جستجوی مقالات مرتبط با کلیدواژه "enterobacter" در نشریات گروه "زیست شناسی"

Phosphorus, the most essential nutrient for plants, becomes quickly unavailable for the plants in the soil. Phosphate solubilizing bacteria (PSB( can play an important role in providing Phosphorus for plants. In this study, the PSBs were screened from plant rhizosphere by Pikovskaya method. Then, the growth rate and phosphate solubilizing ability of 9 superior strains were measured at different temperatures and levels of salinity and pH. The best strain was identified by 16S rDNA gene sequence analysis. Finally, the genetic diversity of phosphate solubilizing strains were examined by RAPD markers. Results showed that 25 strains were capable of solubilizing insoluble phosphates among the 57 isolates studied. Of the nine superior strains, Cke1 had the highest solubilizing index with the average growth rate under all conditions and was introduced as the best PSB strain identified in the present study. 16S rDNA gene sequence analysis showed that this strain belonged to the Enterobacter genus. The results of genetic variation showed that all stains were divided into six groups and three strains that had the lowest similarity with other strains were placed in three separate groups. Given that Cke1 strain has the ability of solubilizing the insoluble phosphate in different stresses, it can be a good candidate for providing phosphorus at temperatures of 30 and 35 °C, 1.2% and 1.8% salinity levels and pH levels of 6 and 8 for the crops.

Cutin is a polymer that is constructed in plants by the condensation and oxidation of fatty acids and plays a key role in the protection of plants against pathogens. Cutinase is a hydrolase enzyme that breaks down the cutin. The purpose of this study was to extract cutin from red apples with oxalate buffer, cutinase enzyme activity assay in LB culture, and bioinformatic analysis. To attain these purposes the cutinase-producing strains that had previously been isolated were inoculated in culture medium containing cutin. After initial culture, the bacteria were cultured in LB medium and cutinase activity was measured using the p-Nitrophenyl butyrate. In order to execute bioinformatic analysis, the isolated sequences of six cutinase-producing bacteria were analyzed based on computational data bases and their phylogenetic trees were prepared. Then, the similarities in the sequences of a large number of cutinase-producing samples were analyzed by drawing the phylogenetic tree. The results showed the separation of cutinase-producing prokaryotes from cutinase-producing eukaryotes. Then, the sequence of 16S rDNA of these cutinase-producing samples as well as the samples we had prepared were evaluated and their phylogenetic relationships were determined. This analysis showed that the new sequence stood alongside the bacterial samples. Thus, our cutinases may be similar with these bacterial cutinases in structure and function.

Although cyanide is a poisonous and lethal compound, it is used in several industries such as gold extraction. Industrial wastewater contains highly amounts of cyanide. That in order to degrade it, different chemical and physical methods are used. These methods not only include high expenses, but also if they combine with other materials, will produce more hazardous compound as well. On the other hand, utilizing biodegradation method, in addition to decreasing expenses, is environmentally friendly. In this study, bacterium was isolated from Muteh gold mining wastewater. Determination of morphological and biochemical characteristics and 16S rDNA described that the bacterium belong to Enterobacter genus. To achieve the maximum degradation by Enterobacter ZS, culture conditions has been optimized. The variables parameters that effect on the degradation procedure with maximum efficiency was achieved. By optimizing the values of affective factors and consider the interactions between factors, culture conditions were optimized by response surface methodology (RSM).

Biofilms are population of bacteria cells that cause irreversible binding to the surfaces by producing extracellular polymers. Biofilm formation in bacteria causes resistance to antimicrobial agents and can lead to severe problems in this ground. The purpose of this study was to evaluate biofilm formation in some isolates of Pseudomonas aeruginosa (13 case), Staphylococcus aureus (13 case), Enterobacter (13 case) and Acinetobacter (13 case) which were collected from human infections of Alzahra hospital in Isfahan. Also the minimum inhibitory concentration of chlorhexidine and its impact on the growth of planktonic and biofilm formation for these isolates were determined. Statistical analysis and graphing have been carried out by using SPSS software (version 20) and Excel. All isolates (52 isolates) have produced biofilm. The mean of MIC of chlorehexidine antiseptic for the p.aeruginosa, S.aureus, Enterobacter and Acinetobacter were 0/001, 0/00013, 0/001, 0/0003 g/ml respectively. Planktonic bacterial growth inhibition from p.aeruginosa and Enterobacter in 1/4 MIC and 1/8 MIC respectively was seen in 40 and 60 % cases. Acinetobacter and Staphylobacter aureus, have been controlled in 40 % of cases in 1/4 MIC and 60 % of cases in 1/8 MIC. Biofilm has not been produced in any of MIC and 2MIC dilution, and the power of biofilm formation had been increased significantly by reducing concentration of chlorhexidine dilution.Discussion and The results indicate that the use of chlorhexidine in appropriate concentrations (MIC) can prevent bacterial growth and biofilm formation in different species causing hospital infections, but doses of chlorhexidine that are less than the MIC can stimulate biofilm formation.

The antibiotic resistant of In Enterobacteriaceae bacteria family to carbapenem drugs is continuously increasing. The aims of this study were to determine the prevalence of carbapenems resistance in multidrug-resistant (MDR) strains of E. coli and Enterobacter and to determine their standard antibiotic resistance patterns and frequency of Klebsiella pneumoniae carbapenemase (KPC) enzyme in Isfahan.

This cross-sectional study, was carried out on 300 clinical samples collected from three hospitals in Isfahan. Antibiotic susceptibility of bacteria was determined by disk diffusion method. In carbapenem resistant strains, the minimum inhibitory concentration (MIC) of imipenem and meropenem were calculated by E-test. The resistance rate to 31 antibiotics belonging to 17 classes were evaluated. The frequency of MDR, extended drug resistance (EDR) and pan drug resistant (PDR) strains were determined. The prevalence of the KPC enzyme in these strains was determined by phenotype method.

Totally, 191 strains of E. coli and 43 Enterobacter strains were isolated, among them 151 (79%) and 35 (81%) were MDR respectively. In both bacteria, effective antibiotics were carbapenem, piperacillin/tazobactam, amikacin, cefepime and nitrofurantoin. Five strains of E. coli (3.3%) and three strains of Enterobacter (6.8%) were resistant to carbapenems and the MIC results confirmed these results. Overall 7 strains out of these 8 strains were MDR and only one strain of E. coli was XDR. No PDR strain was detected. KPC enzymes in four E. coli strains (6.2%) and two strains  (7.5%) belonged to Enterobacter strains.

This study demonstrated the high prevalence of MDR among hospitalized patients in Isfahan. This results shows the emergent changes in the level of antibiotic utilization in hospitals.