The aim of the present work was to study the possibility of producing an effective bacteriocin from bacteria naturally exists in the mouth. Streptococcus salivarius KA101 was selected among 120 oral isolates collected from healthy people based on its ability to produce an effective bactericidal bacteriocin. Modified tryptic soy agar with 2% yeast extract and 0.1% calcium carbonate was the best medium for the production of bacteriocin with an activity of 40 AU/ml. Response surface methodology (RSM) based on central composite design (CCD) was employed to build a model in order to evaluate the optimum effective factors for bacteriocin production using four factors: yeast extract, CaCO3, pH and incubation time. Based on the optimization plot generated by RSM, the suggested optimal concentrations of yeast extract and CaCO3, as well as pH and incubation time for maximum bacteriocin production (80.2 AU/ml), were 13 g/l, 1.4 g/l, 7 and 24 hrs respectively. The results showed that bacteriocin was active for 30min at 20, 30 and 40˚C while 50% of its activity was lost at 50˚C. In addition, maximum bacteriocin activity was observed at pH 6 and 7 for 30min and disappeared completely at pH 4 and 9. Moreover, bacteriocin activity was completely lost after 90min of incubation with trypsin and pepsin which confirm its protein nature. Antimicrobial activity of bacteriocin was tested against 47 clinical isolates collected from patients suffering from different dental diseases. The results showed that the bacteriocin had an inhibitory activity against different isolates of S. mitis, S. mutans, S. oralis and Enterococcus.
Background: The Streptococcus genus are the predominant bacteria in the mouth and the Streptococcus sanguinis is one of them which performing a primary function for expansion of dental biofilm. Gingival and periodontal disorders are caused by dental biofilm, today, there is a necessity to discover naturally presenting antibacterial compounds from herbs with less side effects as a substitutive to the commonly handled chlorohexidine. Thus, the purpose of this study was to assess the antibacterial activity of thymus vulgaris oil on Streptococcus sanguinis bacteria In vitro. Materials and Methods: Human supragingival plaque samples were taken from 10 subjects, then morphological and microscopical examination, bioch
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This study focuses on the relative frequency of Streptococcus pneumoniae in children with culture-proven bacterial meningitis. The epidemiology has been investigated with clinical and laboratory findings in The Central Public Health Laboratory, Iraq from April to September, 2010. From (138) samples , (55) cases (39.85 %) were diagnosed by physician as bacterial meningitis, (23) cases (16.66 %) as viral menginitis , (18) cases (13.04 %) as different medical cases (e.g febrile convulsion , meningoencephalitis , epilepsy …etc) and (42) cases (30.43 %) as unidentified medical cases. For bacterial meningitis S.pneumoniae was isolated from (10) cases (18.18 %) only. The median age for bacterial meningitis was (130.75) month and the predomina
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Abstract
Friction stir welding is a relatively new joining process, which involves the joining of metals without fusion or filler materials. In this study, the effect of welding parameters on the mechanical properties of aluminum alloys AA2024-T351 joints produced by FSW was investigated.
Different ranges of welding parameters, as input factors, such as welding speed (6 - 34 mm/min) and rotational speed (725 - 1235 rpm) were used to obtain their influences on the main responses, in terms of elongation, tensile strength, and maximum bending force. Experimental measurements of main responses were taken and analyzed using DESIGN EXPERT 8 experimental design software which was used to develop t
... Show MoreThe distribution of chilled water flow rate in terminal unit is an important factor used to evaluate the performance of central air conditioning unit. A prototype of A/C unit has been made, which contains three terminal units with a complete set of accessories (3-way valve, 2-way valve, and sensors) to study the effect of the main parameters, such as total water flow rate and chilled water supply temperature with variable valve opening. In this work, 40 tests were carried out. These tests were in two groups, 20 test for 3-way valve case and 20 test for 2-way valve case. These tests were performed at three levels of valve opening, total water flow rate and water supply temperature according to the design matrices establis
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Abstract
This paper concerned with study the effect of a graphite micro powder mixed in the kerosene dielectric fluid during powder mixing electric discharge machining (PMEDM) of high carbon high chromium AISI D2 steel. The type of electrode (copper and graphite), the pulse current and the pulse-on time and mixing powder in kerosene dielectric fluid are taken as the process main input parameters. The material removal rate MRR, the tool wear ratio TWR and the work piece surface roughness (SR) are taken as output parameters to measure the process performance. The experiments are planned using response surface methodology (RSM) design procedure. Empirical models are developed for MRR, TWR and SR, using the analysis
... Show MoreObjectives: The study aims at:
1- Measuring the level of lead in workers’ saliva and blood in the factory.
2- Studying the correlation between the saliva lead level and the infection that caused by microorganisms, isolation and
identification.
3-Studying the influence of high blood lead level on the total white blood cells.
Methodology: This study has been conducted for the period from March 15th, 2010 to May, 20th
, 2010. A total of (60)
saliva and blood samples were collected from workers in batteries industry factory in Baghdad and another (20) samples
were collected as a control group. Lead level had been measured in blood and saliva samples, then microorganisms were
isolated the from the saliva samples.
this study aimed to study the effect of Cordia myxa extract on the growth and activities of the following types of bacteria : Escherichia coli , Pseudomonas aeruginosa, Proteus Spp., Klebsiella pneumoniae , Staphylococcus aureus, Streptococcus pyogenes , Bacillus subtilus, and the yeast Candida albicans .the results showed an inhibitory effect of the methanol extract on both the growth and activity of the tested microbes .this was reflected by the minimum inhibitory concentration ( MIC ) of different type of bacteria and the yeast.