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Appl. Environ. Microbiol. doi:10.1128/AEM.00980-08
Copyright (c) 2008, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Microscopic and molecular study on the diversity of free-living protozoa in meat cutting plants

Department of Veterinary Public Health and Food Safety, Ghent University, Belgium; Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Belgium

^* To whom correspondence should be addressed. Email: Kurt.Houf{at}UGent.be.

	Abstract

The diversity of free-living protozoa in five meat cutting plants was determined. Light microscopy after enrichment culture was combined with sequencing of PCR-amplified, DGGE-separated 18S rRNA gene fragments which was used as a fast screening method. The general outcome of the survey showed that a protozoan community of amoebae, ciliates, and flagellates was present in all plants. Protozoa were mainly detected in floor drains, in standing water on the floor, on soiled bars of cutting tables, on plastic pallets, in out of use hot water knife sanitizers but also on surfaces which come into direct contact with meat such as conveyer belts, working surfaces of cutting tables, and needles of a meat tenderizer. After seven days of incubation at refrigerator temperature, protozoa were detected in about half of the enrichment cultures. Based on microscopic observations, 61 morphospecies were found including Bodo saltans, Bodo spp., Epistylis spp., Glaucoma scintillans, Petalomonas spp., Prodiscophrya collini, and Vannella sp. as most frequently encountered identified organisms. Sequencing of DGGE bands resulted in a total of 49 phylotypes including representatives of Amoebozoa, Chromalveolata, Excavata, Opisthokonta, and Rhizaria. Sequences of small heterotrophic flagellates affiliated mainly to Alveolata (Apicomplexa), Stramenopiles (Chrysophyceae), and Rhizaria (Cercozoa). The survey shows the presence of a high protozoan species richness in meat cutting processing plants, including species related to known hosts of foodborne pathogens.