Bacteriocin-like inhibitory substances (BLIS) produced by Bacillus cereus: Preliminary characterization and application of partially purified extract containing BLIS for inhibiting Listeria monocytogenes in pineapple pulp

Synergistic Effect of Combination of Various Microbial Hurdles in the Biopreservation of Meat and Meat Products—Systematic Review

The control of spoilage microorganisms and foodborne pathogens in meat and meat products is a challenge for food producers, which potentially can be overcome through the combined use of biopreservatives, in the form of a mix of various microbial hurdles. The objective of this work is to systematically review the available knowledge to reveal whether various microbial hurdles applied in combination can pose an effective decontamination strategy for meat and meat products. PubMed, Web of Science, and Scopus were utilized to identify and evaluate studies through February 2023. Search results yielded 45 articles that met the inclusion criteria. The most common meat biopreservatives were combinations of various starter cultures (24 studies), and the use of mixtures of non-starter protective cultures (13 studies). In addition, studies evaluating antimicrobial combinations of bacteriocins with other bacteriocins, BLIS (bacteriocin-like inhibitory substance), non-starter protective cultures, reuterin, and S-layer protein were included in the review (7 studies). In one study, a biopreservative mixture comprised antifungal protein PgAFP and protective cultures. The literature search revealed a positive effect, in most of the included studies, of the combination of various bacterial antimicrobials in inhibiting the growth of pathogenic and spoilage bacteria in meat products. The main advantages of the synergistic effect achieved were: (1) the induction of a stronger antimicrobial effect, (2) the extension of the spectrum of antibacterial action, and (3) the prevention of the regrowth of undesirable microorganisms. Although further research is required in this area, the combination of various microbial hurdles can pose a green and valuable biopreservation approach for maintaining the safety and quality of meat products.

Purification, HR-LC-ESI-MS-MS Identification, and Peptide Prediction of Bacteriocin-Like Inhibitory Substances Produced by Streptomyces sp. Isolated from Chanos chanos

Consumption of fresh and minimally processed food is closely related to foodborne diseases. To minimize the adverse effects, bacteriocin-like inhibitory substance (BLIS) as a natural preservative can be used. One of the bacteriocins with promising activity was produced by Streptomyces sp. Using gel filtration chromatography, the bacteriocin purification process succeeded in obtaining semi-purified fractions with broad-spectrum inhibitory activity to foodborne pathogen bacteria. These fractions are also stable up to 100 °C and pH 2.0–7.0. High-Resolution Liquid Chromatography Electrospray Ionization-Tandem Mass Spectrometry analysis followed by orthogonal projection to latent structure showed that each fraction had eight peaks with the highest positive correlation to BLIS-specific activity. Peptide identification based on MS spectrum found 597 predictive peptides, of which 42 predictive peptides with antimicrobial peptide characteristics and the highest iAMPpred antimicrobial peptide probability (>0.5) were selected. The selected predictive peptides have molecular mass of 247.13-615.37 Da and consist of at least 20% hydrophobic amino acids with a hydrophobicity value of 14.72 Kcal mol⁻¹. The results of this study indicate the effectiveness of BLIS purification by gel filtration chromatography and the promising potential of semi-purified BLIS as a natural preservative. Besides, the active peptides in semi-purified BLIS can also be identified quickly so that the isolation process to obtain purified-BLIS can be carried out more efficiently.

Lactic Acid Bacteria in Raw-Milk Cheeses: From Starter Cultures to Probiotic Functions

Traditional cheeses produced from raw milk exhibit a complex microbiota, characterized by a sequence of different microorganisms from milk coagulation and throughout maturation. Lactic acid bacteria (LAB) play an essential role in traditional cheese making, either as starter cultures that cause the rapid acidification of milk or as secondary microbiota that play an important role during cheese ripening. The enzymes produced by such dynamic LAB communities in raw milk are crucial, since they support proteolysis and lipolysis as chief drivers of flavor and texture of cheese. Recently, several LAB species have been characterized and used as probiotics that successfully promote human health. This review highlights the latest trends encompassing LAB acting in traditional raw milk cheeses (from cow, sheep, and goat milk), and their potential as probiotics and producers of bioactive compounds with health-promoting effects.

Partial Purification and Characterization of Bacteriocin-Like Inhibitory Substances Produced by Streptomyces sp. Isolated from the Gut of Chanos chanos

Bacteriocin-like inhibitory substances (BLIS) have sparked great interest because of their promising use in food as natural antimicrobial agents. In this work, six Streptomyces isolates obtained from the gut of Chanos chanos demonstrated their ability to produce extracellular metabolites with inhibitory activity against Salmonella enterica serovar Typhimurium, Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus. Exposure of the extracellular metabolites to proteolytic enzymes (i.e., proteinase-K, trypsin, and pepsin) revealed high sensitivity and confirmed their proteinaceous nature. The metabolites were stable at high temperatures (up to 100°C for 30 min) and a wide range of pH (pH 2.0–7.0). Fractionation of the crude BLIS by filtration yielded three fractions based on molecular weight: <3 kDa, 3–10 kDa, and >10 kDa. Analysis of the antibacterial activity of these fractions showed increased specific activity, especially in the fraction with a molecular weight (MW) of <3 kDa, relative to the crude sample. The fraction with MW < 3 kDa had minimum inhibitory and bactericidal concentrations in ranges 0.04–0.62 mg·mL⁻¹ and 0.08–1.25 mg·mL⁻¹, respectively. This fraction also showed better temperature and pH stability compared with crude BLIS. Brine shrimp toxicity assay revealed that this fraction has moderate toxicity with a 50% lethal concentration of 226.975 μg·mL⁻¹ (i.e., moderate toxicity) to Artemia salina. Identification of the peptide sequences of this fraction by liquid chromatography–tandem mass spectrometry yielded 130 proteins with retention times of 15.21–19.57 min. Eleven proteins with MWs of 1345.66–2908.35 Da and composed of less than 30 amino acid residues with high hydrophobicity (15.34–26.22 kcal·mol⁻¹) appeared to be responsible for the antibacterial activity of the fraction. This study revealed the potential application of BLIS from Streptomyces, especially BLIS SCA-8, as antibacterial agents.

A Review on Microbial Products and Their Perspective Application as Antimicrobial Agents

Microorganisms including actinomycetes, archaea, bacteria, fungi, yeast, and microalgae are an auspicious source of vital bioactive compounds. In this review, the existing research regarding antimicrobial molecules from microorganisms is summarized. The potential antimicrobial compounds from actinomycetes, particularly Streptomyces spp.; archaea; fungi including endophytic, filamentous, and marine-derived fungi, mushroom; and microalgae are briefly described. Furthermore, this review briefly summarizes bacteriocins, halocins, sulfolobicin, etc., that target multiple-drug resistant pathogens and considers next-generation antibiotics. This review highlights the possibility of using microorganisms as an antimicrobial resource for biotechnological, nutraceutical, and pharmaceutical applications. However, more investigations are required to isolate, separate, purify, and characterize these bioactive compounds and transfer these primary drugs into clinically approved antibiotics.

Characterization of the antimicrobial activity produced by Bacillus sp. isolated from wetland sediment

Bacteria of the genus Bacillus sp. present the potential for inhibiting various pathogens, making them a promising starting point in the search for new antimicrobial substances. In this study, bacteria were isolated from sediment samples from humid areas of a Natural Conservation Unit in the state of Rio Grande do Sul, Brazil. The isolate Bacillus sp. sed 1.4 was selected for production of antimicrobial activity, and was characterized by MALDI-TOF and 16S rDNA sequencing. Phylogenetic analysis showed that Bacillus sed 1.4 was closely related to Bacillus altitudinis and Bacillus pumilus. The cell-free supernatant was partially purified using ammonium sulfate precipitation, gel filtration chromatography (Sephadex G-200) and an ultrafiltration membrane. Partial purification resulted in specific activity of 769.23 AU/mg, with a molecular mass of approximately 148 kDa. This antimicrobial substance showed stability at 100°C for 5 min, and was inactivated by proteolytic enzymes. An antimicrobial effect against Listeria species was observed. Considering the importance of the Listeria genus in the area of food safety, this antimicrobial activity should be further explored, specifically in the field of dairy products and with a focus on food biopreservation studies.

Bacillus sp. Bacteriocins: Natural Weapons against Bacterial Enemies

BACKGROUND

Currently, antibiotic-resistant pathogenic bacteria are emerging as an important health problem worldwide. The search for new compounds with antibiotic characteristics is the most promising alternative. Bacteriocins are natural compounds that are inhibitory against pathogens, and Bacillus species are the major producers of these compounds, which have shown antimicrobial activity against clinically important bacteria. These peptides not only have potential in the pharmaceutical industry but also in food and agricultural sectors.

OBJECTIVE

We provide an overview of the recent bacteriocins isolated from different species of Bacillus including their applications and the older bacteriocins.

RESULTS

In this review, we have revised some works about the improvements carried out in the production of bacteriocins.

CONCLUSION

These applications make bacteriocins very promising compounds that need to study for industrial production.

Bacteriocin-like inhibitory substance of Pediococcus pentosaceus as a biopreservative for Listeria sp. control in ready-to-eat pork ham

The growing demand of consumers for synthetic chemical-free foods has increased the search for natural preservatives such as bacteriocins and bacteriocin-like inhibitory substances (BLIS) to give them adequate microbiological safety, sensory characteristics, and shelf life. In this study, the antimicrobial activity of BLIS produced by Pediococcus pentosaceus ATCC 43200 was compared with that of nisin. Lactobacillus sakei ATCC 15521, Listeria seeligeri NCTC 11289, Enterococcus En2052 and En2865, and Listeria monocytogenes CECT 934 and NADC 2045 exhibited larger inhibition halos in BLIS-treated than in Nisaplin-treated samples, unlike Listeria innocua NCTC 11288. In artificially contaminated ready-to-eat pork ham, BLIS was effective in inhibiting the growth of L. seeligeri NCTC 11289 for 6 days (counts from 1.74 to 0.00 log CFU/g) and ensured lower weight loss (2.7%) and lipid peroxidation (0.63 mg MDA/kg) of samples compared with the control (3.0%; 1.25 mg MDA/kg). At the same time, coloration of ham samples in terms of luminosity, redness, and yellowness as well as discoloration throughout cold storage was not influenced by BLIS or Nisaplin taken as a control. These results suggest the potential use of P. pentosaceus BLIS as a biopreservative in meat and other food processing industries.

Biomanufacturing process for the production of bacteriocins from Bacillaceae family

Members of Bacillaceae family are of major interest in medical industry due to vast antimicrobial peptides they produce as therapeutic agents. For decades, synthetic and natural occurring antibiotics have been used to treat infectious diseases, but heavy dependence on these drugs has led to significant drawbacks which propel continuous development of new antibiotics generation. Recent findings have shown several bacteriocins of Bacillaceae as promising alternatives to the conventional drugs to combat the emergence of new drug-resistant pathogens. In this present review, Bacillaceae bacteriocins’ classification such as lantibiotics and thiazole/oxazole-modified microcins as well as their biochemical characterization such as sensitivity to enzymes, temperature, pH and chemicals are described. This article enlightens on the medical application of several Bacillaceae bacteriocins emphasizing those that underwent and on-going preclinical trials. This review also discusses the development of Bacillaceae bacteriocins production, focusing strains selection and fermentation factors such as inocula size, medium (carbon, nitrogen, minerals sources), temperature, pH, agitation and aeration rate, dissolved oxygen tension (DOT), fermentation time, inducers and mode of operation via various statistical methods for their optimization. It also highlights recent advance in the production of bioengineered and recombinant bacteriocins in bioreactors system which are rarely disclosed in literature.

Effects of pH and sugar supplements on bacteriocin-like inhibitory substance production by Pediococcus pentosaceus

To improve bacteriocin-like inhibitory substance (BLIS) production by Pediococcus pentosaceus ATCC 43200, the influence of pH as well as the addition of sugars-either prebiotic (inulin) or not (sucrose)-on its metabolism were investigated. This strain was grown at pH 5.0 or 6.0 either in glucose-based MRS medium (control) or after addition of 0.5, 1.0 or 1.5% (w/w) sucrose and inulin (GSI-MRS) in the same percentages. In the control medium at pH 5.0, cell mass concentration after 48 h of fermentation (X_max = 2.26 g/L), maximum specific growth rate (µ_max = 0.180 h^-1) and generation time (T_g = 3.84 h) were statistically coincident with those obtained in supplemented media. At pH 6.0 some variations occurred in these parameters between the control medium (X_max = 2.68 g/L; µ_max = 0.32 h^-1; T_g = 2.17 h) and the above supplemented media (X_max = 1.90, 2.52 and 1.86 g/L; µ_max = 0.26, 0.33 and 0.32 h^-1; T_g = 2.62, 2.06 and 2.11 h, respectively). Lactate production was remarkable at both pH values (13 and 16 g/L) and improved in all supplemented media, being 34 and 54% higher than in their respective control media, regardless of the concentration of these ingredients. Cell-free supernatant of the fermented control medium at pH 5.0 displayed an antimicrobial activity against Enterococcus 101 5.3% higher than that at pH 6.0 and even 20% higher than those of all supplemented media, regardless of the concentration of supplements. BLIS production was favored either at pH 5.0 or in the absence of any additional supplements, which were able, instead, to stimulate growth and lactate production by P. pentosaceus.