Recent advancements in encapsulation of bioactive compounds as a promising technique for meat preservation.

Encapsulation is currently considered as one the most valuable methods for preserving aromatic compounds or hiding odors, enhancing their thermal and oxidative stability, and expanding their food applications. Indeed, this current article was aimed to provide an overview regarding the encapsulation of plant bioactive compounds and the spray-drying and extrusion processes with a focused discussion regarding the encountered challenges for meat and meat product preservation. Furthermore, different ranges of carbohydrates as wall materials (carriers) besides the process conditions' effects on the encapsulation effectiveness and the particle size of the encapsulated bioactive compounds have been discussed. The encapsulation of these compounds ameliorates the quality of the stored meat products by further delaying in microflora growth and lipid/protein oxidation. Therefore, the innovative technologies for plant active compounds encapsulation offer a prospective alternative for natural preservation development in the meat industry.

Enterococci: Between Emerging Pathogens and Potential Probiotics.

Enterococci are ubiquitous microorganisms that could be found everywhere; in water, plant, soil, foods, and gastrointestinal tract of humans and animals. They were previously used as starters in food fermentation due to their biotechnological traits (enzymatic and proteolytic activities) or protective cultures in food biopreservation due to their produced antimicrobial bacteriocins called enterocins or as probiotics, live cells with different beneficial characteristics such as stimulation of immunity, anti-inflammatory activity, hypocholesterolemic effect, and prevention/treatment of some diseases. However, in the last years, the use of enterococci in foods or as probiotics caused an important debate because of their opportunistic pathogenicity implicated in several nosocomial infections due to virulence factors and antibiotic resistance, particularly the emergence of vancomycin-resistant enterococci. These virulence traits of some enterococci are associated with genetic transfer mechanisms. Therefore, the development of new enterococcal probiotics needs a strict assessment with regard to safety aspects for selecting the truly harmless enterococcal strains for safe applications. This review tries to give some data of the different points of view about this question.

Herbal medicine as an auspicious therapeutic approach for the eradication of Helicobacter pylori infection: A concise review.

Helicobacter pylori (H. pylori) causes gastric mucosa inflammation and gastric cancer mostly via several virulence factors. Induction of proinflammatory pathways plays a crucial role in chronic inflammation, gastric carcinoma, and H. pylori pathogenesis. Herbal medicines (HMs) are nontoxic, inexpensive, and mostly anti-inflammatory reminding meticulous emphasis on the elimination of H. pylori and gastric cancer. Several HM has exerted paramount anti-H. pylori traits. In addition, they exert anti-inflammatory effects through several cellular circuits such as inhibition of 5'-adenosine monophosphate-activated protein kinase, nuclear factor-κB, and activator protein-1 pathway activation leading to the inhibition of proinflammatory cytokines (interleukin 1α [IL-1α], IL-1ß, IL-6, IL-8, IL-12, interferon γ, and tumor necrosis factor-α) expression. Furthermore, they inhibit nitrous oxide release and COX-2 and iNOS activity. The apoptosis induction in Th1 and Th17-polarized lymphocytes and M2-macrophagic polarization and STAT6 activation has also been exhibited. Thus, their exact consumable amount has not been revealed, and clinical trials are needed to achieve optimal concentration and their pharmacokinetics. In the aspect of bioavailability, solubility, absorption, and metabolism of herbal compounds, nanocarriers such as poly lactideco-glycolide-based loading and related formulations are helpful. Noticeably, combined therapies accompanied by probiotics can also be examined for better clearance of gastric mucosa. In addition, downregulation of inflammatory microRNAs (miRNAs) by HMs and upregulation of those anti-inflammatory miRNAs is proposed to protect the gastric mucosa. Thus there is anticipation that in near future HM-based formulations and proper delivery systems are possibly applicable against gastric cancer or other ailments because of H. pylori.

Bio-guided Purification and Mass Spectrometry Characterisation Exploring the Lysozyme-like Protein from Enterococcus lactis Q1, an Unusual Marine Bacterial Strain.

Lactic acid bacteria produce various antibacterial peptides such as bacteriocins that are active against pathogenic and spoilage microorganisms. Very little attention has been paid to the production of lysozyme as an antimicrobial enzyme. The present work represents one of the few studies reporting lysozyme production by enterococci. Indeed, this study was first conducted to evaluate the antimicrobial activity of Enterococcus lactis Q1, an enterocin P-producing strain previously isolated from fresh shrimp (Penaeus vannamei), against multidrug-resistant clinical isolates. Results showed significant inhibitory activity (P < 0.05) towards diverse pathogens. The purification of the antimicrobial substances produced by Q1 strain leads to the isolation of two active fractions. The SDS-PAGE and mass spectrometry analyses of fraction number 2 (fraction 2) revealed the presence of a protein with molecular mass of 14.3 kDa. Additionally, the experimental results are consistent with mass spectra of industrial lysozyme (Fluka ref. 62970). The lysozyme produced by Enterococcus lactis Q1 strain was confirmed by a plate method against Micrococcus luteus ATCC 4698. Also, sensitivity of the Q1 strain to different concentrations of lysozyme was investigated. For the first time, this study shows that E. lactis Q1 produces lysozyme which could be an excellent candidate in food biopreservation or production of functional foods to promote health benefits.

Genetic Analysis with Random Amplified Polymorphic DNA of the Multiple Enterocin-Producing Enterococcus lactis 4CP3 Strain and Its Efficient Role in the Growth of Listeria monocytogenes in Raw Beef Meat.

In this manuscript, a multiple enterocin-producing Enterococcus lactis strain named 4CP3 was used to control the proliferation of Listeria monocytogenes in refrigerated raw beef meat model. Also, the intraspecific genetic differentiation of 4CP3 strain was assessed by Random Amplified Polymorphic DNA Polymerase Chain Reaction (RAPD-PCR) analysis. E. lactis 4CP3 strain was found to produce the enterocins A, B, and P. It displayed activity against L. monocytogenes EGDe 107776 by agar-well diffusion method. The application of E. lactis 4CP3 culture at 107 CFU/g in raw beef meat was evaluated using both ANOVA and ANCOVA linear models in order to examine its effect on the growth of the pathogen L. monocytogenes during refrigerated storage. Hence, a very interesting result in decreasing (P<0.05) and suppressing the growth of L. monocytogenes in refrigerated raw beef meat was shown during 28 days of storage. In conclusion, E. lactis 4CP3 strain might be useful for prevention of the proliferation and survival of L. monocytogenes in raw meat during refrigerated storage.

Safety characterisation and inhibition of fungi and bacteria by a novel multiple enterocin-producing Enterococcus lactis 4CP3 strain.

This study aims to characterise a potential bacteriocinogenic lactic acid bacterial strain isolated from a raw pink shrimp (Palaemon serratus) and evaluate its safety aspect. The strain designated as 4CP3 was noted to display antibacterial activities (P < 0.05) against Gram-positive and Gram-negative foodborne pathogens (Listeria monocytogenes and Pseudomonas aeruginosa) and some filamentous fungi (e.g. Aspergillus niger A79). Phenotypic and molecular techniques as well as phylogenetic analysis identified the isolate 4CP3 as Enterococcus lactis. Its produced antimicrobial substance was determined as a bacteriocin that was stable over a wide range of pH (2-10) and after heating at 100 °C for 15 min. The maximum bacteriocin production was 1400 AU/ml recorded after 12 h of incubation in de Man, Rogosa and Sharpe (MRS) broth medium at 30 °C. The mode of action of the bacteriocin produced by 4CP3 strain was identified as bactericidal against L. monocytogenes EGDe 107776 and P. aeruginosa ATCC 27853. By specific PCR amplifications, E. lactis 4CP3 was shown to produce the enterocins A, B and P. To our knowledge, this feature is newly described for E. lactis strain isolated from raw shrimps. Regarding safety aspect of E. lactis 4CP3, it has been demonstrated that this strain was not haemolytic, gelatinase negative, sensitive to vancomycin, and free of common antibiotic resistance genes and virulence factors. Therefore, it may be useful as a safe natural agent in preservation of foods or as a new probiotic strain in food and feed.

Safety, potential biotechnological and probiotic properties of bacteriocinogenic Enterococcus lactis strains isolated from raw shrimps.

The aims of this study are to isolate new bacteriocinogenic lactic acid bacterial strains from white (Penaeus vannamei) and pink (Palaemon serratus) raw shrimps and evaluate their technological and probiotic potentialities. Seven strains were selected, among fifty active isolates, as producing interesting antimicrobial activity. Identified as Enterococcus lactis, these isolates were able to produce enterocins A, B and/or P. The safety aspect, assessed by microbiological and molecular tests, demonstrated that the strains were susceptible to relevant antibiotics such as vancomycin, negative for haemolysin and gelatinase activities, and did not harbour virulence and antibiotic resistance genes. The assessment of potential probiotic and technological properties showed a low or no lipolytic activity, moderate milk-acidifying ability, high reducing power, proteolytic activity and tolerance to bile (P < 0.05) and good autoaggregation and coaggregation capacities. Two strains designated as CQ and C43 exhibiting high enzymatic activities and bile salt hydrolase activity were found to display high survival under simulated in vitro oral cavity and gastrointestinal tract conditions caused by presence of lysozyme, pepsin, pancreatin, bile salts and acidic pH. This study highlights safe Enterococcus lactis strains with great technological and probiotic potentials for future application as new starter, adjunct, protective or probiotic cultures in food industry.

Isolation and characterisation of an enterocin P-producing Enterococcus lactis strain from a fresh shrimp (Penaeus vannamei).

Screening for lactic acid bacteria (LAB) from fresh shrimp samples (Penaeus vannamei) collected from retail seafood markets in the Tunisian's coast, resulted in the isolation of an Enterococcus strain termed Q1. This strain was selected for its antagonistic activity against pathogenic bacteria such as Listeria monocytogenes, Pseudomonas aeruginosa, Lactococcus garvieae and against fungi (Aspergillus niger and Fusarium equiseti). The Q1 strain was characterised using standard morphological and biochemical tests, growth assays at different temperatures, pH and salinity. 16S rRNA, rpoA and pheS gene sequencing, as well as the 16S-23S rRNA intergenic spacer analyses, were combined to identify strain Q1 as a strain of Enterococcus lactis. The bacteriocin produced by E. lactis Q1 is thermostable, active in the pH range from 4.0 to 9.0 and has a bactericidal mode of action. The enterocin P structural gene was detected by specific PCR in strain E. lactis Q1, which is in good agreement with SDS-PAGE data of the purified bacteriocin. A lack of significant antibiotic resistance genes and virulence determinants was confirmed by specific PCRs. This work provides the first description of an enterocin P producer E. lactis strain isolated from a fresh shrimp. Based on its safety properties (absence of haemolytic activity, virulence factors and antibiotic resistance genes), this strain has the potential to be used as a natural additive or adjunct protective culture in food biopreservation and/or probiotic culture.

Evaluation of marine bacteriocinogenic enterococci strains with inhibitory activity against fish-pathogenic Gram-negative bacteria.

Use of lactic acid bacteria (LAB) as probiotics may provide an alternative to the use of antibiotics in aquaculture. LAB strains isolated from wild fish viscera and skin were evaluated for bacteriocin production and safety aspects (lack of antibiotic resistance, production of virulence factors). 16S rRNA gene sequences revealed the presence of Enterococcus faecium (13 isolates) and Lactococcus lactis (3 isolates) from fish samples. Pulsed-field gel electrophoresis analyses of the 13 enterococci isolates showed that they were all clustered, with greater than 95% similarity. However, RAPD analysis revealed significant molecular diversity between enterococci strains. Six enterococci strains were chosen and evaluated for their antibacterial activities. These strains produced a bacteriocin-like substance and exhibited a broad spectrum of inhibition against pathogenic bacteria isolated from diseased fish, including Streptococcus parauberis, Vagococcus spp., and Carnobacterium maltaromaticum, and in particular against the Gram-negative bacteria Flavobacterium frigidarium, Vibrio pectenicida, V. penaeicida, and Photobacterium damselae. The inhibition activity towards bacterial indicator strains was at a maximum when bacteria were grown at 37°C. However, bacteriocin production was observed at 15°C after 12 h of incubation. Only structural genes of enterocins A and B were detected by PCR in the 6 enterococci strains, suggesting the production of these enterocins. In addition, these strains did not harbor any virulence factors or any significant antibiotic resistance, and they tolerated bile. Our results suggest that enterococci are an important part of the bacterial flora of fish and that some strains have the potential to be used as probiotics.