فهرست مطالب نازنین صانعی

Medicinal plants are one of the most important natural resources in each country. The aim of this study was to evaluate the anti-biofilm effect of ethanol and methanol extracts of Ziziphus spina-christi leaves, Peganum harmala, Salvia officinalis, and Querqus brantii on the growth and formation of biofilm by Staphylococcus aureus.

Following evaluation of the susceptibility of the studied Staphylococcus aureus strain to various antibiotics, the growth inhibitory effect of extracts on the bacterium was investigated by disc diffusion method and then the inhibitory effect of the extracts on biofilm formation was evaluated in 96 well micro-titer plates. The means were compared with ANOVA test.

The results from antibacterial effect of the extracts showed that the methanol extract of Peganum harmala and Querqus brantii seeds at 350 and 450 mg/ml concentrations had a greater inhibitory effect on the growth of Staphylococcus aureus than other extracts as well as synthetic antibiotics. The results from anti-biofilm formation effect of the extracts showed that methanol extract of Salvia officinalis leaves and Querqus brantii seeds at 350 mg/ml concentration, and ethanol extract of Salvia officinalis leaves at 350 mg/ml concentration were the lowest concentrations that showed the greatest inhibitory effect on biofilm formation by Staphylococcus aureus. Other extracts inhibited biofilm formation by this bacterium in higher concentrations. The lowest anti-biofilm effect on Staphylococcus aureus was observed by ethanolic and methanolic extracts of Ziziphus spina-christi leaf.

The studied extracts in this study, especially the methanol extracts of Salvia officinalis leaves and Peganum harmala seeds, and ethanol extract of Salvia officinalis leaves are good solutions for S. aureus infection and biofilms formation control and are suggested that be evaluated in In vivo experiments and clinical applications.

Based on information about the types and numbers of microorganisms in the surface soil samples, the distribution range of underlying oil and gas reservoirs can be judged. In the present study, methane oxidizing bacteria were isolated and characterized from oil contaminated soils in Khuzestan, Iran and their growth was optimized in the presence of methane as sole carbon and energy sources. 

Materials & Methods:

Bacteria were isolated in nitrate mineral salt (NMS) medium in the presence of 50% air and 50% methane. The cultures were incubated on a shaker for 10 days at 30°C in dark place, and every two days, the gas mixture was replaced. The isolated bacteria were characterized based on biochemical and molecular identification tests. Then the optimum growth conditions was detected in different pH values and incubation temperatures in NMS medium containing methane.

Three Gram-negative rods were isolated from soil samples that were able to grow in isolation condition. The isolates were characterized as Achromobacter and Sphingomonas spp. The strains could also grow in the NMS medium with a high methanol concentration (3%). The optimal pH and temperature for the isolates were 7.4 and 30°C respectively.

Methanotrophic strains that were isolated in the present study were able to grow and oxidize methane in high ranges of temperature and pH and can be proposed for the removal of mono-carbon compounds such as methane and as biological detectors for prospecting for oil and gas reservoirs