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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.
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.
Besides their established antioxidant activity, many phenolic compounds may exhibit significant antibacterial activity. Here, the effect of a large dataset of 35 polyphenols on the growth of 6 ...foodborne pathogenic or food-spoiling bacterial strains, three Gram-positive ones (
s,
, and
) and three Gram-negative ones (
, and
Enteritidis), have been characterized. As expected, the effects of phenolic compounds were highly heterogeneous ranging from bacterial growth stimulation to antibacterial activity and depended on bacterial strains. The effect on bacterial growth of each of the polyphenols was expressed as relative Bacterial Load Difference (BLD) between a culture with and without (control) polyphenols at a 1 g L
concentration after 24 h incubation at 37°C. Reliable Quantitative Structure-Activity Relationship (QSAR) models were developed (regardless of polyphenol class or the mechanism of action involved) to predict BLD for
. Enteritidis,
s, and
, unlike for
and
.
was generally sensitive to polyphenols whereas
was not. No satisfactory models predicting the BLD of
and
were obtained due to their specific and quite constant behavior toward polyphenols. The main descriptors involved in reliable QSAR models were the lipophilicity and the electronic and charge properties of the polyphenols. The models developed for the two Gram-negative bacteria (
. Enteritidis) were comparable suggesting similar mechanisms of toxic action. This was not clearly observed for the two Gram-positive bacteria (
s and
). Interestingly, a preliminary evaluation by Microbial Adhesion To Solvents (MATS) measurements of surface properties of the two Gram-negative bacteria for which QSAR models were based on similar physico-chemical descriptors, revealed that MATS results were also quite similar. Moreover, the MATS results of the two Gram-positive bacterial strains
and
for which QSARs were not based on similar physico-chemical descriptors also strongly differed. These observations suggest that the antibacterial activity of most of polyphenols likely depends on interactions between polyphenols and bacterial cells surface, although the surface properties of the bacterial strains should be further investigated with other techniques than MATS.
Foodborne pathogens are causing a great number of diseases with significant effects on human health and economy. The characteristics of the most common pathogenic bacteria (
,
,
,
,
,
,
,
spp.,
spp.,
...,
spp. and
), viruses (Hepatitis A and Noroviruses) and parasites (
,
and
), together with some important outbreaks, are reviewed. Food safety management systems based on to classical hazard-based approach has been proved to be inefficient, and risk-based food safety approach is now suggested from leading researchers and organizations. In this context, a food safety management system should be designed in a way to estimate the risks to human health from food consumption and to identify, select and implement mitigation strategies in order to control and reduce these risks. In addition, the application of suitable food safety education programs for all involved people in the production and consumption of foods is suggested.
Natural fruit pulp is highly appreciated because it retains the flavor and nutrients of the fresh fruit. However, fruit pulp is susceptible to contamination by pathogenic bacteria, mainly because of ...improper handling and storage. Therefore, this study evaluated and quantified the presence of pathogenic bacteria in fruit pulp sold in São Raimundo das Mangabeiras, Maranhão, Brazil. Two fruit pulp samples each of açaí (A and B), acerola (C and D), cajá (E and F), cashew (G and H), and passion fruit (I and J) were obtained from supermarkets and subjected to the following microbiological analyses: enumeration of mesophilic bacteria using plate count agar; quantification of total (TC) and thermotolerant (TTC) coliforms using the multiple tube technique; qualitative detection of Escherichia coli on eosin methylene blue agar and that of Salmonella on xylose lysine base agar and enteric agar. Mesophilic bacteria were found to grow in all the samples, with the highest value obtained for the acerola pulp (sample D; average: 1.08 x 105 colony-forming units g-1). However, all samples were in accordance with the Brazilian legislation for this parameter. The most probable number of colonies (MPN g-1) of TC and TTC were ≥1,100 in açaí (sample A), cajá (sample E), and cashew (sample G) pulps, which is in disagreement with the maximum value allowed. E. coli and Salmonella were not found to grow in the samples evaluated in this study. Collectively, the data indicate inadequate handling and storage in the production chain of fruit pulp sold in the municipality of São Raimundo das Mangabeiras, suggesting that the population in the region is exposed to a probable risk of food contamination.
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•Nanocomposite film are fabricated by incorporating CuONPs/ZnONPs into SA/CS matrix.•Packaging properties of SA/CS film are improved by incorporation of CuONPs/ZnONPs.•SA-CS@CuO/ZnO ...film inhibits growth of bacteria and regulates their gene expression.•SA-CS@CuO/ZnO film regulates cellular antioxidant pathway of E. coli and S. aureus.•SA-CS@CuO/ZnO film affects bacterial gene guiding repair of cell membranes and DNA.
In this study, the nanocomposite film (SA-CS@CuO/ZnO) composed of sodium alginate (SA) and chitosan (CS) functionalized by copper oxide nanoparticles (CuONPs) and zinc oxide nanoparticles (ZnONPs) was fabricated, then its antibacterial mechanisms against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were systematically investigated. When the contents of CuONPs and ZnONPs reached 1.5 % (w/w) and 0.5 % (w/w), respectively, the SA-CS@CuO/ZnO exhibited great mechanical, barrier, and optical properties. Moreover, the incorporation of ZnONPs enhanced the photocatalytic ability of SA-CS@CuO/ZnO, producing a high level of reactive oxygen species under light irradiation. Further, antibacterial results showed that SA-CS@CuO/ZnO treatment inhibited the growth of E. coli and S. aureus higher than 60 % in the dark and exceeded 90 % under light irradiation. This was also manifested in the incompleteness of bacterial cell structure, accompanied by unstable cellular redox balance and DNA disruption. The functions of differentially expressed genes screened by transcriptome analysis were mainly involved in membrane transport, cell wall and membrane synthesis, cellular antioxidant defense system, cell membrane and DNA repair system. The changes in bacterial transcriptional regulation reflected the disturbance in the physiological activities and loss of cell integrity, leading to damage of bacterial cells or death.
Foodborne disease poses an enormous threat to the safety of human beings all over the world. The rapid and accurate monitoring and determination of foodborne pathogenic bacteria is of great ...significance to food safety. In recent years, with the evolution of nanotechnology, reduced graphene oxide (rGO) nanocomposites have been frequently introduced into the construction of electrochemical biosensors due to their unique physicochemical properties and biocompatibility. The combination of biomolecules with specific recognition capabilities and rGO nanocomposites provide a promising strategy to construct more stable and sensitive electrochemical biosensors for the detection of foodborne pathogenic bacteria. This review tracks the development of rGO nanocomposite materials electrochemical biosensors for the detection of foodborne pathogenic bacteria, mainly including the preparation of rGO nanocomposite electrochemical biosensors and their working mechanism. The challenges in this field are discussed, and a perspective for further development is proposed, with the goal of promoting development of sensing technology for foodborne pathogenic bacteria to help prevent outbreaks of foodborne disease.
Microplastic pollution and associated impacts in the aquatic environment are spreading at an alarming rate worldwide. Plastic waste is increasing in the environment, and microplastics (MPs) are ...becoming a growing issue because they serve as vectors for pathogen transmission. This is the first comprehensive review that specifically addresses MPs as a source and vector of pathogenic bacteria, mainly associated with genera Vibrio, Pseudomonas, Acinetobacter, and so on, which are discovered to be more abundant on the aquatic plastisphere than that in the surrounding wastewater, freshwater, and marine water ecosystems. The horizontal gene transfer, chemotaxis, and co–selection and cross-selection could be the potential mechanism involved in the enrichment and dissemination of bacterial pathogens through the aquatic plastisphere. Further, bacterial pathogens through aquatic plastisphere can cause various ecological and human health impacts such as disrupted food chain, oxidative stress, tissue damages, disease transmission, microbial dysbiosis, metabolic disorders, among others. Last but not least, future research directions are also described to find answers to the challenging questions about bacterial pathogens in the aquatic plastisphere to ensure the integrity and safety of ecological and human health.
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•Microplastics (MPs) enriched more bacterial pathogens than the surrounding water.•Vibrio, Pseudomonas, &Acinetobacter associated pathogens are most common on MPs•Pathogens transfer via horizontal gene transfer, chemotaxis, & selection mechanism.•Food chain disruption, coral albinism, & immune response are main ecological impacts.•Drug resistance, metabolic disorders, & inflammation are major human health impacts.
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