ABSTRACT
Inactivation and microbial regrowth of penicillin-, ampicillin-, cefalexin-, tetracycline-, chloramphenicol-, and rifampicin-resistant bacteria were studied to explore risks associated with selection and regrowth of antibiotic-resistant bacteria after PAA disinfection. The results showed that after exposure to 20 mg/L PAA for 10 min, inactivation of ampicillin-resistant bacteria reached 2.3-log, which was significantly higher than that of total heterotrophic bacteria with a decrease of 2.0-log. In contrast, inactivation of tetracycline- resistant bacteria was significantly less efficient, reaching only 1.1-log. Chloramphenicol-and tetracycline-resistant bacteria, as well as total heterotrophic bacteria regrew more than 10 fold compared to those in the untreated wastewater sample with 22 h stilling culture after exposure to 2 or 5 mg/L PAA as for 10 min. Selection and potential regrowth of tetracycline-and chloramphenicol-resistant bacteria are potential risks when utilizing PAA disinfection, which may induce the spread of specific antibiotic-resistant bacteria in reclaimed water.
Subject(s)
Anti-Bacterial Agents , Pharmacology , Bacteria , Disinfection , Waste Disposal, Fluid , Wastewater , Water Microbiology , Water PurificationABSTRACT
<p><b>OBJECTIVE</b>To evaluate the effect of white rot fungus Phanerochaete chrysosporium on removal of gaseous chlorobenzene.</p><p><b>METHODS</b>Fungal mycelium mixed with a liquid medium was placed into airtight bottles. A certain amount of chlorobenzene was injected into the headspace of the bottles under different conditions. At a certain interval, the concentrations in the headspace were analyzed to evaluate the degradation of chlorobenzene by P. chrysosporium.</p><p><b>RESULTS</b>The degradation effects of P. chrysosporium on chlorobenzene under different conditions were investigated. The difference in the optimum temperature for the growth of the fungi and chlorobenzene degradation was observed. The data indicated that a lower temperature (28 degrees C) would promote the degradation of chlorobenzene than the optimum temperature for the growth of the fungi (37 degrees C). A low nitrogen source concentration (30 mg N/L) had a better effect on degrading chlorobenzene than a high nitrogen source concentration (higher than 100 mg N/L). A high initial concentration (over 1100 mg/m3) of chlorobenzene showed an inhibiting effect on degradation by P. chrysosporium. A maximum removal efficiency of 95% was achieved at the initial concentration of 550 mg/m3.</p><p><b>CONCLUSION</b>P. chrysosporium has a rather good ability to remove gaseous chlorobenzene. A low nitrogen source concentration and a low temperature promote the removal of chlorobenzene by P. chrysosporium. However, a high initial chlorobenzene concentration can inhibit chlorobenzene degradation.</p>
Subject(s)
Air Pollutants , Metabolism , Biodegradation, Environmental , Chlorobenzenes , Metabolism , Culture Media , Chemistry , Microbiological Techniques , Nitrogen , Pharmacology , Phanerochaete , Metabolism , Temperature , Time FactorsABSTRACT
Quinone is one of the electron transporters of the microbial respiratory chain. The dominant quinone of one species of bacteria is different from other bacteria. So the quinone profile of environmental samples can reflect the microbial community. This paper briefly introduces the analytical method used for microbial quinones. The microbial community in an activated sludge sample is studied using this method.
ABSTRACT
Quite recently,among new emerging contaminants,pharmaceutical and personal care products(PPCPs)and their active metabolites are an emerging environmental issue,due to their presence in the aquatic environment and potential for impacts on wildlife and humans.Carbamazepine is one of the most frequently and at the relatively high concentration levels detected pharmaceuticals in surface water and even in drinking water.Moreover,this drug has displayed high chronic ecotoxicity.A strain of carbamazepine-degrading bacterium was isolated from activated sludge treating pharmaceutical wastewater in Suzhou,China.It was identified as Acinetobacter sp.HY-7,based on biochemical test,16S rRNA and gyrB gene se-quence analysis.Strain HY-7 could grow in liquid mineral salt medium with carbamazepine as sole source of carbon,nitrogen and energy.HPLC analysis revealed the carbamazepine degradation percentage by HY-7 after 10 days was 48% at pH 6.0 and 25?C.Among carbamazepine and the similar structure compounds,in-dole,catechol,naphthalene,anthracene could also be utilized by strain HY-7 for growth,which exhibited a very broad substrate profile.