title: Effect of different heterotrophic plate count methods on the estimation of the composition of the culturable microbial community.
abstract: Heterotrophic plate counts (HPC) are routinely determined within the scope of water quality assessment. However, variable HPC methods with different cultivation parameters (i.e., temperature and media type) are applied, which could lead to significant effects in the outcome of the analysis. Therefore the effect of different HPC methods, according to DIN EN ISO 6222 and EPA, on the culturable microbial community composition was investigated by 16S rRNA gene sequence analysis and statistical evaluation was performed. The culturable community composition revealed significant effects assigned to temperature (p < 0.01), while for media type no statistical significance was observed. However, the abundance of certain detected bacteria was affected. Lower temperature (22 °C) showed the abundance of naturally occurring Pseudomonadaceae and Aeromonadaceae, whereas at high temperature (37 °C) numerous Enterobacteriaceae, Citrobacter spp. and Bacilli were identified. The highest biodiversity was detected at lower temperature, especially on R2A medium. These results indicate that different temperatures (low and high) should be included into HPC measurement and selection of media should, ideally, be adjusted to the monitored water source. Accordingly, it can be inferred that the HPC method is more suitable for continuous monitoring of the same water source than for single assessments of a water sample.
authors: AIT Austrian Institute of Technology GmbH, Bioresources Unit , Tulln , Austria.
authors: Eva Theres
authors: ET
authors: Gensberger
authors: AIT Austrian Institute of Technology GmbH, Bioresources Unit , Tulln , Austria.
authors: Eva-Maria
authors: EM
authors: Gössl
authors: AIT Austrian Institute of Technology GmbH, Bioresources Unit , Tulln , Austria.
authors: Livio
authors: L
authors: Antonielli
authors: AIT Austrian Institute of Technology GmbH, Bioresources Unit , Tulln , Austria.
authors: Angela
authors: A
authors: Sessitsch
authors: AIT Austrian Institute of Technology GmbH, Bioresources Unit , Tulln , Austria.
authors: Tanja
authors: T
authors: Kostić
keywords: 16S rRNA gene sequence analysis; Culturable community composition; Heterotrophic plate count; Media type; Microbial water quality assessment; Temperature