Isolation and Characterization of Crude Oil Degrading Bacillus Spp.

Today, application of microorganisms for removing crude oil pollution from contaminated sites as bioremediation studies, was considered by scientists because other methods such as surfactant washing and incineration lead to production of more toxic compounds and they are non-economic. Fifteen crude oil degrading Bacillus   spp. were isolated from contaminated sites. Two isolated showed best growth in liquid media with 1-3% (v/v) crude oil and mineral salt medium, then studied for enzymatic activities on tested media. The results showed maximal increase in optical densities and total viable count concomitant with decrease in pH on fifth day of experimental period for bacillus S6. Typical generation time on mineral salt with 1% crude oil is varying between 18-20h, 25-26h respectively for bacillus S6 and S35. Total protein was monitored at determined time intervals as biodegradation indices. Increasing of protein concentration during the incubation period reveals that isolated bacillus can degrade crude oil and increase microbial biomass. These bacillus spp. reduced surface tension from 60 (mN/m) to 31 and 38 (mN/m), It means that these bacillus spp. can produce sufficient surfactant and have good potential of emulsification capacity. The results demonstrated that these bacillus spp. can utilize crude oil as a carbon and energy source

In Vivo Diagnostic Accuracy of Digital Radiography in the Detection of Secondary Caries in Anterior Teeth

Background and Aim: Secondary caries are a common challenge for dentists. Many researchers have evaluated the accuracy of digital radiographic systems in the detection of secondary caries and have reported controversial results. Therefore, the aim of this in vivo study was to determine the diagnostic accuracy of digital radiography in the detection of secondary caries in anterior teeth. Materials and Methods: In this diagnostic in vivo study, 34 patients were selected from among the individuals who wished to replace their anterior teeth restorations. The restorations in need of replacement were class III or class IV composite resin restorations which were at least 5 years aged with either a crack in the restoration body or with more than 0.5mm marginal maladaptation or marginal discoloration. Digital radiographs were obtained and were observed randomly by four oral and maxillofacial radiologists. Caries detection was classified using a 5-point Likert scale. Statistics were computed to assess Kappa coefficients. Results: According to the data, observer reliability for PSP sensor was between 0.79 and 0.88 which is an indicator of the high accuracy of PSP sensor. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 90, 77, 86, 85 and 86 % respectively. Conclusion: The results suggest that in vivo digital radiography with PSP sensors is sufficiently accurate in the detection of secondary caries