Effect Of Bacteriocin Research Articles

The effect of bacteriocins on prolongation of shelf life and toxicological parameters of chilled meat

The effect of bacteriocins on prolongation of shelf life and toxicological parameters of chilled meat

Assessment of Bacteriocin-Antibiotic Synergy for the Inhibition and Disruption of Biofilms of Listeria monocytogenes and Vancomycin-Resistant Enterococcus

In this study, we have evaluated the effects of previously characterized bacteriocins produced by E. faecium strains ST651ea, ST7119ea, and ST7319ea, against biofilm formation and biofilms formed by L. monocytogenes ATCC15313 and vancomycin-resistant E. faecium VRE19. The effects of bacteriocins on the biofilms formed by L. monocytogenes ATCC151313 were evaluated by crystal violet assay and further confirmed by quantifying viable cells and cell metabolic activities through flow cytometry and TTC assay, respectively, indicating that bacteriocin activities required to completely eradicate biofilms are at least 1600 AU mL−1, 3200 AU mL−1, and 6400 AU mL−1, respectively for each bacteriocin evaluated. Furthermore, bacteriocins ST651ea and ST7119ea require at least 6400 AU mL−1 to completely eradicate the viability of cells within the biofilms formed by E. faecium VRE19, while bacteriocin ST7319ea requires at least 12800 AU mL−1 to obtain the same observations. Assessment of synergistic activities between selected conventional antibiotics (ciprofloxacin and vancomycin) with these bacteriocins was carried out to evaluate their effects on biofilm formation and pre-formed biofilms of both test microorganisms. Results showed that higher concentrations are needed to completely eradicate metabolic activities of cells within pre-formed biofilms in contrast with the biofilm formation abilities of the strains. Furthermore, synergistic activities of bacteriocins with both ciprofloxacin and vancomycin are more evident against vancomycin-resistant E. faecium VRE19 rather than L. monocytogenes ATCC15313. These observations can be further explored for possible applications of these combinations of antibiotics as a possible treatment of clinically relevant pathogens.

Comparison of the Effect of Extracted Bacteriocin and Lytic Bacteriophage on the Expression of Biofilm Associated Genes in Streptococcus mutans

Today, various biological approaches are used to combat dental plaque biofilms. In the current study, we aimed to compare the effect of extracted bacteriocin and lytic bacteriophage on the expression of biofilm associated genes in Streptococcus mutans. Streptococcus mutans was isolated from plaques of decayed dental and the existence of their gtfs genes was confirmed by PCR. For bacteriocin extraction, at first two probiotic lactobacilli were isolated from traditional foods, then bacteriocin was extracted by partial purification method, and SDS-PAGE was used for estimation of its molecular weight. The previously extracted lytic bacteriophage from raw urban sewage was used against Streptococcus mutans. Finally, the effect of isolated bacteriocin and bacteriophage on gtfs genes expression level was measured by real-time PCR. Out of 81 dental plaque samples, 32 (39.5%) Streptococcus mutans strains were isolated. The frequency of genes was as follows: gtfD32 (100%), gtfB 17 (53.12%), and gtfC 19 (53.37%). 120 traditional food samples (milk, yogurt, pickle, and salty pickle) were evaluated for isolation of lactobacillus. Three strains of Lactobacillus fermentum and four Lactobacillus plantarum with probiotic potential activity were isolated. Two types of bacteriocins from Lactobacillus fermentum and a single type of bacteriocin from Lactobacillus plantarum were extracted, and their molecular weights were 60, 58, and 70 kDa, respectively. In our previous study, two bacteriophages belonging to the Siphoviridae and Tectiviridae families were isolated. Real-time PCR results had shown that both bacteriocin and bacteriophage had a decreasing effect on the expression of gtfs genes. The different modes in our study for the effects of bacteriocin and bacteriophage showed that both of them had good potential as suitable options to fight dental plaque biofilms, and bacteriophages alone showed a stronger reducing effect.

The Effect of Bacteriocin Isolated From Lactobacillus rhamnosus on Pseudomonas aeruginosa Lipopolysaccharides

Background: Bacteriocins are heterogeneous inhibitory substances that could affect the bacteria belonging to the same genus. Both gram-positive and gram-negative bacteria produce bacteriocins. One of the best sources of producing bacteriocins is Lactobacillus. The aim of this study was to isolate and purify bacteriocin from Lactobacillus rhamnosus and assess its effects on Pseudomonas aeruginosa and synthesis of its lipopolysaccharide. Methods: L. rhamnosus was prepared and cultured at MRS broth and incubated at 37ºC for 24 hours. Then, the medium was centrifuged for the isolation of bacteriocin and the supernatant was considered as bacteriocin. Antibacterial properties of different concentrations of bacteriocin (50, 100, 200, and 400 μg/mL) against P. aeruginosa were assayed by using agar diffusion and broth micro dilution methods. Also, the effect of bacteriocin against lipopolysaccharide synthesis in P. aeruginosa was analyzed by using one unit of minimum inhibitory concentration (MIC) for bacteriocin. Results: The results showed that all bacteriocin concentrations had antibacterial activity against P. aeruginosa. The MIC value was 31.25 μg/mL and minimal bactericidal concentration (MBC) was 62.5 μg/mL. Also, the synthesis of lipopolysaccharide decreased during P. aeruginosa growth period, and it reached zero after 5 hours. Conclusions: The results of this study showed the antibacterial effect of bacteriocin isolated from L. rhamnosus against P. aeruginosa. In addition, this bacteriocin prevented the lipopolysaccharide synthesis in P. aeruginosa.

QUORUM SENSING ANALYSIS AND EFFECT OF BACTERIOCIN IN CONTROLLING THE BIOFILM FORMATION OF PSEUDOMONAS AERUGINOSA

Objective: Pseudomonas aeruginosa is the commonest causative agent of Hospital Acquired Infection (HAI). Resistance of Pseudomonas aeruginosa towards disinfectants and antibiotics is high when compared to other organisms. There are various reviews on antibacterial effect of herbal extracts and nanoparticles against Pseudomonas aeruginosa. Thus, this study aims to prove the effectiveness of bacteriocin against Pseudomonas aeruginosa, which may help in benefiting the health care center by replacing normal disinfectants.
 Methods: 100 strains of Pseudomonas aeruginosa were collected from different patients, with a study period of 6 mo. Ammonium sulfate precipitation method was used to extract bacteriocin and its efficiency was checked by paper disc diffusion assay. Biofilm formation assay and quorum sensing analysis was performed by Microtitre plate methods and Thin Layer Chromatography (TLC), respectively.
 Results: In this study, 91%of P. aeruginosa strains were strong, 8% were intermediate, and 1% were weak biofilm producers. From TLC analysis, 67% of the strains produced Acyl Homoserine Lactone molecules. Out of which, 49% has shown unknown analytes of Retardation factor (Rf) value greater than 1. The Rf values identified were 3 unsubstitutedC4 (5%), 3 unsubstituted C6 (4%), 3 oxo C8 (3%), 3 oxo C4 (3%), 3 oxo C6 (2%), 3 oxo C1 (1%). Biofilm production, before and after bacteriocin exposure, was proved significant by paired t-test.
 Conclusion: Quorum sensing was confirmed to play a major role in biofilm formation. As bacteriocin was found to be effective in controlling the biofilm formation, it can be incorporated in any disinfectant, which helps in controlling the transmission of infection caused by Pseudomonas aeruginosa.

Process parameters optimization and molecular studies on bacteriocin-producing lactic acid bacteria from ‘Kati’

This work described the isolation and identification of bacteriocin-producing lactic acid bacteria (LAB) from ‘Kati’(a sorghum based fermented food), and to evaluate the antibacterial effect of bacteriocin on selected pathogenic bacteria. The identities of the isolates were revealed to be as Lactobacillus plantarum, L. brevis, L. fermentum KAT1, L. fermentum KAT2 and Lactococcus lactis using 16S rRNA gene sequence analysis. Out of 28 LAB, five were found to inhibit selected pathogenic bacteria namely; Escherichia coli, Staphylococcus aureus, Salmonella typhimurium and Bacillus cereus. The unpurified bacteriocins produced by the isolated LAB were characterized with respect to the effect of temperature, pH and surfactant. The test isolates showed activities of 6400, 6400, 6400, 3200 and 1600 AU/ml respectively. Crude bacteriocin from L. brevis and L. lactis were the most heat stable at 121ºC for 60 min. Bacteriocins from L. plantarum, L. lactis and L. fermentum KAT1 showed the highest antibacterial activity and stability at pH 2.0 to 6.0. Exposure to Tween 20 increased the bacteriocin activity of the LAB isolates except for L. fermentum KAT2 where loss of activity occurred. The findings from this study suggest that bacteriocinogenic LAB present in ‘kati’ have potentials to inhibit pathogenic/spoilage microorganisms in foods.

Lactobacillus acidophilus JCM 1132 Strain and Its Mutant with Different Bacteriocin-Producing Behaviour Have Various in Situ Effects on the Gut Microbiota of Healthy Mice.

The production of bacteriocin is considered to be a probiotic trait of lactic acid bacteria (LAB). However, not all strains of LAB harbour bacteriocin genes, even within the same species. Moreover, the effects of bacteriocins on the host gut microbiota and on host physiological indicators are rarely studied. This study evaluated the effects of the bacteriocin-producing Lactobacillus acidophilus strain JCM1132 and its non-producing spontaneous mutant, L. acidophilus CCFM720, on the physiological statuses and gut microbiota of healthy mice. Mice that received the bacteriocin-producing strain JCM1132 exhibited reduced water and food intake. Furthermore, the administration of these strains induced significant changes in the compositional abundance of faecal microbiota at the phylum and genus levels, and some of these changes were more pronounced after one week of withdrawal. The effects of CCFM720 treatment on the gut microbiota seemed to favour the prevention of metabolic diseases to some extent. However, individuals that received JCM1132 treatment exhibited weaker inflammatory responses than those that received CCFM720 treatment. Our results indicate that treatment with bacteriocin-producing or non-producing strains can have different effects on the host. Accordingly, this trait should be considered in the applications of LAB.

Enhanced killing of multiresistant strains of Staphylococcus aureus and Acinetobacter baumannii through a combined action of antibiotics and bacteriocins

A search for multidrug-resistant bacteria was conducted in 1,143 clinical samples in Morocco from which 244 isolates were tested against 29 different antibiotics. This showed a prevalence of resistant strains of 68.4%. The spectra of resistance ranged from 1 to 21. Ampicillin, Ticarcilin, Amoxicillin, Piperacillin and Ciproflaxin were the most frequently resisted. Eight antibiotics were tested against two selected strains, S. aureus 400037 from conjunctive mucosa and A. baumannii 280291 urine, which showed resistance to concentrations up to 240 µg.ml-1. A. baumannii 280291 also resisted the two bacteriocins nisin A and pediocin PA-1, while S. aureus 400037 showed relative sensitivity to nisin A with a MIC of 125 µg.ml-1 but was insensitive to pediocin PA-1. However, the combined use of antibiotics and bacteriocins showedpotentiating effects of bacteriocins on antibiotics or synergistic effects between the two antimicrobials. Combinations with nisin A resulted for instance in a sensitisation of S. aureus 400037 to penicillin G, amoxicillin, ampicillin, cefaclor and ciprofloxacin with MIC values as low as 0.19; 0.78; 0.31; 3.75 and 0.62 µg.ml-1 respectively. Against A. baumannii 280291, the MIC value of gentamycin decreased from 60 to 3.75 µg.ml-1, in the presence of nisin. Similar results were obtained when antibiotics were combined with pediocin PA-1 and such effects were even stronger when both bacteriocins were used along with antibiotics. The present study shows that pathogenic bacteria that developed high levels of resistance to a wide array of antibiotics can be rendered sensitive to the same antibiotics simply by combining them with bacteriocins.

Effect of Bacteriocin on Soft Cheese

Effect of Bacteriocin on Soft Cheese

Effect of bacteriocin and exopolysaccharides isolated from probiotic on P. aeruginosa PAO1 biofilm.

Microorganisms develop biofilms on indwelling medical devices and are associated with biofilm-related infections, resulting in substantial morbidity and mortality. Therefore, to prevent and control biofilm-associated infections, the present study was designed to assess the anti-biofilm potential of postbiotics derived from probiotic organisms against most prevalent biofilm-forming Pseudomonas aeruginosa PAO1. Eighty lactic acid bacteria isolated from eight neonatal fecal samples possessed antibacterial activity against P. aeruginosa PAO1. Among these, only four lactic acid bacteria produced both bacteriocin and exopolysaccharides but only one isolate was found to maximally attenuate the P. aeruginosa PAO1 biofilm. More specifically, the phenotypic and probiotic characterization showed that the isolated lactic acid bacteria were gram positive, non-motile, and catalase and oxidase negative; tolerated acidic and alkaline pH; has bile salt concentration; showed 53% hydrophobicity; and was found to be non-hemolytic. Phylogenetically, the organism was found to be probiotic Lactobacillus fermentum with accession no. KT998657. Interestingly, pre-coating of a microtiter plate either with bacteriocin or with exopolysaccharides as well as their combination significantly (p<0.05) reduced the number of viable cells forming biofilms to 41.7% compared with simultaneous coating of postbiotics that had 72.4% biofilm-forming viable cells as observed by flow cytometry and confocal laser scanning microscopy. Therefore, it can be anticipated that postbiotics as the natural biointerventions can be employed as the prophylactic agents for medical devices used to treat gastrointestinal and urinary tract infections.

Antagonistic effect of bacteriocin from Bacillus subtilis against food-borne pathogens

Preservation of food items through natural and biological methods has become a norm in order to prevent huge financial losses that may be incurred as a result of contamination of raw foods and/or food products. Biological preservation methods help avert the chances of food born ailments thus ensuring the fulfillment of ever-increasing global food requirements. Growing skepticism among the customers in recent years regarding food safety and preservatives used in food industry has fetched remarkable consideration to the use of Bacillus bacteriocin in food processing as well as human health care. Bacillus subtilis was isolated from soil samples for determination of its microscopic and biochemical characteristics. The proteinaceous antimicrobial compounds were extracted through ammonium sulfate precipitation method. The bacteriocin was partially purified through SDS-PAGE; optimization of bacteriocin at different pH levels, heating temperatures and storage conditions was performed. Indicator strains were procured from CMS, UAF, Faisalabad. The antimicrobial assays of extracted bacteriocin were determined on Mueller-Hinton media through agar well diffusion method. The extracted bacteriocin showed comparatively better antibacterial activity against indicator Staphylococcus aureus followed by E. coli and Salmonella. Maximum activity was observed at pH 7, heating temperature 37°C and storage 4°C, comparatively higher activity against Gram positive bacteria was noticed. Keywords: Biological preservation; Economic losses; Antimicrobial compounds; Optimization http://dx.doi.org/10.19045/bspab.2017.60060

Effectiveness of Bacteriocin from Bacillus Subtilis (KY808492) and its Application in Biopreservation

In this study, bacterial strains were isolated from curd and evaluated its bactericidal potential against two aquatic pathogens Salmonella sp and Vibrio sp isolated from marine fish, Parastromateus niger and squid, Loligo duvauceli. Based on the antimicrobial activity, potential strain was selected and identified as Bacillus sp. Further, bacteriocin was partially purified from the Bacillus sp by ammonium sulphate precipitation and dialysis. The molecular weight of the partially purified bacteriocin was estimated by SDS-PAGE. To understand the biopreservative ability of the purified bacteriocin, tissues of Salmonella and Vibrio-infected fish, Parastromateus niger and Loligo duvauceli were treated with bacteriocin for 30 days at different storage conditions (-4°C and -20°C) and the microbial load was counted at 5, 10, 15, 20, 25 and 30 days. Results showed that bacteriocin significantly reduced the total bacterial count at both storage temperatures in a time dependent manner. This study proved the efficiency of bactericidal and biopreservative activity of bacteriocin isolated from Bacillus subtilis (KY808492).

Effect of Bacteriocins (from Bifidobacterium Spp.)on Prevalence of some Aeromonas and Pseudomonas Species in Minced Meat during Cold Storage

Effect of Bacteriocins (from Bifidobacterium Spp) on Prevalence of some Aeromonas and Pseudomonas Species in Minced Meat during Cold Storage The effect of bifidin (1.6%), bifilact Bb-12 (1.6%), B. bifidum and B. lactis Bb-12 cultures (106 CFU/g), on prevalence of some Aeromonas and Pseudomonas spp. were studied into chilled ground meat during storage for 15 days, pH values also were evaluated. The obtained results showed that at the end of the day nine, reduced the number of Pseudomonas spp. (fragi, flauresent, aeruginosa) by 1.071, 2.000 and 1.541 log CFU/g for sample treated with bifidin and by 1.236, 1.986 and 1.495 log CFU/g for bifilact Bb-12 treatment, while the number of Aeromonas spp (hydrophilia, caviae, sobria) reduced by 0.871, 2.456 and 2.403 log CFU/g and by 0.218, 2.339 and 2.753 log CFU/g for the same treatments respectively. The same trend observed for other treatments (B. bifidum and B. lactis Bb-12).

Flow Cytometry as a Tool to Study the Effects of Bacteriocins on Prokaryotic and Eukaryotic Cells

Researchers use a combination of techniques to study and contrast the impact of antimicrobials, such as bacteriocins, on sensitive and resistant variants. Flow cytometry is one such technique, which allows researchers to evaluate the activity of antimicrobials at a single-cell level in real-time. The generation of an increasing number of probes/dyes that can be used in flow cytometry studies has vastly expanded the potential applications of this technique. Furthermore, flow cytometry has the potential to replace, or at the very least be used as an adjunct to traditional growth-based techniques, including viable plate counts, growth curves, microscopic analysis and cell culture, many of which have limitations when used on their own. Here we review studies conducted using flow cytometry as a technique to assess the impact of antimicrobials from the bacteriocin family on individual cells, either prokaryotic or eukaryotic.

The synergistic bactericidal effects of bacteriocin and pressurization against E.coli O157:H7 in raw milk

Colonies of E.coli O157:H7 were isolated from 35 raw milk sample and their identification were confirmed based on biochemical reactions and both cultural and serological characteristics. Presumptive E.coli O157:H7 isolates obtained by selective plating on both CT-SMAC and Chromogenic agars were further tested serologically for the presence of both O157 and H7 antigenes using the commercial available latex agglutination test kit. The unhygienic practices in the production of milk in Al-Thahab Al- Abiedh , Abu-Graib, Al-Zedan and Khan Dharie were reflected on the highest significant (p&lt;0.01)prevalence level of contamination with E.coli O157:H7 that appeared to be 80%, 80%, 60% and60% respectively. Homogenization pressure of 1000 psi and 2000 psi for five passes had significantly (p&lt;0.05) influenced the inactivation degree of E.coli O157:H7 in both whole milk and nutrient broth. Milk homogenized at a pressure level of 3000 psi for three passes and 4000 psi for two passes resulted in a further increase of the antimicrobial effectiveness and produced an additional significant (p&lt;0.05) reduction of E.coli O157:H7. Complete elimination (inactivation) of viable E.coli O157:H7 was achieved when cultured whole milk was homogenized at pressure level of 5000 psi for a single pass. Agar well diffusion bioassay was used for the evaluation of antimicrobial activity of the crude bacteriocin produced by L.acidophilus LA-K against E.coli O157:H7. Enterohaemorrhagic E.coli O157:H7 expressed its resistance to the crude bacteriocin since it did not show any inhibition zone around each well treated with bacteriocin. The average diameters of the inhibition zones of crude bacteriocin against stressed E.coli O157:H7 by pressurization at 4000 psi, 3000 psi, 2000 psi and 1000 psi were 14 mm, 12mm, 10mm and 8mm respectively. The homogenization pressure level (moderate or high) had significantly (p&lt;0.05) influenced the inactivation degree of the crude bacteriocin against the stressed E.coli O157:H7 by pressurization. Quantitative measurement of crude bacteriocin antimicrobial activity was determined by using photometric or turbidometric method. The results revealed that no growth of stressed E.coli O157:H7 with no visible turbidity in the nutrient broth with bacteriocin that diluted to 1/2, 1/4 and 1/8 were observed. Bacteriocin that diluted to 1/8 which resulted in no visible turbidity after overnight of incubation at 37C° and gave an optical density reading of 1.448.

Effect of Bactericine as a Treatment for the Control of &lt;i&gt;Listeria monocytogenes&lt;/i&gt; in Refrigerated Meat Products

The aim of this research was to investigate the inhibitory effect of bacteriocin for use as a biological control agent against Listeria monocytogenes in refrigerated meat products. And this bacteriocin was evaluated for their effectiveness as a preservative on pork. The bacteriocin-treated pork was compared with a control pork sample regarding the number of listeria colony count. After 10 days of storage at 4 °C, the population of Listeria monocytogenes was increased from 5.7×105 to 3.7×108 CFU/mL in control samples. In test samples, the population of Listeria monocytogenes underwent a slight increased from 5.7×103 to 6.0×105 CFU/mL. During 10 days of storage, the percentage of growth inhibition ranged from 82.6% to 99.8%, bacteriocin showed their inhibitory effect on Listeria monocytogenes. These results indicated that the studied bacteriocin exhibited bactericidal effect against Listeria monocytogenes strain at refrigerated temperatures, and bacteriocin could be used as antimicrobial agent to preserve the shelf life of refrigerated meat products.

Effect of Bacteriocins and Conditions that Mimic Food and Digestive Tract on Biofilm Formation, In Vitro Invasion of Eukaryotic Cells and Internalin Gene Expression by Listeria monocytogenes.

In this report, Listeria monocytogenes isolates were evaluated for their ability to form biofilms, for adhesion/invasion of eukaryotic cells and for differential expression of internalin A (inl A) gene, which is related to virulence potential. The presence of bacteriocins of lactic acid bacteria and incubation at 5°C were the main factors that influenced biofilm formation by L. monocytogenes, in comparison with BHI (control). In general, adhesion and invasion of Caco-2 cells were significantly lower in low pH (4.5), in incubation at 5°C and in the presence of Oxgall 0.3%. On the other hand, two L. monocytogenes isolates (INCQS 353 and Reg 26c) showed higher invasion rates when cultivated in the presence of NaCl 5% (P<0.05). One L. monocytogenes isolate (H-2) showed the strongest ability to form biofilm and to invade Caco-2 cells, under selected conditions, suggesting there is a relationship between biofilm formation and virulence potential. For all isolates, expression of inl A gene was down-regulated by the presence of bacteriocins, Oxgall 0.3%, pH 4.5 and incubation at 5°C. Nonetheless, for one L. monocytogenes isolate (HU 471), expression of inl A gene was eight times higher in the presence of sucrose, indicating that food components can increase the infectiveness of L. monocytogenes.

Effect of yeast with bacteriocin from rumen bacteria on growth performance, caecal flora, caecal fermentation and immunity function of broiler chicks

SUMMARYThe aim of the current study was to investigate the effects of bacteriocin ofRuminococcus albus7 that is expressed by yeast on growth performance, caecal flora, caecal fermentation and immunity function of broilers. A total of 180, one-day-old healthy broiler chicks were randomly divided into three groups: control, bacteriocin (2·5 g/kg feed) and nosiheptide (NHT) (2·5 mg/kg, as antibiotic control). Growth performance, caecal flora, caecal fermentation products and immunoglobulin (Ig) concentration were determined when chicks were 21 and 35 days old. The gene expression of avianβ-defensin (AvBD) and mucin (MUC2) were measured at 35 days old. The supplementation of bacteriocin and NHT had no significant effect on body weight gain (BWG) during the experimental period. Bacteriocin supplementation significantly enhanced the growth ofLactobacillus(P&lt;0·05) and resulted in higher lactate concentration (P&lt;0·01) in broiler caeca at 21 days old. Both bacteriocin and NHT supplementation resulted in lowerEscherichia coil(P=0·072) andEnterococcus(P=0·038) counts than in the control group at 35 days old. The bacteriocin treatment group tended to increase bile IgA and showed higher bile IgA than the NHT treatment group (P=0·059) at 35 days old. Higher levels of AvBD1, AvBD4 and MUC2 gene expression were observed in the NHT treatment group (P&lt;0·05), but expression of AvBD9 was significantly decreased in both bacteriocin and NHT treatment groups (P&lt;0·05). In conclusion, bacteriocin supplementation elevated the caecalLactobacilluscounts and affected the immunity function. These benefits suggested that bacteriocin supplementation could be a potential alternative to antibiotics in broiler feed.

The influence of environmental factors on the intensity of the antimicrobial activity of bacteriocins

The use of lactic acid bacteria (LAB) in the production of fermented food products, due to the positive impact on the nutritional and organoleptic properties, as well as their sustainability, has long been known. LAB lead to faster acidification of raw materials through the production of weak organic acids, primarily lactic acid. In addition, the production of acetic acid, ethanol, aromatic compounds, exopolysaccharides (EPS), several enzymes and bacteriocins is significant. Bacteriocins arepeptide or protein molecules synthesized on ribosomes with antimicrobial activity. Many species of the LAB genus produce bacteriocins of rather broad spectrum of antimicrobial activity, with several LAB bacteriocins which can potentially find their use in the food industry as preservatives. In this way, we can reduce the use of synthetic preservatives and/or intensity of heat treatment during food production. Application of bacteriocins may be an alternative in an effort to meet consumer needs for safe, fresh and minimally processed foods. In order to fully realize this potential, it is necessary to understand their nature, mechanism of production, regulation and operation, as well as the effect of environmental factors on the antimicrobial activity of bacteriocins. Achieved progress in the development of molecular microbial ecology contributes to a better understanding of the overall effects of bacteriocins in food ecosystems, while the current study of bacterial genomes may lead to the discovery of new bacteria-producers of bacteriocins. This paper discusses the influence of external environmental factors such aspH, temperature, composition and food structure on efficiency, e.g. on the intensity of the antimicrobial activity of some bacteriocins of LAB.

Effect of bacteriocin from Lactobacillus sp. Var. SCG 1223 on microbiological quality of fresh meat.

Inhibition technology of microorganism on meat can be done biologically and chemically. Biologically, inhibition to microbe can be conducted by addition antimicrobe, for example bacteriocin that have character as biopreservative. The aim of this research was to study the microbiological quality of fresh meat with bacteriocin isolated from Lactobacillus sp. SCG 1223 storaged at certain addition and temperature with different storage time. This experiment was done based on Completely of Random Design (CRD) with factorial arragement 3 x 4 for meat kept at room temperature (27 0 C) and 3x3 for meat kept at cold temperature (4oC) in three replications. The first factor was addition of biopreservative: addition bacteriocin (B), without addition antimicrobia (TB), and addition of nisin (N) on fresh meat. The second factor was different storage time at room temperature (H0, H6, H12 and H18) and low temperature (D0, D14, D28). Other treatments as indicators was contaminated with indicator bacteria ( S. thypimurium, E. coli, L. monocytogenes ). Variable analyzed were initial TPC (Total Plate Count) and total indicator bacteria S. thypimurium; E. coli; L. monocytogenes at fresh meat, meat quality consist of total indicator of bacteria, pH value of meat; and protein level. Result indicated that bacteriocin from Lactobacillus sp. SCG 1223 isolat could inhibit bacteria growth ( S. thypimurium, L. monocytogenes, and E. coli . Bacteriocin produced by Lactobacillus sp. can work at room temperature (27 0 C) and cold temperature (4 0 C). Nisin effectivity almost same to bacteriosin produced from Lactobacillus sp. SCG 1223 isolated from cow fresh milk in inhibiting Gram positive L. monocytogenes . Key Word s: Microbiological, Bacteriocin, Lactobacillus sp. Var. SCG 1223