Rumen acidosis can be caused by overeating of readily fermentable carbohydrate, and as a result an imbalance may be seen in rumen microbial population. In order to characterization of lactate producing bacteria 30 isolates were collected from ruminal fluid of three male Mehraban sheep (receiving a diet containing 60% concentrate and 40% alfalfa hay) using specific cultural media. The isolates were evaluated based on gram staining, catalase activity, indole production test and their ability to ferment some sugars. Identification of isolates was undertaken using 16s rRNA gene sequences. A RFLP procedure was used to test the genetic homogeneity of isolates. Four isolates were selected and their 16s rRNA were sequenced. Based on information obtaind from Gene Bank, the isolates were closely (>99%) related to Streptococcus macedonicus, Streptococcus luteciae, Enterococcus faecalis and Escherichia fergusonii.

Background and aim: Tooth decay is one of the most common diseases in the world. The use of herbal substances to prevent and treat this disease has been considered for various reasons, such as increasing the resistance of bacteria to antibiotics, high cost, and adverse effects of some chemicals used in dentistry. This study aimed to investigate the effect of Tanacetum balsamita L essential oil on Streptococcus mutans, Streptococcus salivarius, and Streptococcus sanguinis. Material and Method: In this study, the aerial part of the Tanacetum balsamita L plant was extracted by distillation with essential oil, the antimicrobial effect of essential oil in concentrations (12. 5, 25, 50, and 100 µ g / ml) was investigated. The diffusion disc method was used to evaluate the antimicrobial activity of essential oil. Results: According to the results, the essential oil in concentration of 100 µ g/m had inhibitory effect on growth of streptococcus mutans, salivaris, and sanguis. This effect was better than Irsha mouth wash and somehow less than Chlorhexidine and Oral B mouth washes. This differ was not significant so the essential oil with concentration of 100 µ g/ml had similar effect as Oral B and Chlorhexidine mouth washes. The positive effect was seen in the concentrations of 25 and 50 µ g/ml but it was not considerable comparing to control groups. There was no effect in 12. 5 µ g/ml concentration. Conclusion: Based on the results of this study, it is suggested to prepare mouth washes containing the concentration of 100 µ g/ml of the essential oil Tanacetum balsamita L. to evaluate the antimicrobial effects in more in othe in vitro and in vivo studies.

Introduction: Mastitis is one of the most prevalent and important diseases in dairy cow herds. It is an inflammatory disease of mammary gland which is caused by many infectious agents. Streptococcus uberis and Streptococcus agalactiae have been frequently isolated from bovine mastitic milk. This research was carried out to study the prevalence of Streptococcus uberis and Streptococcus agalactiae in the milk of cows with clinical mastitis in industrial dairy farms around the province of Isfahan.Materials and Methods: In total, 123 milk samples were collected from cows with clinical mastitis and then, were immediately transferred to the laboratory. Mastitic milks were confirmed using California Mastitis Test and then, all samples were tested using microbial and biochemical tests. Finally, all 123 samples were tested using PCR.Results: Culture results showed that 16% and 7.31% of the milk samples were positive for Streptococcus agalactiae and Streptococcus uberis, respectively. The PCR showed that 19.51% and 10.56% of the samples were infected with Streptococcus agalactiae and Streptococcus uberis, respectively.Discussion and Conclusion: This study showed that the Polymerase Chain Reaction has a higher accuracy and safety than the culture method. Therefore, we recommend the use of Polymerase Chain Reaction for inspection of microbial quality of milk samples.

Background and Aim: Reports indicate an increase in the resistance of oral bacteria to the antibiotics. This study was conducted with the aim to compare the antibacterial effects of colloidal Nanosilver and Nigella sativa oil.Materials and Methods: In this experimental laboratory study, the disk diffusion method was used on 76 samples to evaluate the anti-bacterial properties of Nigella sativa oil extract in concentrations of 330mg/mL (up to 10.312 mg/ mL) and similar properties of Nanosilver in concentrations of 3.125 to 3500ppm.The samples were divided into 2 groups of oral bacteria consisting of Streptococcus mutans and S.sanguis. The results were compared with anti-bacterial effect of the standard disk of amoxicillin (25 µg). The growth medium consisted of Mueller Hinton agar plates in which standard strains of bacteria with 0.5 McFarland concentrations were cultured. The bacterial inhibitory zone of each disk was measured and the data was analyzed using the ANOVA statistical test.Results: The Nigella Sativa oil in concentration of 330mg/mL and Nanosilver in concentration of 3500 ppm demonstrated an inhibitory zone of 22-33.5mm respectively for S. mutans and 9.75-11 mm respectively for S.sanguis. The inhibition zone of standard amoxicillin disc (25 mg) was 19.75 – 21.75mm.Conclusion: Colloidal Nanosilver showed the highest antibacterial activity against both strains of the bacteria. The antibacterial effects of Nigella sativa and amoxicillin were similar on S. mutans whereas, Nigella stevia was found to be more effective than amoxicillin on S.sanguis.

Background: RNA extraction with efficient quality and quantity is very important for RT PCR, hybridization on northern blotting and gene expression analysis by real time PCR. Soluble and insoluble extracellular polysaccharides in Streptococcus mutans biofilm cells interfere with RNA extraction procedures. Therefore, finding efficient methods for polysaccharide removal, RNA extraction and purification is necessary for RNA based molecular research. The aim of present study was to evaluate the efficary of a few methods in RNA extraction from Streptococcus mutans.Methods: In this research we used Streptococcus mutans ATCC 35668 and one clinical isolate of S. mutans from dental plaque. RNA extraction was carried out from biofilms form in 24 well polystyrene microtiter plate using 3 methods. 1: Routine method for RNA extraction from planktonic cells with RNX-Plus solution (Cinagen), 2: Using HYBAID ribolyser Kit, instrument and tubes containing pearls. 3: Using HYBAID ribolyser instrument and RNX-Plus solution. Finally, determination of the isolated RNA purity and integrity was done.Results: The results showed that RNA extraction from biofilm cells of S. mutans is challenging because of extracellular polysaccharides and the current RNA isolation protocols from planktonic cells (eg. protocol 1) are not suitable for biofilm cells. For this reason, we used HYBAID ribolyser instrument and tubes containing glass and plastic pearls with different size and shapes for maximum cell lysis without disturbing the RNA. The mean photo absorbtion from extracted RNA in latter methods showed statistical significant difference compared to current in-use method (P<0.05).Conclusion: RNA extraction from S.mutans biofilm cells needs techniques with maximum Polysaccharide removal and maximum cell lysis without disturbing the RNA. The 2nd and 3rd methods were more  effective than 1st one. The 3rd protocol is recommended due to it’s lower cost.

Background: Reducing the microbial flora in the mouth and teeth, preventing gum disease and tooth decay; the use of antimicrobial agents, especially plant antimicrobial substances are very important due to their side effects than the chemical substances.Eucalyptusis one of these plants which show antimicrobial activity. The aim of this study was to evaluate antimicrobial effects of methanolic essential oil of Eucalyptus glubulos leaves against a number of oral cavity bacteria Method: Eucalyptus tree leaves after collection, distillation with water byclevenger (BP), afterwards the weight of oil and diluted with double dilution method to 400, 200, 100, 50, 25, 12.5 mg / ml which was prepared with methanol, then the antimicrobial effect was determined by E. Test method based minimum growth inhibitory concentration (MIC) on four oral bacteria; S. sangois S. salivarius, Streptococcus mutans, Lactobacillus casei.Results: The MICs obtained for tested bacteria were 125, 250 and 125 mg / ml for S. mutans, S. salivarius and L. casei respectively. S. sangoiswas resistance to this essential oil. All bacteria were resistant to the methanol that it was used as a negative control.Conclusion: Most of oral cavity pathogen bacteria which tested in this study showed a valuable sensitivity to Eucalyptus glubulos extract. This recommends use of this compound as an alternative for antimicrobial chemical agents.

Background and Objectives: Streptococcus sanguinis and mutans are dental infections agents. Due to the adverse effects of chemical mouthwashes, the aim of the present study was to determine the antibacterial effects of cetylpyridinium chloride mouthwash and alcoholic extracts of Melissa officinalis plant on the growth of these bacteria.Materials and Methods: In this laboratory study, M. officinalis leaves were collected and extracted using percolation method. Well diffusion method and determination of minimum inhibitory and bactericidal concentrations were used for the antibacterial effects determination of alcoholic extracts of the plant and mouthwash in the concentrations of 250, 125, 62.5, 31.25, 15.62, 7.81, 3.9, 1.95, 0.97 and 0.48 mg/ml. Statistical analysis was performed using Pearson’s correlation coefficient.Results: The most antibacterial effect of ethanolic and methanolic extracts of M. officinalis and mouthwash on S.mutans and sanguinis was in the concentration of 250 mg/ml and the least inhibitory concentrations against S. mutans were 3.9, 31.25 and 15.26 and against S. sanguinis were 31.25, 15.62and 31.25 mg/ml, respectively. The minimum bactericidal concentrations of ethanolic and methanolic extracts of M. officinalis and mouthwash against S. mutans were 125, 62.5 and 31.25 and against S. sanguinis were 62.5, 31.5 and 62.5 mg/ml, respectively. There was a positive significant correlation between increasing concentration of extracts and inhibition of bacterial growth (p<0.001).Conclusion: It seems that M. officinalis extract like mouthwash can be used as an oral and teeth antiseptic. However, in-vivotests and proves that there is no harmful effects on the human body are essential for the production of this type of herbal mouthwash.

Introduction: Increased resistance of oral pathogens to conventional antimicrobial agents has led to the use of alternative methods to overcome microbial resistance. The purpose of this in vitro study was to evaluate the effect of antimicrobial photodynamic therapy on Streptococcus mutans.Materials & Methods: In this in vitro study, a diode laser emitting a wavelength of 810nm was used in association with EmunDo as a photosensitizing agent. Suspensions of Streptococcus mutans were prepared and divided into six groups by treatment: 1) EmunDo, 2) diode laser irradiation (100mW, 90 seconds), 3) diode laser irradiation (300mW, 30 seconds); 4) EmunDo+diode laser irradiation (100mW, 90seconds), 5) EmunDo+diode laser irradiation (300mW, 30 seconds), 6) control (no treatment). Immediately and 24 hours after photodynamic therapy, the bacterial suspensions were cultured. After incubation at 37°C, viable microorganisms of Streptococcus mutans were counted and the results were reported in colony-forming units (CFU). Data were analyzed by repeated measures analysis of variance at significance level of 0.05.Results: According to the repeated measures analysis, no significant between-group differences were found in the number of Streptococcus mutans colonies, either immediately or 24 hours after photodynamic therapy (P>0.05). The number of Streptococcus mutans colonies increased significantly at 24 hours after photodynamic therapy compared to immediately after treatment in all groups (P<0.001).Conclusion: Under the conditions used in this study, photodynamic therapy had no effect on viability of Streptococcus mutans. However, more evidence-based data are required regarding different photosensitizing agents and laser parameters for a definite conclusion.