Physical and antibacterial properties of bacterial cellulose films supplemented with cell-free supernatant enterocin-producing Enterococcus faecium TJUQ1

The potential of postbiotics as a novel approach in food packaging and biopreservation: a systematic review of the latest developments

Metabolic by-products are part of the so-called postbiotics of probiotics and other beneficial microorganisms, particularly lactic acid bacteria, which have gained popularity as a feasible alternative to improving food quality and safety. Postbiotics in dry and liquid forms can be easily integrated into food formulations and packaging materials, exhibiting antimicrobial and antioxidant effects owing to the presence of multiple antimicrobials, such as organic acids, bacteriocins, exopolysaccharides and bioactive peptides. Postbiotics can thus control the growth of pathogens and spoilage microorganisms, thereby extending the shelf life of food products. Because of their ability to be easily manufactured without requiring extensive processing, postbiotics are regarded as a safer and more sustainable alternative to synthetic preservatives, which can have negative environmental consequences. Additionally, food manufacturers can readily adopt postbiotics in food formulations without significant modifications. This systematic review provides an in-depth analysis of studies on the use of postbiotics in the biopreservation and packaging of a wide range of food products. The review evaluates and discusses the types of microorganisms, postbiotics preparation and modification techniques, methods of usage in dairy products, meat, poultry, seafood, fruits, vegetables, bread, and egg, and their effects on food quality and safety.

Development and characterization of a novel sodium alginate based active film supplemented with Lactiplantibacillus plantarum postbiotic

In this study, sodium alginate based biodegradable films were prepared by the supplementation with postbiotics of Lactiplantibacillus plantarum subsp. plantarum (L. plantarum) W2 strain and the effect of probiotics (probiotic-SA film) and postbiotics (postbiotic-SA film) incorporation on physical, mechanical (tensile strength and elongation at break), barrier (oxygen and water vapor permeability), thermal and antimicrobial properties of the films were investigated. The pH, titratable acidity and brix of the postbiotic was 4.02, 1.24 % and 8.37, respectively while gallic acid, protocatechuic acid, myricetin and catechin were the major phenolic compounds. Mechanical and barrier properties of the alginate-based films were improved by probiotic or postbiotic supplementation while postbiotic showed a more pronounced (P < 0.05) effect. Thermal analysis showed that postbiotics supplementation increased thermal stability of the films. In FTIR spectra, the absorption peaks at 2341 and 2317 cm^-1 for probiotic-SA and postbiotic-SA edible films confirmed the incorporation of probiotics/postbiotics of L. plantarum W2 strain. Postbiotic supplemented films showed strong antibacterial activity against gram-positive (L. monocytogenes, S. aureus and B. cereus) and one gram-negative bacterial strain (E. coli O157:H7) while probiotic incorporation did not add an antibacterial effect to the films. SEM images revealed that the supplementation of postbiotics provided a rougher and rigid film surface. Overall, this paper brought a new perspective for development of novel active biodegradable films by incorporation of postbiotics with improved performance.

Screening of bacteriocin-producing dairy Enterococcus strains using low-cost culture media

This study was carried out to select the bacteriocinogenic strains among Enterococcus strains isolated from Ukrainian traditional dairy products using a low-cost media for screening, that containing molasses and steep corn liquor. A total of 475 Enterococcus spp. strains were screened for antagonistic activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes indicator strains. The initial screening revealed that 34 Enterococcus strains during growth in low-cost medium containing corn steep liquor, peptone, yeast extract, and sucrose produced metabolites with inhibition activity against at least of the indicator strains used. Enterocin genes entA, entP, and entB were detected in 5 Enterococcus strains by PCR assay. Genes of enterocins A and P were found in E. faecalis 58 and Enterococcus sp. 226 strains, enterocins B and P - in Enterococcus sp. 423, enterocin A - in E. faecalis 888 and E. durans 248 strains. Bacteriocin-like inhibitory substances (BLIS) produced by these Enterococcus strains were thermostable and sensitive to proteolytic enzymes. To our knowledge, this is the first report on the isolation of enterocin-producing wild Enterococcus strains from traditional Ukrainian dairy products using a low-cost media for screening bacteriocinogenic strains. Strains E. faecalis 58, Enterococcus sp. 423, and Enterococcus sp. 226 are promising candidates for practical use as producers of bacteriocins with inhibitory activity against L. monocytogenes using molasses and steep corn liquor as cheap sources of carbon and nitrogen, that can significantly reduce the cost of industrial bacteriocin production. Further studies will be required to determine the dynamic of bacteriocin production, its structure, and mechanisms of antibacterial action.

Enterocin: Promising Biopreservative Produced by Enterococcus sp

Food preservation is a method used to handle and treat food products to slow down food spoilage and subsequently reduce the risk of foodborne illness. Nowadays, the demand for natural preservatives over chemical preservatives in food is increasing due to the awareness of consuming healthy food products without the risk of harmful side effects. Thus, the research and development of preservation techniques, referred to as biopreservation, is growing rapidly. In biopreservation methods, microorganisms that are known as lactic acid bacteria (LAB) and their antimicrobial substances are used to extend shelf life and maintain the nutritional value of foods. Among the most studied LAB are from the genus Enterococcus, which produces a bacteriocin called enterocin. Bacteriocins are ribosomal-synthesized antimicrobial peptides that are capable of inhibiting the growth of pathogenic bacteria that cause spoilage in food. LAB is generally regarded as safe (GRAS) for human consumption. The current application of LAB, notably Enterococcus sp. in the biopreservation of meat and meat-based products was highlighted in this review. This report also includes information on the effects of enzymes, temperature, and pH on the stability of bacteriocin produced by Enterococcus sp. An extensive compilation of numerous industry procedures for preserving meat has also been emphasized, highlighting the benefits and drawbacks of each method.

Ecofriendly green biosynthesis and characterization of novel bacteriocin-loaded bacterial cellulose nanofiber from Gluconobacter cerinus HDX-1

A new strain of bacterial cellulose (BC)-producing Gluconobacter cerinus HDX-1 was isolated and identified, and a simple, low-cost complexation method was used to biosynthesis Lactobacillus paracasei 1∙7 bacteriocin BC (BC-B) nanofiber. The structure and antibacterial properties of the nanofibers were evaluated. Solid-state nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR) and x-ray diffraction (XRD) analysis showed that BC and BC-B nanofibers had typical crystalline form of the cellulose I. X-ray photoelectron spectrometer (XPS), scanning electron microscope (SEM) and atomic force microscopy (AFM) revealed that the bacteriocin and BC were successfully compounded, and the structure of BC-B nanofiber was tighter than BC nanofiber, with lower porosity, swelling ratio and water vapor transmission rate (WVTR). The tensile strength and Young's modulus of BC-B nanofibers were 13.28 ± 1.26 MPa and 132.10 ± 4.92 MPa, respectively, higher than that of BC nanofiber (6.12 ± 0.87 MPa and 101.59 ± 5.87 MPa), indicating that bacteriocin enhance the mechanical properties of BC nanofiber. Furthermore, the BC-B nanofibers exhibited significant thermal stability, antioxidant capacity and antibacterial activity than BC nanofiber. Therefore, bacteriocin-loaded BC nanofiber may be used as antimicrobial agents in active food packaging and medical material.