Treatment with lauric arginate ethyl ester and commercial bacteriophage, alone or in combination, inhibits Listeria monocytogenes in chicken breast tissue

Thermal Inactivation of Escherichia Phage OSYSP and Host Strain Escherichia coli O157:H7 EDL933: A Comparative Kinetic Analysis

Lytic bacteriophages are promising biocontrol agents against pathogenic bacteria for food and therapeutic applications. Investigating the feasibility of combining phage and physical lethal agents, such as heat, as an effective hurdle combination could lead to beneficial applications. The current research was initiated to compare the thermal inactivation kinetics of a lytic phage (Escherichia phage OSYSP) and its host (Shiga toxin-producing Escherichia coli O157:H7 EDL933), considering they have different critical thermal targets in their structures. To provide a basis for comparison, thermal inactivation kinetics were determined on suspensions of these agents in buffered peptone water using a thermally controlled circulating water bath. Results showed that the bacteriophage virions have a remarkable heat resistance (p < 0.05) compared to their host cells. The D-values of the populations of phage (PFU/mL) and EDL933 strain (CFU/mL) were 166.7 and 7.3 min at 55°C, compared to 44.4 and 0.3 min at 60°C, respectively. Additionally, D-values were significantly (p < 0.05) more influenced by temperature changes in the case of E. coli O157:H7 EDL933 (z-value 3.7°C) compared to that for phage OSYSP (z-value 7.7°C). When the phage suspension was heat-treated in a thermal cycler instead of a water bath, no significant differences between the two treatment procedures (p > 0.05) in estimating virus D- and z-values were observed. Based on these findings, it may be feasible to combine phage OSYSP with mild heat during processing of food to selectively inactivate E. coli O157:H7 EDL933 and subsequently maintain product safety during storage by the surviving phage population; however, the feasibility of this application needs to be investigated. Additionally, the relatively heat-resistant phage OSYSP could qualify as a biological indicator to validate thermal treatments of minimally processed foods in which E. coli O157:H7 EDL933 is the pathogen-of-concern.

Investigation of the Suitability of a Combination of Ethyl-Να-dodecanyl-L-arginat_HCl (LAE) and Starter Culture Bacteria for the Reduction of Bacteria from Fresh Meat of Different Animal Species

Meat can be contaminated with (pathogenic) microorganisms during slaughter, dissection and packaging. Therefore, preservation technologies are frequently used to reduce the risk of (fatal) human infections due to the consumption of meat. In this study, we first investigated, if the application of ethyl-Nα-dodecanyl-L-arginate hydrochloride (LAE) and the starter culture bacteria Staphylococcus carnosus and Lactobacillus sakei, either single or in combination, influences the bacteria number on pork, chicken meat and beef, inoculated with Brochothrix (Br.) thermosphacta (all meat species) or Salmonella (S.) Typhimurium (pork), Campylobacter (C.) jejuni (chicken) and Listeria (L.) monocytogenes (beef), before packaging under modified atmosphere and on days 7 and 14 of storage. To evaluate effects of the treatment on the appearance during storage, additionally, the physicochemical parameters color and myoglobin redox form percentages were analyzed. LAE regularly resulted in a significant reduction of the number of all bacteria species on day 1 of storage, whereas up to day 14 of storage, the preservation effect did not persist in nearly all samples, except in the beef with Br. thermosphacta. However, with the starter culture bacteria on day 1, only L. monocytogenes on beef was significantly reduced. Interestingly, on day 7 of storage, this reducing effect was also found with S. Typhimurium on pork. Br. thermosphacta, which was principally not influenced by the starter culture bacteria. The combinatory treatment mainly resulted in no additional effects, except for the S. Typhimurium and Br. thermosphacta results on pork on day 7 and the Br. thermosphacta results on beef on day 14. The physicochemical parameters were not influenced by the single and combinatory treatment. The results indicate that LAE was mainly responsible for the antimicrobial effects and that a combination with starter culture bacteria should be individually evaluated for the meat species.

The effects of novel alginate-lauric arginate coatings with temperature on bacterial quality, oxidative stability, and organoleptic characteristics of frozen stored chicken drumsticks

Although alginate has been reported to be used as an edible film and coating in food, to the best of our knowledge, this study is the first to investigate the individual effects of coatings, temperatures, storage times, as well as their interactions, on the bacterial quality, deterioration criteria, and sensory attributes of chicken drumsticks. To accomplish this, six groups of chicken drumsticks were treated with different coatings, temperatures, and storage conditions. The groups included 2 % alginate at 25 °C (Alg₂₅) and 50 °C (Alg₅₀), a mixture of 2 % alginate and 2 % LAE at 25 °C (M₂₅) and 50 °C (M₅₀), besides control untreated samples in distilled water at 25 °C (C₂₅) and 50 °C (C₅₀). The chicken drumsticks were stored at -18 °C for 3 months. The results showed that all treated chicken drumsticks induced a significant reduction in all bacterial counts, as well as a significant decrease in pH and thiobarbituric acid values, with an improvement in all sensory attributes, particularly in the M₂₅ and M₅₀ coated samples compared to the C₂₅ and C₅₀. Furthermore, exposing alginate and LAE to a temperature of 50 °C can increase their antimicrobial activity. In conclusion, the innovative combinations of LAE and alginate can be used successfully to decontaminate chicken carcasses in poultry processing plants.

Lauric arginate ethyl ester: An update on the antimicrobial potential and application in the food systems

Lauric arginate ethyl ester (LAE), a cationic surfactant with low toxicity, displays excellent antimicrobial activity against a broad range of microorganisms. LAE has been approved as generally recognized as safe (GRAS) for widespread application in certain foods at a maximum concentration of 200 ppm. In this context, extensive research has been carried out on the application of LAE in food preservation for improving the microbiological safety and quality characteristics of various food products. This study aims to present a general review of recent research progress on the antimicrobial efficacy of LAE and its application in the food industry. It covers the physicochemical properties, antimicrobial efficacy of LAE, and the underlying mechanism of its action. This review also summarizes the application of LAE in various foods products as well as its influence on the nutritional and sensory properties of such foods. Additionally, the main factors influencing the antimicrobial efficacy of LAE are reviewed in this work, and combination strategies are provided to enhance the antimicrobial potency of LAE. Finally, the concluding remarks and possible recommendations for the future research are also presented in this review. In summary, LAE has the great potential application in the food industry. Overall, the present review intends to improve the application of LAE in food preservation.

Sustainable bio-based antimicrobials derived from fatty acids: Synthesis, safety, and efficacy

Some conventional sanitizers and antibiotics used in food industry may be of concerns due to generation of toxic byproducts, impact on the environment, and the emergence of antibiotic resistance bacteria. Bio-based antimicrobials can be an alternative to conventional sanitizers since they are produced from renewable resources, and the bacterial resistance to these compounds is of less concern than those of currently used antibiotics. Among the bio-based antimicrobial compounds, those produced via either fermentation or chemical synthesis by covalently or electrovalently attaching specific moieties to the fatty acid have drawn attention in recent years. Disaccharide, arginine, vitamin B1, and phenolics are linked to fatty acids resulting in the production of sophorolipid, lauric arginate ethyl ester, thiamin dilauryl sulfate, and phenolic branched-chain fatty acid, respectively, all of which are reported to exhibit antimicrobial activity by targeting the cell membrane of the bacteria. Also, studies that applied these compounds as food preservatives by combining them with other compounds or treatments have been reviewed regarding extending the shelf life and inactivating foodborne pathogens of foods and food products. In addition, the phenolic branched-chain fatty acids, which are relatively new compounds compared to the others, are highlighted in this review.

Application and challenge of bacteriophage in the food protection

In recent years, foodborne diseases caused by pathogens have been increasing. Therefore, it is essential to control the growth and transmission of pathogens. Bacteriophages (phages) have the potential to play an important role in the biological prevention, control, and treatment of these foodborne diseases due to their favorable advantages. Phages not only effectively inhibit pathogenic bacteria and prolong the shelf life of food, but also possess the advantages of specificity and an absence of chemical residues. Currently, there are many cases of phage applications in agriculture, animal disease prevention and control, food safety, and the treatment of drug-resistant disease. In this review, we summarize the recent research progress on phages against foodborne pathogenic bacteria, including Escherichia coli, Salmonella, Campylobacter, Listeria monocytogenes, Shigella, Vibrio parahaemolyticus, and Staphylococcus aureus. We also discuss the main issues and their corresponding solutions in the application of phages in the food industry. In recent years, although researchers have discovered more phages with potential applications in the food industry, most researchers use these phages based on their host spectrum, and the application environment is mostly in the laboratory. Therefore, the practical application of these phages in different aspects of the food industry may be unsatisfactory and even have some negative effects. Thus, we suggest that before using these phages, it is necessary to identify their specific receptors. Using their specific receptors as the selection basis for their application and combining phages with other phages or phages with traditional antibacterial agents may further improve their safety and application efficiency. Collectively, this review provides a theoretical reference for the basic research and application of phages in the food industry.

Isolation, characterization, and genomic analysis of the novel T4-like bacteriophage ΦCJ20

Pathogenic Escherichia coli infections have been consistently reported annually. The basic characteristics and genome of the newly isolated ΦCJ20 from swine feces was analyzed. To determine basic characteristics, dotting assays and double-layer agar assays were conducted. Bacteriophage particles were analyzed via transmission electron microscopy. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was performed to determine the sizes of major structural proteins. The complete genome of the phage was analyzed. Bacteriophage particles were identified as Myoviridae, with a head measuring 110.57 ± 1.89 nm and a contractile tail measuring 107.97 ± 3.20 nm and were found to infect E. coli. Major structural proteins of ΦCJ20 showed two well-pronounced bands of approximately 53.6 and 70.9 kDa. The genome size of ΦCJ20 was 169,884 bp, and 118 of 307 open reading frames were annotated. This study provides a baseline for the development of E. coli infection treatment strategies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-021-00906-y.

Cranberry extract-based formulations for preventing bacterial biofilms

Generating formulations for the delivery of a mixture of natural compounds extracted from natural sources is a challenge because of unknown active and inactive ingredients and possible interactions between them. As one example, natural cranberry extracts have been proposed for the prevention of biofilm formation on dental pellicle or teeth. However, such extracts may contain phenolic acids, flavonol glycosides along with other constituents like coumaroyl iridoid glycosides, flavonoids, alpha-linolenic acid, n-6 (or n-3) fatty acids, and crude fiber. Due to the presence of a variety of compounds, determining which molecules (and how many molecules) are essential for preventing biofilm growth is nontrivial to ascertain. Therefore, a formulation that could contain natural, unrefined, cranberry extract (with all its constituent compounds) at high loading would be ideal. Accordingly, we have generated several candidate formulations including poly(lactic-co-glycolic) acid (PLGA)-based microencapsulation of cranberry extract (CE15) as well as formulations including stearic acid along with polyvinylpyrrolidone (PVP) or Ethyl lauroyl arginate (LAE) complexed with cranberry extracts (CE15). We found that stearic acid in combination with PVP or LAE as excipients led to higher loading of the active and inactive compounds in CE15 as compared with a PLGA microencapsulation and also sustained release of CE15 in a tunable manner. Using this method, we have been able to generate two successful formulations (one preventative based, one treatment based) that effectively inhibit biofilm growth when incubated with saliva. In addition to cranberry extract, this technique could also be a promising candidate for other natural extracts to form controlled release systems.Graphical abstract.

Micro/nanoencapsulation strategy to improve the efficiency of natural antimicrobials against Listeria monocytogenes in food products

Listeria monocytogenes (Lm), the etiological agent of listeriosis diseases in humans, is a serious pathogenic microorganism threatening the food safety especially in ready-to-eat food products. Adhesion on both biotic and abiotic surfaces is making it a potential source of contamination by Lm. Also, this bacterium has become more tolerant in food processing conditions, including in the presence of adverse conditions such as cold and dehydration. One of the attractive and effective methods to inhibit the growth of Lm in the food products is using natural antimicrobial agents, which can be a suitable alternative to synthetic preservatives for producing organic food products. The use of pure natural antimicrobials has some limitations including low stability against harsh conditions, low solubility and absorption, and un-controlled release, which can decrease their functions. These limitations have been overcome by using new advanced encapsulation techniques, which have boosted the anti-listerial activity of natural agents. Therefore, the current paper is aiming to review the results of recent studies conducted on using natural antimicrobials added directly or as encapsulated forms into the food formulation to control the growth of Lm. The information of current study can be used by the researchers as well as the food companies for the optimization of food formulations through encapsulation strategies to control Lm and potentially produce safe foods for the consumers.

Inactivation of Pseudomonas deceptionensis CM2 on chicken breasts using plasma-activated water

The aim of this study was to examine the effectiveness of plasma-activated water (PAW) for inactivating Pseudomonas deceptionensis CM2 on chicken breasts. Sterile distilled water (SDW) was activated by gliding arc discharge plasma for 60 s, which was defined as PAW60. The chicken breast samples inoculated P. deceptionensis CM2 were dipped in PAW60 or SDW for the indicated time intervals, respectively. After the treatment of PAW60 for 12 min, the population of P. deceptionensis CM2 on chicken breast was significantly reduced by 1.05 log₁₀ CFU/g (p < 0.05), which was higher than that of SDW-treated samples for the same time intervals (p < 0.05). The L* value of chicken breasts were increased whereas a* and b* values were decreased following PAW60 treatment, while there was no significant differences in the values of a* and b* between PAW60- and SDW-treated samples for the same time intervals (p > 0.05). As compared with SDW, PAW60 caused no significant changes in the texture characteristics (e.g. hardness, springiness, cohesiveness and gumminess) and sensory properties (e.g. appearance, color, odor, texture, acceptability). Thus, PAW can be very effective to improve microbiological safety of chicken breasts with resulting slight changes to the sensory qualities. This synergistic treatment of PAW with other non-thermal technologies should be well investigated in order to improve inactivation efficacy of PAW.

Whole-Genome Sequencing and Genomic Analysis of a Virulent Bacteriophage Infecting Bacillus cereus

OBJECTIVE

Infants with a weak immune system are prone to infection with Bacillus cereus, which is commonly found in natural environments. With the aim of achieving better control of this pathogenic bacterium, in the present study we characterized a new bacteriophage, ΦBC01.

METHODS

Bacteriophage particles were analyzed by transmission electron microscopy. Factors influencing adsorption were identified in a double-layer plaque assay. Sodium dodecyl sulfate polyacrylamide gel electrophoresis was conducted to determine the size of major structural proteins. The complete genome of the phage was analyzed.

RESULTS

Bacteriophage particles (105.3 ± 3.1 nm icosahedral head and 208.8 ± 3.6 nm contractile tail) were identified as Myoviridae. ΦBC01 was found to have host specificity to B. cereus. Major structural proteins of ΦBC01 showed 2 well-pronounced bands of 99 and 56 kDa. The 158,385-bp genome sequence of ΦBC01 was determined: 56 of the 239 open reading frames were annotated, indicating involvement in bacteriophage DNA manipulation, cell lysis, packaging, virion structure, and other functions.

CONCLUSION

Because of characterization and genotyping of a new bacteriophage from soil samples containing earthworms, this study provides a baseline for the development of alternatives to antibiotics.

Listeria monocytogenes in Food-Processing Facilities, Food Contamination, and Human Listeriosis: The Brazilian Scenario

Listeria monocytogenes is a foodborne pathogen that contaminates food-processing environments and persists within biofilms on equipment, utensils, floors, and drains, ultimately reaching final products by cross-contamination. This pathogen grows even under high salt conditions or refrigeration temperatures, remaining viable in various food products until the end of their shelf life. While the estimated incidence of listeriosis is lower than other enteric illnesses, infections caused by L. monocytogenes are more likely to lead to hospitalizations and fatalities. Despite the description of L. monocytogenes occurrence in Brazilian food-processing facilities and foods, there is a lack of consistent data regarding listeriosis cases and outbreaks directly associated with food consumption. Listeriosis requires rapid treatment with antibiotics and most drugs suitable for Gram-positive bacteria are effective against L. monocytogenes. Only a minority of clinical antibiotic-resistant L. monocytogenes strains have been described so far; whereas many strains recovered from food-processing facilities and foods exhibited resistance to antimicrobials not suitable against listeriosis. L. monocytogenes control in food industries is a challenge, demanding proper cleaning and application of sanitization procedures to eliminate this foodborne pathogen from the food-processing environment and ensure food safety. This review focuses on presenting the L. monocytogenes distribution in food-processing environment, food contamination, and control in the food industry, as well as the consequences of listeriosis to human health, providing a comparison of the current Brazilian situation with the international scenario.