title: Rapid quantitative estimation of chlorinated methane utilizing bacteria in drinking water and the effect of nanosilver on biodegradation of the trichloromethane in the environment.
abstract: BACKGROUND
  Halomethanes are toxic and carcinogenic chemicals, which are widely used in industry. Also they can be formed during water disinfection by chlorine. Biodegradation by methylotrophs is the most important way to remove these pollutants from the environment.
  
  
  OBJECTIVE
  This study aimed to represent a simple and rapid method for quantitative study of halomethanes utilizing bacteria in drinking water and also a method to facilitate the biodegradation of these compounds in the environment compared to cometabolism.
  
  
  METHODS
  Enumeration of chlorinated methane utilizing bacteria in drinking water was carried out by most probable number (MPN) method in two steps. First, the presence and the number of methylotroph bacteria were confirmed on methanol-containing medium. Then, utilization of dichloromethane was determined by measuring the released chloride after the addition of 0.04 mol/L of it to the growth medium. Also, the effect of nanosilver particles on biodegradation of multiple chlorinated methanes was studied by bacterial growth on Bushnell-Haas Broth containing chloroform (trichloromethane) that was treated with 0.2 ppm nanosilver.
  
  
  RESULTS
  Most probable number of methylotrophs and chlorinated methane utilizing bacteria in tested drinking water were 10 and 4 MPN Index/L, respectively. Chloroform treatment by nanosilver leads to dechlorination and the production of formaldehyde. The highest growth of bacteria and formic acid production were observed in the tubes containing 1% chloroform treated with nanosilver.
  
  
  CONCLUSIONS
  By combining the two tests, a rapid approach to estimation of most probable number of chlorinated methane utilizing bacteria is introduced. Treatment by nanosilver particles was resulted in the easier and faster biodegradation of chloroform by bacteria. Thus, degradation of these chlorinated compounds is more efficient compared to cometabolism.
authors.affiliation: Department of Biology, Faculty of Science, University of Isfahan, Isfahan, IR Iran.
authors.forename: Isaac
authors.initials: I
authors.lastname: Zamani
authors.affiliation: Department of Biology, Faculty of Science, University of Isfahan, Isfahan, IR Iran.
authors.forename: Majid
authors.initials: M
authors.lastname: Bouzari
authors.affiliation: Department of Biology, Faculty of Science, University of Isfahan, Isfahan, IR Iran.
authors.forename: Giti
authors.initials: G
authors.lastname: Emtiazi
authors.affiliation: Department of Biology, Faculty of Science, University of Isfahan, Isfahan, IR Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Fanaei
keywords: Biodegradation, Environmental; Drinking Water; Methylobacillus
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