase.

Asunto(s)

RESUMEN

Zinc is essential for animals, playing a vital role in enzyme systems and various biochemical reactions. It is crucial to ensure a sufficient intake of zinc through the diet to maintain efficient homeostasis. Only few studies on zinc effect in cow lactating diet evaluated the effects on milk and cheese quality, with conflicting findings. 24 cows of the Friesian breed were divided into two groups (CTR: control and TRT: treated group). Cows were selected for age, body weight, parity and phase of lactations (mid lactation, 140-160 days). CTR diet contained 38 mg/kg of Zn and TRT diet was supplied with 120 mg/kg of complete feed for 60 days. The objective of current investigation was to evaluate the impact of a dietary Zinc Oxide (ZnO) integration of lactating Friesian cows on chemical composition, zinc content, fatty acid and proteic profile, ammine content, pH, aw, texture, and sensory profile of cheese and to improve the chemical-nutritional quality of milk and cheese. The results showed that ZnO supplementation reduced mesophilic aerobic bacteria and Presumptive Pseudomonas spp. growth, proteolysis, biogenic amines content, lipid oxidation, odour intensity and sour and increased hardness, gumminess, chewiness, elasticity of cheese. Biogenic amines are considered an important aspect of food safety. ZnO integration in cow diet could represent a promising strategy for improving the quality, the safety and shelf-life of caciotta cheese.

RESUMEN

The cocoa shell (CS) is being incorporated into different food products due to its recognized content of bioactive compounds. In the case of cocoa shell infusions (CSI), the bioactive compounds that manage to be transferred to the infusion have yet to be clearly known, i.e., what is really available to the consumer. In this study, CS was obtained from toasted Colombian Criollo cocoa beans. Three particle sizes (A: >710 µm; B: >425 and <710 µm; C: <425 µm) were evaluated in the CSI, which was traditionally prepared by adding CS to hot water (1%). The decrease in particle size increased the antioxidant capacity (DPPH and ABTS) and the total phenolic compounds. A significant effect (p < 0.05) both of the particle size and of the temperature of tasting was found on some sensory attributes: greater bitterness, acidity, and astringency were due to the greater presence of epicatechin, melanoidins, and proanthocyanidins in the smaller particle sizes. The analysis of the volatile organic compounds showed that the CSI aroma was characterized by the presence of nonanal, 2-nonanone, tetramethylpyrazine, α-limonene, and linalool, which present few variations among the particle sizes. Moreover, analysis of biogenic amines, ochratoxin A, and microbial load showed that CSI is not a risk to public health. Reducing particle size becomes an important step to valorize the functional properties of CS and increase the quality of CSI.

RESUMEN

Fruits and vegetables are constantly affected by postharvest diseases, of which anthracnose is one of the most severe and is caused by diverse Colletotrichum species, mainly C. gloeosporioides. In the last few decades, chemical fungicides have been the primary approach to anthracnose control. However, recent trends and regulations have sought to limit the use of these substances. Greener management includes a group of sustainable alternatives that use natural substances and microorganisms to control postharvest fungi. This comprehensive review of contemporary research presents various sustainable alternatives to C. gloeosporioides postharvest control in vitro and in situ, ranging from the use of biopolymers, essential oils, and antagonistic microorganisms to cultivar resistance. Strategies such as encapsulation, biofilms, coatings, compounds secreted, antibiotics, and lytic enzyme production by microorganisms are revised. Finally, the potential effects of climate change on C. gloeosporioides and anthracnose disease are explored. Greener management can provide a possible replacement for the conventional approach of using chemical fungicides for anthracnose postharvest control. It presents diverse methodologies that are not mutually exclusive and can be in tune with the needs and interests of new consumers and the environment. Overall, developing or using these alternatives has strong potential for improving sustainability and addressing the challenges generated by climate change.

RESUMEN

Biofilms represent an evolutionary form of life, which translates from life in free-living cells to a community lifestyle. In natural habitats, biofilms are a multispecies complex, where synergies or antagonisms can be established. For example, Listeria monocytogenes and Pseudomonas fluorescens are associated with a dual-species biofilm that is widespread in dairy plants. In food plants, multiple strategies are devised to control biofilms, including natural compounds such as essential oils (EOs). In this respect, this study evaluated the effectiveness of Thymbra capitata (L.) Cav. (TEO) and Cinnamomum zeylanicum (CEO) against a dual-species biofilm of L. monocytogenes and P. fluorescens, mimicking dairy process conditions. Based on Minimum Inhibitory Concentrations results, the EOs concentration (10 µL/mL) was chosen for the antibiofilm assay at 12°C on polystyrene (PS), and stainless-steel surfaces for 168 h, using a Ricotta-based model system as culture medium. Biofilm biomass was assessed by crystal violet staining, and the planktonic and sessile cells were quantified in terms of Log CFU/cm2. Results showed that CEO displayed the greatest antibiofilm activity, reducing significantly (P<0.05) P. fluorescens and L. monocytogenes sessile cells of about 2.5 and 2.8 Log CFU/cm2 after 72 h, respectively. However, L. monocytogenes gained the protection of P. fluorescens, evading CEO treatment and showing a minimal sessile cell reduction of 0.7 Log CFU/cm2 after 72 h. Considering the outcome of this study, CEO might have promising perspectives for applications in dairy facilities.

RESUMEN

To date, the impossibility of treating resistant forms of bacteria and fungi (AMR) with traditional drugs is a cause for global alarm. We have made the green synthesis of Argirium silver ultra nanoclusters (Argirium-SUNCs) very effective against resistant bacteria (< 1 ppm) and mature biofilm (0.6 ppm). In vitro and preclinical tests indicate that SUNCs are approximately 10 times less toxic in human cells than bacteria. Unique chemical-physical characteristics such as particle size < 2 nm, a core composed of Ag0, and a shell of Ag +, Ag2+ , Ag3+ never observed before in stable form in ultra pure water, explain their remarkable redox properties Otto Cars (Lancet Glob. Health 9:6, 2021). Here we show that Argirium-SUNCs have strong antimicrobial properties also against resistant Aspergillus niger GM31 mycelia and spore inactivation (0.6 ppm). The membrane depolarization is a primary target leading to cell death as already observed in bacteria. Being effective against both bacteria and fungi Argirium-SUNCs represent a completely different tool for the treatment of infectious diseases.

Asunto(s)

RESUMEN

The SARS-CoV-2 pandemic is being questioned for its possible food transmission, due to several reports of the virus on food, outbreaks developed in food companies, as well as its origins linked to the wet market of Wuhan, China. The purpose of this review is to analyze the scientific evidence gathered so far on the relationship between food and the pandemic, considering all aspects of the food system that can be involved. The collected data indicate that there is no evidence that foods represent a risk for the transmission of SARS-CoV-2. In fact, even if the virus can persist on food surfaces, there are currently no proven cases of infection from food. Moreover, the pandemic showed to have deeply influenced the eating habits of consumers and their purchasing methods, but also to have enhanced food waste and poverty. Another important finding is the role of meat processing plants as suitable environments for the onset of outbreaks. Lessons learned from the pandemic include the correct management of spaces, food hygiene education for both food workers and common people, the enhancement of alternative commercial channels, the reorganization of food activities, in particular wet markets, and intensive farming, following correct hygiene practices. All these outcomes lead to another crucial lesson, which is the importance of the resilience of the food system. These lessons should be assimilated to deal with the present pandemic and possible future emergencies. Future research directions include further investigation of the factors linked to the food system that can favor the emergence of viruses, and of innovative technologies that can reduce viral transmission.

RESUMEN

Sheep meat is consumed and appreciated all over the world for its nutritional value and flavor. However, this meat is very perishable and easily subjected to the action of both spoilage and pathogenic microorganisms. For this reason, in combination with cold storage, effective preservation techniques are required. There is increasing interest in the application of natural antimicrobials, such as essential oils, extracts, spices, and by-products of the food industry. This review analyses the studies on natural antimicrobials in sheep meat and sheep meat products and gathers evidence about the encouraging results achieved on the reduction and/or elimination of spoilage and pathogenic microorganisms. The use of these natural antimicrobial alternatives might open up important perspectives for industrial application, considering that this specific meat is often traded over long distances. In fact, on the basis of scientific literature, natural antimicrobials can be considered a sustainable and affordable alternative to extend the shelf life of sheep meat and guarantee its safety, although many factors need to be further investigated, such as the sensory impact, potential toxicity, and economic aspects. For all these issues, investigated in some of the studies reviewed here, it is fundamental to obtain the antimicrobial effect with the minimum amount of effective substance to avoid sensory modifications, toxic effects, and unbearable costs. This study sets foundations for the possible direction of future studies, which will contribute to identify effective solutions for industrial applications of natural antimicrobials in the sheep meat industry.

Asunto(s)

RESUMEN

Yeasts isolated from the worker caste of the Colombian leaf-cutting ant, Atta cephalotes (Hymenoptera: Myrmicinae) were cultured and identified by molecular methods. Abundant, persistent, and omnipresent species were classified as "prevalent". Experimental data were compared with information gathered from published reports on the yeast species composition in other leaf-cutting ant species. Diversity analysis was conducted using diversity values (q0, q1, and q2) to compare the richness and abundance of yeasts present in different leaf-cutting ant species. Clustering analysis was carried out to assess the similarity of yeast community according to ant species. The yeast species composition was highly variable among the ant species. A. laevigata and A. capiguara showed the highest degree of similarity and differed from the group composed by A. cephalotes, A. sexdens, A. sexdens rubropilosa, and A. texana. The isolation of dominant yeasts in different ant castes within the different compartments of a colony strongly suggests that the identified microorganisms are not transient but are native to the soil surrounding ant colonies and the substrates used by the ants to grow their fungal cultivars. It is apparent that the ant-fungus mutualism does not operate in an environment devoid of other microbes, but rather that the association must be seen within the context of a background of other microorganisms, particularly the dominant yeasts.

Asunto(s)

RESUMEN

In this work, we determined the degree of filamentous fungi contamination in cocoa fermented seeds and the fungal potential to produce enzymes that could contribute to the cocoa quality. Internal transcribed spacer amplicon sequencing (ITS) showed 11 different species with Byssochlamys spectabilis, Aspergillus niger, Aspergillus flavus, Aspergillus carbonarius, Circinella muscae and Penicillium citrinum as the most abundant species. Our results evidenced intra and inter-species differences in the enzymes production. Cellulases, ß-glucosidase, ornithine decarboxylase and phenylalanine decarboxylase were the most diffused enzymes expressed in the 53 strains here studied. Moreover, A. niger (6/12), A. carbonarius (2/3), and P. citrinum (3/3) showed high pectinolytic activity. Remarkable was the amino decarboxylase activity of P. citrinum, and A. flavus strains. For the first time we reported the presence of B. spectabilis in cocoa fermented beans, which could play an important role in the biogenic amines formation. In addition, we explored the capability of the Aspergillus section Nigri strains, to produce ochratoxin A (OTA) in a cacao model system (CPMS) and in malt extract medium (MEL). We observed that CPMS, but not MEL, stimulated the OTA production in 6 out 15 strains of Aspergillus section Nigri, reaching values ranging between 1.70 and 4995 µg OTA kg-1 dry mycelium.

Asunto(s)

RESUMEN

This research aimed to evaluate the impact of atmospheric cold plasma (ACP) treatment on the fungal spores naturally present in sundried tomatoes, as well as their influence on the physico-chemical properties and antioxidant activity. ACP was performed with a Surface Dielectric Barrier Discharge (SDBD), applying 6 kV at 23 kHz and exposure times up to 30 min. The results showed a significant reduction of mesophilic aerobic bacteria population and of filamentous fungi after the longer ACP exposure. In particular, the effect of the treatment was assessed on Aspergillus rugulovalvus (as sensible strain) and Aspergillus niger (as resistant strain). The germination of the spores was observed to be reliant on the species, with nearly 88% and 32% of non-germinated spores for A. rugulovalvus and A. niger, respectively. Fluorescence probes revealed that ACP affects spore viability promoting strong damage to the wall and cellular membrane. For the first time, the sporicidal effect of ACP against A. rugulovalvus is reported. Physicochemical parameters of sundried tomatoes such as pH and water activity (aw) were not affected by the ACP treatment; on the contrary, the antioxidant activity was not affected while the lycopene content was significantly increased with the increase in ACP exposure time (p ≤ 0.05) probably due to increased extractability.

RESUMEN

Microbial biofilms represent a constant source of contamination in the food industry, being also a real threat for human health. In fact, most of biofilm-producing bacteria are becoming resistant to sanitizers, thus arousing the interest in natural alternatives to prevent biofilm formation on foods and food-contact surfaces. In particular, studies on biofilm control by essential oils (EOs) application are increasing, being EOs characterized by unique mixtures of compounds able to impair the mechanisms of biofilm development. This review reports the anti-biofilm properties of EOs in bacterial biofilm control (inhibition, removal and prevention of biofilm dispersion) on food-contact surfaces. The relationship between EOs effect and composition, concentration, involved bacteria, and surfaces is discussed, and the possible sites of action are also elucidated. The findings prove the high biofilm controlling capability of EOs through the regulation of genes and proteins implicated in motility, Quorum Sensing and exopolysaccharides (EPS) matrix. Moreover, incorporation in nanosized delivery systems, formulation of blends and combination of EOs with other strategies can increase their anti-biofilm activity. This review provides an overview of the current knowledge of the EOs effectiveness in controlling bacterial biofilm on food-contact surfaces, providing valuable information for improving EOs use as sanitizers in food industries.

Asunto(s)

RESUMEN

AIMS: This study aimed to evaluate the effectiveness of selected essential oils (EOs) and hydrolates (Hs) against Listeria monocytogenes biofilms on polystyrene (PS) and stainless steel (SS) surfaces. METHODS AND RESULTS: Among others, Origanum hirtum EO, Corydothymus capitatus EO and Citrus aurantium H were selected to treat L. monocytogenes biofilms during and after biofilm formation. Sub-minimum inhibitory concentrations (MICs) of C. capitatus EO (0.31 µl/ml) showed the highest inhibiting effect against biofilm formation on PS, while on SS no significant differences between the EOs were observed (43.7%-88.7% inhibition). Overall, the tested biosanitizers showed limited activity as biofilm removal agents. Although generally less effective, C. aurantium H exhibited good biofilm inhibition performance at 62.5 µl/ml, particularly on PS. Confocal laser scanning microscopy proved that sub-MICs of the biosanitizers drastically changed L. monocytogenes biofilm architecture, with bacterial cells elongation in the presence of C. capitatus EO. CONCLUSIONS: Our findings suggest that the tested EOs and H are able to control Listeria biofilms, particularly preventing biofilm formation on both materials. Considering its mild aroma and hydrophilicity, the H exhibited promising perspectives of application. SIGNIFICANCE AND IMPACT OF STUDY: This study raises the possibility of applying EOs and Hs to control biofilms on different surfaces in the food industry.

Asunto(s)

RESUMEN

Anthracnose of papaya (Carica papaya L.) caused by the fungus Colletotrichum spp. is one of the most economically important postharvest diseases. Coating with chitosan (CS) and Ruta graveolens essential oil (REO) might represent a novel eco-friendly method to prevent postharvest anthracnose infection. These compounds show both antimicrobial and eliciting activities, although the molecular mechanisms in papaya have not been investigated to date. In this study, the effectiveness of CS and REO alone and combined (CS-REO) on postharvest anthracnose of papaya fruit during storage were investigated, along with the expression of selected genes involved in plant defense mechanisms. Anthracnose incidence was reduced with CS, REO, and CS-REO emulsions after 9 days storage at 25°C, by 8, 21, and 37%, respectively, with disease severity reduced by 22, 29, and 44%, respectively. Thus, McKinney's decay index was reduced by 22, 30, and 44%, respectively. A protocol based on reverse transcription quantitative real-time PCR (RT-qPCR) was validated for 17 papaya target genes linked to signaling pathways that regulate plant defense, pathogenesis-related protein, cell wall-degrading enzymes, oxidative stress, abiotic stress, and the phenylpropanoid pathway. CS induced gene upregulation mainly at 6 h posttreatment (hpt) and 48 hpt, while REO induced the highest upregulation at 0.5 hpt, which then decreased over time. Furthermore, CS-REO treatment delayed gene upregulation by REO alone, from 0.5 to 6 hpt, and kept that longer over time. This study suggests that CS stabilizes the volatile and/or hydrophobic substances of highly reactive essential oils. The additive effects of CS and REO were able to reduce postharvest decay and affect gene expression in papaya fruit.

RESUMEN

This work highlights how our silver ultra nanoclusters (ARGIRIUM-SUNc) hand-made synthesized, are very useful as a bactericide and anti-biofilm agent. The Argirium-SUNc effective antibacterial concentrations are very low (< 1 ppm) as compared to the corresponding values reported in the literature. Different bacterial defense mechanisms are observed dependent on ARGIRIUM-SUNc concentrations. Biochemical investigations (volatilome) have been performed to understand the pathways involved in cell death. By using fluorescence techniques and cell viability measurements we show, for the first time, that membrane depolarization and calcium intracellular level are both primary events in bacteria death. The ARGIRIUM-SUNc determined eradication of different biofilm at a concentration as low as 0.6 ppm. This suggests that the effect of the nanoparticles follows a common mechanism in different bacteria. It is highly probable that the chemical constitution of the crosslinks could be a key target in the disrupting mechanism of our nanoparticles. Since the biofilms and their constituents are essential for bacterial survival in contact with humans, the silver nanoparticles represent a logical target for new antibacterial treatments.

Asunto(s)

RESUMEN

Among pathogens, L. monocytogenes has the capability to persist on Food Processing Environment (FPE), first of all posing safety issues, then economic impact on productivity. The aim of this work was to determine the influence of biofilm forming-ability and molecular features on the persistence of 19 Listeria monocytogenes isolates obtained from FPE, raw and processed products of a cold-smoked salmon processing plant. To verify the phenotypic and genomic correlations among the isolates, different analyses were employed: serotyping, Clonal Complex (CC), core genome Multi-Locus Sequence Typing (cgMLST) and Single Nucleotide Polymorphisms (SNPs) clustering, and evaluation of the presence of virulence- and persistence-associated genes. From our results, the biofilm formation was significantly higher (*P < 0.05) at 37 °C, compared to 30 and 12 °C, suggesting a temperature-dependent behaviour. Moreover, the biofilm-forming ability showed a strain-specific trend, not correlated with CC or with strains persistence. Instead, the presence of internalin (inL), Stress Survival Islet (SSI) and resistance to erythromycin (ermC) genes was correlated with the ability to produce biofilms. Our data demonstrate that the genetic profile influences the adhesion capacity and persistence of L. monocytogenes in food processing plants and could be the result of environmental adaptation in response to the external selective pressure.

Asunto(s)

RESUMEN

Drug resistance in antifungal therapy, a problem unknown until a few years ago, is increasingly assuming importance especially in immunosuppressed patients and patients receiving chemotherapy and radiotherapy. In the past years, the use of essential oils as an approach to improve the effectiveness of antifungal agents and to reduce antifungal resistance levels has been proposed. Our research aimed to evaluate the antifungal activity of Colombian rue, Ruta graveolens, essential oil (REO) against clinical strains of Candida albicans, Candida parapsilopsis, Candida glabrata, and Candida tropicalis. Data obtained showed that C. tropicalis and C. albicans were the most sensitive strains showing minimum inhibitory concentrations (MIC) of 4.1 and 8.2 µg/mL of REO. Time-kill kinetics assay demonstrated that REO showed a fungicidal effect against C. tropicalis and a fungistatic effect against C. albicans. In addition, an amount of 40% of the biofilm formed by C. albicans was eradicated using 8.2 µg/mL of REO after 1 h of exposure. The synergistic effect of REO together with some antifungal compounds was also investigated. Fractional inhibitory concentration index (FICI) showed synergic effects of REO combined with amphotericin B. REO Lead a disruption in the cellular membrane integrity, consequently resulting in increased intracellular leakage of the macromolecules, thus confirming that the plasma membrane is a target of the mode of action of REO against C. albicans and C. tropicalis.

RESUMEN

The cocoa pod husk is considered a source of dietary fiber with a high content of water-soluble pectins, bioactive compounds which should be viewed as a by-product with the potential to be incorporated into food. This study aimed to investigate the effect of adding different cocoa pod husk flour (CPHF) levels as a starch replacement for reformulating frankfurters. Results showed that the addition of 1.5 and 3.0% pod husk proportionally increased the frankfurter's fiber content by 0.49 ± 0.08 and 0.96 ± 0.19 g/100 g, which is acceptable for a product that does not contain fiber. Textural properties and sensory characteristics were affected when substituting the starch with CPHF, either totally or partially, although these samples had higher water content, hardness, and adhesiveness while springiness decreased. Non-adverse effects of nitrite on polyphenolic compounds content were evidenced in samples enriched with CPHF. The incorporation of CPHF did not significantly affect the color parameters (ΔE < 3). Finally, the panelists indicated a sensation of the unsalted sausage, suggesting that CPHF may have natural mucoadhesion properties. In conclusion, in formulated meat products such as sausages, plant co-products such as cacao pod husks could be a valid new ingredient to improve technological parameters, functional characteristics, and stability.