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Testing of lactic acid bacteria Lactobacillus genus for bacteriocins production
Volecová, Veronika ; Němcová, Andrea (referee) ; Trachtová, Štěpánka (advisor)
Antimicrobial substances, or bacteriocins are substances produced by probiotic lactic acid bacteria. They have a positive effect on the gastrointestinal tract of humans and are especially suitable for the food, but also the pharmaceutical industry. The aim of the thesis was the molecular identification of lactic acid bacteria of the Lactobacillus genus, species and their subsequent inclusion PCR method. Using the PCR method were tested also genes responsible for the production of bacteriocins. To confirm the production of bacteriocins has been selected the microbiological method, agarose droplet spot-test. In the present study also included the bioinformatics part to assess the specificity and non-specificity of the primers using in Primer-BLAST program.
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Methods for detection of antimicrobial properties of lactic acid bacteria
Vránová, Petra ; Němcová, Andrea (referee) ; Trachtová, Štěpánka (advisor)
Lactic acid bacteria are classified as probiotics producing substances that act against microorganisms. These antimicrobial substances include organic acids, carbon dioxide, hydrogen peroxide and bacteriocins. Currently, the focus is on bacteriocins, which are used in the food and pharmaceutical industries. The aim of this thesis is creating an overview of antimicrobial properties of lactic acid bacteria, methods of their determination and their applications in the food industry. The experimental part deals with identification of lactic acid bacteria present in selected samples of bacterial DNA. In addition, we tested for bacteriocin Gassericin K7A-producing gene. Molecular diagnostic methods such as real-time polymerase chain reaction (qPCR) and conventional polymerase chain reaction were used to distinguish bacterial DNA as well as the bacteriocin.
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Study of Probiotic Lactic Acid Bacteria Producing Antimicrobial Compounds
Turková, Kristýna ; Doležal, Petr (referee) ; Rada,, Vojtěch (referee) ; Španová, Alena (advisor)
The sixty-eight strains isolated from breastfed full-term infant feces and from another sources were identified using genus-specific polymerase chain reaction (PCR) for Lactobacillus, species-specific PCRs, multiplex PCR, pheS PCR, rep-PCR, RAPD-PCR and 16S rDNA sequencing into Lactobacillus species or group of species. Seven strains produced antimicrobial proteinaceous substances in the supernatants. Antimicrobial proteinaceous substances of three strains were tested on temperature, pH a detergent stability. All tested strains produced temperature-stable antimicrobial proteinaceous substances. Antimicrobial activity was not influenced by detergents with exception of SDS. Presence of genes for production of bacteriocins (acidocin B, gassericin A, gassericin T, gassericin K7A and gassericin K7B) were detected in DNA of fourteen strains using PCR and DNA/DNA hybridization. Selected PCR products were sequenced and analyzed using BLAST algorithm and CLUSTAL W2 programme. The sequences of specific PCR products in DNA of two strains had 100% similarity with the sequences from the database GeneBank. Selected strains of Lactobacillus acidophilus group were tested for the surveillance in gastrointestinal tract, for the production of antimicrobial substances, for the adhesion on Caco-2 cells and for the presence of genes of antibiotic resistance. DNA of strains was tested using specific primers on the presence of genes for histidine-decarboxylase, tyrosine-decyrboxylase and linoleate isomerase. The gene for histidine-decarboxylase production was detected in DNA of seven strains, for tyrosine-decarboxylase production in DNA of one strain and for linoleate isomerase in DNA of four strains. Imunomagnetic separation of the cells was optimized. Magnetic particles functionalized with streptavidin and the anti-Lactobacillus antidote was used for the separation of the cells of Lactobacillus rhamnosus LOCK 0900 from MRS medium, UHT milk and from the yogurt. The IMS-PCR was used for detection of imunomagnetic separated bacterial cells.
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Bakteriociny a jejich aplikace v potravinářském a farmaceutickém průmyslu
Tesarčík, David
This bachelor thesis deals with bacteriocins, their current utilisation and potential use in the future at food industry and pharmacy. The first part of the thesis focuses on their general description, their chemical and biological properties,as well as on their ecological importance and synthesis. Than it summarises their distribution to individual classes and subclasses. There are briefly mentioned some representatives of certain classes, together with germs, which produce them,as well as their properties. The second part of thesis deals with utilisation of bacteriosins in the food industy and pharmacy. There are par-ticular examples of bacteriosins yet utilised. Especially in case of food preservation. Next there is a summary of the potential utilisations of these agents in the future. Which are either in the stage of research, testing or theory.
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Production and application of antimicrobial substances produced by lactic acid bacteria
Utíkalová, Kristýna ; Dzurická, Lucia (referee) ; Márová, Ivana (advisor)
The bachelor’s thesis deals with the production of antimicrobial substances by selected lactic acid bacteria of the genera Lactobacillus, Pediococcus and Bifidobacterium, in which the production of bacteriocins was assumed based on the conducted research. Bacteriocins are peptide-based antimicrobial substances with the potential to be widely used primarily as biopreservatives in the food industry. The theoretical part of the bachelor’s thesis focuses on antimicrobial substances produced by probiotic bacteria with a further concentration on bacteriocins produced by selected bacterial species and their current research and application in the industry. In the experimental part, the antimicrobial activity of prepared isolates from probiotic bacteria was tested on selected gram-negative and gram-positive bacteria. Specifically, this was done by the agar diffusion method, the broth dilution method and the cell viability test using resazurin. The amount of lactic acid and acetic acid in the individual isolates was determined using high performance reverse-phase liquid chromatography, which made it possible to further discuss their influence on the antimicrobial activity of the isolates. Strong antimicrobial activity against indicator bacteria was found in all isolates. For some isolates, it was higher than the antimicrobial activity of lactic acid itself together with its concentration which is found in the isolate according to the measurements. That is a significant stimulus for further research of these probiotic isolates, especially the L. acidophilus and L. plantarum isolates. For example, it was found that the tested isolate from L. acidophilus showed an inhibitory activity against S. epidermidis of 90,76 % and 81,62 % against E. coli at a concentration of 20,47 mg/ml. The isolate from L. acidophilus was subsequently applied to plant packaging with the potential of usage in the food industry, and the inhibitory activity of this isolate against contaminating microorganisms was observed.
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Production and characterization of antimicrobial substances from lactic acid bacteria
Franeková, Eliška ; Smetana, Jan (referee) ; Márová, Ivana (advisor)
This bachelor thesis is focused on the production of antimicrobial compounds using lactic acid bacteria, their characterization and testing of their antimicrobial activity. The theoretical part of this work deals with the characteristics of lactic acid bacteria and the bacteriocins they produce, the possibilities of bacteriocin production and the factors that influence it. In the experimental part of this work, lactic acid bacteria Lactococcus lactis subsp. lactis, Lactobacillus helveticus and Bifidobacterium bifidum were cultivated, their growth curves and total protein content in supernatants after cultivation were measured. Cell-free culture supernatants were prepared by lyophilization and their antimicrobial activity against gram-positive and gram-negative bacteria was determined. The antimicrobial activity of commercial antimicrobial peptide nisin and a commercial preservative obtained using lactic acid bacteria was also measured. The sample obtained from Bifidobacterium bifidum was selected as the most effective of the isolates. Its antimicrobial activity was further tested on polymeric sausage packaging materials. Antimicrobial substances produced by lactic acid bacteria can be used in the food industry as preservatives or as a part of antimicrobial packaging, and in the pharmaceutical industry in materials for antimicrobial wound dressings.
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Vyhodnocení kvality a trvanlivosti sýrů s protektivní kulturou
Skýpalová, Veronika
The aim of this thesis is to investigate the topic of protective cultures. The work deals with the effects of protective cultures on semi-hard ripened cheeses, and their impact on a process of ageing on given types of cheese. An important part of this thesis represented in a chapter that deals with bacteriocins, their properties and effect in food processing. The effect of protective cultures on the chemical properties is observed in the practical part of the thesis. This part monitors mainly acidity of cheeses, pH, dry matter, and content of salt in cheeses. Given indicators are compared with and without addition of protective cultures on cheeses. In conclusion, this thesis observes if the protective cultures affect quality and shelf-life of semi-hard ripened cheeses.
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Methods for detection of antimicrobial properties of lactic acid bacteria
Vránová, Petra ; Němcová, Andrea (referee) ; Trachtová, Štěpánka (advisor)
Lactic acid bacteria are classified as probiotics producing substances that act against microorganisms. These antimicrobial substances include organic acids, carbon dioxide, hydrogen peroxide and bacteriocins. Currently, the focus is on bacteriocins, which are used in the food and pharmaceutical industries. The aim of this thesis is creating an overview of antimicrobial properties of lactic acid bacteria, methods of their determination and their applications in the food industry. The experimental part deals with identification of lactic acid bacteria present in selected samples of bacterial DNA. In addition, we tested for bacteriocin Gassericin K7A-producing gene. Molecular diagnostic methods such as real-time polymerase chain reaction (qPCR) and conventional polymerase chain reaction were used to distinguish bacterial DNA as well as the bacteriocin.
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Využití bakterií mléčného kysání s protektivními účinky ve výrobě čerstvých sýrů
Mešková, Ivana
The thesis is focused on lactic acid bacteria with protective effects. The work deals with the effects of protective cultures on fresh cheeses and their effect on the sensory properties of fresh cheeses. The thesis also includes a chapter on bacteriocins, their properties and effect of the action on cells. The thesis also provides informations about applications of protective cultures and their methods of uses in the production of fresh cheese. In the practical part of the thesis is observed effect of protective culture on the sensory properties. There are sensory evaluated cheese with protective cultures and cheeses without these cultures. Also is observed the acidification of cheeses, with the protective cultures and the status of their durability compared to cheese without these cultures.
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Testing of lactic acid bacteria Lactobacillus genus for bacteriocins production
Volecová, Veronika ; Němcová, Andrea (referee) ; Trachtová, Štěpánka (advisor)
Antimicrobial substances, or bacteriocins are substances produced by probiotic lactic acid bacteria. They have a positive effect on the gastrointestinal tract of humans and are especially suitable for the food, but also the pharmaceutical industry. The aim of the thesis was the molecular identification of lactic acid bacteria of the Lactobacillus genus, species and their subsequent inclusion PCR method. Using the PCR method were tested also genes responsible for the production of bacteriocins. To confirm the production of bacteriocins has been selected the microbiological method, agarose droplet spot-test. In the present study also included the bioinformatics part to assess the specificity and non-specificity of the primers using in Primer-BLAST program.
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