Preliminary characterisation of bacteriocin produced by Lactobacillus acidophilus TS1 isolated from traditional dahi (original) (raw)
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The Iraqi Journal of Veterinary Medicine, 2012
Two isolates of Lactobacillus acidophilus were isolated from locally homemade soft cheese and identified in accordance with their main features as described by bergeys manual of determinative bacteriology .Agar well diffusion bioassay was used for the evaluation of antimicrobial activity of cell free supernatant (culture filtrates) of Lactobacillus acidophilus isolates against the sensitive strain Lactobacillus acidophilus R0052 and the diameter of the inhibition zone was proportional to the bacteriocin concentration. The antimicrobial activity of the bacteriocin was proportional to the reciprocal of the highest dilution factor producing a detectable zone of inhibition . The storage temperature of the crude bacteriocin had a significant(P˂ 0.01) effect on its potency against the sensitive strain .The potential of the antimicrobial activities of the crude bacteriocin that was stored for 10 days at refrigeration temperature (4°C) was significantly (P˂ 0.01) higher than that stored at ...
Applied Biochemistry and Microbiology, 2013
As demand for reduction of the use of chemical additives in food and for more natural and microbiologically safe food products is increasing, bacteriocins may have considerable potential for food preservation. This work aimed to isolate Lactobacillus strains of potential bioprotective application from Egyptian home-made yogurt. Out of 73 strains of isolated Lactobacillus strains, only four strains of Lactobacillus plantarum (AA110, AA125, AA135 and AA140) demonstrated production of antagonistic activity against foodborne pathogens. The antimicrobial agent excreted by L. plantarum AA135 was the most active against a wide range of Gram-positive and Gram-negative pathogens. Because of the interesting inhibition spectrum of agent AA135, it was selected for further characterization. The activity of the antimicrobial substance produced from L. plantarum AA135 was resistant to heat (121 o C for 30 min), catalase and lysozyme, but was destroyed by papain, trypsin and pepsin. The AA135 compound was produced during growth phase and, when the neutralized and concentrated supernatant was added to a culture of Pseudomonas aeruginosa in logarithmic phase, it produced a rapid decrease in optical density indicative of cell lysis. The AA135 agent could be extracted from the culture supernatant fluids with n-butanol. When 40% ammonium sulphateprecipitated agent was analysed by 10% SDS-PAGE, two peptides with high molecular sizes of ~45 kDa and <45 kDa were seen. L. plantarum AA135 does not contain any plasmid, which indicates that the antagonistic compound' s production is encoded by chromosomal genes. The antibacterial agent was characterized as a bacteriocin-like inhibitory substance and designated as plantaricin AA135. The potential significance for improving the hygiene and safety of the food products is discussed.
2012
Bacteriocins are biologically active proteins or protein complexes that display a bactericidal mode of action towards usually closely related species. Bacteriocin producing Lactococcus lactis AP2 was isolated from fermented milk products (dahi, lassi etc.) from the different regions of Solan district of Himachal Pradesh, India. The strain was selected and screened for their ability to produce bacteriocin by agar well diffusion method using the supernatant of centrifuged test culture. The bacteriocin had wide spectrum of inhibitory activity against test strains of pathogenic and food spoilage micro organisms. The cell-free supernatant of Lactococcus lactis AP2 inhibited the growth of Escherechia coli, Pseudomonas aeruginosa, Shigella dysenteries, Stapyhlococcus aureus and Bacillus cereus. The bacteriocin of Lactococcus lactis AP2 was recovered at 30-40 % ammonium sulphate saturation level and the protein was 0.10 mg/ml. Purified bacteriocin was found to possess a molecular weight of ...
Determination of antimicrobial activity of bacteriocin of lactic acid producing bacteria
A study was conducted to explore the potential of bacteriocins, produced by lactic acid producing bacteria, against Staphylococcus aureus, Eneterococcus fecalis and Escherichia coli. Different lactic acid producing bacteria viz. Lactobacillus fermentum, Lactobacillus acidophilus and Lactobacillus rhamnosus were isolated from milk, milk products of dairy animals and intestinal contents of healthy broiler chicken. The isolated bacterial species were identified morphologically and biochemically by conventional methods. From these bacteria, bacteriocins were isolated by precipitation method and antibacterial activity was determined by disk diffusion method. Isolated bacteriocin showed the inhibitory activity against Staphylococcus aureus and Enterococcus feacalis. Whereas bacteriocins showed very poor inhibitory activity (2mm) against Eschrechia coli. The study showed that bacteriocins are quite useful against commonly known food pathogens and thus can be used for the preservation of fo...
ANTIBACTERIAL ACTIVITY OF BACTERIOCIN PRODUCING Lactobacillus spp., FROM VARIOUS MILK SAMPLES
Bacteriocin are highly specific antibacterial protein (polypeptides) produced by gram positive bacteria ,in particular the lactic acid bacteria display fairly broad inhibitory spectra with food preservative and therapeutic potentials. This work aims at to isolate bacteriocin-producing Lactobacillus spp., and to determine the antibacterial activity against pathogenic bacteria. This work involves methodology as follows Lactobacills spp., was isolated from various milk samples by using MRS Agar (Hi-media, India) at 37°C for 48h. The isolates were identified by using conventional biochemical tests. Antibacterial characteristics of bacteriocin were studied by agar well diffusion method and it partially purified by Ammonium sulphate precipitation and dialyzed. The present study revealed that the Lactobacillus spp., strain isolated from various milk samples was capable of producing bacteriocin and inactivating the widest range of pathogenic bacteria. Totally 48 isolates of Lactobacillus spp., was identified in that only 8 (17%) Lactobacillus spp., have the antibacterial activity against pathogenic bacteria. The study revealed that the antibacterial property of bacteriocin act as a food preservative agent against pathogenic microorganisms.
IP Innovative Publication Pvt. Ltd., 2018
Lactobacilli are a group of bacteria that are ubiquitous and contribute to the normal microbial flora of human beings. They are Generally Regarded as Safe (GRAS) and are not lethal to host. Bacteriocins are ribosomally synthesized antimicrobial peptides produced by Lactic Acid Bacteria (LAB) that exhibit antagonistic activity against food contaminating microorganisms and inhibit similar or closely related bacterial strains. Hence, these bacteriocins are considered bio-preservative and are demonstrated as food preservatives, as therapeutics for veterinary and medicinal uses or as phytosanitary means for plant protection. The present study involved isolation of Lactobacillus species from dairy samples, purification of bacteriocin and the study of antagonistic activity against food borne pathogens. The study showed that purified bacteriocin exhibited inhibitory activity against Escherichia coli and Shigella flexneri. Keywords: Bacteriocin, Lactic Acid bacteria, Pathogens, Cell free supernatants
Production and Optimization of Bacteriocin by Lactobacillus Species Isolated from the Curd Sample
International Journal of Science, Engineering and Management (IJSEM), 2021
From the isolated species of LAB (Lactic Acid Bacteria) shows pronounced antibacterial activity between the initial logarithmic and stationary phase. The most enormous activity in the composed medium was achieved at pH of 7, incubation temperature 37°C and incubation period of 48 h under static condition. Supplementation of nutrients demonstrated that the huge quantities of bacteriocin and could be produced by addition of glucose (2%) manipulating the dextrose (2%) and NaCl (0.5%-2.0%). Since it displayed the increase in the activity from 981.25 AU/mL to 1139.74 AU/mL. The compound produced by LAB was wholly/partially inactivated by some of the proteolytic enzymes, which confirms their proteinaceous nature. The activity of bacteriocin producing, the organism is not dependent on the glycosylation because the antimicrobial activity of bacteriocin was unaffected by the α-amylase and other enzymes. The bacteriocin shows broad range of thermo stability from 37°C to 121°C for 30 minutes. The Folin's Lowery method describes their concentration. The well diffusion assay showed the bacteriocin produced by LAB is inhibiting the growth of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis presenting a wide spectrum of inhibition. The antimicrobial activity of the proteinaceous compound namely bacteriocin or BLIS (Bacteriocin like inhibitory substance) produced by Lactobacilli isolated in this work are largely identified and have been found to have potential antimicrobial activities toward closely related bacteria and undesirable harmful microorganisms. On this account, they are helpful in the field of food preservation/safety or pharmaceutical applications and healthcare.
Characterization of some bacteriocins produced by lactic acid bacteria isolated from fermented foods
World Journal of Microbiology and Biotechnology, 2014
Lactic acid bacteria (LAB) isolated from different sources (dairy products, fruits, fresh and fermented vegetables, fermented cereals) were screened for antimicrobial activity against other bacteria, including potential pathogens and food spoiling bacteria. Six strains have been shown to produce bacteriocins: Lactococcus lactis 19.3, Lactobacillus plantarum 26.1, Enterococcus durans 41.2, isolated from dairy products and Lactobacillus amylolyticus P40 and P50, and Lactobacillus oris P49, isolated from bors. Among the six bacteriocins, there were both heat stable, low molecular mass polypeptides, with a broad inhibitory spectrum, probably belonging to class II bacteriocins, and heat labile, high molecular mass proteins, with a very narrow inhibitory spectrum, most probably belonging to class III bacteriocins. A synergistic effect of some bacteriocins mixtures was observed. We can conclude that fermented foods are still important sources of new functional LAB. Among the six characterized bacteriocins, there might be some novel compounds with interesting features. Moreover, the bacteriocin-producing strains isolated in our study may find applications as protective cultures.
Lactic acid bacteria from freshly prepare 'Ogi' and 'Kunun' were isolated by plating on nutrient agar modified with glacial acetic acid. The identification of the isolates was carried out using biochemical methods. The identified isolates (Lactobacillus planetarium, Lactobacillus sake, Lactobacillus acidophilus fermentum) were screened for their ability to produce bacterocin against food borne pathogens (Escherichia coli and Staphylococcus aures) using the pour plate method. The isolated organisms inhibited different food borne pathogens with different zones of inhibition. The highest was exhibited by Lactobacillus fermentum on Escherichia coli (38mm) while the least was by Lactobacillus acidophilus on Staphylococcus aures (18mm). Fresh Ogi constituted a better source of lactic acid bacteria than that of Kunun. The antimicrobial activity of the four LAB strains was inactivated by the addition of proteinase K, thus confirming the proteinaceous nature of the inhibition. The bacterocin of lactic acid bacteria have potential application for assessing and improving food quality, and safety
Benha Veterinary Medical Journal
Bacteriocins are natural metabolites produced by many strains of Lactic acid bacteria that used in food preservation. They have potential healthy role in suppressing the growth of some spoilage and pathogenic bacteria. The aim of the current study was to demonstrate the stability of the bacteriocin extracted from Lactobacillus acidophilus at different pH values, heat treatments and proteinase K enzyme. The obtained results revealed that the inhibitory effectiveness of bacteriocins was higher on Gram-positive bacteria than Gram-negative bacteria. Further, the largest inhibition zone was obtained by L. acidophilus bacteriocin against Bacillus subtilis while the smallest one was against E.coli. The extracted bacteriocin exhibited broad spectrum of inhibition at concentration 6400AU/ml against Staph. aureus, Bacillus subtilis and E.coli. The antimicrobial activity of crude supernatant fluid was stable after heating at 100°C for 30 min and declined thereafter. Stability of antimicrobial activity was observed at pH ranged from 2.0 to 8.0. Its active principle was proteinaceous in nature since the bacteriocin was inactivated by proteinase K enzyme.