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.Objectives: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.Materials and 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.

Shotgun Metagenomics Reveals Taxonomic and Functional Shifts in Hot Water Microbiome Due to Temperature Setting and Stagnation

“…Many methylotrophs are known to be thermophilic or at least thermotolerant at temperatures such as 60–65°C ( Alawadhi et al, 1989 ; Semrau et al, 2008 ). Methylotrophs can use disinfection byproducts and methylated compounds that are widely present in municipal drinking water as their energy and carbon sources ( Kronberg et al, 1988 ; Zamani et al, 2015 ). Moderately thermophilic Nitrosomonas and Nitrosospira strains were isolated and confirmed to be ammonia oxidizers, with an optimum growth temperature around 50°C ( Golovacheva, 1976 ; Lebedeva et al, 2005 ), although most nitrifying bacteria grow optimally at much lower temperatures (25–30°C) ( AWWA, 2002 ).…”

Identification and Risk Assessment of Priority Control Organic Pollutants in Groundwater in the Junggar Basin in Xinjiang, P.R. China

“…Trichloromethane is commonly applied in organic synthesis, e.g., the production of CFCs, dyes, anesthetics, antibiotics, flavorings, and solvents/extractants for grease and rubber [86][87][88]. As for humans and animals, contact with and/or intake of trichloromethane could cause gastrointestinal tract damage, hepatotoxicity, dermatitis and related forms of cancer [89].…”