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Showing 7 results for Bacillus
Jamile Norouzi,
Volume 6, Issue 4 (1-2003)
Abstract
Background: Lactic acid bacteria serve as the starter of food fermentation. They improve food taste and inhibit the growth of organisms. Bacteriocin is a major natural inhibitor produced by Lactobacillus plantarum. Materials and Methods: For this exploratory study, we have purchased some hotdog and sausage made by different factories. Having one gram of sausage or hotdog in physiologic serum, it was diluted and cultured in MRS media. Bacteria growth was surveyed in different PH, temperature and media. Results: Of 15 samples, Lactobacillus plantarum was isolated in 4. Its optimal condition was as below: Temperature 25 degrees centigrade, pH=4.8-6.4 and basic MRS media with glucose 2%. Its antimicrobial activity was reserved in 100 degrees centigrade for 10 minutes and has not modified by alpha amylase or lysosomes. At 25 degrees centigrade, they had maximum inhibitory effect on staphylococcus (20ml) and listeria (14ml). Conclusion: The stability of Lactobacillus plantarum’s antimicrobial activity against high temperature is of utmost importance since during food processing we require high temperature. We suggest the usage of suitable starter media to produce strong antimicrobial agents in fermentative foods. Employing genetic changes may be helpful to produce Lactobacilli with potentially greater bacteriocin production
Hosein Motamedi , Elnaz Zahedi, Ali Zarei-Mahmoud Abadi ,
Volume 21, Issue 1 (4-2017)
Abstract
Background: With regard to the occurrence of fungal infections, finding new antifungal agents is necessary. Due to its biologic properties Bacillus spp. are suitable sources for this purpose. The aim of this study was to find native bacillus species with potential of antifungal agent production.
Material and Methods: In this experimental study, bacillus species were isolated from heat-treated soil samples and following culturing in TSB, anti-fungal effects of their supernatants were determined by disc diffusion method. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) levels of the selected strains were obtained against two fungal pathogens. Growth curve of the isolate was obtained in different pH and temperatures. The effects of pH, temperature, carbon and nitrogen sources on antibiotic production by the isolate were also investigated. This isolate was identified through biochemical and molecular tests.
Results: Three out of six bacillus isolates were able to produce the antifungal agents, among them Bacillus cereus strain SB15 showed the most significant antifungal effects against a wide range of fungi. Optimized conditions for antibiotic production by this isolate were: temperature=37˚C, pH=7, 48 h incubation and manitol and urea as the best carbon and nitrogen sources, respectively. The MIC and MFC of the produced antibiotic against Aspergillus niger were: 2 and 4 and against Aspergillus flavus 4 and 16 mg/ml, respectively.
Conclusion: Based on the obtained results it may be concluded that this bacillus strain has optimum potential for antifungal agent production. The strain can be used for the control of fungal infections and also fungal growth in food industry and environment.
Mehdi Porshaker, Ardeshir Hesampour,
Volume 23, Issue 1 (4-2019)
Abstract
Background: Among probiotics, lactobacillus species with bacteriocin activities have been used in microbial biotechnology as safe biological preservatives. So, this study aimed to determine antimicrobial activity of bacteriocins of lactobacillus species isolated from lactic acid bacteria in traditional dairy products.
Materials and Methods: In this experimental study, isolated lactic acid bacteria from local yoghurt of Nadushan region were used as probiotics with a bacteriocin production potential. The bacteriocin effect of isolated lactic acid bacteria was investigated against seven pathogenic bacteria using well diffusion and disk methods.
Results: The results of well diffusion analysis showed that the most growth inhibitory effect against Staphylococcus epidermidis, Escherichia coli Staphylococcus aureus, Enterococcus faecalis and Candida albicans pathogen bacteria was caused by isolated lactic acid bacteria including Lactobacillus delbrucki, Lactobacillus caesium and Lactobacillus plantarum, respectively. Also, the results of disc method showed that the highest inhibitory effect against the bacterial pathogens was caused by Lactobacillus delbrucki, Lactobacillus plantarum and Lactobacillus caesium, respectively. Although antimicrobial compounds were inactivated by proteolytic enzymes, they showed stability against variant pH and temperature treatments.
Conclusion: It seems that bacteriocin of the probiotics isolated from dairy products of this region can be used as a safe and healthy biological preservative in food industry.
Hassan Hassani-Bafrani, Monavareh Ahmadi, Gholam Reza Khosravi, Erfan Khosravi, Mohammad Karimian,
Volume 23, Issue 1 (4-2019)
Abstract
Background: Among probiotics, lactobacillus species with bacteriocin activities have been used in microbial biotechnology as safe biological preservatives. So, this study aimed to determine antimicrobial activity of bacteriocins of lactobacillus species isolated from lactic acid bacteria in traditional dairy products.
Materials and Methods: In this experimental study, isolated lactic acid bacteria from local yoghurt of Nadushan region were used as probiotics with a bacteriocin production potential. The bacteriocin effect of isolated lactic acid bacteria was investigated against seven pathogenic bacteria using well diffusion and disk methods.
Results: The results of well diffusion analysis showed that the most growth inhibitory effect against Staphylococcus epidermidis, Escherichia coli Staphylococcus aureus, Enterococcus faecalis and Candida albicans pathogen bacteria was caused by isolated lactic acid bacteria including Lactobacillus delbrucki, Lactobacillus caesium and Lactobacillus plantarum, respectively. Also, the results of disc method showed that the highest inhibitory effect against the bacterial pathogens was caused by Lactobacillus delbrucki, Lactobacillus plantarum and Lactobacillus caesium, respectively. Although antimicrobial compounds were inactivated by proteolytic enzymes, they showed stability against variant pH and temperature treatments.
Conclusion: It seems that bacteriocin of the probiotics isolated from dairy products of this region can be used as a safe and healthy biological preservative in food industry.
Mohammad Mehdi Soltan-Dallal, Zohreh Didar,
Volume 23, Issue 3 (5-2019)
Abstract
Background: Biosurfactants are compounds that are produced by different microorganisms and have an emulsifying property. This study aimed to investigate extractive biosurfactant from bacillus subtilis (PTCC1720) against the biofilms of Staphylococcus aureus (PTCC 1112), Staphylococcus saprophyticus (PTCC 1440) and Staphylococcus epidermidis (PTCC 1435).
Materials and Methods: This study was conducted in vitro to examine the effect of biosurfactant produced by Bacillus subtilis in prevention of biofilm formation and removal of biofilms produced by different staphylococcal species. First, bacillus subtilis was cultured in suitable culture media for producing biosurfactant. Then, extraction of produced biosurfactant was done and anti-biofilm properties were assessed by determination of optical density at 570 nm by ELISA reader equipment. Statistical analysis was performed by SPSS software version 16 and ANOVA. The means were compared at 95% confidence level by Duncan's method.
Results: According to the results, the biosurfactant produced by bacillus subtilis had emulsification index equal to 40% and oil replacement area was 1.8 ± 0.3 cm-2. Produced biosurfactant by bacillus subtilis had a significant effect on preventing microbial formation with the highest effect on biofilm of staphylococcus aureus and Staphylococcus saprophyticus. Also, the results showed that the biofilm of staphylococcus epidermidis had the highest resistance in this respect.
Conclusion: According to this study, the antibiofilm activity of biosurfactant extracted from Bacillus subtilis against the biofilm of staphylococcus aureus, epidermidis and saprophyticus was shown. In addition, this type of biosurfactant can be effective in removing biofilms formed by staphylococcal strains.
Parisa Fouman-Ajirlou , Changiz Ahmadizadeh, Mohamad Zaeifizadeh,
Volume 24, Issue 2 (4-2020)
Abstract
Background: Lactobacillus reuteri has broad-spectrum effects on both gram-positive and negative bacteria as well as fungi and protozoa. Also, Coumarins have high ability to control and treat cancer. Apoptosis is a planned cell death that plays an essential role in the development and homostasis of living creatures. Bax and Bcl2 genes are among key target genes of internal pathway; thus the present study aimed to determine the effect of L. reuteri and Coumarin on the expression of these two genes on AGS cell line.
Materials and Methods: After cultivation of gastric cancer cells, Coumarin and L. reuteri were affected in these concentrations at different concentrations and the inhibitory effect on cell proliferation was evaluated using the MTT method. Afterwards, the RNA content of cells was extracted using an RNA extraction kit. Then the cDNA was synthesized for Bax and Bcl2 genes and finally Real time PCR was run.
Results: The results of the MTT assay on gastric cancer cells showed the inhibitory effect of Coumarin and L. reuteri. Also, the results of Real Time PCR showed that the expression of Bax and Bcl2 expression in comparison with the control group was significantly increased.
Conclusion: Considering the effects of Coumarin and L. reuteri on inhibiting proliferation of AGS cells and increasing the Bax and Bcl2 gene, it can be concluded that Coumarin and L. reuteri can induce apoptosis in cancerous cells by affecting the expression of genes involved in apoptosis.
Mohammad Tajik, Fatemeh Noorbakhsh, Masoumeh Mahdavi Ortakand,
Volume 29, Issue 1 (3-2025)
Abstract
Background and Aim: The indiscriminate use of antibiotics has led to the emergence of antibiotic-resistant bacterial strains, highlighting the need for alternative therapeutic strategies such as probiotics. This study aimed to investigate the inhibitory effects of bacteriocin derived from Lactobacillus plantarum and the antibiotic polymyxin B on biofilm formation and certain virulence factors of Pseudomonas aeruginosa.
Methods: In this experimental study, 30 clinical isolates of P. aeruginosa were obtained from various clinical samples. The isolates were identified using standard biochemical and microbiological assays. Bacteriocin was extracted from the L. plantarum strain MT.ZH293. The effects of bacteriocin and polymyxin B on biofilm formation, surface hydrophobicity, alginate production, and bacterial motility were assessed. The minimum inhibitory concentration (MIC) was determined using the microdilution method.
Results: For polymyxin B, the MIC was 4 µg/mL in 13.33% of isolates and 8 µg/mL in 86.6% of isolates. Regarding bacteriocin, 20% of isolates showed an MIC of 125 µg/mL, while 80% exhibited an MIC of 250 µg/mL. Following treatment with polymyxin B, 46.6% of isolates formed strong biofilms, 46.6% moderate, and 6.6% weak biofilms. In contrast, treatment with bacteriocin resulted in 13.3% of isolates forming moderate biofilms and 86.6% forming weak biofilms. Bacteriocin was more effective than polymyxin B in inhibiting biofilm formation, reducing surface hydrophobicity, and suppressing alginate production. Additionally, bacteriocin exhibited greater inhibition of twitching motility (within the range of 40 to 60 mm), while both treatments enhanced swarming motility.
Conclusion: The bacteriocin derived from L. plantarum demonstrated greater efficacy than polymyxin B in inhibiting biofilm formation and associated virulence factors, such as surface hydrophobicity and alginate production in P. aeruginosa. Thus, this bacteriocin may serve as a promising alternative strategy for managing antibiotic-resistant bacterial infections.
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