Safety and Beneficial Properties of Bacteriocinogenic Lactococcus lactis and Pediococcus pentosaceus Strains, and Their Effect Versus Oral Cavity Related and Antibiotic-Resistant Pathogens.

Pediococcus pentosaceus 732, Lactococcus lactis subsp. lactis 431, and Lactococcus lactis 808, bacteriocinogenic strains previously isolated from kimchi and banana, were investigated for their safety, beneficial properties and in vitro inhibition of pathogens such as Listeria monocytogenes ATCC 15313 and Staphylococcus simulans KACC 13241 and Staphylococcus auricularis KACC 13252. The results of performed physiological, biochemical, and biomolecular tests suggest that these strains can be deemed safe, as no virulence genes were detected in their DNA. Notably, only the gad gene associated with GABA production was identified in the DNA isolated of Lc. lactis 808 and Lc. lactis subsp. lactis 431 strains. All tested LAB strains exhibited γ-hemolysins and were non-producers of gelatinase and biogenic amines, which suggested their safety potential. Additionally, they were relatively susceptible to antibiotics except for streptomycin, tobramycin, and vancomycin for Pd. pentosaceus 732. The growth of Pd. pentosaceus 732, Lc. lactis subsp. lactis 431, and Lc. lactis 808 and their survival were minimally affected by up to 3% ox bile and low pH (except pH 2.0 and 4.0). Moreover, these LAB strains were not inhibited by various commercial extracts as well as most of the tested medications tested in the study. They did not produce proteolytic enzymes but exhibited production of D/L-lactic acid and ß-galactosidase. They were also hydrophilic. Furthermore, their survival in artificial saliva, gastric simulation, and enteric passage was measured followed by a challenge test to assess their ability to inhibit the selected oral pathogens in an oral saliva model conditions.

Constipation anti-aging effects by dairy-based lactic acid bacteria.

Constipation, which refers to difficulties in defecation and infrequent bowel movement in emptying the gastrointestinal system that ultimately produces hardened fecal matters, is a health concern in livestock and aging animals. The present study aimed to evaluate the potential effects of dairy-isolated lactic acid bacteria (LAB) strains to alleviate constipation as an alternative therapeutic intervention for constipation treatment in the aging model. Rats were aged via daily subcutaneous injection of D-galactose (600 mg/body weight [kg]), prior to induction of constipation via oral administration of loperamide hydrochloride (5 mg/body weight [kg]). LAB strains (L. fermentum USM 4189 or L. plantarum USM 4187) were administered daily via oral gavage (1 × 10 Log CFU/day) while the control group received sterile saline. Aged rats as shown with shorter telomere lengths exhibited increased fecal bulk and soften fecal upon administration of LAB strains amid constipation as observed using the Bristol Stool Chart, accompanied by a higher fecal moisture content as compared to the control (p < 0.05). Fecal water-soluble metabolite profiles showed a reduced concentration of threonine upon administration of LAB strains compared to the control (p < 0.05). Histopathological analysis also showed that the administration of LAB strains contributed to a higher colonic goblet cell count as compared to the control (p < 0.05). The present study illustrates the potential of dairy-sourced LAB strains as probiotics to ameliorate the adverse effect of constipation amid aging, and as a potential dietary intervention strategy for dairy foods including yogurt and cheese.

Bacteriocins and Antimicrobial Peptides Symposium, Part of International Probiotic Conference, Prague 18-20 June 2024.

It has become a tradition for the BAMP (Bacteriocins and Antimicrobial Peptides) symposium to be a part of the IPC (International Probiotic Conference). In 2024, IPC/BAMP will be held on the 18th-20th of June in Prague, Czech Republic ( www.probiotic-conference.net ) and will reunite scientists, students, and representatives from industry and regulations agencies from all around the world. The meeting will serve as a platform for the exchange of knowledge and ideas regarding the past, present, and future of beneficial microbes, probiotics, antimicrobials, and proteins, and their influence on a prosperous and healthier future.

Identification of safe putative probiotics from various food products.

The objective of this study was to isolate, identify, and assess the safety and functionality in vitro of putative probiotic bacterial strains. Isolation procedures were based on standard methods using elective and selective media. The isolates were identified by comparative 16S rRNA sequencing analysis while their safety was determined according to the safety tests recommended by the FAO/WHO such as antibiotic resistance, hemolysin, and biogenic amine production. Most of the isolates did not pass the in vitro safety tests; therefore, only Lactiplantibacillus plantarum (from ant intestine and cheese), Lacticaseibacillus paracasei (from goat milk and kimchi), Enterococcus faecium (from chili doenjang and vegetables with kimchi ingredients), Limosilactobacillus fermentum (from saliva), and Companilactobacillus alimentarius (from kimchi) were identified and selected for further studies. The isolates were further differentiated by rep-PCR and identified to the strain level by genotypic (16S rRNA) and phenotypic (Gen III) approaches. Subsequently, the strain tolerance to acid and bile was evaluated resulting in good viability after simulated gastrointestinal tract passage. Adhesion to mucin in vitro and the presence of mub, mapA, and ef-tu genes confirmed the adhesive potential of the strains and the results of features associated with adhesion such as hydrophobicity and zeta potential extended the insights. This study reflects the importance of fermented and non-fermented food products as a promising source of lactic acid bacteria with potential probiotic properties. Additionally, it aims to highlight the challenges associated with the selection of safe strains, which often fail in the in vitro tests, thus hindering the possibilities of "uncovering" novel and safe probiotic strains.

Antimicrobial Peptides (Bacteriocins) Produced by Lactococcus lactis and Pediococcus pentosaceus Strains with Activity Against Clinical and Food-Borne Pathogens.

Bacteriocins are ribosomal-synthesized peptides with antimicrobial activity, produced by different groups of bacteria, including lactic acid bacteria (LAB). Most of the produced by LAB bacteriocins can be described with rather broad spectra of inhibition and they offer suggested applications in food preservation and pharmaceutical sector. Different LAB were isolated from fermented food products and fruits, obtained from the region of Pohang, Korea, and identified based on physiological, biochemical, and molecular methods. The promising isolates, Pediococcus pentosaceus 732, Lactococcus lactis 808, and Lactococcus lactis subsp. lactis 431, were identified based on biochemical, physiological, and biomolecular approaches, including 16S rRNA partial sequencing, and were evaluated for production of bacteriocin, including stability in presence of enzymes, chemicals, pH, and temperatures. Adherence properties for the expressed bacteriocins by P. pentosaceus 732, Lc. lactis 808, and Lc. lactis subsp. lactis 431 were evaluated at presence of selected chemicals, pH, and temperatures. The presence of bacteriocin genes in the strains was investigated and analyzed. The bacterial effect of bacteriocin produced by studied strains on Listeria spp. and Staphylococcus spp. has been shown for actively growing and stationary cells. Similar growth and bacteriocin production were observed when studied strains were cultured in MRS at 30 °C or 37 °C. The presence of nisin operon with some point mutations on the genomic DNA was recorded based on the performed PCR reactions targeting different genes associated with nisin expression for both lactococcal strains. Pediocin PA-1 operon was evaluated in a similar manner for P. pentosaceus 732.

Potential of Cheese-Associated Lactic Acid Bacteria to Metabolize Citrate and Produce Organic Acids and Acetoin.

Lactic acid bacteria (LAB) are pivotal in shaping the technological, sensory, and safety aspects of dairy products. The evaluation of proteolytic activity, citrate utilization, milk pH reduction, and the production of organic compounds, acetoin, and diacetyl by cheese associated LAB strains was carried out, followed by Principal Component Analysis (PCA). Citrate utilization was observed in all Leuconostoc (Le.) mesenteroides, Le. citreum, Lactococcus (Lc.) lactis, Lc. garvieae, and Limosilactobacillus (Lm.) fermentum strains, and in some Lacticaseibacillus (Lact.) casei strains. Most strains exhibited proteolytic activity, reduced pH, and generated organic compounds. Multivariate PCA revealed Le. mesenteroides as a prolific producer of acetic, lactic, formic, and pyruvic acids and acetoin at 30 °C. Enterococcus sp. was distinguished from Lact. casei based on acetic, formic, and pyruvic acid production, while Lact. casei primarily produced lactic acid at 37 °C. At 42 °C, Lactobacillus (L.) helveticus and some L. delbrueckii subsp. bulgaricus strains excelled in acetoin production, whereas L. delbrueckii subsp. bulgaricus and Streptococcus (S.) thermophilus strains primarily produced lactic acid. Lm. fermentum stood out with its production of acetic, formic, and pyruvic acids. Overall, cheese-associated LAB strains exhibited diverse metabolic capabilities which contribute to desirable aroma, flavor, and safety of dairy products.

Antimicrobial Compounds in Wine.

Ipsum vinum est potestas et possession (wine itself is power and possession). Wine is a complex system that triggers multisensory cognitive stimuli. Wine and its consumption are thoroughly intertwined with the development of human society. The beverage was appreciated in many ancient mythologies and plays an essential part in Christianity and rituals to this day. Wine has been said to enlighten and inspire artists and has even been prohibited by law and some religions, but has nevertheless played a role in human civilizations since the beginning. Winemaking is also a prospering and economically important industry and a longtime symbol of status and luxury. In winemaking, the formation of the final product is influenced by several factors that contribute to the chemical and sensory complexity often associated with quality vintages. Factors such as terroir, climatic conditions, variety of the grape, all aspects of the winemaking process to the smallest details, including metabolic processes carried out by yeast and malolactic bacteria, and the conditions for the maturation and storage of the final product, up to, and even beyond the point of deciding to open the bottle and enjoy the wine. In conjunction with the empiric and scientific process of winemaking, different molecules with antibacterial activity can be identified in wine during the production process, and several of them are clearly present in the final product. Some of these antibacterial components are phytochemicals, such as flavonoids and phenolic compounds, that may be delivered to the final product (wine) as a part of the grape, a variety of potential additive compounds, or from the oak barrels or clay amphoras used during the maturation process. Others are produced by yeasts and malolactic bacteria and play a role not only in the moderation of the fermentation process but contributing to the microbiological safety and beneficial properties spectra of the final product. Lactic acid bacteria, responsible for conducting malolactic fermentation, contribute to the final balance of the wine but are also directly involved in the production of different compounds exhibiting antibacterial activity. Some examples of these compounds include bacteriocins (antibacterial peptides), diacetyl, organic acids, reuterin, hydrogen peroxide, and carbon dioxide. Major aspects of these different beneficial metabolites are the subject of discussion in this review with the aim of highlighting their beneficial functions.

Probiotic Improves Skin Oxidation, Elasticity, and Structural Properties in Aging Rats.

Skin aging, which affects all living organisms, is associated with oxidative stress. Probiotics exhibit antioxidant properties by producing reactive metabolites that counter oxidative stress. We hypothesized that Limosilactobacillus fermentum USM 4189 (LF 4189) has antioxidative properties and may prevent skin aging. In the present study, we used a D-galactose senescence-induced rat model to evaluate the potential antioxidative capability of LF 4189. The results indicated that rats administered LF 4189 exhibited increased plasma antioxidative activity (P=0.004), lipid peroxidation capacity (P=0.007), and skin elasticity compared with untreated aged rats (P=0.005). LF 4189 prevented telomere length shortening (P<0.05), indicating the potential to prevent senescence. A higher apoptotic activity was observed in old rats compared with young rats, whereas LF 4189 reduced the expression of four antioxidative enzyme genes that function as radical scavengers (all P<0.05), suggesting that the LF 4189 group had a reduced need to scavenge free radicals. Our findings indicate the potential of probiotics, such as LF 4189, as an anti-aging dietary intervention with antioxidant potential to improve skin health.

Dual Role of Probiotic Lactic Acid Bacteria Cultures for Fermentation and Control Pathogenic Bacteria in Fruit-Enriched Fermented Milk.

The food industry has been developing new products with health benefits, extended shelf life, and without chemical preservation. Bacteriocin-producing lactic acid bacteria (LAB) strains have been evaluated for food fermentation to prevent contamination and increase shelf life. In this study, potentially probiotic LAB strains, Lactiplantibacillus (Lb.) plantarum ST8Sh, Lacticaseibacillus (Lb.) casei SJRP38, and commercial starter Streptococcus (St.) thermophilus ST080, were evaluated for their production of antimicrobial compounds, lactic acid and enzyme production, carbohydrate assimilation, and susceptibility to antibiotics. The characterization of antimicrobial compounds, the proteolytic activity, and its inhibitory property against Listeria (List.) monocytogenes and Staphylococcus (Staph.) spp. was evaluated in buriti and passion fruit-supplemented fermented milk formulations (FMF) produced with LAB strains. Lb. plantarum ST8Sh was found to inhibit List. monocytogenes through bacteriocin production and produced both L(+) and D(-) lactic acid isomers, while Lb. casei SJRP38 mainly produced L(+) lactic acid. The carbohydrate assimilation profiles were compatible with those usually found in LAB. The potentially probiotic strains were susceptible to streptomycin and tobramycin, while Lb. plantarum ST8Sh was also susceptible to ciprofloxacin. All FMF produced high amounts of L(+) lactic acid and the viability of total lactobacilli remained higher than 8.5 log CFU/mL during monitored storage period. Staph. aureus ATCC 43300 in fermented milk with passion fruit pulp (FMFP) and fermented milk with buriti pulp (FMB), and Staph. epidermidis KACC 13234 in all formulations were completely inhibited after 14 days of storage. The combination of Lb. plantarum ST8Sh and Lb. casei SJRP38 and fruit pulps can provide increased safety and shelf-life for fermented products, and natural food preservation meets the trends of the food market.

Bacteriocin and Antioxidant Production, a Beneficial Properties of Lactic Acid Bacteria Isolated from Fermented Vegetables of Northwest Bulgaria.

Lactiplantibacillus plantarum ST01BG, ST07BG, ST10BG, and ST15BG; Latilactobacillus curvatus ST02BG; Lacticaseibacillus paracasei ST04BG; Pediococcus pentosaceus ST05BG; Leuconostoc mesenteroides ST06BG; and Enterococcus faecium ST11BG were isolated from home-made fermented vegetables from Northwest Bulgaria and identified by biochemical, physiological, and biomolecular analyses, including partial 16S rRNA sequencing. The strains were designated as bacteriocin producers and the expressed antimicrobials partially characterized with a focus on their proteinaceous nature, stability to different pH and temperatures. The bacteriocins were effective in inhibiting different strains of Listeria spp., Enterococcus spp. (including vancomycin resistant enterococci) and Staphylococcus spp. These strains can be considered safe, based on the evaluation of hemolytic activity, production of biogenic amines, mucin degradation, antibiotic susceptibility/resistance, and gelatinase enzyme production. Moreover, the strains can be considered potentially beneficial based on their stability and survival under simulated gastrointestinal tract conditions (stomach and duodenum), the production of diacetyl, and specific levels of hydrophobicity. Special attention was given to antioxidant properties (DPPH radical, hydroxyl radical, superoxide anion radical scavenging activity, Fe+2 ion chelating activity, and anti-lipid peroxidation) of the strains. Antioxidant properties were found to be strain specific. The beneficial attributes (antimicrobial and antioxidant) of these cultures to fermented food products may enable the reduction of chemical additives in line with consumers' demand for more natural and chemical-free food commodities.

Bacillus Strains Isolated from Korean Fermented Food Products with Antimicrobial Activity Against Staphylococci, an Alternative for Control of Antibiotic-Resistant Pathogens.

Multidrug resistance in foodborne and clinical pathogens is a worldwide health problem. The urgent need for new alternatives to the existing antibiotics is emerging. Bacteriocin-like inhibitory substances can be considered part of the new generation of antimicrobials, which can be potentially applied in the food industry and health care practices. This study aimed to select Bacillus strains with antimicrobial activity against Staphylococcus spp. with future application in the formulation of pharmaceutical antimicrobial preparations. Putative antimicrobial agent-producing strains, previously isolated and preidentified as Bacillus spp. were profiled by repetitive element sequence-based polymerase chain reaction (rep-PCR) and 16s rRNA sequencing identified the strains as Bacillus tequilensis ST1962CD with 99.47% identity confidence and as Bacillus subtilis subsp. stercoris ST2056CD with 98.45% identity confidence. Both the selected Bacillus strains were evaluated via biomolecular and physiological approaches related to their safety and virulence, beneficial properties, enzyme production profile, and presence of corresponding genes for the production of antimicrobials and virulence. Both strains were confirmed to harbor srfa and sbo genes and be free of hemolysin binding component (B) and two lytic components (L1 and L2) [BL] and nonhemolytic enterotoxin-associated genes. Produced antimicrobial agents by strains ST1962CD and ST2056CD were partially purified through the combination of ammonium sulfate precipitation and hydrophobic-based chromatography on SepPakC18 and evaluated regarding their cytotoxicity. The dynamics of bacterial growth, pH change, accumulation of produced antimicrobials, and the mode of action were evaluated. Obtained results were pointing to the potential application of safe B. tequilensis ST1962CD and B. subtilis subsp. stercoris ST2056CD strains as functional beneficial microbial cultures that are putative producers of surfactin and/or subtilosin, as potent antimicrobials, for the treatment of some staphylococcal-associated infections. Expressed antimicrobials were shown to be not cytotoxic, and appropriate biotechnological approaches need to be developed for cost-effective production, isolation, and purification of expressed antimicrobials by studied strains.

Beneficial, safety, and antioxidant properties of lactic acid bacteria: A next step in their evaluation as potential probiotics.

The role of lactic acid bacteria (LAB) as probiotics as health promoting factors for human or veterinary practice has gained increasing interest during the last three decades. This is reflected in screening approaches of LAB strains in line with minimal requirements for a "probiotic" with regard to safety and functionality. The latter might also include natural antioxidant properties, thereby constituting an additional benefit in substituting synthetic antioxidants. The in vitro antioxidant assays conducted in this study included the scavenging of the 2,2-diphenyl-1-picrylhydrazil (DPPH) free radical, metal (Fe+2) ion chelation, determining the scavenging properties of the hydroxyl and superoxide radicals, and anti-lipid peroxidation. Analysis of DPPH free radical scavenging property for the microorganisms included in current study, showed Streptococcus salivarius ST59HK to exhibit the highest activity at a level of 85.24%. The greatest Fe+2 chelation activity with 98.2% was recorded for Str. salivarius ST62HK while the lowest was recorded for Str. salivarius ST48HK at 71.5%. The greatest and minimal hydroxyl radical scavenging levels were detected for Str. salivarius ST59HK (98.6%) and Lactiplantibacillus plantarum ST63HK (35.60%), respectively. Superoxide anion radical scavenging activity was highly exhibited by Str. salivarius ST61HK (54.62%) and the least exhibited by Enterococcus faecium ST651ea (18.7%). Lastly, the strains Lactobacillus gasseri ST16HK and E. faecium ST7319ea showed the highest and lowest anti-lipid peroxidation levels with 69.43% and 26.15%, respectively. Anti-oxidative properties appear to be strain specific and thus some of these strains could be potentially applied as natural antioxidants in fermented food products.

Vaginal Infections during Pregnancy Increase Breast Milk Microbiome Alpha Diversity and Alter Taxonomic Composition.

We previously reported that breast milk from women with (W) or without (WO) vaginal yeast infection during pregnancy differs in its immunological and antimicrobial properties, especially against pathogenic vaginal Candida sp.. Here, we investigated the differences in microbiota profiles of breast milk from these groups. Seventy-two breast milk samples were collected from lactating mothers (W, n=37; WO, n=35). The DNA of bacteria was extracted from each breast milk sample for microbiota profiling by 16S rRNA gene sequencing. Breast milk from the W-group exhibited higher alpha diversity than that from the WO-group across different taxonomic levels of class (P=0.015), order (P=0.011), family (P=0.020), and genus (P=0.030). Compositional differences between groups as determined via beta diversity showed marginal differences at taxonomic levels of phylum (P=0.087), family (P=0.064), and genus (P=0.067). The W-group showed higher abundances of families Moraxellaceae (P=0.010) and Xanthomonadaceae (P=0.008), and their genera Acinetobacter (P=0.015), Enhydrobacter (P=0.015), and Stenotrophomonas (P=0.007). Meanwhile, the WO-group showed higher abundances of genus Staphylococcus (P=0.046) and species Streptococcus infantis (P=0.025). This study shows that, although breast milk composition is affected by vaginal infection during pregnancy, this may not pose a threat to infant growth and development.

Special Issue: Beneficial Properties and Safety of Lactic Acid Bacteria.

The application of LAB in various sectors, including in the biotechnical and food industry, in human and veterinary practice, and in health-promoting practices and cosmetics, has been the subject of intensive research across the globe, with a range of traditional and innovative methods currently being explored [...].

In Vitro Anti-Candida albicans Mode of Action of Enterococcus mundtii and Enterococcus faecium.

Candida albicans is an important vaginosis causative agent, affecting several women worldwide each year. This study reports on two strains of lactic acid bacteria (Enterococcus mundtii CRL35 and Enterococcus faecium ST88Ch) expressing bacteriocin-like inhibitor substances (BLIS) active against C. albicans 1281. Both strains were γ-hemolytic and not affected by numerous antibiotics, contraceptives, and commercial drugs, suggesting safety for human use. The recorded antimicrobial activity of semi-purified BLIS was 25,600 AU/mL for E. mundtii CRL35 and 800 AU/mL for E. faecium ST88Ch. Treatment of BLIS with 1 mg/mL proteinase K resulted in complete loss of antimicrobial activity against Listeria monocytogenes ATCC 15313 and partial loss of activity against C. albicans 1281. The killing effect of the semi-purified BLIS on cell suspensions of C. albicans 1281 after 9 h of contact was dose-dependent: for E. mundtii CRL35, 400 AU/mL to 25,600 AU/mL caused 63.61% to 79.35% lysis, while for E. faecium ST88Ch, 200 AU/mL to 800 AU/mL caused 29.32% to 31.25% cell lysis. The effects of temperature, pH, and presence of the contraceptive Nordette-28 on the adsorption levels of the BLIS to C. albicans 1281 were also evaluated. Nordette-28 (10% or 20%) promoted increased adsorption of both studied BLIS to the cells of C. albicans 1281 at pH 5.0, while a minor effect was observed at pH 3.0. Different levels of aggregation between C. albicans 1281 and E. mundtii CRL35 or E. faecium ST88Ch were recorded, and optimal adsorption levels were recorded at 37 °C. Appropriate BLIS-producing strains can effectively contribute to the equilibrium of vaginal microbial status quo and reduce negative consequences from the development of C. albicans infections.

Breast milk from healthy women has higher anti-Candida properties than women with vaginal infections during pregnancy.

The aim of this study was to investigate the different immunological and antimicrobial properties of breast milk from women with (W) or without (WO) vaginal yeast infections during pregnancy in 85 lactating women (W, n = 43; WO, n = 42). Concentrations of IL-10, IgA, IgM, IgG, EGF, and TGF-α were similar in both groups. However, breast milk of women aged below 31 years old from the W-group showed higher concentration of EGF than the WO-group (p = 0.031). Breast milk from WO-group exhibited higher anti-Candida properties than W-group, both via growth inhibition and aggregation of yeast cells (p < 0.001). Correlation analysis showed that breast milk concentration of TGF-α positively correlated with concentrations of IL-10 (p = 0.001) and IgA (p = 0.021) in the W-group. Data from our present study shows that although breast milk from women with vaginal infections during pregnancy may not sufficiently hinder Candida growth, other immuno-modulatory bioactives may substitute for such a protective effect.

Plasmid-Associated Bacteriocin Produced by Pediococcus pentosaceus Isolated from Smoked Salmon: Partial Characterization and Some Aspects of his Mode of Action.

Strain ST3Ha, isolated from commercially available smoked salmon, was identified as Pediococcus pentosaceus based on biochemical and physiological tests and 16S rRNA sequencing. Strain ST3Ha produces a class IIa bacteriocin active against lactic acid bacteria, Listeria monocytogenes and Enterococcus faecalis. The antimicrobial peptide was inactivated by proteolytic enzymes, confirming his proteinaceous nature, but was not affected when treated with α-amylase, SDS, Tween 20, Tween 80, urea, and EDTA. No change in activity was recorded after 2 h at pH values between 2.0 and 9.0 and after treatment at 100 °C for 120 min or 121 °C for 15 min. The mode of action against Listeria ivanovii subsp. ivanovii ATCC 19119 and E. faecalis ATCC 19443 was bactericidal, resulting in cell lyses and enzyme leakage. The highest level of activity (1.6 × 106 AU/mL) was recorded when cells were grown at 37 °C or 30 °C in MRS broth (pH 6.5). Antimicrobial peptide ST3Ha adsorbs at high levels to the sensitive test organisms on strain-specific manner and depending on incubation temperature, environmental pH, and presence of supplemented chemicals. Based on PCR analysis, P. pentosaceus ST3Ha harbor a 1044-bp plasmid-associated fragment corresponding in size to that recorded for pediocin PA-1. Sequencing of the fragment revealed a gene identical to pedB, reported for pediocin PA-1. The combined application of the low levels (below MIC) of ciprofloxacin and bacteriocin ST3Ha results in the synergetic effect in the inhibition of L. ivanovii subsp. ivanovii ATCC 19119. Expressed by P. pentosaceus ST3Ha, bacteriocin was characterized as low cytotoxic, a characteristic relevant for its application in food industry and/or in human and veterinary medical practices.

Impact of Microgravity on Virulence, Antibiotic Resistance and Gene Expression in Beneficial and Pathogenic Microorganisms.

During space missions, the impact of the space conditions (both microgravity and radiation) on physiologic and metabolic aspects of the microbiota of astronauts' bodies should be considered. Changes depend on the mission's duration, types of organisms, and ecology. Reported alterations are related to changes in morphology, growth, gene expression, and physiology of cells, resulting in increased virulence, acid, antibiotic resistance, biofilm formation, secondary metabolism, and microbial mutations. Accordingly, recent research indicates the impacts of simulated microgravity on human physiology and bacterial characteristics. This paper has reviewed the aspects of microgravity on changes in microbiota, including virulence, antibiotic resistance, and gene expression. Microgravity can undermine humans and makes influence bacterial pathogenicity. The review of papers shows that some microorganisms showed higher pathogenicity under microgravity conditions. Moreover, sulfamethoxazole had the highest resistance among Gram-positive microorganisms, and gentamicin had the highest resistance in Gram-negative bacteria. All antibiotics reviewed under microgravity conditions were robust in both groups of microorganisms compared to the gravity condition. Furthermore, some gene expression was altered in bacteria under microgravity conditions compared to Earth conditions (standard bacterial growth conditions). Changes in microbial behavior under microgravity directly influence astronauts' health conditions, and a detailed analysis of known facts can provide essential information for the selection of appropriate probiotics for these specific cases during the missions and after the recovery processes. Moreover, the study of microorganisms changes in the absence of gravity will help to understand the mechanisms of causing diseases on Earth and may be applied in clinical practice.

Diversity of the bacteriocins, their classification and potential applications in combat of antibiotic resistant and clinically relevant pathogens.

There is almost a century since discovery of penicillin by Alexander Fleming, a century of enthusiasm, abuse, facing development of antibiotic-resistance and clear conclusion that the modern medicine needs a new type of antimicrobials. Bacteriocins produced by Gram-positive and Gram-negative bacteria, Archaea and Eukaryotes were widely explored as potential antimicrobials with several applications in food industry. In last two decades bacteriocins showed their potential as promising alternative therapeutic for the treatment of antibiotic-resistant pathogens. Bacteriocins can be characterised as highly selective antimicrobials and therapeutics with low cytotoxicity. Most probably in order to solve the problems associated with the increasing number of antibiotic-resistant bacteria, the application of natural or bioengineered bacteriocins in addition to synergistically acting preparations of bacteriocins and conventional antibiotics, can be the next step in combat versus drug-resistant pathogens. In this overview we focussed on diversity of specific lactic acid bacteria and their bacteriocins. Moreover, some additional examples of bacteriocins from non-lactic acid, Gram-positive and Gram-negative bacteria, Archaea and eukaryotic organisms are presented and discussed. Therapeutic properties of bacteriocins, their bioengineering and combined applications, together with conventional antibiotics, were evaluated with the scope of application in human and veterinary medicine for combating (multi-)drug-resistant pathogens.

Evaluation of Antifungal Metabolites Produced by Lactic Acid Bacteria.

This study aimed to select and characterize lactic acid bacteria (LAB) with potential antifungal activities against the filamentous fungi Alternaria alternata ATCC MYA-4642, Aspergillus flavus KACC 45470, Aspergillus niger KACC 42589, Cladosporium sphaerospermum ATCC MYA-4645, Penicillium chrysogenum ATCC MYA-4644, and Penicillium expansum KACC 40815. Initial screening of the antifungal activity has identified six LAB strains belonging to the genera Enterococcus and Leuconostoc, selected by their antagonistic activities against at least three of the filamentous fungi in the test panel. Preliminary prediction of bioactive compounds was carried out to narrow down the possible identity of the antagonistic metabolites produced by the studied LAB. Furthermore, metabolic profiles were assessed and used as a basis for the identification of key metabolites based on VIP scores and PCA plot scores. Key metabolites were identified to be ß-phenyllactic acid, ⍺-hydroxyisobutyric acid, 1,3-butanediol, phenethylamine, and benzoic acid. Individual assessment of each metabolic compound against the test panel showed specificity inhibitory patterns; yet, combinations between them only showed additive, but not synergetic effects. The pH neutralization significantly reduced the antifungal activity of the cell-free supernatant (CFS), but no bioactive compounds were found to be stable in high temperatures and pressure. This study will be beneficial as an additional building block on the existing knowledge and future antifungal application of LAB produced metabolites. Furthermore, this study also provides a new bio-preservative perspective on unexplored antifungal metabolites produced by LAB as biocontrol agents.