Activity Of Bacteriocin-like Inhibitory Substances Research Articles

Production and SERS characterization of bacteriocin-like inhibitory substances by latilactobacillus sakei in whey permeate powder: exploring natural antibacterial potential.

Bacteriocins are antimicrobial compounds that have awakened interest across several industries due to their effectiveness. However, their large-scale production often becomes unfeasible on an industrial scale, primarily because of high process costs. Addressing this challenge, this work analyzes the potential of using low-cost whey permeate powder, without any supplementation, to produce bacteriocin-like inhibitory substances (BLIS) through the fermentation of Latilactobacillus sakei. For this purpose, different concentrations of whey permeate powder (55.15gL-1, 41.3gL-1 and 27.5gL-1) were used. The ability of L. sakei to produce BLIS was evaluated, as well as the potential of crude cell-free supernatant to act as a preservative. Raman spectroscopy and surface-enhanced Raman scattering (SERS) provided detailed insights into the composition and changes occurring during fermentation. SERS, in particular, enhanced peak definition significantly, allowing for the identification of key components, such as lactose, proteins, and phenylalanine, which are crucial in understanding the fermentation process and BLIS characteristics. The results revealed that the concentration of 55.15gL-1 of whey permeate powder, in flasks without agitation and a culture temperature of 32.5°C, presented the highest biological activity of BLIS, reaching 99% of inhibition of Escherichia coli and Staphylococcus aureus with minimum inhibitory concentration of 36-45%, respectively. BLIS production began within 60h of cultivation and was associated with class II bacteriocins. The results demonstrate a promising approach for producing BLIS in an economical and environmentally sustainable manner, with potential implications for various industries.

Antagonistic Activity of Bacteriocin-like Inhibitory Substances from Enterococcus lactis Isolated from the Surface of Jalapeno Pepper against Foodborne Pathogens

Lactic acid bacteria (LAB) can produce peptides known as bacteriocins with antagonistic activity against foodborne pathogens. The potential of LAB isolated from the surface of jalapeno peppers to produce bacteriocins with antagonistic activity against Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7, and Salmonella Typhimurium was evaluated. Previously isolated LAB strains were reactivated, and their cell-free supernatants (CFSs) were evaluated. Out of 390 reactivated strains, 60 produced bacteriocin-like inhibitory substances (BLIS) since their antagonistic activity was lost after proteases addition. Subsequently, 16 BLIS showed heat resistance (HR-BLIS), retaining their bioactivity after heat treatment (121 °C for 15 min). By 16S rRNA gene sequencing and antibiotic susceptibility tests, LAB strains producing HR-BLIS were identified as Enterococcus lactis. Four HR-BLIS exhibited a minimum inhibitory concentration (MIC) of 80 mg/mL against L. monocytogenes. MIC and minimum bactericidal concentration (MBC) of HR-BLIS-67 for S. aureus (MIC = 80 mg/mL; MBC = 320 mg/mL), S. Typhimurium (MIC = 150 mg/mL; MBC = 250 mg/mL), and E. coli O157:H7 (MIC = 250 mg/mL; MBC = 400 mg/mL) were determined. LAB isolated from the surface of jalapeno pepper produced HR-BLIS (possibly enterocin) that exhibited broad-spectrum antagonistic activity against foodborne pathogens; therefore, they are a promising source of natural antimicrobials to ensure food safety.

Anti-Listerial Activity of Bacteriocin-like Inhibitory Substance Produced by Enterococcus lactis LBM BT2 Using Alternative Medium with Sugarcane Molasses.

Listeria monocytogenes is a foodborne pathogen that contaminates food-processing environments and persists within biofilms on equipment, thus reaching final products by cross-contamination. With the growing demand for clean-label products, the search for natural antimicrobials as biopreservants, such as bacteriocins, has shown promising potential. In this context, this study aimed to evaluate the anti-listerial action of bacteriocins produced by Enterococcus lactis LBM BT2 in an alternative medium containing sugarcane molasses (SCM). Molecular analyses were carried out to characterize the strain, including the presence of bacteriocin-related genes. In the kinetic study on SCM medium E. lactis, LBM BT2 showed biomass and bacteriocin productions similar to those observed on a sucrose-based medium (control), highlighting the potential of the sugarcane molasses as a low-cost substrate. Stability tests revealed that the molecule remained active in wide ranges of pH (4-10) and temperature (60-100 °C). Furthermore, the proteolytic treatment reduced the biomolecule's antimicrobial activity, highlighting its proteinaceous nature. After primary purification by salting out and tangential flow filtration, the bacteriocin-like inhibitory substance (BLIS) showed bacteriostatic activity on suspended L. monocytogenes cells and against biofilm formation at a concentration of 0.625 mg/mL. These results demonstrate the potential of the produced BLIS as a biopreservative in the food industry.

The composition of Tibetan kefir grain TKG-Y and the antibacterial potential and milk fermentation ability of S. warneri KYS-164 screened from TKG-Y.

This study utilized high-throughput sequencing and SEM observation to elucidate the microbial composition of a Tibetan herder's homemade kefir grain named TKG-Y. Subsequently, S. warneri KYS-164 was isolated from TKG-Y, which can produce mixed protein substances with antibacterial activity, namely bacteriocin-like inhibitory substances (BLIS). BLIS can significantly reduce the growth rate of Escherichia coli 366-a, Staphylococcus aureus CICC 10384 and mixed strains at low concentrations (1 × MIC). The presence of the warnericin-centered gene cluster in KYS-164 may explain the antibacterial properties of the BLIS. Pepsin and an acidic environment can reduce the number of colonies of KYS-164 by 2.5 Log10 CFU mL-1 within 1 h, and reduce the antibacterial activity of BLIS by 21.48%. S. warneri KYS-164 showed no antibiotic resistance and biological toxicity after 80 subcultures, while BLIS produced by 40 generations of the strain retained their inhibitory efficacy against pathogenic bacteria. After 48-hour fermentation of milk with KYS-164, volatile compounds such as aldehydes, phenols, esters, and alcohols, giving it a floral, fruity, milky, oily, and nutty aroma, were released, enriching the sensory characteristics of dairy products. This study not only revealed the bacterial colony composition information of home-made kefir grain TKG-Y but also discovered and proved that S. warneri KYS-164 has the potential to inhibit bacteria and ferment dairy products. This will provide a basis for subsequent applied research on KYS-164.

Simple Purification and Antimicrobial Properties of Bacteriocin-like Inhibitory Substance from Bacillus Species for the Biopreservation of Cheese.

Bacteriocins may be used as natural preservatives and antibiotic substitutes in various foods. However, the multistep purification process of bacteriocins results in high production costs, which is an obstacle to their commercial use and consumer accessibility. In this study, a bacteriocin-like inhibitory substance (BLIS) from Bacillus spp. isolated from Korean fermented foods was partially purified using the aqueous two-phase system (ATPS). The maximum activity of the BLIS was achieved for ATPS composed of PEG 1000 (15% [w/w])/ammonium sulfate (20% [w/w])/sodium chloride (2% [w/w]), which caused BLIS activity to increase by 3 times with a 99% recovery rate. In particular, B. amyloliquefaciens Y138-6 BLIS exhibited broad antibacterial activity, high resistance to acid-base stress, and excellent thermal stability. This antibacterial substance inhibited the growth of aerobic bacteria and fungi on the walls of cheese and ripening rooms. These antibacterial properties have been shown to increase food safety and have the potential for use as biopreservatives. Moreover, considering that the execution of the ATPS requires only salts and PEG, it is a simple, environmentally friendly, and cost-effective process and may have industrial applications in the recovery of BLIS from fermentation broth.

Enhancing food preservation with postbiotic metabolites γ-aminobutyric acid (GABA) and bacteriocin-like inhibitory substances (BLIS) produced by Lactobacillus brevis C23 co-cultures in plant-based medium

Lactic acid bacteria (LAB) can produce γ-aminobutyric acid (GABA) with antioxidant properties and sedative effects when it binds to the GABA receptor in the human brain. LAB can also produce bacteriocin-like inhibitory substances (BLIS) with antimicrobial capabilities during carbohydrate fermentation. GABA and BLIS are natural compounds with potential health benefits and food preservation properties. Lactobacillus brevis C23 was co-cultured with three different LABs as inducers, which produced the highest GABA content and BLIS activity. They were cultured in various plant-based media to obtain an edible and better-tasting final product over commercially available media like MRS broth. A coconut-based medium with additives was optimized using response surface methodology (RSM) to increase GABA and BLIS production. The optimized medium for maximum GABA production (3.22 ± 0.01 mg/mL) and BLIS activity (84.40 ± 0.44%) was a 5.5% coconut medium containing 0.23% glucose, 1.44% Tween 20, 0.48% L-glutamic acid, and 0.02% pyridoxine. Due to the presence of GABA, the cell-free supernatant (CFS) as a postbiotic showed higher antioxidant activity than other food preservatives like nisin and potassium sorbate. Finally, microbiological tests on food samples showed that the postbiotic was more effective than other preservatives at combating the growth of LAB, molds and coliform bacteria, making it a possible food preservative.

Bacteriocin-like inhibitory substances as green bio-preservatives; nanoliposomal encapsulation and evaluation of their in vitro/in situ anti-Listerial activity

In this study, predominant lactic acid bacteria (LAB) isolated from a traditional pickle (Persian pickled Litteh) were screened based on their ability to produce bacteriocin-like inhibitory substances (BLIS) with inhibitory effects on foodborne bacteria tested. The isolated BLIS was also characterized using liquid chromatography-mass spectrometry (LC-MS), and loaded into nanoliposomes; then, it's in vitro and in situ inhibitory effects were evaluated. Sequencing results of the PCR products led to the identification of Lactococcus lactis LI04 as the selected BLIS-producing LAB. The highest inhibitory activity of the BLIS was observed against Listeria monocytogenes PTCC 1298, which was significantly (P < 0.05) higher than the other foodborne bacteria studied. According to LC-MS analysis, presence of two peptides with retention times of 1.45 and 1.76 min corresponding to mass to charge ratio of 456.45 and 194.79 was approved in the BLIS. Produced empty and BLIS-loaded nanoliposomes had diameters of 92.99 and 139.10 nm, respectively. Results of Fourier transform infrared analysis showed that BLIS loading induced high degree of hydration in nanoliposomes. The increased Tm of loaded nanoliposomes (verified by differential scanning calorimetry) implied that the rigidity of liposomal membrane was enhanced. The loaded nanoliposomes were also able to maintain their inhibitory activity after treatment in simulated gastrointestinal conditions and commercial sterilization; whereas, the free (non-encapsulated) BLIS lost its effect. Furthermore, anti-Listerial activity of nanoliposomal BLIS after pasteurization was higher than the free BLIS. The highest release of the BLIS from nanoliposomes at 4 °C was observed after 16 days' storage. After this period, anti-Listerial activity of nanoliposomal BLIS was significantly higher than the free BLIS in the produced homemade beef steak.

Harnessing the probiotic properties and immunomodulatory effects of fermented food-derived Limosilactobacillus fermentum strains: implications for environmental enteropathy.

Environmental enteropathy (EE), a chronic small intestine disease characterized by gut inflammation, is widely prevalent in low-income countries and is hypothesized to be caused by continuous exposure to fecal contamination. Targeted nutritional interventions using potential probiotic strains from fermented foods can be an effective strategy to inhibit enteric pathogens and prevent chronic gut inflammation. We isolated potential strains from fermented rice water and lemon pickle and investigated their cell surface properties, antagonistic properties, adhesion to HT-29 cells, and inhibition of pathogen adherence to HT-29 cells. Bacteriocin-like inhibitory substances (BLIS) were purified, and in vivo, survival studies in Caenorhabditis elegans infected with Salmonella enterica MW116733 were performed. We further checked the expression pattern of pro and anti-inflammatory cytokines (IL-6, IL8, and IL-10) in HT-29 cells supplemented with strains. The strains isolated from rice water (RS) and lemon pickle (T1) were identified as Limosilactobacillus fermentum MN410703 and MN410702, respectively. Strains showed probiotic properties like tolerance to low pH (pH 3.0), bile salts up to 0.5%, simulated gastric juice at low pH, and binding to extracellular matrix molecules. Auto-aggregation of T1 was in the range of 85% and significantly co-aggregated with Klebsiella pneumoniae, S. enterica, and Escherichia coli at 48, 79, and 65%, respectively. Both strains had a higher binding affinity to gelatin and heparin compared to Bacillus clausii. Susceptibility to most aminoglycoside, cephalosporin, and macrolide classes of antibiotics was also observed. RS showed BLIS activity against K. pneumoniae, S. aureus, and S. enterica at 60, 48, and 30%, respectively, and the protective effects of BLIS from RS in the C. elegans infection model demonstrated a 70% survival rate of the worms infected with S. enterica. RS and T1 demonstrated binding efficiency to HT-29 cell lines in the 38-46% range, and both strains inhibited the adhesion of E. coli MDR and S. enterica. Upregulation of IL-6 and IL-10 and the downregulation of IL-8 were observed when HT-29 cells were treated with RS, indicating the immunomodulatory effects of the strain. The potential strains identified could effectively inhibit enteric pathogens and prevent environmental enteropathy.

BIOCHEMICAL CHARACTERIZATION AND PARTIAL PURIFICATION OF A BACTERIOCIN LIKE-INHIBITORY SUBSTANCE PRODUCED FROM Bacillus sp. T68 STRAIN

Bacteriocins are peptides produced by various types of bacteria. Members of the Bacillus genus are known to produce compounds with inhibitory activity in protein structure against pathogenic and non-pathogenic microorganisms. In this study, a bacteriocin-like inhibitory substance (BLIS) synthesized by Bacillus sp. T68 strain, which was previously isolated from soil, was characterized. T68 strain was grown on different media to produce bacteriocin. Crude BLIS obtained was tested by well diffusion method against indicator bacterium. It was investigated within the temperature range of 10-121 C and pH range from 3.0 to 10.0. It was examined in terms of different organic solvents, enzymes and chemicals. Extracellularly produced BLIS was partially purified by ammonium sulphate precipitation method and analyzed on SDS-PAGE. Activity of partially purified BLIS was investigated. It was observed that BLIS produced in Luria Bertani Broth medium was higher as compared to the other media against indicator bacterium at 30 °C for 24 h. BLIS activity maintained at low temperatures (10-40 °C) and lost completely at high temperatures (&gt; 60 °C). It was detected that BLIS exhibited activity in the pH range between 5.0 and 10.0. The effect of EDTA on BLIS activity was slightly positive. Proteinase K and trypsin inhibited BLIS activity. Among the detergents, sodium dodecyl sulphate and Triton X-100 reduced BLIS activity, while Tween 20 and Tween 80 retained it. Additionally, it was determined that application of Tween 20 at 30 °C for 5 hours increased the BLIS activity by 40%. It was found that the solvents used other than butan 1-ol preserved the BLIS activity over 80%. Chloroform and isopropanol increased the BLIS activity slightly. An inhibitory zone formed by the BLIS corresponding to a molecular weight of about 15 kDa was detected. This BLIS exhibited stability over wide pH and temperature ranges and in organic solvent treatments.

Influence of growth parameters on bacteriocin-like inhibitory substances (BLIS) production by lactic acid bacteria.

This study aimed to investigate the possible production of bacteriocin-like inhibitory substances (BLIS) and optimize it by Lactobacillus sakei and combined Lactobacillus curvatus/Pediococcus acidilactici, lactic acid bacteria used for the meat fermentation. The effect of growth parameters on BLIS production was evaluated by measuring the antibacterial activity of the cell-free supernatant of these bacteria. The stability of the cell-free supernatant of combined L.curvatus/P.acidilactici bacteria was also examined after heat treatment and pH variations. Results showed highest BLIS production by L.curvatus/P.acidilactici was at growth temperatures of 28°C and pH 5, while the optimum condition for production of BLIS by L.sakei was 24°C and pH 6.5. The BLIS production by L. curvatus/P. acidilactici bacteria was greatly influenced by carbon and nitrogen sources. The antimicrobial activity of BLIS in supplemented De Man, Rosa, and Sharpe broth (MRS) was 2044.44 AU/mL, 4.84-fold greater than unsupplemented MRS. None of the carbon sources used in this study affected the BLIS production by the L.sakei, while pea peptone enhanced the antimicrobial activity and showed a value of 188.89 AU/mL, 1.47-fold greater than unsupplemented MRS. The characterization of the cell-free supernatant of L. curvatus/P. acidilactici bacteria showed the heat stability and activity of BLIS at pH 2-10.

Antimicrobial Activity of Bacteriocin-Like Inhibitory Substances Produced by Bacillus subtilis Isolated from “Iru”

Antimicrobial Activity of Bacteriocin-Like Inhibitory Substances Produced by Bacillus subtilis Isolated from “Iru”

Bacteriocin-Like Inhibitory Substances from Probiotics as Therapeutic Agents for Candida Vulvovaginitis.

Probiotics can potentially prevent and treat diseases. We examined the inhibitory activity of bacteriocin-like inhibitory substances (BLISs) from potentially probiotic lactobacilli and streptococci on Candida albicans and non-Candida albicans clinical isolates from women with vulvovaginitis. Using agar well diffusion assays, BLISs inhibited both Candida albicans and non-Candida albicans isolates. The BLIS from L. pentosus isolates had the highest anti-Candida activity (33/45; 73.3%), followed by BLISs from isolates of L. paracasei subsp. paracasei (31/45; 68.9%), L. rhamnosus I (30/45; 66.7%), L. delbrueckii subsp. lactis I (30/45; 66.7%), and S. uberis II (30/45; 66.7%). Upon characterization according to the retained activity under variable physical and chemical conditions, the BLISs showed stability against heat, pH, and surfactants, but were protease-sensitive, which suggests a proteinaceous nature of the active substances. Using crystal violet assays, the BLISs reduced the Candida biofilm biomass significantly as compared to a control group that lacked BLISs. In vivo testing of the antagonistic activity was performed using the Galleria mellonella (G. mellonella) larvae model. BLISs significantly improved survival in G. mellonella larvae treated with Candida isolates on the first, second, and seventh days, as compared to larvae inoculated with Candida only (p < 0.01). The results show that BLISs can be used as biotherapeutic agents in vulvovaginal candidiasis.

In Vitro Evaluation of Potential Probiotic Strain Lactococcus lactis Gh1 and Its Bacteriocin-Like Inhibitory Substances for Potential Use in the Food Industry.

Determination of a microbial strain for the joining into sustenance items requires both in vitro and in vivo assessment. A newly isolated bacteriocin-like inhibitory substance (BLIS) producing lactic acid bacterium, Lactococcus lactis Gh1, was isolated from a traditional flavour enhancer and evaluated in vitro for its potential applications in the food industry. Results from this study showed that L. lactis was tolerant to NaCl (≤ 4.0%, w/v), phenol (≤0.4%, w/v), 0.3% (w/v) bile salt, and pH 3. BLIS from L. lactis showed antimicrobial activity against Listeria monocytogenes ATCC 15313 and was susceptible to 10 types of antibiotics. The absence of haemolytic activity and the presence of acid phosphatase and naphthol-AS-BI-phosphohydrolase were observed in L. lactis. L. lactis could coagulate milk and showed a negative response to amylolytic and proteolytic activities and did not secrete β-galactosidase. The antimicrobial activity of BLIS was completely abolished at 121°C. The BLIS was conserved at 4°C in BHI and MRS medium up to 6-4months, respectively. BLIS activity was more stable in BHI as compared to MRS after four freeze-thaw cycles and was not affected by a wide range of pH (pH 4-8). BLIS was sensitive to proteinase k and resistant to catalase and trypsin. The antimicrobial activity was slightly reduced by acetone, ethanol, methanol, and acetonitrile at 10% (v/v) and also towards Tween-80, urea, and NaCl 1% (v/v). Results from this study have demonstrated that L. lactis has a vast potential to be applied in the food industry, such as for the preparation of starter culture, functional foods, and probiotic products.

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 6days (counts from 1.74 to 0.00 log CFU/g) and ensured lower weight loss (2.7%) and lipid peroxidation (0.63mg MDA/kg) of samples compared with the control (3.0%; 1.25mg 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.

Application of Bacteriocin-Like Inhibitory Substances (BLIS)-Producing Probiotic Strain of Lactobacillus plantarum in Control of Staphylococcus aureus in White-Brined Cheese Production

The aim of this study was to investigate the antimicrobial activity of an autochthonous probiotic strain of bacteriocin-like inhibitory substances (BLIS)-producing Lactobacillus plantarum, previously isolated from a Tulum cheese and satisfied technological criteria as adjunct culture in cheese production, in reducing Staphylococcus aureus during production and ripening of white-brined cheeses. Cheeses were manufactured in two trials from pasteurized milk artificially contaminated with S. aureus to the mean level of 6.243 log MPN mL-1. Lb. plantarum BG33 was added at 1% as adjunct to the starter culture. The study was also carried out with control group cheeses produced without the adjunct culture. S. aureus counts were monitored for up to 90 days by BAM’s 5-tube MPN method and each positive tube of MPN (most probable number) method was confirmed by PCR amplification of a 400 bp fragment of the nuc gene, which encodes the thermostable nuclease of S. aureus. The capacity of Lb. plantarum BG33 to reduce S. aureus count was found as 0.9 log unit on the 18th day of ripening. After 39 and 59 days of ripening, Lb. plantarum BG33 lowered S. aureus count by 1.9 and 2.0 log units, respectively, when compared to control group cheeses in which it was lowered by 0.5 and 1.0 log units, respectively. As a result, the BLIS activity of Lb. plantarum BG33 throughout ripening of white-brined cheese could make it useful as bioprotective adjunct culture in white-brined cheese production to prevent S. aureus growth which is an important foodborne pathogen in respect of safe cheese production. inhibitory substances (BLIS)-producing Lactobacillus plantarum, previously isolated from a Tulum cheese and satisfied technological criteria as adjunct culture in cheese production, in reducing Staphylococcus aureus during production and ripening of white-brined cheeses. Cheeses were manufactured in two trials from pasteurized milk artificially contaminated with S. aureus to the mean level of 6.243 log MPN mL-1. Lb. plantarum BG33 was added at 1% as adjunct to the starter culture. The study was also carried out with control group cheeses produced without the adjunct culture. S. aureus counts were monitored for up to 90 days by BAM’s 5-tube MPN method and each positive tube of MPN (most probable number) method was confirmed by PCR amplification of a 400 bp fragment of the nuc gene, which encodes the thermostable nuclease of S. aureus. The capacity of Lb. plantarum BG33 to reduce S. aureus count was found as 0.9 log unit on the 18th day of ripening. After 39 and 59 days of ripening, Lb. plantarum BG33 lowered S. aureus count by 1.9 and 2.0 log units, respectively, when compared to control group cheeses in which it was lowered by 0.5 and 1.0 log units, respectively. As a result, the BLIS activity of Lb. plantarum BG33 throughout ripening of white-brined cheese could make it useful as bioprotective adjunct culture in white-brined cheese production to prevent S. aureus growth which is an important foodborne pathogen in respect of safe cheese production.

Application of Bacteriocin-Like Inhibitory Substances (BLIS)- Producing Probiotic Strain of Lactobacillus plantarum in Control of Staphylococcus aureus in White-Brined Cheese Production

The aim of this study was to investigate the antimicrobial activity of an autochthonous probiotic strain of bacteriocin-like inhibitory substances (BLIS)-producing Lactobacillus plantarum, previously isolated from a Tulum cheese and satisfied technological criteria as adjunct culture in cheese production, in reducing Staphylococcus aureus during production and ripening of white-brined cheeses. Cheeses were manufactured in two trials from pasteurized milk artificially contaminated with S. aureus to the mean level of 6.243 log MPN mL-1. Lb. plantarum BG33 was added at 1% as adjunct to the starter culture. The study was also carried out with control group cheeses produced without the adjunct culture. S. aureus counts were monitored for up to 90 days by BAM’s 5-tube MPN method and each positive tube of MPN (most probable number) method was confirmed by PCR amplification of a 400 bp fragment of the nuc gene, which encodes the thermostable nuclease of S. aureus. The capacity of Lb. plantarum BG33 to reduce S. aureus count was found as 0.9 log unit on the 18th day of ripening. After 39 and 59 days of ripening, Lb. plantarum BG33 lowered S. aureus count by 1.9 and 2.0 log units, respectively, when compared to control group cheeses in which it was lowered by 0.5 and 1.0 log units, respectively. As a result, the BLIS activity of Lb. plantarum BG33 throughout ripening of white-brined cheese could make it useful as bioprotective adjunct culture in white-brined cheese production to prevent S. aureus growth which is an important foodborne pathogen in respect of safe cheese production.

&lt;b&gt;Bacteriocin-like inhibitory substance in aquaculture: a classic method of protein precipitation for a new aplicability

Techniques to decrease losses from bacterial diseases are always important to improve the fish production. The use of antagonistic substances (bacteriocins) has been proven to be a viable option. The aim of this study was to evaluate different methods of purification for bacteriocin like inhibitory substances (BLIS). For the purification process, we isolated and used two Gram-positive bacilli that produce antagonistic substances for pathogens in aquaculture. Tests for detection of interfering factors were also performed. After the confirmation that the antagonistic action was due the BLIS activity, we carried out the purification methods. The methods tested were: cell free supernatant, acid extraction and ammonium sulfate precipitation at two concentrations (20 and 50%). Salmonella Tiphy CFP/IAL1472 and Aeromonas hydrophila (isolated in a tilapia production environment) were used as indicators of the efficiency of extracts in controlling pathogenic potentials. A mmonium sulfate precipitation at 50% was the most appropriate for purifying the antagonistic substance for both indicators. The extracts of the two isolates remained active for 22 days at 25oC. These are promising results regarding the water and fish health without the use of antibiotics, in this manner being a safer environmental practice.

Antimicrobial activity of bacteriocin-like inhibitory substance produced by Pediococcus pentosaceus: from shake flasks to bioreactor

Bacteriocins are peptides produced by various species of bacteria, especially lactic acid bacteria (LAB), which have a large spectrum of action against spoilage bacteria and foodborne pathogens. However, when not entirely characterized, they are alternatively called bacteriocin-like inhibitory substances (BLIS). Pediococcus pentosaceus ATCC 43200 grew and produced BLIS optimally when cultivated anaerobically in bioreactor for 24h at 30°C and 200rpm in De Man, Rogosa and Sharp (MRS) medium supplemented with 1.5% peptone. Under such optimal conditions, the cell mass concentration (3.41g/L) was 66% higher, the generation time (1.28h) 38% shorter and the BLIS activity against different indicator strains significantly higher than in MRS medium without any supplement taken as a control, and the exponential phase started 4h before. The agar diffusion method showed BLIS inhibition halos against LAB strains with diameter in the range 11.0-19.5mm and specific areas between 377.1 and 2654.6mm2/mL, while BLIS activity against Listeria strains was better quantified by the liquid medium assay that showed, for the fermented broth without any dilution, 100 and 50% inhibition of Listeria innocua and Listeria seeligeri growth, respectively. These results highlight the potential of P. pentosaceus BLIS as a natural antimicrobial for application in the food industry.

Correction to: Evaluation of the antimicrobial activity of bacteriocin-like inhibitory substances of enological importance produced by Oenococcus oeni isolated from wine

In the original publication, values in table rows are incorrectly aligned to their respective columns in Tables.

Evaluation of the antimicrobial activity of bacteriocin-like inhibitory substances of enological importance produced by Oenococcus oeni isolated from wine

We experimentally determined that bacteriocin-like inhibitory substances synthetized by Oenococcus oeni may act as a natural preservative and may thus be of importance for the wine industry. An O. oeni strain isolated from wine was tested for antimicrobial activity against ten indicator lactic acid wine spoilage bacteria of enological origin from the genera Lactobacillus, Leuconostoc, and Pediococcus. A strong competition effect of O. oeni against all the tested indicator bacteria was noted. The antimicrobial extracellular metabolites were produced at the end of O. oeni’s exponential growth phase and the maximum activity occurred between hours 15 and 20 of cultivation. The bioactive compounds synthetized by O. oeni were found to be strain-specific. Their bactericidal activity was stable at high temperatures (100 °C, 20 min) and in low pH environments (with the greatest activity at pH 2–8), but was totally degraded by proteolytic enzymes (pronase E, proteinase K, trypsin, pepsin, and α-chymotrypsin). They can thus be classified as heat-resistant proteins active at low pH. The dynamics of the biosynthesis and their activity were temperature-dependent, being best at 20 °C. Our results indicate that the use of an O. oeni starter culture with the appropriate antimicrobial potential may be a useful tool in winemaking procedures to control microbial stability and inhibit wine spoilage.