Degradation of 2,4,6-trinitrotoluene by P. aeruginosa and characterization of some metabolites.

Degradation of 2,4,6-trinitrotoluene (TNT), a nitroaromatic explosive found in the soil and ground water, was investigated using Pseudomonas aeruginosa in in vitro experiments . Biodegradable abilitiy of this bacteria was performed with 50 and 75 mg L (-1) TNT concentrations in a defined liquid medium for 96 h time period. Treatment of TNT in supernatant samples taken at 0, 6, 12, 24, 48, 72 and 96 h from agitated vessels was followed by reverse-phase high-performance liquid chromatography (HPLC). In cultures supplemented with 50 and 75 mgL (-1) TNT, after 96 h of incubation 46% and 59% reduction were detected respectively. Two metabolites as degradation intermediates with nitrite release into the medium, 2,4-dinitrotoluene (2,4-DNT) and 4-aminodinitrotoluene (4-ADNT), were elucidated by thin layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS). These findings clearly indicate that Pseudomonas aeruginosa can be used in bioremediation of TNT contaminated sites.

Degradation of 2,4,6-trinitrotoluene by P. aeruginosa and characterization of some metabolites

Degradation of 2,4,6-trinitrotoluene (TNT), a nitroaromatic explosive found in the soil and ground water, was investigated using Pseudomonas aeruginosa in in vitro experiments. Biodegradable abilitiy of this bacteria was performed with 50 and 75 mg L−1 TNT concentrations in a defined liquid medium for 96 h time period. Treatment of TNT in supernatant samples taken at 0, 6, 12, 24, 48, 72 and 96 h from agitated vessels was followed by reverse-phase high-performance liquid chromatography (HPLC). In cultures supplemented with 50 and 75 mgL−1 TNT, after 96 h of incubation 46% and 59% reduction were detected respectively. Two metabolites as degradation intermediates with nitrite release into the medium, 2,4-dinitrotoluene (2,4-DNT) and 4-aminodinitrotoluene (4-ADNT), were elucidated by thin layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS). These findings clearly indicate that Pseudomonas aeruginosa can be used in bioremediation of TNT contaminated sites.

Preliminary examination of herbal extracts on the inhibition of Helicobacter pylori.

BACKGROUND: This work aims at describing the traditional uses, to determine the antimicrobial potential of two different extracts hexane, acetone of the leaves of Citrus unshiu, Citrus sinensis, Citrus limon, Laurus nobilis, Citrus paradisi on clinical strain of H. pylori in a bid to identify potential sources of cheap starting materials for the synthesis of new drugs. H. pylori strain was a culture collection of Hacettepe University, Turkey. METHODS: The activity was quantitatively assessed on the basis of the inhibition zone, and their activity index was also calculated along with the MIC method. RESULTS: All the plants demonstrated antimicrobial activity against H. pylori with zone of inhibition diameters ranging from 0 - 30 mm and minimum inhibitory concentration (MIC) values ranging from 1:512-1:4096 dilutions. CONCLUSION: The results may serve as scientific validation of the ethnomedicinal uses of the Citrus unshiu, Citrus sinensis, Citrus limon, Laurus nobilis, and Citrus paradisi in the treatment of H. pylori-related infections. However, further investigations would be necessary to determine their toxicological properties, in-vivo potencies and mechanism of action against H. pylori.

Aerobic biodegradation of 2,4,6-trinitrotoluene (TNT) by Bacillus cereus isolated from contaminated soil.

In this study, biological degradation of 2,4,6-trinitrotoluene (TNT) which is very highly toxic environmentally and an explosive in nitroaromatic character was researched in minimal medium by Bacillus cereus isolated from North Atlantic Treaty Organization (NATO) TNT-contaminated soils. In contrast to most previous studies, the capability of this bacteria to transform in liquid medium containing TNT was investigated. During degradation, treatment of TNT was followed by high-performance liquid chromatography (HPLC) and achievement of degradation was calculated as percentage. At an initial concentration of 50 and 75 mg L(-1), TNT was degraded respectively 68 % and 77 % in 96 h. It transformed into 2,4-dinitrotoluene and 4-aminodinitrotoluene derivates, which could be detected as intermediate metabolites by using thin-layer chromatography and gas chromatography-mass spectrometry analyses. Release of nitrite and nitrate ions were searched by spectrophotometric analyses. Depending upon Meisenheimer complex, while nitrite production was observed, nitrate was detected in none of the cultures. Results of our study propose which environmental pollutant can be removed by using microorganisms that are indigenous to the contaminated site.

Antibiotic and heavy metal resistance in bacteria isolated from the Eastern Mediterranean Sea coast.

In this study it aimed to determine the microbial diversity, level of antibiotic resistance patterns and distribution of heavy metal resistance of bacterial isolates from the Eastern Mediterranean Sea coast. The resistance of 255 gram-negative bacterial isolates to 16 different antibiotics and to 5 heavy metals was investigated. The most common strains isolated from all samples were Citrobacter koseri (9.0%), Escherichia coli (8.2%) and Pantoea agglomerans (8.2%). Our results revealed a high incidence of resistance to ampicillin (74.0%), streptomycin (70.0%) and cefazolin (48.3%). The multiple antibiotic resistance (MAR) index ranged from 0.2 to 0.75. Isolates showed tolerances to different concentrations of heavy metals. Our results show that the Eastern Mediterranean Sea coast has a significant proportion of antibiotic and heavy metal resistant pathogens, or opportunist gram-negative bacteria, and these bacteria may result in a potential public health hazard.

Aeromonas and Pseudomonas: antibiotic and heavy metal resistance species from Iskenderun Bay, Turkey (northeast Mediterranean Sea).

We studied the susceptibility patterns to 15 different antibiotics and six heavy metals in Aeromonas spp. and Pseudomonas spp. isolated from Iskenderun Bay, Turkey (northeast Mediterranean Sea). A high percentage of Aeromonas isolates showed resistance to cefazolin (66.6%) and trimethoprim-sulphamethoxazole (66.6%). Amongst the Pseudomonas isolates, there was a high incidence of resistance to nitrofurantoin (86.2%), cefazolin (84.8%) and cefuroxime (71.7%). Most isolates showed tolerance to different concentrations of heavy metals, and minimal inhibition concentrations ranged from 25 to >3,200 microg/ml. The Aeromonas spp. and Pseudomonas spp. showed high resistance to copper of 98.3% and 75.4%, respectively, and low resistance to lead of 1.7% and 7.2%, respectively. Our results show that antibiotic and heavy metal resistant Aeromonas spp. and Pseudomonas spp. were widespread in Iskenderun Bay in 2007 and 2008. The increasing presence of antibiotic and heavy metal resistant Aeromonas spp. and Pseudomonas spp. may become a potential human health hazard.

Antibacterial agents and heavy metal resistance in Gram-negative bacteria isolated from seawater, shrimp and sediment in Iskenderun Bay, Turkey.

The aim of the present study was to determine the level of antibiotic resistance patterns and distribution of heavy metal resistance of bacterial isolates from seawater, sediment and shrimps, and to determine if there is a relationship between antibiotic and heavy metal resistance. We undertook studies in 2007 in the industrially polluted Iskenderun Bay, on the south coast of Turkey. The resistance of 236 Gram-negative bacterial isolates (49 from seawater, 90 from sediment and 97 from shrimp) to 16 different antibiotics, and to 5 heavy metals, was investigated by agar diffusion and agar dilution methods, respectively. A total of 31 species of bacteria were isolated: the most common strains isolated from all samples were Escherichia coli (11.4%), Aeromonas hydrophila (9.7%) and Stenotrophomonas maltophilia (9.3%). There was a high incidence of resistance to ampicillin (93.2%), streptomycin (90.2%) and cefazolin (81.3%), and a low incidence of resistance to imipenem (16.5%), meropenem (13.9%) and cefepime (8.0%). Some 56.8% of all bacteria isolated from seawater, sediment and shrimp were resistant to 7 or more antibiotics. Most isolates showed tolerance to different concentrations of heavy metals, and minimal inhibition concentrations ranged from 12.5 microg/ml to > 3200 microg/ml. The bacteria from seawater, sediment and shrimp showed high resistance to cadmium of 69.4%, 88.9%, and 81.1% respectively, and low resistance to manganese of 2%, 6.7% and 11.3% respectively. The seawater and sediment isolates which were metal resistant also showed a high resistance to three antibiotics: streptomycin, ampicillin and trimethoprim-sulphamethoxazole. In contrast, the shrimp isolates which were metal resistant were resistant to four antibiotics: cefazolin, nitrofurantoin, cefuroxime and ampicillin. Our results show that Iskenderun Bay has a significant proportion of antibiotic and heavy metal resistant Gram-negative bacteria, and these bacteria constitute a potential risk for public health.

Sorption of basic dyes from aqueous solution by activated sludge.

The adsorption of dyes in the solutions using activated sludge might be a promising approach in wastewater treatment units. The adsorption of Basic Red 18 and Basic Blue 9 from aqueous solution by dried activated sludge was investigated with in a batch system. The activated sludge had the highest dye uptake capacity, having the monolayer adsorption capacity 285.71 and 256.41 mg g(-1) for Basic Red 18 and Basic Blue 9, respectively, at pH value of 7.0 and 20 degrees C. Langmuir and Freundlich adsorption models were used for the mathematical description of the adsorption equilibrium and the equilibrium data fixed very well with both the Langmuir and Freundlich models. The R(L) values showed that, activated sludge was favorable for the adsorption of basic dyes. The suitability of the kinetic models for the adsorption of dyes on the activated sludge was also discussed. It was clear that the adsorption kinetics of dyes to dried activated sludge obeyed pseudo second-order adsorption kinetics.