Análise da contaminação microbiológica das amêijoas (Meretrix meretrix) colectados no estuário dos Bons Sinas.

Abstract

The present study, entitled Analysis of the Microbiological Contamination of Clams Collected in the Bons Sinais Estuary, aimed to identify the occurrence of pathogenic microorganisms in the intravalvar tissue of clams collected in the Bons Sinais estuary, given that these are filter-feeding organisms capable of accumulating suspended substances in the water column, including microorganisms. Sample collections were carried out in August at three main clam harvesting banks, namely Inhangome Bank, with two samples designated Inhangome1 and Inhangome2; Porto Bank, with one sample; and Mitavú Bank, with two samples designated Mitavú1 and Mitavú2. Total coliforms, thermotolerant coliforms and Escherichia coli were quantified using the Most Probable Number (MPN) technique. The presence or absence of Salmonella was determined in 25 g of each sample by plating on XLD agar, followed by biochemical confirmation using Triple Sugar Iron (TSI) and Lysine Iron Agar (LIA). Total coliforms showed the highest incidence, with a minimum MPN of 17/g and a maximum of 350/g, while thermotolerant coliforms and E. coli presented the same results, with minimum values of 4/g and maximum values of 350/g. The results revealed spatial variation in the microbiological load of clams in the Bons Sinais estuary. The counts (MPN/g) were as follows: Inhangome1: 31 (total coliforms, thermotolerant coliforms and E. coli), Salmonella present; Inhangome2: 350 (total coliforms, thermotolerant coliforms and E. coli), Salmonella absent; Porto: 350 (total coliforms, thermotolerant coliforms and E. coli), Salmonella absent; Mitavú1: 49 (total coliforms), 33 (thermotolerant coliforms) and 33 (E. coli), Salmonella absent; Mitavú2: 17 (total coliforms), 4 (thermotolerant coliforms) and 4 (E. coli), Salmonella absent. The conformity of the results with the microbiological standards established by national regulations was assessed. All samples fell into category B; however, the Inhangome1 sample, despite presenting values corresponding to this category, was considered unfit for consumption. In contrast, the Inhangome2, Porto, Mitavú1 and Mitavú2 samples were considered fit for consumption and/or commercialisation after depuration, as pre-treatment is mandatory before consumption.