Microbiology
Razieh Sadati; Nima Shaykh-Baygloo; Rasoul Shokri
Volume 14, Issue 9 , September 2023, , Pages 515-523
Abstract
Isolation of new microbial species from extreme environments is one of the most efficient approaches for the development of novel bioactive metabolites. The aim of the present study was to explore the pharmaceutical bacterial resources from the water and sediments of hypersaline Lake Urmia. Using different ...
Read More
Isolation of new microbial species from extreme environments is one of the most efficient approaches for the development of novel bioactive metabolites. The aim of the present study was to explore the pharmaceutical bacterial resources from the water and sediments of hypersaline Lake Urmia. Using different culture conditions and media led to the isolation of 20 bacterial strains. Halophilic bacteria were screened for the production of antibacterial agent against multi-drug resistant strains of Escherichia coli through agar well diffusion assay. Halophilic bacteria DNA extraction was done by boiling method. The results showed that two Halomonas strains, LUH16 and LUH20 identified by analysis of 16S rRNA gene sequences were the potent producers of antimicrobial metabolites against various strains of E. coli. Furthermore, gas chromatography-mass spectrometry (GC-MS) analysis revealed the presence of eight secondary metabolites with the relevant antimicrobial properties. Our findings led us to focus on Halomonas strains as potent producers of antimicrobial compound that might be an alternative against antibiotic-resistant pathogens such as pathogenic Escherichia coli.
Farhad Tavarideh; Fazel Pourahmad; Mostafa Nemati
Volume 13, Issue 3 , September 2022, , Pages 409-415
Abstract
To search endophytic bacteria diversity and evaluate their antibacterial activity, healthy medicinal plant of Scrophularia striata was chosen in this study. One hundred endophytic bacteria were isolated from surface-sterilized tissues (root, stem and leaf) of S. striata. Using sequence analysis targeting ...
Read More
To search endophytic bacteria diversity and evaluate their antibacterial activity, healthy medicinal plant of Scrophularia striata was chosen in this study. One hundred endophytic bacteria were isolated from surface-sterilized tissues (root, stem and leaf) of S. striata. Using sequence analysis targeting 16S rRNA gene, eight genera, including Agrococcus, Arthrobacter, Bacillus, Chryseobacterium, Delftia, Kocuria, Pseudomonas and Sphingomonas were identified. Antibacterial activity of endophytic bacteria was examined against some test bacteria, employing agar well diffusion method. Out of 31 endophytic bacterial isolates, 24(77.42%) isolates showed significant antimicrobial activity against Bacillus cereus, 17(54.84%) isolates exhibited maximum activity against Staphylococcus aureus, 14(45.16%) isolates against Escherichia coli and 5(16.13%) isolates showed positive activity against Proteus mirabilis.The results obtained in this study suggested that the medicinal plant, S. striatais is a potent source of endophytic bacteria with antibacterial activity and offers promise for discovery of more impressive biological compounds.
Food Hygiene
Mehdi Fathollahi; Majid Aminzare; Mehran Mohseni; Hassan Hassanzadazar
Volume 10, Issue 4 , December 2019, , Pages 299-305
Abstract
This study aimed to evaluate the composition, antioxidant capacity and antibacterial effects of Pistacia atlantica subsp. kurdica (baneh) essential oil on some important bacteria in food safety. Essential oil was derived using hydro-distillation method of the baneh fruits. Essential oil composition was ...
Read More
This study aimed to evaluate the composition, antioxidant capacity and antibacterial effects of Pistacia atlantica subsp. kurdica (baneh) essential oil on some important bacteria in food safety. Essential oil was derived using hydro-distillation method of the baneh fruits. Essential oil composition was determined using gas chromatography–mass spectrometry. The 2,2′-azinobis-(3-ethylbenzothiaziline-6-sulfonate; ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) methods were used to evaluate antioxidant activity and Folin-Ciocalteu method was used to determine total phenolic content of essential oil. The antibacterial effect of the essential oil against six pathogen bacteria was determined using minimum inhibitory concentration, minimum bactericidal concentration and disc diffusion methods. Monoterpene and sesquiterpene hydrocarbons were main compounds of total identified constituents in the essential oil (approximately 93.50% and 5.45%, respectively). The main compounds were α-pinene, myrcene, limonene, β-pinene and γ-terpineol, respectively. The mean concentration of essential oil providing 50.00% inhibition was 7.54 ± 0.01 mg mL-1. Dose-dependent and scavenging activities were seen in DPPH and ABTS tests and total phenolic content within test range of concentrations (0.0625 to 4.00 mg mL-1). The highest DPPH radical scavenging activity (48.67 ± 0.84%) was seen at a concentration of 4 mg mL-1. The responses of essential oil concentrations to ABTS assay were quite similar to the DPPH reaction, especially in higher concentrations. Both antimicrobial methods demonstrated that the essential oil had broader antibacterial effects against the Gram-positive bacteria than the tested Gram-negative bacteria. Essential oil of Pistachia atlantica subsp. kurdica can be one of the performing essential oils to be used as a preservative in food industry to increase food safety and reduce food pathogens risks.
Hassan Hassanzadazar; Ali Ehsani; Karim Mardani; Javad Hesari
Volume 3, Issue 3 , September 2012, , Pages 181-185
Abstract
Lactobacillus strains are a major part of the probiotics, microflora of the intestine and of fermented dairy products, and are found in a variety of environments. The aim of this study was to find out the ability of bile and acid tolerance and antibacterial properties of the twenty eight isolates of ...
Read More
Lactobacillus strains are a major part of the probiotics, microflora of the intestine and of fermented dairy products, and are found in a variety of environments. The aim of this study was to find out the ability of bile and acid tolerance and antibacterial properties of the twenty eight isolates of three group lactobacilli namely Lactobacillus plantarum, Lactobacillus casei and Lactobacillus delbruki. For this purpose Twenty eight different Lactobacillus strains that isolated from Koozeh cheese as a traditional cheese were screened. The acid tolerance test was studied under pH 2.0 and 3.0 with 7.5 as control. The cell count for the acid tolerance test was obtained at an interval of 0, 1, 2 and 3 hours respectively and was pour plated on Man, Rogosa, and Sharpe (MRS) agar to be incubated at 37 °C for 24 hours. All cells were selected for bile tolerance test in MRS broth containing bile concentrations of 0% as control and 0.3% as test. Then cell counts were enumerated after 24 hours of incubation on MRS agar. Results showed twenty seven isolates did not have ability to tolerate acid and bile salts and antimicrobial activity against four indicator bacteria included Eshirichia coli, Listeria monocytogenesis, bacillus cereus, Salmonella entritidis. Only one Isolate namely Lactobacillus casei could tolerate acid and bile salt and had antibacterial activity against of L. monocytogenesis. Therefore we can consider this strain as a native probiotic but extra examinations was required.
