Stress tolerance-Bacillus with a wide spectrum bacteriocin as an alternative approach for food bio-protective culture production

Enterocin LD3 from Enterococcus hirae LD3 Inhibits the Growth of Salmonella enterica subsp. enterica serovar Typhimurium ATCC 13311 in Fruit Juice

In order to prevent the growth of pathogens in food, bacteriocins produced by various probiotic lactic acid bacteria have been recognized as potential substitutes of chemical preservatives. In this study, enterocin LD3 was purified from the cell-free supernatant of a food isolate, Enterococcus hirae LD3 using multistep chromatography. In the fruit juice, lethal concentration (LC50) of enterocin LD3 was found to be 260 µg/mL against Salmonella enterica subsp. enterica serovar Typhimurium ATCC 13311. The cells treated with enterocin LD3 were red colour indicating dead cells after propidium iodide staining, while untreated cells were found blue after staining with 4', 6-diamidino-2-phenylindole. The mechanism of cell killing was analyzed using infrared spectrum of cells treated with enterocin LD3 which was found altered in the range of 1,094.30 and 1,451.82 cm-1 corresponding to nucleic acids and phospholipids, respectively. The morphology of target cells were severely ruptured and lysed as observed under electron microscopy. Thus, the present study suggested that enterocin LD3 showed bactericidal activity against Salm. enterica subsp. enterica serovar Typhimurium ATCC 13311 and may be applied as a bio-preservative for the safety of fruit juices.

Draft genome sequence of Bacillus velezensis strains AOA1 and AKS2, the potential plant growth-promoting rhizobacteria

This report describes the draft genome sequence of Bacillus velezensis strains AOA1 and AKS2 isolated from maize rhizosphere soil in South Africa. Bacillus velezensis plays important biological roles as plant growth promoting rhizobacterium (PGPR). Bacillus velezensis strains also exhibit numerous biotechnological application potentials in agriculture and diverse industrial settings.

Potential Impact of Combined Inhibition by Bacteriocins and Chemical Substances of Foodborne Pathogenic and Spoilage Bacteria: A Review

In recent years, food safety caused by foodborne pathogens and spoilage bacteria has become a major public health problem worldwide. Bacteriocins are a kind of antibacterial peptide synthesized by microbial ribosomes, and are widely used as food preservatives. However, when used individually bacteriocins may have limitations such as high cost of isolation and purification, narrow inhibitory spectrum, easy degradation by enzymes, and vulnerability to complex food environments. Numerous studies have demonstrated that co-treatment with bacteriocins and a variety of chemical substances can have synergistic antibacterial effects on spoilage microorganisms and foodborne pathogens, effectively prolonging the shelf life of food and ensuring food safety. Therefore, this paper systematically summarizes the synergistic bacteriostatic strategies of bacteriocins in combination with chemical substances such as essential oils, plant extracts, and organic acids. The impacts of bacteriocins when used individually and in combination with other chemical substances on different food substrates are clarified, and bacteriocin-chemical substance compositions that enhance antibacterial effectiveness and reduce the potential negative effects of chemical preservatives are highlighted and discussed. Combined treatments involving bacteriocins and different kinds of chemical substances are expected to be a promising new antibacterial method and to become widely used in both the food industry and biological medicine.

Bioactive protein hydrolysates obtained from amaranth by fermentation with lactic acid bacteria and Bacillus species

Protein hydrolysates are a promising source of bioactive peptides. One strategy by which they can be obtained is fermentation. This method uses the proteolytic system of microorganisms to hydrolyze the parental protein. Fermentation is a little-explored method for obtaining protein hydrolysates from amaranth. Different strains of lactic acid bacteria (LAB) and Bacillus species isolated from goat milk, broccoli, aguamiel, and amaranth flour were used in this work. First, the total protein degradation (%TPD) of amaranth demonstrated by the strains was determined. The results ranged from 0 to 95.95%, the strains that produced a higher %TPD were selected. These strains were identified by molecular biology and were found to correspond to the genera Enterococcus, Lactobacillus, Bacillus, and Leuconostoc. Fermentation was carried out with amaranth flour and the selected strains. After this process, water/salt extracts (WSE) containing the released protein hydrolysates were obtained from amaranth doughs. The peptide concentration was measured by the OPA method. The antioxidant, antihypertensive and antimicrobial activity of the WSE was evaluated. In the FRAP test, the best WSE was LR9 with a concentration of 1.99 μMTE/L ± 0.07. In ABTS, 18C6 obtained the highest concentration with 19.18 μMTE/L ± 0.96. In the DPPH test, there was no significant difference. In terms of antihypertensive activity, inhibition percentages ranging from 0 to 80.65% were obtained. Some WSE were found to have antimicrobial properties against Salmonella enterica and Listeria monocytogenes. Fermentation of amaranth with LAB and Bacillus spp. allowed the release of protein hydrolysates with antioxidant, antihypertensive, and antimicrobial activity.

Lacticaseibacillus rhamnosus C1 effectively inhibits Penicillium roqueforti: Effects of antimycotic culture supernatant on toxin synthesis and corresponding gene expression

Recently, consumers are increasingly concerned about the contamination of food by molds and the addition of chemical preservatives. As natural and beneficial bacteria, probiotics are a prospective alternative in food conservation because of their antimycotic activities, although the mechanism has not been explained fully at the level of metabolites. This study aimed at investigating the antifungal activities and their mechanisms of five potential probiotic strains (Lacticaseibacillus rhamnosus C1, Lacticaseibacillus casei M8, Lactobacillus amylolyticus L6, Schleiferilactobacillus harbinensis M1, and Limosilactobacillus fermentum M4) against Penicillium roqueforti, the common type of mold growth on the bread. Results showed that C1 emerged the strongest effectiveness at blocking mycelium growth, damaging the morphology of hyphae and microconidia, decreasing DNA content and interfering in the synthesis of the fungal toxins patulin, roquefortine C and PR-toxin, as well as downregulating the expression of key genes associated with the toxin biosynthesis pathways. Further metabonomic investigation revealed that protocatechuic acid with the minimum inhibitory concentration of 0.40 mg/mL, may be most likely responsible for positively correlated with the antimycotic effects of C1. Thus, C1 is expected to be both a potentially greatly efficient and environmental antimycotic for controlling P. roqueforti contamination in foods.

A comprehensive review of microorganism-derived cyclic peptides: Bioactive functions and food safety applications

Cyclic peptides possess advanced structural characteristics of stability and play a vital role in medical treatment and agriculture. However, the biological functions of microorganism-derived cyclic peptides (MDCPs) and their applications in food industry were relatively absent. MDCPs are derived from extensive fermented food or soil. In this review, the synthesis approaches and structural characteristics are overviewed, while the interrelationship between bioactivities and functions is emphasized. This review summarizes the bioactivities of MDCPs from in vitro to in vivo, including antimicrobial activities, immune regulation, and antiviral cell activation. Their multiple functions as well as applications during food product processing, packaging, and storage are also comprehensively reviewed. Remarkably, some potential risks and cytotoxicity of MDCPs are also critically discussed. Moreover, future applications of MDCPs in the development of novel food additives and bioengineering materials are organized. Based on this review of native MDCPs, it is noteworthy that expected improvements of synthetic cyclic peptides in bioactive properties present potential valuable applications in future food, including artificial meat.

Pharmacological Efficacy of Probiotics in Respiratory Viral Infections: A Comprehensive Review

Mortality and morbidity from influenza and other respiratory viruses are significant causes of concern worldwide. Infections in the respiratory tract are often underappreciated because they tend to be mild and incapacitated. On the other hand, these infections are regarded as a common concern in clinical practice. Antibiotics are used to treat bacterial infections, albeit this is becoming more challenging since many of the more prevalent infection causes have acquired a wide range of antimicrobial resistance. Resistance to frontline treatment medications is constantly rising, necessitating the development of new antiviral agents. Probiotics are one of several medications explored to treat respiratory viral infection (RVI). As a result, certain probiotics effectively prevent gastrointestinal dysbiosis and decrease the likelihood of secondary infections. Various probiotic bacterias and their metabolites have shown immunomodulating and antiviral properties. Unfortunately, the mechanisms by which probiotics are effective in the fight against viral infections are sometimes unclear. This comprehensive review has addressed probiotic strains, dosage regimens, production procedures, delivery systems, and pre-clinical and clinical research. In particular, novel probiotics' fight against RVIs is the impetus for this study. Finally, this review may explore the potential of probiotic bacterias and their metabolites to treat RVIs. It is expected that probiotic-based antiviral research would be benefitted from this review's findings.

Enhanced treatment of organic matters in starch wastewater through Bacillus subtilis strain with polyethylene glycol-modified polyvinyl alcohol/sodium alginate hydrogel microspheres

Starch wastewater is a wide range of environmental issues with organic pollutants. A high efficiency and stability hydrogel-organic degradation system was designed via Bacillus Subtilis with Polyethylene glycol (PEG)-modified Polyvinyl alcohol (PVA)/Sodium alginate (SA) hydrogel microspheres. Bacillus subtilis was immobilized on the surface or inside of PEG-modified PVA/SA hydrogels microspheres via physical adsorption. Results showed PEG-modified PVA/SA microspheres had an effect of adsorption on Bacillus subtilis with enhancing bearing rate to 54.22% compared to the blank control group. The effect of microspheres on degradation was remarkable in simulation starch wastewater with a maximum COD removal rate of 93.35% and compared in reality starch wastewater with 90.02% under the optimal condition of pH = 6, 35℃, 20% dosage, 180 rpm. This novel biological method on starch wastewater enhanced tolerance of microorganisms and degradation effect, reflecting safety, effectiveness, and economy with great significance to environmental protection.