Isolation, characterization, and application of bacteriophage on Vibrio parahaemolyticus biofilm to control seafood contamination

OBJECTIVE

This study intended to isolate a Vibrio-particular phage from the natural environment, analyse its characteristics and genome sequence, and investigate its reduction effect on V. parahaemolyticus biofilm as a biocontrol agent in squid and mackerel.

METHODS

Among 21 phages, phage CAU_VPP01, isolated from beach mud, was chosen for further experiments based on host range and EOP tests. When examining the reduction effect of phage CAU_VPP01 against Vibrio parahaemolyticus biofilms on surfaces (stainless steel [SS] and polyethylene terephthalate [PET]) and food surfaces (squid and mackerel).

RESULTS

The phage showed the most excellent reduction effect at a multiplicity-of-infection (MOI) 10. Three-dimensional images acquired with confocal laser scanning microscopy (CLSM) analysis were quantified using COMSTAT, which showed that biomass, average thickness, and roughness coefficient decreased when treated with the phage. Colour and texture analysis confirmed that the quality of squid and mackerel was maintained after the phage treatment. Finally, a comparison of gene expression levels determined by qRT-PCR analysis showed that the phage treatment induced a decrease in the gene expression of flaA, vp0962, andluxS, as examples.

CONCLUSION

This study indicated that Vibrio-specific phage CAU_VPP01 effectively controlled V. parahaemolyticus biofilms under various conditions and confirmed that the isolated phage could possibly be used as an effective biocontrol weapon in the seafood manufacturing industry.

First organic fluorescence immunoassay for the detection of Enterobacter cloacae in food matrixes

For the first time, a novel fluorescent moiety, 2-amino-4-(7-formyl-1,8-dihydropyren-2-yl)-7-hydroxy-4H-chromene-3-carbonitrile (ACC), was synthesized by an ultrasonication method. The synthesis of this moiety was confirmed via structural elucidation using FTIR and NMR spectroscopy techniques. Further, photophysical properties of the fluorescent moiety were tested using UV-visible and emission spectroscopy techniques. In this case, the moiety was tagged with an antibody of Enterobacter cloacae via 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide (EDC/NHS) coupling and applied as a sensing element for the detection of Enterobacter cloacae (E. cloacae) by UV-visible and emission spectroscopy techniques. The developed fluorescent sensor detected E. cloacae via a FRET mechanism. Under optimized conditions, ACC-anti-E. cloacae detected E. cloacae in the linear range from 101 to 1010 CFU mL-1 with a limit of detection (LOD) of 10.55 CFU mL-1. The developed sensor was applied for the detection of E. cloacae in food samples such as orange, pomegranate, milk, rice, tomato, potato and onion.

Identification and Characterization of Microorganisms Isolated from Non-compliant and/or Atypical Dairy Products in Canada

Despite good manufacturing practices and rigorous cleaning and sanitizing procedures established in dairy processing plants, microbiological contamination remains the main cause of products being non-compliant and/or atypical and hence not fit for human consumption. The objective of this study was to isolate, identify and characterize bacteria, yeasts and molds associated with substandard dairy products in Canada and to create a collection of reference isolates. In addition to conventional microbiological characterization, each isolate was tested for biofilm-forming ability and susceptibility to heat, antimicrobial agents, and common industrial disinfectants. Among the 105 microbial strains isolated from pasteurized milk, cream, and cheese samples, 24 bacterial isolates, belonging mainly to the genus Pseudomonas, were shown to be moderate or strong biofilm producers in 96-well plates and highly resistant to peracetic acid (100 ppm, 5 min contact time) and sodium hypochlorite (70 ppm, 5 min contact time). In addition, 56 bacterial isolates, including Acinetobacter baumannii, Enterobacter bugandensis, Klebsiella pneumoniae and Pseudomonas spp., were found resistant to ampicillin, fosfomycin and/or ceftriaxone, while 14 others, such as Bacillus spp. and Macrococcus spp., withstood a heat treatment equivalent to low-temperature long-time pasteurization (63°C for 30 min). This descriptive study provides new information on potential problematic microorganisms in dairies and will guide the development of novel control strategies intended to prevent and reduce microbiological contamination and the associated economic losses.

The use of biomimetic surfaces to reduce single- and dual-species biofilms of Escherichia coli and Pseudomonas putida

The ability of bacteria to adhere to and form biofilms on food contact surfaces poses serious challenges, as these may lead to the cross-contamination of food products. Biomimetic topographic surface modifications have been explored to enhance the antifouling performance of materials. In this study, the topography of two plant leaves, Brassica oleracea var. botrytis (cauliflower, CF) and Brassica oleracea capitate (white cabbage, WC), was replicated through wax moulding, and their antibiofilm potential was tested against single- and dual-species biofilms of Escherichia coli and Pseudomonas putida. Biomimetic surfaces exhibited higher roughness values (SaWC = 4.0 ± 1.0 μm and SaCF = 3.3 ± 1.0 μm) than the flat control (SaF = 0.6 ± 0.2 μm), whilst the CF surface demonstrated a lower interfacial free energy (ΔGiwi) than the WC surface (-100.08 mJ m-2 and -71.98 mJ m-2, respectively). The CF and WC surfaces had similar antibiofilm effects against single-species biofilms, achieving cell reductions of approximately 50% and 60% for E. coli and P. putida, respectively, compared to the control. Additionally, the biomimetic surfaces led to reductions of up to 60% in biovolume, 45% in thickness, and 60% in the surface coverage of single-species biofilms. For dual-species biofilms, only the E. coli strain growing on the WC surface exhibited a significant decrease in the cell count. However, confocal microscopy analysis revealed a 60% reduction in the total biovolume and surface coverage of mixed biofilms developed on both biomimetic surfaces. Furthermore, dual-species biofilms were mainly composed of P. putida, which reduced E. coli growth. Altogether, these results demonstrate that the surface properties of CF and WC biomimetic surfaces have the potential for reducing biofilm formation.

Controlling of foodborne pathogen biofilms on stainless steel by bacteriophages: A systematic review and meta-analysis

This study investigates the potential of using bacteriophages to control foodborne pathogen biofilms on stainless steel surfaces in the food industry. Biofilm-forming bacteria can attach to stainless steel surfaces, rendering them difficult to eradicate even after a thorough cleaning and sanitizing procedures. Bacteriophages have been proposed as a possible solution, as they can penetrate biofilms and destroy bacterial cells within, reducing the number of viable bacteria and preventing the growth and spread of biofilms. This systematic review and meta-analysis evaluates the potential of bacteriophages against different biofilm-forming foodborne bacteria, including Cronobacter sakazakii, Escherichia coli, Staphylococcus aureus, Pseudomonas fluorescens, Pseudomonas aeruginosa and Listeria monocytogenes. Bacteriophage treatment generally causes a significant average reduction of 38 % in biofilm formation of foodborne pathogens on stainless steel. Subgroup analyses revealed that phages are more efficient in long-duration treatment. Also, applying a cocktail of phages is 1.26-fold more effective than applying individual phages. Phages at concentrations exceeding 107 PFU/ml are significantly more efficacious in eradicating bacteria within a biofilm. The antibacterial phage activity decreases substantially by 3.54-fold when applied at 4 °C compared to temperatures above 25 °C. This analysis suggests that bacteriophages can be a promising solution for controlling biofilms in the food industry.

Eradication of multiple-species biofilms from food industrial and domestic surfaces using essential oils

Microbial biofilm formation represents a serious problem for both food industry and households. Natural biofilms are formed mostly by multiple species, and show resistance against most of the usual sanitizers. In this study, the effects of cinnamon (Cinnamomum zeylanicum), marjoram (Origanum majorana) and thyme (Thymus vulgaris) essential oils (EOs) and their main components (cinnamaldehyde, terpinene-4-ol, and thymol) were investigated on four-species biofilms of Escherichia coli, Listeria monocytogenes, Pseudomonas putida and Staphylococcus aureus. Minimum bactericide concentration (MBC) and killing time were determined by means of the microdilution method. MBC of the investigated EOs and components was between 0.5 mg/mL (cinnamaldehyde) to 25 mg/mL (terpinene-4-ol). Killing times for the four-species suspension were 5 or 10 min, time spans usable in the food industry. For eradication of the mixed-population biofilm from stainless steel (SS), polypropylene (PP), tile and wood surfaces, EO- or EO component-based disinfectant solutions were developed, and their effects were compared to a peracetic acid-based industrial sanitizer (HC-DPE). Total eradication of biofilms (99.9%) was achieved, with solutions containing cinnamon and thyme EO and EO components, from SS and PP, but not from tile or wood surfaces. Apparently, cinnamon EO, terpinene-4-ol and thymol have better disinfectant activity than HC-DPE.

Decoding the influence of low temperature on biofilm development: The hidden roles of c-di-GMP

Biofilms are widely used and play important roles in biological processes. Low temperature of wastewater inhibits the development of biofilms derived from wastewater activated sludge. However, the specific mechanism of temperature on biofilm development is still unclear. This study explored the mechanism of temperature on biofilm development and found a feasible method to enhance biofilm development at low temperature. The amount of biofilm development decreased by approximately 66 % and 55 % at 4 °C and 15 °C, respectively, as compared to 28 °C. The cyclic dimeric guanosine monophosphate (c-di-GMP) concentration also decreased at low temperature and was positively correlated with extracellular polymeric substance (EPS) content, formation, and adhesion strength. Microbial community results showed that low temperature inhibited the normal survival of most microorganisms, but promoted the growth of some psychrophile bacteria like Sporosarcina, Caldilineaceae, Gemmataceae, Anaerolineaceae and Acidobacteriota. Further analysis of functional genes demonstrated that the abundance of functional genes related to the synthesis of c-di-GMP (K18968, K18967 and K13590) decreased at low temperature. Subsequently, the addition of exogenous spermidine increased the level of intracellular c-di-GMP and alleviated the inhibition effect of low temperature on biofilm development. Therefore, the possible mechanism of low temperature on biofilm development could be the inhibition of the microorganism activity and reduction of the communication level between cells, which is the closely related to the EPS content, formation, and adhesion strength. The enhancement of c-di-GMP level through the exogenous addition of spermidine provides an alternative strategy to enhance biofilm development at low temperatures. The results of this study enhance the understanding of the influence of temperature on biofilm development and provide possible strategies for enhancing biofilm development at low temperatures.

Plant-derived bioactive compounds for the inhibition of biofilm formation: a comprehensive review

Biofilm formation is a widespread phenomenon that impacts different fields, including the food industry, agriculture, health care and the environment. Accordingly, there is a serious need for new methods of managing the problem of biofilm formation. Natural products have historically been a rich source of varied compounds with a wide variety of biological functions, including antibiofilm agents. In this review, we critically highlight and discuss the recent progress in understanding the antibiofilm effects of several bioactive compounds isolated from different plants, and in elucidating the underlying mechanisms of action and the factors influencing their adhesion. The literature shows that bioactive compounds have promising antibiofilm potential against both Gram-negative and Gram-positive bacterial and fungal strains, via several mechanisms of action, such as suppressing the formation of the polymer matrix, limiting O2 consumption, inhibiting microbial DNA replication, decreasing hydrophobicity of cell surfaces and blocking the quorum sensing network. This antibiofilm activity is influenced by several environmental factors, such as nutritional cues, pH values, O2 availability and temperature. This review demonstrates that several bioactive compounds could mitigate the problem of biofilm production. However, toxicological assessment and pharmacokinetic investigations of these molecules are strongly required to validate their safety.

Antibacterial and antibiofilm activities of iodinated hydrocarbons against Vibrio parahaemolyticus and Staphylococcus aureus

Food-related illnesses have become a growing public concern due to their considerable socioeconomic and medical impacts. Vibrio parahaemolyticus and Staphylococcus aureus have been implicated as causative organisms of food-related infections and poisoning, and both can form biofilms which confer antibiotic resistance. Hence, the need for continuous search for compounds with antibiofilm and antivirulence properties. In this study, 22 iodinated hydrocarbons were screened for their antibiofilm activity, and of these, iodopropynyl butylcarbamate (IPBC) was found to effectively control biofilm formation of both pathogens with a MIC of 50 µg/mL which was bactericidal to V. parahaemolyticus and S. aureus. Microscopic studies confirmed IPBC inhibits biofilm formation of both bacteria and also disrupted their mixed biofilm formation. Furthermore, IPBC suppressed virulence activities such as motility and hemolytic activity of V. parahaemolyticus and the cell surface hydrophobicity of S. aureus. It exhibited a preservative potential against both pathogens in a shrimp model. IPBC disrupted the cell membrane of S. aureus and V. parahaemolyticus and differentially affected gene expressions related to biofilm formation and virulence. Additionally, it displayed broad-spectrum antibiofilm activities against other clinically relevant pathogens. These findings indicate IPBC offers a potential means of controlling infections mediated by Vibrio and Staphylococcus biofilms.

Oxidative Stress-Mediated Repression of Virulence Gene Transcription and Biofilm Formation as Antibacterial Action of Cinnamomum burmannii Essential Oil on Staphylococcus aureus

This work aimed to identify the chemical compounds of Cinnamomum burmannii leaf essential oil (CBLEO) and to unravel the antibacterial mechanism of CBLEO at the molecular level for developing antimicrobials. CBLEO had 37 volatile compounds with abundant borneol (28.40%) and showed good potential to control foodborne pathogens, of which Staphylococcus aureus had the greatest inhibition zone diameter (28.72 mm) with the lowest values of minimum inhibitory concentration (1.0 μg/mL) and bactericidal concentration (2.0 μg/mL). To unravel the antibacterial action of CBLEO on S. aureus, a dynamic exploration of antibacterial growth, material leakage, ROS formation, protein oxidation, cell morphology, and interaction with genome DNA was conducted on S. aureus exposed to CBLEO at different doses (1/2-2×MIC) and times (0-24 h), indicating that CBLEO acts as an inducer for ROS production and the oxidative stress of S. aureus. To highlight the antibacterial action of CBLEO on S. aureus at the molecular level, we performed a comparative association of ROS accumulation with some key virulence-related gene (sigB/agrA/sarA/icaA/cidA/rsbU) transcription, protease production, and biofilm formation in S. aureus subjected to CBLEO at different levels and times, revealing that CBLEO-induced oxidative stress caused transcript suppression of virulence regulators (RsbU and SigB) and its targeted genes, causing a protease level increase destined for the biofilm formation and growth inhibition of S. aureus, which may be a key bactericidal action. Our findings provide valuable information for studying the antibacterial mechanism of essential oil against pathogens.

Small Schiff Base Molecules-A Possible Strategy to Combat Biofilm-Related Infections

Microorganisms participating in the development of biofilms exhibit heightened resistance to antibiotic treatment, therefore infections involving biofilms have become a problem in recent years as they are more difficult to treat. Consequently, research efforts are directed towards identifying novel molecules that not only possess antimicrobial properties but also demonstrate efficacy against biofilms. While numerous investigations have focused on antimicrobial capabilities of Schiff bases, their potential as antibiofilm agents remains largely unexplored. Thus, the objective of this article is to present a comprehensive overview of the existing scientific literature pertaining to small molecules categorized as Schiff bases with antibiofilm properties. The survey involved querying four databases (Web of Science, ScienceDirect, Scopus and Reaxys). Relevant articles published in the last 10 years were selected and categorized based on the molecular structure into two groups: classical Schiff bases and oximes and hydrazones. Despite the majority of studies indicating a moderate antibiofilm potential of Schiff bases, certain compounds exhibited a noteworthy effect, underscoring the significance of considering this type of molecular modeling when seeking to develop new molecules with antibiofilm effects.

Rapid discrimination of Lentilactobacillus parabuchneri biofilms via in situ infrared spectroscopy

Microbial contamination in food industry is a source of foodborne illnesses and biofilm-related diseases. In particular, biogenic amines (BAs) accumulated in fermented foods via lactic acid bacterial activity exert toxic effects on human health. Among these, biofilms of histamine-producer Lentilactobacillus parabuchneri strains adherent at food processing equipment surfaces can cause food spoilage and poisoning. Understanding the chain of contamination is closely related to elucidating molecular mechanisms of biofilm formation. In the present study, an innovative approach using integrated chemical sensing technologies is demonstrated to fundamentally understand the temporal behavior of biofilms at the molecular level by combining mid-infrared (MIR) spectroscopy and fluorescence sensing strategies. Using these concepts, the biofilm forming capacity of six cheese-isolated L. parabuchneri strains (IPLA 11151, 11150, 11129, 11125, 11122 and 11117) was examined. The cut-off values for the biofilm production ability of each strain were quantified using crystal violet (CV) assays. Real-time infrared attenuated total reflection spectroscopy (IR-ATR) combined with fluorescence quenching oxygen sensing provides insight into distinct molecular mechanisms for each strain. IR spectra showed significant changes in characteristic bands of amides, lactate, nucleic acids, and extracellular polymeric substances (i.e., lipopolysaccharides, phospholipids, phosphodiester, peptidoglycan, etc.), which are major contributors to biofilm maturation involved in the initial adhesion processes. Chemometric methods including principal component analysis and partial least square-discriminant analysis facilitated the rapid determination and classification of cheese isolated L. parabuchneri strains unambiguously differentiating the IR signatures based on their ability to produce biofilm. All biofilms were morphologically characterized by confocal laser scanning microscopy on relevant industrial equipment surfaces. In summary, this innovative approach combining MIR spectroscopy with luminescence sensing enables real-time insight into the molecular composition and formation of L. parabuchneri biofilms.

Insights into the mechanisms and key factors influencing biofilm formation by Aeromonas hydrophila in the food industry: A comprehensive review and bibliometric analysis

Biofilm formation by Aeromonas hydrophila in the food industry poses significant challenges to food safety and quality. Therefore, this comprehensive review aimed to provide insights into the mechanisms and key factors influencing A. hydrophila biofilm formation. It explores the molecular processes involved in initial attachment, microcolony formation, and biofilm maturation; moreover, it concurrently examines the impact of intrinsic factors, including quorum sensing, cyclic-di-GMP, the efflux pump, and antibiotic resistance, as well as environmental conditions, such as temperature, nutrient availability, and osmotic pressure, on biofilm architecture and resilience. Furthermore, the article highlights the potential of bibliometric analysis as a promising method for conceptualizing the research landscape of and identifying knowledge gaps in A. hydrophila biofilm research. The findings underscore the requirement for focused interventions that prevent biofilm development and raise food sector safety. The consolidation of current information and incorporation of bibliometric analysis enhances existing understanding of A. hydrophila biofilm formation and offers insights for future research and control strategies within a food industry context.

Antibiofilm activity of marine microbial natural products: potential peptide- and polyketide-derived molecules from marine microbes toward targeting biofilm-forming pathogens

Controlling and treating biofilm-related infections is challenging because of the widespread presence of multidrug-resistant microbes. Biofilm, a naturally occurring matrix of microbial aggregates, has developed intricate and diverse resistance mechanisms against many currently used antibiotics. This poses a significant problem, especially for human health, including clinically chronic infectious diseases. Thus, there is an urgent need to search for and develop new and more effective antibiotics. As the marine environment is recognized as a promising reservoir of new biologically active molecules with potential pharmacological properties, marine natural products, particularly those of microbial origin, have emerged as a promising source of antibiofilm agents. Marine microbes represent an untapped source of secondary metabolites with antimicrobial activity. Furthermore, marine natural products, owing to their self-defense mechanisms and adaptation to harsh conditions, encompass a wide range of chemical compounds, including peptides and polyketides, which are primarily found in microbes. These molecules can be exploited to provide novel and unique structures for developing alternative antibiotics as effective antibiofilm agents. This review focuses on the possible antibiofilm mechanism of these marine microbial molecules against biofilm-forming pathogens. It provides an overview of biofilm development, its recalcitrant mode of action, strategies for the development of antibiofilm agents, and their assessments. The review also revisits some selected peptides and polyketides from marine microbes reported between 2016 and 2023, highlighting their moderate and considerable antibiofilm activities. Moreover, their antibiofilm mechanisms, such as adhesion modulation/inhibition targeting biofilm-forming pathogens, quorum sensing intervention and inhibition, and extracellular polymeric substance disruption, are highlighted herein.

Exopolysaccharide produced by Lactiplantibacillus plantarum Y12 exhibits inhibitory effect on the Shigella flexneri genes expression related to biofilm formation

Shigella is a specific enteric pathogen in humans, causing symptoms of bacterial dysentery. The biofilm formation of S. flexneri contributes to the emergence of multidrug resistance and facilitates the establishment of persistent chronic infections. This study investigated the regulatory effects of Lactiplantibacillus plantarum Y12 exopolysaccharide (L-EPS) on gene expression and its spatial hindrance effects in inhibiting the biofilm formation of S. flexneri. The transcriptome analysis revealed a significant impact of L-EPS on the gene expression profile of S. flexneri, with a total of 968 genes showing significant changes (507 up-regulated and 461 down-regulated). The significantly down-regulated KEGG metabolic pathway enriched in phosphotransferase system, Embden-Meyerhf-Parnas, Citrate cycle, Lipopolysaccharide biosynthesis, Cationic antimicrobial peptide resistance, Two-component system. Moreover, L-EPS significantly down-regulated the gene expression levels of fimbriae synthesis (fimF), lipopolysaccharide synthesis (lptE, lptB), anchor protein repeat domain (arpA), virulence factor (lpp, yqgB), antibiotic resistance (marR, cusB, mdtL, mdlB), heavy metal resistance (zraP), and polysaccharide synthesis (mtgA, mdoB, mdoC). The expression of biofilm regulator factor (bssS) and two-component system suppressor factor (mgrB) were significantly up-regulated. The RT-qPCR results indicated that a major component of L-EPS (L-EPS 2-1) exhibited the gene regulatory effect on the S. flexneri biofilm formation. Furthermore, electrophoresis and isothermal microtitration calorimetry demonstrated that the interaction between L-EPS 2-1 and eDNA is electrostatic dependent on the change in environmental pH, disrupting the stable spatial structure of S. flexneri biofilm. In conclusion, L-EPS inhibited the biofilm formation of S. flexneri through gene regulation and spatial obstruction effects.

Advancing understanding of microbial biofilms through machine learning-powered studies

Microbial biofilms are prevalent in various environments and pose significant challenges to food safety and public health. The biofilms formed by pathogens can cause food spoilage, foodborne illness, and infectious diseases, which are difficult to treat due to their enhanced antimicrobial resistance. While the composition and development of biofilms have been widely studied, their profound impact on food, the food industry, and public health has not been sufficiently recapitulated. This review aims to provide a comprehensive overview of microbial biofilms in the food industry and their implication on public health. It highlights the existence of biofilms along the food-producing chains and the underlying mechanisms of biofilm-associated diseases. Furthermore, this review thoroughly summarizes the enhanced understanding of microbial biofilms achieved through machine learning approaches in biofilm research. By consolidating existing knowledge, this review intends to facilitate developing effective strategies to combat biofilm-associated infections in both the food industry and public health.

A review of mechanism analysis methods in multi-species biofilm of foodborne pathogens

Biofilms are an aggregation of microorganisms that have high resistance to antimicrobial agents. In the food industry, it has been widely studied that foodborne pathogens on both food surfaces and food-contact surfaces can form biofilms thereby threatening the safety of the food. In the natural environment, multi-species biofilms formed by more than two different microorganisms are abundant. In addition, the resistance of multi-species biofilms to antimicrobial agents is higher than that of mono-species biofilms. Therefore, studies to elucidate the mechanisms of multi-species biofilms formed by foodborne pathogens are still required in the food industry. In this review paper, we summarized the novel analytical methods studied to evaluate the mechanisms of multi-species biofilms formed by foodborne pathogens by dividing them into four categories: spatial distribution, bacterial interaction, extracellular polymeric substance production and quorum sensing analytical methods.

Effects of Flavonoids and Antibiotics Combination on Preformed Biofilms and Small RNA of Staphylococcus aureus

Antibiotic resistance of Staphylococcus aureus has considerably increased among non-clinical or asymptomatic individuals. The formation of biofilms denies antimicrobial access to its targets present on the surface and inside the cell. The present study tested the effect of the combination of flavonoids and antibiotics over the preformed biofilms of S. aureus. The eradication of the preformed biofilms was analyzed using the crystal violet method. It has shown that 2500 µg mL-1 Rutin and 100 µg mL-1 Erythromycin (MIC Concentration) combination efficiently reduced the growth of the cells, which were adhered to the surfaces forming the biofilms. Fluorescence microscopic analysis indicated that the Rutin and Erythromycin (MIC value) combinations could eradicate the preformed biofilm cells more efficiently than other combinations. We found that the flavonoids and antibiotics with MIC concentration show a significant effect over the preformed biofilms cells of S. aureus. In addition, the semi-quantitative real-time PCR analysis for the sRNAs under the treatment of Rutin and Erythromycin combinations showed that few small RNAs expression (SprF, SprG, ArtR, Teg49, Teg41, and RNAIII) are getting downregulated upon the treatment; but again recovers with the incubation time interval increases. Combinations have a significant effect on Teg49 where there is a very faint intensity of the band, but for other small RNAs, there is an irregular pattern on the gel image. It has been concluded that at the initial period of incubation, the combinations have an effect on all the sRNAs but once the incubation increases, the effects have been slowly decreasing. It has been concluded that the combination has been able to reduce the doubling time of S. aureus upon treatment. Whereas, the small RNAs used in the study can be further evaluated for expression profiling through qRT-PCT.

Graphical abstract

Towards sustainable Cleaning-in-Place (CIP) in dairy processing: Exploring enzyme-based approaches to cleaning in the Cheese industry

Cleaning-in-place (CIP) is the most commonly used cleaning and sanitation system for processing lines, equipment, and storage facilities such as milk silos in the global dairy processing industry. CIP employs thermal treatments and nonbiodegradable chemicals (acids and alkalis), requiring appropriate neutralization before disposal, resulting in sustainability challenges. In addition, biofilms are a major source of contamination and spoilage in dairy industries, and it is believed that current chemical CIP protocols do not entirely destroy biofilms. Use of enzymes as effective agents for CIP and as a more sustainable alternative to chemicals and thermal treatments is gaining interest. Enzymes offer several advantages when used for CIP, such as reduced water usage (less rinsing), lower operating temperatures resulting in energy savings, shorter cleaning times, and lower costs for wastewater treatment. Additionally, they are typically derived from natural sources, are easy to neutralize, and do not produce hazardous waste products. However, even with such advantages, enzymes for CIP within the dairy processing industry remain focused mainly on membrane cleaning. Greater adoption of enzyme-based CIP for cheese industries is projected pending a greater knowledge relating to cost, control of the process (inactivation kinetics), reusability of enzyme solutions, and the potential for residual activity, including possible effects on the subsequent product batches. Such studies are essential for the cheese industry to move toward more energy-efficient and sustainable cleaning solutions.

Biofilm-forming ability of Salmonella enterica strains of different serotypes isolated from multiple sources in China

Salmonella is an important zoonotic and foodborne pathogen that can infect humans and animals, causing severe concerns about food safety and a heavy financial burden worldwide. The pathogen can adhere to living and abiotic surfaces by forming biofilms, which increases the risk of transmission and infection. In this study, we investigated the biofilm-forming ability of 243 Salmonella strains of 36 serotypes from different sources in China using microplate crystal violet staining method. The results showed that 99.6% tested strains, with the exception of one strain of S. Thompson, were capable of forming biofilms. The strains with the biofilm-forming ability of strong, medium and weak accounted for 2.88%, 24.28% and 72.43%, respectively. The strains of S. Havana and S. Hvittingfoss had the strongest biofilm-forming ability, with the OD570 of 0.81 ± 0.02 and 0.81 ± 0.38, respectively, while the strains of S. Agona and S. Bovismorbificans had the weakest biofilm-forming ability, with the OD570 of 0.16 ± 0.02 and 0.15 ± 0.00, respectively. Furthermore, statistical analysis results demonstrated that isolation of source had no effect on the biofilm formation ability, while the detection rates of pefABCD and ddhC were positively correlated with the biofilm formation ability of Salmonella. In particular, the detection rate of ddhC gene was more than 60% in the biofilm forming strains. These findings have important guiding significance for the investigation of pathogenesis, as well as the prevention and control of salmonellosis.

A Selective Review on the Novel Approaches and Potential Control Agents of Anti-biofouling and Anti-biofilming

Specific aggregates of bacterial colonies, which, when embedded in a self-produced matrix, are known to cause biofouling. These complex structures are highly resistant to extreme stress conditions like antibiotics, complex cleaning strategies, or even the human immune system. The formation of biofilm matrices and biofouling is chosen as the preferred microbial environment owing to the advantages offered for the embedded cells for their long-term survival. This increased resistance and virulence emphasizes the urgency of finding newer alternatives for its complete eradication. Combined approaches using enzymes, biomimetic surface modification, and a fusion of physical and chemical methods are gaining more prominence. In brief, this review discusses the structure and biology of biofilms, their mechanism of action, and the new-age anti-biofilm and biofouling agents in food industries, bioelectric, and medical devices. Current anti-biofouling methods, including engineered polymers, surface coatings to antimicrobials, and antibiotics, have also been described.

Evaluation of Hygiene Practice for Reducing Campylobacter Contamination on Cutting Boards and Risks Associated with Chicken Handling in Kitchen Environment

Cutting boards can serve as potential carriers for the cross-contamination of pathogens from chicken to other surfaces. This study aimed to assess chefs' handling practices of cutting boards across five provinces in China and identify the key factors contributing to unsafe cutting board usage, including cleaning methods and handling practices. Handling practices associated with cutting boards were examined through a web-based survey (N = 154), while kitchen environment tests were conducted to investigate the splashing or survival of Campylobacter, inoculated in chicken or on cutting boards, to mimic the practices of chefs. Among chefs in the five provinces of China, wood and plastic cutting boards were the most commonly used for preparing chicken meat. Approximately 33.7% of chefs washed boards with running tap water, 31.17% of chefs washed boards with detergent, and 24.03% of chefs cleaned boards by scraping them with a knife after preparing other meats or chicken. The study tested 23 cutting boards from commercial kitchens for Campylobacter presence before and after chicken preparation and cleaning. Among these, 17 were cleaned with a knife, 5 with running tap water, and only 1 with disinfectant. Results showed that cleaning with a knife significantly reduced Campylobacter presence on cutting boards (p < 0.05), while the three main cleaning methods were inadequate in eliminating contamination to a safe level. In kitchen environment tests, contaminated chicken was chopped on cutting boards, with a maximum distance of 60 cm for low contamination, and 120 cm for medium and high contamination levels. This suggested a contamination risk exposure area ranging from 60 cm to 120 cm. Campylobacter survival on surfaces of wood, plastic, and stainless steel was also tested, with plastic surfaces showing the longest survival time (4.5 h at 15 °C and 3.5 h at 25 °C) In comparison, survival time on stainless steel or wood surfaces was only 3 h, implying a cross-contamination risk exposure period of 3 to 4.5 h after chicken preparation. In conclusion, based on the current study data, the practices employed by chefs play an important role in Campylobacter transfer in the kitchen environment. The presence of Campylobacter on cutting boards even after wiping or droplet splashing highlights its potential as a source of cross-contamination in the kitchen environment. So, chefs in China should reinforce their hygiene culture and adopt effective cutting board cleaning practices to prevent pathogen contamination.

Preliminary Study on Rapid and Simultaneous Detection of Viable Escherichia coli O157:H7, Staphylococcus aureus, and Salmonella by PMA-mPCR in Food

Escherichia coli O157:H7, Staphylococcus aureus, and Salmonella are major foodborne pathogens that are widespread in nature and responsible for several outbreaks of food safety accidents. Thus, a rapid and practical technique (PMA-mPCR) was developed for the simultaneous detection of viable E. coli O157:H7, S. aureus, and Salmonella in pure culture and in a food matrix. To eliminate false positive results, propidium monoazide (PMA) was applied to selectively suppress the DNA amplification of dead cells. The results showed the optimum concentration of PMA is 5.0 µg/mL. The detection limit of this assay by mPCR was 103 CFU/mL in the culture broth, and by PMA-mPCR was 104 CFU/mL both in pure culture and a food matrix (milk and ground beef). In addition, the detection of mixed viable and dead cells was also explored in this study. The detection sensitivity ratio of viable and dead counts was less than 1:10. Therefore, the PMA-mPCR assay proposed here might provide an efficient detection tool for the simultaneous detection of viable E. coli O157:H7, S. aureus, and Salmonella and also have great potential for the detection and concentration assessment of VBNC cells.

Microbial Biofilm: A Review on Formation, Infection, Antibiotic Resistance, Control Measures, and Innovative Treatment

Biofilm is complex and consists of bacterial colonies that reside in an exopolysaccharide matrix that attaches to foreign surfaces in a living organism. Biofilm frequently leads to nosocomial, chronic infections in clinical settings. Since the bacteria in the biofilm have developed antibiotic resistance, using antibiotics alone to treat infections brought on by biofilm is ineffective. This review provides a succinct summary of the theories behind the composition of, formation of, and drug-resistant infections attributed to biofilm and cutting-edge curative approaches to counteract and treat biofilm. The high frequency of medical device-induced infections due to biofilm warrants the application of innovative technologies to manage the complexities presented by biofilm.

Untargeted Metabolomics for Unraveling the Metabolic Changes in Planktonic and Sessile Cells of Salmonella Enteritidis ATCC 13076 after Treatment with Lippia origanoides Essential Oil

Nontyphoidal Salmonella species are one of the main bacterial causes of foodborne diseases, causing a public health problem. In addition, the ability to form biofilms, multiresistance to traditional drugs, and the absence of effective therapies against these microorganisms are some of the principal reasons for the increase in bacterial diseases. In this study, the anti-biofilm activity of twenty essential oils (EOs) on Salmonella enterica serovar Enteritidis ATCC 13076 was evaluated, as well as the metabolic changes caused by Lippia origanoides thymol chemotype EO (LOT-II) on planktonic and sessile cells. The anti-biofilm effect was evaluated by the crystal violet staining method, and cell viability was evaluated through the XTT method. The effect of EOs was observed by scanning electron microscopy (SEM) analysis. Untargeted metabolomics analyses were conducted to determine the effect of LOT-II EO on the cellular metabolome. LOT-II EO inhibited S. Enteritidis biofilm formation by more than 60%, without decreasing metabolic activity. Metabolic profile analysis identified changes in the modulation of metabolites in planktonic and sessile cells after LOT-II EO treatment. These changes showed alterations in different metabolic pathways, mainly in central carbon metabolism and nucleotide and amino acid metabolism. Finally, the possible mechanism of action of L. origanoides EO is proposed based on a metabolomics approach. Further studies are required to advance at the molecular level on the cellular targets affected by EOs, which are promising natural products for developing new therapeutic agents against Salmonella sp. strains.

Inhibitory effects of vorinostat (SAHA) against food-borne pathogen Salmonella enterica serotype Kentucky mixed culture biofilm with virulence and quorum-sensing relative expression

Salmonella is a food-borne microorganism that is also a zoonotic bacterial hazard in the food sector. This study determined how well a mixed culture of Salmonella Kentucky formed biofilms on plastic (PLA), silicon rubber (SR), rubber gloves (RG), chicken skin and eggshell surfaces. In vitro interactions between the histone deacetylase inhibitor-vorinostat (SAHA)-and S. enterica serotype Kentucky were examined utilizing biofilms. The minimum inhibitory concentration (MIC) of SAHA was 120 µg mL-1. The addition of sub-MIC (60 µg mL-1) of SAHA decreased biofilm formation for 24 h on PLA, SR, RG, Chicken skin, and eggshell by 3.98, 3.84, 4.11, 2.86 and 3.01 log (p < 0.05), respectively. In addition, the initial rate of bacterial biofilm formation was higher on chicken skin than on other surfaces, but the inhibitory effect was reduced. Consistent with this conclusion, virulence genes expression (avrA, rpoS and hilA) and quorum-sensing (QS) gene (luxS) was considerably downregulated at sub-MIC of SAHA. SAHA has potential as an anti-biofilm agent against S. enterica serotype Kentucky biofilm, mostly by inhibiting virulence and quorum-sensing gene expression, proving the histone deacetylase inhibitor could be used to control food-borne biofilms in the food industry.

Characterization of the Biofilms Formed by Histamine-Producing Lentilactobacillus parabuchneri Strains in the Dairy Environment

Lentilactobacillus parabuchneri, a lactic acid bacterium, is largely responsible for the production and accumulation of histamine, a toxic biogenic amine, in cheese. L. parabuchneri strains can form biofilms on the surface of industry equipment. Since they are resistant to cleaning and disinfection, they may act as reservoirs of histamine-producing contaminants in cheese. The aim of this study was to investigate the biofilm-producing capacity of L. parabuchneri strains. Using the crystal violet technique, the strains were first categorized as weak, moderate or strong biofilm producers. Analysis of their biofilm matrices revealed them to be mainly composed of proteins. Two strains of each category were then selected to analyze the influence on the biofilm-forming capacity of temperature, pH, carbon source, NaCl concentration and surface material (i.e., focusing on those used in the dairy industry). In general, low temperature (8 °C), high NaCl concentrations (2–3% w/v) and neutral pH (pH 6) prevented biofilm formation. All strains were found to adhere easily to beech wood. These findings increase knowledge of the biofilm-forming capacity of histamine-producing L. parabuchneri strains and how their formation may be prevented for improving food safety.

Effect and Mechanism of Eliminating Staphylococcus aureus by Electron Beam Irradiation and Reducing the Toxicity of Its Metabolites

The purpose of this study was to evaluate the mechanism of sterilization of Staphylococcus aureus by electron beam irradiation (0.5-, 1-, 2-, 4-, and 6-kGy treatments) and whether it reduces the toxicity of its fermentation supernatant. In this study, we investigated the mechanism of sterilization of S. aureus by electron beam irradiation using colony count, membrane potential, intracellular ATP, and UV absorbance measurements; we used hemolytic, cytotoxic, and suckling mouse wound models to verify that electron beam irradiation reduced the toxicity of the S. aureus fermentation supernatant. The results showed that 2 kGy of electron beam irradiation treatment completely inactivated S. aureus in suspension culture, and 4 kGy inactivated cells in S. aureus biofilms. This study suggests that the bactericidal effect of electron beam irradiation on S. aureus may be attributed to reversible damage to the cytoplasmic membrane, resulting in its leakage and the significant degradation of genomic DNA. The combined results of hemolytic, cytotoxic, and suckling mouse wound models demonstrated that the toxicity of S. aureus metabolites was significantly reduced when the electron beam irradiation dose was 4 kGy. In summary, electron beam irradiation has the potential to control S. aureus and reduce its toxic metabolites in food. IMPORTANCE Electron beam irradiation of >1 kGy damaged the cytoplasmic membrane, and reactive oxygen species (ROS) penetrated the cells. Electron beam irradiation of >4 kGy reduces the combined toxicity of virulent proteins produced by Staphylococcus aureus. Electron beam irradiation of >4 kGy can be used to inactivate Staphylococcus aureus and biofilms on milk.

Antibacterial Activity of Epigallocatechin Gallate (EGCG) against Shigella flexneri

Shigella flexneri (S. flexneri), a major intestinal pathogen, is a global public health concern. The biofilms formed by S. flexneri threaten environmental safety, since they could promote the danger of environmental contamination and strengthen the disease-causing properties of bacteria. Epigallocatechin gallate (EGCG) is an important catechin in tea, which has a high antibacterial activity. However, its antibacterial mechanism is still unclear. This research aims to quantify the antibacterial function and investigate the possible mechanism of EGCG inhibition of S. flexneri. The minimum inhibitory concentration (MIC) of EGCG against planktonic S. flexneri in the investigation was measured to be 400 μg/mL. Besides, SDS-PAGE and field emission scanning electron microscopy showed that EGCG interfered with protein synthesis and changed bacteria morphology. Through controlling the expression of the mdoH gene, EGCG was found to be able to prevent an S. flexneri biofilm extracellular polysaccharide from forming, according to experiments utilizing the real-time PCR test. Additional research revealed that EGCG might stimulate the response of S. flexneri to oxidative stress and prevent bacterial growth. These findings suggest that EGCG, a natural compound, may play a substantial role in S. flexneri growth inhibition.

Biosensors based on functional nucleic acids and isothermal amplification techniques

In the past few years, with the in-depth research of functional nucleic acids and isothermal amplification techniques, their applications in the field of biosensing have attracted great interest. Since functional nucleic acids have excellent flexibility and convenience in their structural design, they have significant advantages as recognition elements in biosensing. At the same time, isothermal amplification techniques have higher amplification efficiency, so the combination of functional nucleic acids and isothermal amplification techniques can greatly promote the widespread application of biosensors. For the purpose of further improving the performance of biosensors, this review introduces several widely used functional nucleic acids and isothermal amplification techniques, as well as their classification, basic principles, application characteristics, and summarizes their important applications in the field of biosensing. We hope to provide some references for the design and construction of new tactics to enhance the detection sensitivity and detection range of biosensing.

Nano-Conjugated Food-Derived Antimicrobial Peptides As Natural Biopreservatives: A Review of Technology and Applications

In recent years, microbial food safety has garnered a lot of attention due to worldwide expansion of the food industry and processed food products. This has driven the development of novel preservation methods over traditional ones. Food-derived antimicrobial peptides (F-AMPs), produced by the proteolytic degradation of food proteins, are emerging as pragmatic alternatives for extension of the shelf-life of food products. The main benefits of F-AMPs are their wide spectrum antimicrobial efficacy and low propensity for the development of antibiotic resistance. However, direct application of F-AMPs in food limits its efficacy during storage. Therefore, the development of nanocarriers for the conjugation and distribution of potential AMPs may hold great potential to increase their bioactivity. This review highlights the significance of F-AMPs as a feasible and sustainable alternative to conventional food preservatives. The most recent developments in production, characterization, and mode of action of these AMPs against planktonic and biofilm forming pathogens are thoroughly discussed in this work. Moreover, nano-conjugation of F-AMPs with different nano-carriers and potential future application in food packaging are emphasized. This review may aid in comprehending the nano-conjugation of F-AMPs and offer insightful recommendations for further exploration and potential uses in the food processing industry.

[Shiga toxin producing Escherichia coli: the challenge of adherence to survive]

Shiga Toxin-producing Escherichia coli (STEC) is recognized as being responsible for a large number of foodborne illnesses around the world. The pathogenicity of STEC has been related to Stx toxins. However, the ability of STEC to colonize the host and other surfaces can be essential for developing its pathogenicity. Different virulence profiles detected in STEC could cause the emergence of strains carrying new genes codified in new pathogenicity islands linked to metabolism and adherence. Biofilm formation is a spontaneous mechanism whereby STEC strains resist in a hostile environment being able to survive and consequently infect the host through contaminated food and food contact surfaces. Biofilm formation shows intra-and inter-serotype variability, and its formation does not depend only on the microorganisms involved. Other factors related to the environment (such as pH, temperature) and the surface (stainless steel and polystyrene) influence biofilm expression. The «One Health» concept implies the interrelation between public, animal, and environmental health actors to ensure food safety, prevent cross-contamination and resistance to sanitizers, highlighting the need to identify emerging pathogens through new molecular markers of rapid detection that involve STEC strains carrying the Locus of Enterocyte Effacement or Locus of Adhesion and Autoaggregation.

The Use of Natural Methods to Control Foodborne Biofilms

Biofilms are large aggregates of various species of bacteria or other microorganisms tightly attached to surfaces through an intricate extracellular matrix. These complex microbial communities present quite the challenge in the food processing industry, as conditions such as raw meats and diverse food product content in contact with workers, drains, machinery, and ventilation systems, make for prime circumstances for contamination. Adding to the challenge is the highly resistant nature of these biofilm growths and the need to keep in mind that any antimicrobials utilized in these situations risk health implications with human consumption of the products that are being processed in these locations. For that reason, the ideal means of sanitizing areas of foodborne biofilms would be natural means. Herein, we review a series of innovative natural methods of targeting foodborne biofilms, including bacteriocins, bacteriophages, fungi, phytochemicals, plant extracts, essential oils, gaseous and aqueous control, photocatalysis, enzymatic treatments, and ultrasound mechanisms.

Nutrient Availability and Biofilm Polysaccharide Shape the Bacillaene-Dependent Antagonism of Bacillus subtilis against Salmonella Typhimurium

Salmonella enterica is one of the most common foodborne pathogens and, due to the spread of antibiotic resistance, new antimicrobial strategies are urgently needed to control it. In this study, we explored the probiotic potential of Bacillus subtilis PS-216 and elucidated the mechanisms that underlie the interactions between this soil isolate and the model pathogenic strain S. Typhimurium SL1344. The results reveal that B. subtilis PS-216 inhibits the growth and biofilm formation of S. Typhimurium through the production of the pks cluster-dependent polyketide bacillaene. The presence of S. Typhimurium enhanced the activity of the PpksC promoter that controls bacillaene production, suggesting that B. subtilis senses and responds to Salmonella. The level of Salmonella inhibition, overall PpksC activity, and PpksC induction by Salmonella were all higher in nutrient-rich conditions than in nutrient-depleted conditions. Although eliminating the extracellular polysaccharide production of B. subtilis via deletion of the epsA-O operon had no significant effect on inhibitory activity against Salmonella in nutrient-rich conditions, this deletion mutant showed an enhanced antagonism against Salmonella in nutrient-depleted conditions, revealing an intricate relationship between exopolysaccharide production, nutrient availability, and bacillaene synthesis. Overall, this work provides evidence on the regulatory role of nutrient availability, sensing of the competitor, and EpsA-O polysaccharide in the social outcome of bacillaene-dependent competition between B. subtilis and S. Typhimurium. IMPORTANCE Probiotic bacteria represent an alternative for controlling foodborne disease caused by Salmonella enterica, which constitutes a serious concern during food production due to its antibiotic resistance and resilience to environmental stress. Bacillus subtilis is gaining popularity as a probiotic, but its behavior in biofilms with pathogens such as Salmonella remains to be elucidated. Here, we show that the antagonism of B. subtilis is mediated by the polyketide bacillaene and that the production of bacillaene is a highly dynamic trait which depends on environmental factors such as nutrient availability and the presence of competitors. Moreover, the production of extracellular polysaccharides by B. subtilis further alters the influence of these factors. Hence, this work highlights the inhibitory effect of B. subtilis, which is condition-dependent, and the importance of evaluating probiotic strains under conditions relevant to the intended use.

Anti-Fungal Activity of Moutan cortex Extracts against Rice Sheath Blight (Rhizoctonia solani) and Its Action on the Pathogen's Cell Membrane

Rice sheath blight (RSB) caused by Rhizoctonia solani is one of the most destructive diseases of rice (Oryza sativa). Although chemical fungicides are the most important control methods, their long-term unreasonable application has brought about problems such as environmental pollution, food risks, and non-target poisoning. Therefore, considering the extraction of fungistatic substances from plants may be an alternative in the future. In this study, we found that the Moutan cortex ethanol extract has excellent antifungal activity against R. solani, with a 100% inhibition rate at 1000 μg/mL, which aroused our great exploration interest. In-depth exploration found that the antifungal active ingredients of M. cortex were mainly concentrated in the petroleum ether extract of the M. cortex ethanol extract, which still maintained a 100% inhibition rate with 250 μg/mL, and its effective medium concentration (EC₅₀) was 145.33 μg/mL against R. solani. Through the measurement of extracellular relative conductivity and OD₂₆₀, the petroleum ether extract induced leakage of intracellular electrolytes and nucleic acids, indicating that the cell membrane was ruined. Therefore, we preliminarily determined that the cell membrane may be the target of the petroleum ether extract. Moreover, we found that petroleum ether extract reduced the content of ergosterol, a component of the cell membrane, which may be one of the reasons for the cell membrane destruction. Furthermore, the increase of MDA content would lead to membrane lipid peroxidation, further aggravating membrane damage, resulting in increased membrane permeability. Also, the destruction of the cell membrane was observed by the phenomenon of the mycelium being transparent and broken. In conclusion, this is the first report of the M. cortex petroleum ether extract exhibiting excellent antifungal activity against R. solani. The effect of the M. cortex petroleum ether extract on R. solani may be on the cell membrane, inducing the disorder of intracellular substances and metabolism, which may be one of the antifungal mechanisms against R. solani.

"Multidimensional correlation analysis of temperature and contact time on eradication of biofilms of Cronobacter sakazakii on abiotic surfaces by combination of hypochlorite and malic acid"

AIM

In the present study, malic acid in combination with sodium hypochlorite is evaluated for eradication of biofilms formed by Cronobacter sakazakii strains individually and in a cocktail on different abiotic surfaces.

METHOD AND RESULTS

The biofilm formation by five strains of C. sakazakii and their cocktail culture on different substrates was studied in Tryptone Soy Broth (TSB) and reconstituted Powdered Infant Formula (PIF). Further, the effect of temperature (4, 27, 37 and 50°C) and contact time (10, 20, 30, 40, 50 and 60 min) on antibiofilm potential of test solution (0.0625 mol l-1 malic acid and 0.00004 mol l-1 sodium hypochlorite) against biofilm formed by C. sakazakii cocktail culture was investigated on these surfaces. The effect was evaluated in terms of viable cell count and biofilm texture using scanning electron microscopy (SEM). Principal Component Analysis (PCA) revealed that the maximum biofilm reduction was observed for stainless steel at 4°C after 60 min of contact whereas at 25, 37 and 50°C, maximum biofilm reduction was observed for polycarbonate. For glass and polyurethane, maximum log reductions were observed at 50°C. The SEM images revealed cell surface deformation and disruption in biofilms after treatment with the test solution.

CONCLUSIONS

The antibiofilm potential was observed to be greatly affected by contact time and temperature. These results indicated that the combination of malic acid NaOCl can effectively kill and remove C. sakazakii biofilms from food contact surfaces and enteral feeding tubes.

Encapsulation of Benzyl Isothiocyanate with β-Cyclodextrin Using Ultrasonication: Preparation, Characterization, and Antibacterial Assay

Benzyl isothiocyanate (BITC) is widely utilized in multiple biomedical fields, due to its significant antibacterial properties and low toxicity. However, poor water solubility and pungent odor has limited its application in the food industry. In this study, we first prepared inclusion complexes of BITC in GLU-β-CD and HP-β-CD using ultrasound, which is able to overcome the hindrance of poor water solubility and high volatility. Then, the BITC-β-CD inclusion complexes were characterized by using high-performance liquid chromatography (HPLC), nuclear magnetic resonance hydrogen spectra (¹H-NMR), infrared absorption spectra (IR), and differential scanning calorimetry (DSC) to confirm their stability. Further, the evaluation of antibacterial and antitumor effects of the BITC-β-CD inclusion complexes showed that they had great bactericidal activity against both Escherichia coli and Staphylococcus aureus cells, and also inhibited the growth of HepG2 cells in vitro. In addition, our results indicated that BITC-β-CD complexes were able to inhibit the growth of S. aureus in broccoli juice and extend the shelf life of broccoli juice, demonstrating the potential of β-cyclodextrin to improve the stability and controlled release of BITC. Taken together, our results show that BITC-β-CD complexes have good potential for application in the food industry.

Molecular co-localization of multiple drugs in a nanoscopic delivery vehicle for potential synergistic remediation of multi-drug resistant bacteria

Anti-microbial resistant infection is predicted to be alarming in upcoming years. In the present study, we proposed co-localization of two model drugs viz., rifampicin and benzothiazole used in anti-tuberculosis and anti-fungal agents respectively in a nanoscopic cationic micelle (cetyl triethyl ammonium bromide) with hydrodynamic diameter of 2.69 nm. Sterilization effect of the co-localized micellar formulation against a model multi-drug resistant bacterial strain viz., Methicillin resistant Staphylococcus aureus was also investigated. 99.88% decrease of bacterial growth in terms of colony forming unit was observed using the developed formulation. While Dynamic Light Scattering and Forsters Resonance Energy Transfer between benzothiazole and rifampicin show co-localization of the drugs in the nanoscopic micellar environment, analysis of time-resolved fluorescence decays by Infelta-Tachiya model and the probability distribution of the donor-acceptor distance fluctuations for 5 μM,10 μM and 15 μM acceptor concentrations confirm efficacy of the co-localization. Energy transfer efficiency and the donor acceptor distance are found to be 46% and 20.9 Å respectively. We have also used a detailed computational biology framework to rationalize the sterilization effect of our indigenous formulation. It has to be noted that the drugs used in our studies are not being used for their conventional indication. Rather the co-localization of the drugs in the micellar environment shows a completely different indication of their use in the remediation of multi-drug resistant bacteria revealing the re-purposing of the drugs for potential use in hospital-born multi-drug resistant bacterial infection.

Advancements in antimicrobial nanoscale materials and self-assembling systems

Antimicrobial resistance is directly responsible for more deaths per year than either HIV/AIDS or malaria and is predicted to incur a cumulative societal financial burden of at least $100 trillion between 2014 and 2050. Already heralded as one of the greatest threats to human health, the onset of the coronavirus pandemic has accelerated the prevalence of antimicrobial resistant bacterial infections due to factors including increased global antibiotic/antimicrobial use. Thus an urgent need for novel therapeutics to combat what some have termed the 'silent pandemic' is evident. This review acts as a repository of research and an overview of the novel therapeutic strategies being developed to overcome antimicrobial resistance, with a focus on self-assembling systems and nanoscale materials. The fundamental mechanisms of action, as well as the key advantages and disadvantages of each system are discussed, and attention is drawn to key examples within each field. As a result, this review provides a guide to the further design and development of antimicrobial systems, and outlines the interdisciplinary techniques required to translate this fundamental research towards the clinic.

Insights into antibiofilm mechanisms of phytochemicals: Prospects in the food industry

The recalcitrance of microbial aggregation or biofilm in the food industry underpins the emerging antimicrobial resistance among foodborne pathogens, exacerbating the phenomena of food spoilage, processing and safety management failure, and the prevalence of foodborne illnesses. The challenges of growing tolerance to current chemical and disinfectant-based antibiofilm strategies have driven the urgency in finding a less vulnerable to bacterial resistance, effective alternative antibiofilm agent. To address these issues, various novel strategies are suggested in current days to combat bacterial biofilm. Among the innovative approaches, phytochemicals have already demonstrated their excellent performance in preventing biofilm formation and bactericidal actions against resident bacteria within biofilms. However, the diverse group of phytochemicals and their different modes of action become a barrier to applying them against specific pathogenic biofilm-formers. This phenomenon mandates the need to elucidate the multi-mechanistic actions of phytochemicals to design an effective novel antibiofilm strategy. Therefore, this review critically illustrates the structure - activity relationship, functional sites of actions, and target molecules of diverse phytochemicals regarding multiple major antibiofilm mechanisms and reversal mechanisms of antimicrobial resistance. The implementation of the in-depth knowledge will hopefully aid future studies for developing phytochemical-based next-generation antimicrobials.