Quantification of vibrios, total and termotolerant coliforms in wild oyster rassostrea rhizophorae and in water from the Jaguaribe River estuary, Fortim- Ceará State

Abstract

This study was designed to assess the contamination of oysters (Crassostrea rhizophorae) and its living water by Vibrio, total coliforms (TC) and thermotolerants fecal coliforms (TFC) through Most Probable Number (MPN) estimates. The material consists of samples withdrawn at the Jaguaribe River estuary (Ceará State) which were readily taken over to laboratory where the pertinent microbiological tests were made. The MPN estimates for TFC varied in the ranges of <1.8 – 3,500/100mL and <1.8 – 9,200/g in water and oyster, while those for CT varied in the ranges of <1.8 - 490/100mL and <1.8 - 430/g, respectively. Contents of Vibrio and coliforms were found to be statistically greater in oysters than in water, what attests to the bioaccumulative potential of these organisms. The water-derived estimates were kept within the limits set up by CONAMA’s Act  357/2005. The oyster-derived estimates were also kept within acceptable quality limits, but in this case according to standards set up by The European Union Shellfish Quality Assurance Programme, given the lack of lawful  MPN values for Vibrio and TFC to regulate the consumption of fresh oysters in Brazil. Since most bivalve mollusks, especially oysters, are eaten in their raw state, it would be highly desirable that specific guidelines were undertaken to prevent their contamination by Vibrio and coliforms.