Comparison of antibacterial effects of a carrier produced in microemulsion system from aqueous extract of Aloe vera with selected antibiotics on Enterobacteriacea.

BACKGROUND AND OBJECTIVES: Antibiotics resistance has recently increased. The aim of this study was the evaluation of antibacterial efficacy of Aloe vera carrier produced in microemulsion system in comparison with ordinary antibiotics against some Enterobacteriacea. MATERIALS AND METHODS: The aquatic extract of Aleo vera was produced by the Soxhlet method and a nonocarrier in the microemulsion system was prepared by two emulsifiers. The clinical isolates of Escherichia coli, Klebsiella pneumoniae, Salmonella enterica, Shigella dysenteriae, Salmonella Typhimurium, Salmonella Paratyphi, Serratia marcescens, Proteus mirabilis, Enterobacter aerogenes, Citrobacter freundii and Morganella morganii were obtained from patients and were identified by microbiological methods. Diffusion disk was used for evaluation of antibacterial properties in comparison with selected ordinary antibiotics. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) for tested materials were determined using MTT in the Micro Broth dilution method. RESULTS: The results proved that effect of carrier on studied isolates is dependent on concentration level. The inhibitory effect of carrier in concentration of 15 µg/ml by 18 mm zone of inhibition for Klebsiella pneumoniae was comparable to Ceftazidime and Cefalothin. The lowest MIC and MBC determined by the Microbroth dilution method with MTT belonged to Klebsiella pneumoniae as 0.1 and 3 µg/ml and higher concentrations belonged to Enterobacter aerogenes at 7 and 15 µg/ml. The greatest effect of carrier of Aleo vera aquatic extract was observed for Klebsiella pneumoniae and the lowest effect belonged to Enterobacter aerogenes, Citrobacter freundii and Morganella morganii. CONCLUSION: It was concluded that the carrier of Aloe vera produced in microemulsion system was most effective and had equal effects in comparison with ordinary antibiotics against Enterobacteriacea.

Efficacy evaluation and kinetic study of biosorption of nickel and zinc by bacteria isolated from stressed conditions in a bubble column.

OBJECTIVE: To investigate the biosorption potential of isolated bacteria as an alternative biosorbent material for the removal of zinc and nickel from aqueous solution in a bubble column bioreactor. METHORDS: In this study from four points of waste water treatment plant, some Gram-positive and Gram-negative bacteria under heavy metal stress conditions were isolated by microbiological methods. Biosorption experiments were conducted in a bubble column containing waste water in high concentrations of nickel and zinc inoculated by isolated bacteria. A kinetic study was done to investigate the fitting of either pseudo first-order or second order equations. RESULTS: The 96% removal of zinc and 54% removal of nickel were achieved by biosorption column experiment by the isolated bacteria. A comparison between a non-aerated and aerated column shows a higher removal percentage with the same contact time. The study of contact time in the experiments also confirmed that with more contact time, while the removal efficiency increases the capacity of microorganisms to absorb the metal ions decreases. Results of kinetic study showed pseudo-second-order equation with a coefficient of determination of 0.9648 and 0.9992 for zinc and nickel, and the pseudo-first-order equation with 0.2410 and 0.4794, respectively. CONCLUSIONS: It was be concluded that biosorbtion method is a suitable alternative method to remove metal ions for further study in large scale.