جستجوی مقالات مرتبط با کلیدواژه « باکتریوسین » در نشریات گروه « پزشکی »

Bacteriocins are peptides with antimicrobial properties. They are ribosomally synthesized and produced by both gram-positive and gram-negative bacteria. The bacteriocins produced by Escherichia coli are called colicins. Colicins in commensal bacteria inhibit the growth of pathogenic bacteria and in pathogen strains, they increase bacterial virulence. The aim of this study was to evaluate the frequency of col V and col Ia genes in Escherichia coli specimens isolated from patients with urinary tract infections in Yazd City, Iran.

In this descriptive cross-sectional study, 160 Escherichia coli samples were isolated from urine specimens and identified by common biochemical tests. The amplification of col V and col Ia genes was performed by PCR method using specific primers and after sequencing, the results were analyzed using SPSS version 16 software.

In this study, out of 160 Escherichia coli isolates examined, calicin gene was detected in 26.9% of the isolates. The frequency of col Ia gene was 24.4% and the frequency of col V gene was 10.6%. Furthermore, in 8.12% of isolates, both genes were identified together. The frequency of isolates containing only col Ia gene was 16.2% and isolates containing only col V gene was 2.5%.

In this study, isolates with col Ia gene showed high frequency. Most strains with col V gene also had col Ia gene. Therefore, the col V gene is often observed together with the col Ia gene.

Lactobacillus spp. are widely distributed in environment as well as dairy products. During the fermentation process, these microorganisms produce various compounds such as organic acids and bacteriocins with antimicrobial activities. The aims of this study were to isolate and identify lactobacilli from local yogurts of Behbahan, Iran, and assessment of antimicrobial activity of the bacteriocins produced by these lactobacilli.

In this study, the lactobacilli isolates were identified using 16S rRNA gene analysis. Antimicrobial effects of the bacteriocins were studied against five pathogenic bacteria using well diffusion and disk diffusion methods. Effects of proteolytic enzymes, heat and pH on these compounds were investigated as well.

Results of the well diffusion and disk diffusion methods showed that the most inhibitory effects on Shigella dysenteriae, Staphylococcus aureus, Pseudomonas aeruginosa, Micrococcus luteus and Listeria innocua belonged to Lactobacillus plantarum, Lactobacillus  acidophilus, Lactobacillus casei and Lactobacillus buchneri respectively. Micrococcus luteus was the most susceptible and Pseudomonas aeruginosa was the most resistant pathogens to effects of the bactericidal compounds. Antimicrobial compounds were inactivated by the proteolytic enzymes; however, the compounds preserved their resistance to heat and pH.

Bacteriocins produced by native lactobacilli are able to inhibit activity of various pathogenic microorganisms in foods and can be used as safe, harmless biological preservatives.

Dental plaque is a biofilm that is formed on the surface of the tooth. Carious lesions are caused by inappropriate ecological changes in microbial flora of the plaque biofilm. In this study, the effect of Lactobacillus casei bacteriocin, isolated from dairy products, was investigated on Streptococcus salivarius biofilm formation.

In this experimental study, MRS Broth and MRS Agar medium were used to isolate three strains of Lactobacillus casei probiotic from milk samples under microaerophilic conditions. The initial identification of Lactobacillus casei was performed by sugar fermentation and other biochemical tests. Then, 16SrRNA encoding gene was confirmed by PCR and sequenced. At last, Bacteriocin was isolated by ammonium sulfate sedimentation and its molecular weight was measured by SDS-PAGE and the antimicrobial activities were investigated. The Streptococcus salivarius were isolated from dental plaque and phenotypically and biotypically identified. Molecular confirmation of the isolates was performed using gtfK specific gene by PCR. The ability to form Streptococcus salivarius biofilm and the effect of bacteriocin on biofilm formation were measured by microtiter plate.

After partial purification of Lactobacillus casei probiotic from dairy products, two LC3 and LC1 protein samples formed bands (35-40 kDa and about 75 kDa, respectively). The supernatant fluid from the cultivation of Lactobacillus casei and bacteriocins showed antibacterial effects against Streptococcus salivarius isolates from dental plaque and the formation of biofilm by this bacterium.

According to this study, bacteriocin and supernatant fluid from Lactobacillus casei cultures could inhibit the growth of Streptococcus salivarius and also reduced biofilm formation, so, it could be used in oral care products.