Detection of methane oxidizing bacteria with 16S rRNA targeted probes and their influence on drinking water treatment

摘要

Most of the groundwaters used for drinking water production in North Germany belong to reducedwater types and part of them contain methane. If methane is not sufficiently removed in the course ofdrinking water treatment, methane oxidizing bacteria (methanotrophs) grow and inhibit drinking watertreatment processes, resulting in inferior quality of final treated water. Methanotrophs were detectedby fluorescence in situ hybridization (FISH) with 16S rRNA targeted group- and genus-specificoligonucleotide probes at different sampling sites in waterworks treating raw water with methaneconcentrations between 0.14 and 70 mg/L. In investigations of 7 treatment plants primarily type Imethanotrophs of the family Methylococcaceae were detected. With individual probes up to 46.5% oftotal bacteria were found to be type I methanotrophs. The presence of methanotrophs in thewaterworks samples was confirmed by enrichment cultures grown under methane atmosphere,isolation of methanotrophic bacteria and identification of representative isolates as Methylomonas methanica. Furthermore, methane degradation rates of original samples from waterworks showed highmethane degradation activities in batch culture experiments. Thus, in situ probing of methanotrophswith fluorescent oligonucleotide probes seems to be a promising tool for detection and quantificationof methanotrophs in waterworks and for relation of problems in drinking water treatment to theoccurrence of methane in groundwater.