Immobilization of Bacteriocins from Lactic Acid Bacteria and Possibilities for Application in Food Biopreservation

Bacteriocins are biologically active compounds produced by a large number of bacteria, including lactic acid bacteria (LAB), which exhibit antimicrobial activity against various saprophytic and pathogenic microorganisms. In recent decades, bacteriocins are increasingly becoming more important in different branches of the industry due to their broad antibacterial and antifungal spectrum - in the food industry for natural food preservation and expiry date extension; in the health sector for preparation of probiotic foods and beverages; in the clinical practice as alternatives of conventional antibiotics; in the agriculture as biocontrol agents of plant pathogens and alternatives of chemical pesticides for plant protection. The broad antimicrobial spectrum of bacteriocins has stimulated the research attention on their application mainly in the food industry as natural preservatives. Most scientific achievements concerning the application food biopreservation are related to bacteriocins produced by LAB. The lactic acid bacteria bacteriocins can be produced in the food substrate during its natural fermentation or can be added in the food products after obtaining by in vitro fermentations under optimal physical and chemical conditions. Moreover, the immobilization of LAB bacteriocins on different matrices of organic and inorganic origin has been proposed as an advanced approach in the natural food preservation for their specific antimicrobial activity, anti-biofilm properties and potential use as tools for pathogen detection

Biopreservation of Fresh Strawberries by Carboxymethyl Cellulose Edible Coatings Enriched with a Bacteriocin of Bacillus methylotrophicus BM47

Bacteriocins are a large group of antimicrobial compoundsthat aresynthesized byrepresentatives ofthegenus Bacillusand lactic acid bacteria (LAB). Bacteriocinsare used extensively in thefood industry as biopreservatives. Incorporatedin the composition of edible coatings, bacteriocins canreduce microbial growthand decay incidencein perishable fruits, thusimproving productshelf-life and commercial appearance. The present study aims to investigatethe effect of edible coatings of0.5% carboxymethyl cellulose (CMC) enriched with a purified bacteriocin fromBacillus methylotrophicusBM47 on the shelf-life extension of fresh strawberries. During storage at 4\ub0Cand 75 % relative humidity(RH) for 16 days, measurements of massloss, decay percentage, total soluble solids(TSS), titratable acidity(TA),pH, organic acids, total phenolic and anthocyaninscontents and antioxidant activity were taken.The results demonstrated that the application of 0.5% CMC and 0.5% CMC+bacteriocin (CMC+B) edible coatings led to a significant decrease of massloss in treated strawberriescompared to the uncoated fruit. After the 8-th day of storage, significant reductions in decay percentage along with the absence of fungal growth in CMC+B-coated fruit wereobserved in comparison to the CMC-coated and control strawberries. During the second half of the storage period, CMC and CMC+B treatmentsreduced TSS levels inthe coated fruitcompared to the control, but did not affectincreasedTA and loweredpH valuesthat arenormally associated with post-harvest changes. The CMC and CMC+B coatings wereineffectiveagainst thedecrease inascorbic acid, total phenolics and anthocyanins contentduringcold storage. The application of CMC and CMC+B coatingsexhibited a significant inhibitory effect on decreasing antioxidant activity throughout the storage period and maintained the antioxidant levels inboth treatmentsclose to the initial value of 76.8 mmol TE/100 g of fm

“Green” Synthesis of Sucrose Octaacetate and Characterization of Its Physicochemical Properties and Antimicrobial Activity

Sucrose octaacetate (octa-O-acetylsucrose) has been synthesized by esterification of sucrose with acetic anhydride using ultrasound-assisted irradiation. This sucrose ester is a white, water-insoluble substance with a bitter taste. The FT-IR and NMR spectra confirmed acetylation and revealed the hydrophobic incorporation in sucrose molecule. Furthermore, the foamability, foam stability, emulsification and antimicrobial properties of octa-O-acetylsucrose were evaluated. Foams and 50 % (oil/water) model emulsions were prepared with 2 % (w/w) octa-O-acetylsucrose. The obtained results demonstrate the formation of emulsions and foams with high stability (50–70 %). The antimicrobial activity of octa-O-acetylsucrose was evaluated against seventeen microorganisms (Gram-positive and Gram-negative bacteria, yeasts, and fungi). Octa-O-acetylsucrose inhibited the growth of fungi Penicillium sp., Rhizopus sp. and Fusarium moniliforme at 5 mg cm–3, and yeasts Candida albicans at 1 mg cm–3. Inhibition against Gram-positive and Gram-negative bacteria was not observed. The obtained results demonstrate the potential applications of octa-O-acetylsucrose as a foaming agent, oil-in-water emulsion stabilizer, and antifungal substance in pharmaceutical and cosmetic preparations. This work is licensed under a Creative Commons Attribution 4.0 International License

Isolation, Characterization and Amino Acid Composition of a Bacteriocin Produced by Bacillus methylotrophicus Strain BM47

Poznato je da bakterije roda Bacillus proizvode široki spektar proteinskih antibiotičkih spojeva što inhibiraju različite saprofitne i patogene mikroorganizme. U ovom je radu opisan i identificiran kao bakteriocin peptid iz soja bakterije Bacillus methylotrophicus BM47, prethodno izolirane iz prirodnog termalnog izvora u Bugarskoj. Ispitivanje je antimikrobnog djelovanja in vitro nepročišćene suspenzije bakteriocina iz B. methylotrophicus BM47 pokazalo učinak na fitopatogene plijesni Fusarium moniliforme, Aspergillus awamori, Penicillium sp., Aspergillus niger te na Gram-negativnu bakteriju Pseudomonas aeruginosa. Antimikrobno djelovanje nepročišćene suspenzije bakteriocina djelomično su inhibirali enzimi tripsin, Alcalase®, Savinase®, proteinaza K, papain i Esperase®, dok katalaza nije imala učinkovito djelovanje. Nepročišćena je suspenzija bakteriocina bila otporna na promjene u pH-vrijednostima, ali je bila osjetljiva na djelovanje topline i većine ispitanih organskih otapala i detergenata. Radi dobivanja udjela aktivnog proteina, sirovi je ekstrakt bakteriocina pročišćen pomoću brze tekućinske kromatografije proteina (engl. FPLC) i jake anionske kolone za ionsku izmjenu. Analiza tricin-natrij dodecil sulfat – poliakrilamid gel elektroforezom pokazala je da pročišćeni bakteriocin ima molekulsku masu od 19 578 Da, dok je visokodjelotvornom tekućinskom kromatografijom utvrđeno da sadržava 17 vrsta aminokiselina s najvećim molarnim udjelom serina (29,3 %), valina (10,3 %), alanina (9,8 %) i tirozina (7,1 %).Members of the bacterial genus Bacillus are known as producers of a broad spectrum of antibiotic compounds of proteinaceous nature that possess inhibitory activity against different saprophytic and pathogenic microorganisms. In the current research, a peptide synthesized by Bacillus methylotrophicus strain BM47, previously isolated from a natural thermal spring in Bulgaria, was identified and characterized as a bacteriocin. In vitro antimicrobial screening of the crude bacteriocin substance of B. methylotrophicus BM47 showedn activity against the plant pathogenic fungi Fusarium moniliforme, Aspergillus awamori, Penicillium sp., Aspergillus niger and Gram-negative bacterium Pseudomonas aeruginosa. The antimicrobial activity of the crude bacteriocin substance was partially inhibited by the enzymes trypsin, Alcalase®, Savinase®, proteinase K, papain and Esperase®, while catalase was not effective. The crude bacteriocin substance was relatively pH resistant, but sensitive to the action of heat and most organic solvents and detergents tested. To obtain the active protein fractions, crude bacteriocin substance was purified by fast protein liquid chromatography (FPLC) using a strong anion exchange column. Tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis demonstrated that the purified bacteriocin had molecular mass of 19 578 Da. The amino acid analysis performed by high-performance liquid chromatography (HPLC) revealed that the isolated bacteriocin consisted of 17 types of amino acids, with the highest mol fraction expressed as percent of serine (29.3), valine (10.3), alanine (9.8) and tyrosine (7.1)

Role of the noroviruses as substantial foodborne pathogens: A review

Role of the noroviruses as substantial foodborne pathogens: A review: Acute gastroenteritis is one of the most important diseases in humans. Etiology of the infectious gastroenteritis involves several agents such as viruses, bacteria and parasites. Bacteria and parasites are causative agents of gastroenteritis in developing countries, whereas viruses are responsible for gastroenteritis outbreaks in the industrialized countries. Noroviruses are recognized as leading cause of highly transmissible foodborne disease that affects millions of people every year worldwide. The main sources of infection are seafood, deriving from waters polluted with human faeces, and fruits or vegetables, irrigated with contaminated water during their cultivation. Due to their resistance and rapid spread, noroviruses remain a serious public health problem in many countries

Valorization of Peels of Eight Peach Varieties: GC–MS Profile, Free and Bound Phenolics and Corresponding Biological Activities

Sustainability, becoming essential for food processing and technology, sets goals for the characterization of resources considered as food waste. In this work, information about the GC-MS metabolites of peach peels was provided as a tool that can shed more light on the studied biological activities. In addition, distribution patterns and contribution of the chemical profile and free and bound phenolic compounds as antioxidant, antimicrobial, and enzymatic clusters in peach peels of different varieties of Bulgarian origin were studied. The two applied techniques (alkaline and acid hydrolysis) for releasing the bound phenolics reveal that alkaline hydrolysis is a better extraction approach. Still, the results indicate the prevalence of the free phenolics in the studied peach peel varieties. Total phenolics of peach wastes were positively correlated with their antioxidant activity. The antioxidant activity results certainly defined the need of an individual interpretation for each variety, but the free phenolics fractions could be outlined with the strongest potential. The limited ability of the peels’ extracts to inhibit α-amylase and acetylcholinesterase, and the moderate antimicrobial activity, on the other hand, indicate that the potential of peach peels is still sufficient to seek ways to valorize this waste. Indeed, this new information about peach peels can be used to characterize peach fruits from different countries and/or different food processes, as well as to promote the use of this fruit waste in food preparation

Comparative Study on Physicochemical, Antioxidant and Antimicrobial Properties of Propolis Collected from Different Regions of Bulgaria

Propolis (bee glue), a valuable biological mixture produced by European honey bees (Apis mellifera L.), is widely used as a remedy in traditional and alternative medicine, as an effective food biopreservative and as a nutritional value enhancer. The present study aimed to investigate eighty propolis samples collected from all twenty-eight districts of Bulgaria in the period of 2020–2022 in order to determine their physicochemical properties as well as their antioxidant and antimicrobial potential. The raw propolis samples exhibited brown or green colour depending on the climatic zone from which they are collected and pH values from 4.82 to 5.87, while the moisture content ranged between 0.98% and 2.97%. The total phenolics content (TPC) and total flavonoids content (TFC) varied from 63.14 mg GAE/g to 737.27 mg GAE/g, and from 29.22 mg QE/g to 234.17 mg QE/g, respectively. The propolis samples demonstrated significant antioxidant potential determined by DPPH and FRAP methods, from 18.56 mM TE/g to 1598.66 mM TE/g and from 82.28 mM TE/g to 1208.81 mM TE/g, respectively, whose values showed a positive correlation (r2) with the TPC and TFC. The results from the antimicrobial screening revealed that the methanolic propolis extracts in concentration of 20 mg/ml exhibited the highest inhibitory effect on the Gram-positive bacteria such as Micrococcus luteus 2YC-YT, Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 25923, Listeria monocytogenes NBIMCC 8632 and Listeria innocua ATCC 33090

Isolation, Characterization and Amino Acid Composition of a Bacteriocin Produced by Bacillus methylotrophicus Strain BM47

Members of the bacterial genus Bacillus are known as producers of a broad spectrum of antibiotic compounds of proteinaceous nature that possess inhibitory activity against different saprophytic and pathogenic microorganisms. In the current research, a peptide synthesized by Bacillus methylotrophicus strain BM47, previously isolated from a natural thermal spring in Bulgaria, was identified and characterized as a bacteriocin. In vitro antimicrobial screening of the crude bacteriocin substance of B. methylotrophicus BM47 showedn activity against the plant pathogenic fungi Fusarium moniliforme, Aspergillus awamori, Penicillium sp., Aspergillus niger and Gram-negative bacterium Pseudomonas aeruginosa. The antimicrobial activity of the crude bacteriocin substance was partially inhibited by the enzymes trypsin, Alcalase®, Savinase®, proteinase K, papain and Esperase®, while catalase was not effective. The crude bacteriocin substance was relatively pH resistant, but sensitive to the action of heat and most organic solvents and detergents tested. To obtain the active protein fractions, crude bacteriocin substance was purified by fast protein liquid chromatography (FPLC) using a strong anion exchange column. Tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis demonstrated that the purified bacteriocin had molecular mass of 19 578 Da. The amino acid analysis performed by high-performance liquid chromatography (HPLC) revealed that the isolated bacteriocin consisted of 17 types of amino acids, with the highest mol fraction expressed as percent of serine (29.3), valine (10.3), alanine (9.8) and tyrosine (7.1)

In Silico, In Vitro, and Ex Vivo Biological Activity of Some Novel Mebeverine Precursors

Irritable bowel syndrome (IBS) is a functional gastroenterological disorder with complex pathogenesis and multifaceted therapy approaches, aimed at alleviating clinical symptoms and improving the life quality of patients. Its treatment includes dietary changes and drugs from various pharmacological groups such as antidiarrheals, anticholinergics, serotonin receptor antagonists, targeting chloride ion channels, etc. The present article is focused on the synthesis and biological evaluation of some mebeverine precursors as potential antispasmodics. Methods: In silico analysis aimed at predicting the pharmacodynamic profile of the compounds was performed. Based on these predictions, ex vivo bioelectrical activity (BEA) and immunohistochemical effects of the compounds were established. A thorough biological evaluation of the compounds was conducted assessing their in vitro antimicrobial and cytotoxic activity. Results: All the newly synthesized compounds exerted drug-like properties, whereby 3-methyl-1-phenylbutan-2-amine 3 showed a significant change in BEA due to Ca2+ channel regulation, Ca2+ influx modulation, and a subsequent change in smooth muscle cell response. The immunohistochemical studies showed a good correlation with the obtained data on the BEA, defining amine 3 as a leader structure. No cytotoxicity to human malignant leukemic cell lines (LAMA-84, K-562) was observed for all tested compounds. Conclusion: Based on the experimental results, we outlined 3-methyl-1-phenylbutan-2-amine 3 as a potential effective choice for orally active long-term therapy of IBS