Melittin peptide is a short cationic linear peptide derived from honey bee venom with 26 amino acids, demonstrates potential in controlling and eliminating pathogens. In this study, the genetic ...sequence of melittin was inserted into the pcDNA3.1+ plasmid and expressed in HEK-293 cells with a His-tag. Purification was done through affinity chromatography and a nickel column. In this study, the antimicrobial effect of melittin in beef sirloin was first investigated, and the minimum inhibitory concentration (MIC) was determined. Then, the effect of combining it with nanochitosan (n-CH) coating, melittin (0.1% and 0.2%v/v), and nanochitosan alone on the physicochemical, microbiological, and sensory properties of beef was examined over a 9-day at 4 °C. At the end of the storage period, the coated samples effectively prevented an increase in pH (5.75 ± 0.06) and showed a significant decrease in the peroxide value (PV) (4.50 ± 0.07). The most favorable result was observed when using the n-CH+0.2%M, which led to malondialdehyde level of 0.44 ± 0.0.05 mg/kg in the amount of thiobarbituric acid reactant. Additionally, the total volatile base nitrogen content in the treatment involving 0.2%M and n-CH+0.2% and 0.1%M was deemed acceptable. Although the total viable count (TVC) of microorganisms in samples covered with melittin increased over time (7.88 ± 0.12 CFU/g), the microbial growth rate in these samples was lower than the control sample (12.10 ± 0.13 CFU/g). Therefore, the use of nanochitosan based edible coatings in combination with melittin in meat packaging reduces microbial population and increases its shelf life.
•Melittin peptide (26 aa) demonstrates strong pathogen control potential.•Combined use of melittin and nanochitosan coating enhances beef quality.•Coated samples prevent pH increase and exhibit reduced peroxide value.•Nanochitosan-melittin combination extends shelf life by reducing microbial growth.
Due to increased concerns about food safety, rapid, specific and highly sensitive monitoring of pathogen bacteria in food samples is of great importance to ensure public health. Although traditional ...detection methods are available, they are time consuming, labor intensive, unsuitable for on-site detection, and need highly trained personnel. To overcome these limitations, many efforts have been devoted to develop a new class of bioassays, aptamer-based assays, which use nucleic acid as bio-recognition elements. Aptamer-based assays and aptasensors, as emerging analytical methods, have opened new horizons for simple, specific and sensitive detection of microorganisms including pathogen bacteria. This review therefore will focus on new developed aptamer-based assays and aptasensors for pathogenic bacteria in food samples. We will also highlight advantages and drawbacks of various types of assays developed for pathogen bacteria detection.
•Detection of pathogenic bacteria in food samples is of great impotence to ensure public health.•Traditional detection methods are time consuming and labor intensive.•Development of highly sensitive analytical procedures is required.•Recently, aptamer-based assays have gained a considerable attention.•We have evaluated advantages and limitations of different strategies for the fabrication of aptamer-based assays.
A novel surface-enhanced Raman scattering (SERS)-based analytical technique was proposed to simultaneously detect two highly pathogenic bacteria, namely, Staphylococcus aureus (S. aureus) and ...Listeria monocytogenes (L. mono) by using a dual-recognition pattern with wheat germ agglutinin (WGA) and nucleic acid aptamers. WGA was modified onto Fe3O4@Au magnetic nanoparticles (MNPs) for the efficient capture of S. aureus and L. mono in complex samples (orange juice, extracts of lettuce, and human urine) within 15 min. The streptavidin (SA)/aptamers co-functionalized SERS tags were fabricated by covalent attaching two different Raman reporters and SA molecules onto 45 nm Au NPs and then conjugated with two biotin-aptamers that specifically bind to their target bacteria with high affinity and stability. The combined use of high-sensitive SERS tags, WGA-mediated magnetic enrichment, and SA-mediated aptamer conjugation remarkably improved the assay sensitivity. Under optimized conditions, the developed SERS biosensor can simultaneously detect the two target bacteria with high detection sensitivity (<6 cells/mL), favorable linear relation (10-107 cells/mL), and high accuracy (recovery rate <7.03%). Therefore, the proposed SERS platform is rapid, sensitive, easy to use, and thus show potential as a tool for the timely identification of pathogenic bacteria in real samples.
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•A rapid and ultrasensitive SERS platform for S. aureus and L. mono detection was reported.•WGA modified-Fe3O4@Au MNP was proposed for broad-spectrum capture of multiple bacteria.•The SA/aptamer co-functionalized SERS tags exhibited higher affinity and stability.•The LODs for S. aureus and L. mono were 3 and 5 cells/mL, respectively.
To enhance food safety, the need for swift and precise detection of B. licheniformis, a bacterium prevalent in various environments, including soil and food products, is paramount. This study ...presents an innovative and cost-effective bioassay designed to specifically identify the foodborne pathogen, B. licheniformis, utilizing a colorimetric signal approach. The biosensor, featuring a 3D-printed architecture, incorporates a casein-based liquid-proof gelatine film, selectively liquefying in response to the caseinolytic/proteolytic activity of external enzymes from the pathogen. As the sample liquefies, it progresses through a color layer, causing the migration of dye to an absorbent layer, resulting in a distinct positive signal. This bioassay exhibits exceptional sensitivity, detecting concentrations as low as 1 CFU/mL within a 9.3-h assay duration. Notably, this cost-efficient bioassay outperforms conventional methods in terms of efficacy and cost-effectiveness, offering a straightforward solution for promptly detecting B. licheniformis in food samples.
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•A cost-efficient and highly specific bioassay tailored for detecting the foodborne pathogen, B. licheniformis•Single-step analysis the caseinolytic/proteolytic enzymatic reactions exhibited by B. licheniformis on the casein/gelatin layer•A simple, budget-friendly, and portable biosensor to detect Bacillus licheniformis•The biosensor may specifically detect Bacillus licheniformis in different foods
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•Biofilm formation by pathogenic bacteria is one of the major resistance mechanisms.•Chitosan is a natural product exploited for combating bacterial infections.•Several alternative ...strategies have been developed for the application of chitosan.•Strategies include chemical modifications or combination with another active agent.
Biofilm formed by several pathogenic bacteria results in the development of resistance against antimicrobial compounds. The polymeric materials present in the biofilm architecture hinder the entry of antimicrobial compounds through the surface of bacterial cells which are embedded as well as enclosed beneath the biofilm matrix. Recent and past studies explored the alternative approaches to inhibit the formation of biofilm by different agents isolated from plants, animals, and microbes. Among these agents, chitosan and its derivatives have got more attention due to their properties such as biodegradability, biocompatibility, non-allergenic and non-toxicity. Recent researches have focused on employing chitosan and its derivatives as effective agents to inhibit biofilm formation and attenuate virulence properties by various pathogenic bacteria. Such antibiofilm activity of chitosan and its derivatives can be further enhanced by conjugation with a wide range of bioactive compounds. The present review describes the antibiofilm properties of chitosan and its derivatives against the pathogenic bacteria. This review also summarizes the mechanisms of biofilm inhibition exhibited by these molecules. The knowledge of the antibiofilm activities of chitosan and its derivatives as well as their underlying mechanisms provides essential insights for widening their applications in the future.
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•Rhamnolipids production was evaluated employing the non-pathogen B. thailandensis.•Used cooking oil, deriving from sunflower, was exploited as carbon source.•Co-production of PHB and ...rhamnolipids by B. thailandensis was demonstrated.•Both PHB and RLs were characterized regarding their physicochemical properties.•B. thailandensis used as biocatalyst may result in reducing their fermentation cost.
The present work assessed the feasibility of used cooking oil as a low cost carbon source for rhamnolipid biosurfactant production employing the strain Burkholderia thailandensis. According to the results, B. thailandensis was able to produce rhamnolipids up to 2.2 g/L, with the dominant congener being the di-rhamnolipid Rha-Rha-C14-C14. Rhamnolipids had the ability to reduce the surface tension to 37.7 mN/m and the interfacial tension against benzene and oleic acid to 4.2 and 1.5 mN/m, while emulsification index against kerosene reached up to 64%. The ability of B. thailandensis to accumulate intracellular biopolymers, in the form of polyhydroxyalkanoates (PHA), was also monitored. Polyhydroxybutyrate (PHB) was accumulated simultaneously and consisted of up to 60% of the cell dry weight. PHB was further characterized in terms of its molecular weight and thermal properties. This is the first study reporting the simultaneous production of polyhydroxyalkanoates and rhamnolipids by the non-pathogen rhamnolipid producer B. thailandensis.
In this study, the quality changes of fresh-cut yam slices treated with a mixture of ethanol (25%, w/w) and ascorbic acid (1%, w/w) treatments (EA) were assessed, and the bacterial community ...composition and their metabolic functions for these samples were investigated. Results showed that EA washing treatment notably reduced the respiratory intensity and microbial growth of fresh-cut yams in packaging during refrigeration, maintained the tuber firmness, and delayed discoloration. Proteobacteria was the main phyla significantly associated with off-flavor of yams, Bacteroidetes was the sensitive genera and was positively correlated to CO2 content of the packaging bag and sensory evaluation of yams. Interestingly EA could specifically remove the pathogenic bacteria of Pseudomonas (Proteobacteria), greatly destroy the stability of the bacterial community network on the fresh-cut yam slices’ surface, and achieve a better antibacterial effect. EA washing treatment reduced the metabolic capacity of bacterial community and was helpful to delay the aging and spoilage of fresh-cut yams, meanwhile, significantly inhibited transferase expression, and could help to maintain the quality of the fresh-cut yams. In conclusion, ethanol and ascorbic acid mixture washing agent altered the successional process of bacterial communities to reduce the pathogenic bacteria of fresh-cut yams during cold storage.
•Ethanol-containing washing could destroy the stability of bacterial community network of yams.•Has correlation between quality and microbial composition of yams, especially Proteobacteria.•Ethanol-containing treatment inhibit the expression of transporter genes in microorganisms.
This study aims identify E. coli and its β-lactamase encoding genes, S. aureus and its enterotoxin genes isolated from milk and Kariesh cheese. Moreover, we evaluated the antibacterial effect of ...lactoferrin against these pathogenic bacteria. Sixty samples in total (30 each of raw milk and Kariesh cheese) were collected from various retail-markets in Kafrel-Sheikh Governorate. The percentage of E. coli isolates found in raw milk and Kariesh cheese reached 43.3% and 36.6%, respectively, while S. aureus isolates were recorded at 50% and 23.3% (from raw milk and Kariesh cheese). Twenty-four strains of E. coli were serogrouped, of which 3 strains out of 24 were O17, O91 and O159, 6 strains were O127 and 9 strains were O26. PCR analysis for β-lactamase encoding genes in E. coli indicated that all eight isolates were 100% positive for blaTEM and blaSHV genes while 5 (62.5%) S. aureus isolates were positive for enterotoxin production. Five (62.5%) isolates produced Seb, 2(25%) produced Sec while the Sea gene was not detected in S. aureus isolates. The results indicate that lactoferrin 5% had a significant inhibitory effect on S. aureus and E. coli when they were inoculated into Kariesh cheese. The findings show that dairies didn't take enough hygiene precautions, and we advise following stringent hygiene procedures when dairy products are milked, processed and distributed. To control the growth of E. coli and S. aureus in dairy products,lactoferrin is thought to be a potential strategy.
