First insights into the distribution and diversity of toxic dinoflagellate cysts in the surface sediments of Dakhla Bay (African Atlantic coast): relationships with environmental factors and mollusk intoxication events.

Dakhla Bay, situated on the African Atlantic coast, has witnessed sporadic harmful algal blooms (HABs) caused by toxic dinoflagellate species over the past two decades. In this study, we investigated the distribution, abundance, and diversity of dinoflagellate cysts, with a focus on potentially toxic species that develop in this ecosystem where such data are lacking. Sediment samples were collected in April 2018 through coring at 49 stations distributed across the bay. The highest abundance of dinoflagellate cysts was recorded at 304 cysts/g dry sediment, observed at the inner part of the bay, indicating that this area is the preferential zone for cyst accumulation. Pearson's tests revealed significant positive correlations (P < 0.05) between cyst abundance and the water content, organic matter, and fine fraction (< 63 µm) of the sediment. Cyst morphotypes of potentially toxic dinoflagellate species known to produce saxitoxins, such as Alexandrium minutum, Alexandrium tamarense species complex, Gymnodinium catenatum, and yessotoxins, such as Lingulodinium polyedrum and Gonyaulax cf. spinifera, were identified in the sediment of Dakhla Bay. These findings were further supported by our long-term monitoring period (2005-2018), underscoring the presence of these HAB species in Dakhla Bay. During our survey, sporadic mollusk intoxication events were recorded at station PK25 for the grooved razor shell Solen marginatus and at station Boutelha for the oyster Crassostrea gigas. Paralytic shellfish toxin concentrations exceeded the sanitary threshold (80 µg STX di-HCl eq/100 g of shellfish meat) only twice, in December 2006 and January 2007 at station PK25. Contamination by amnesic shellfish toxins occurred sporadically but never reached the sanitary threshold of 20 µg/g of shellfish meat. Lipophilic shellfish intoxication occurred multiple times in the two investigated areas. These observations suggest that the cysts of the identified HAB species germinated and inoculated the water column, resulting in the observed intoxication events. Relatively low levels of intoxication could be attributed to the moderate abundances of cysts, which may reduce the seeding capacity. This could be explained by the significant interaction of Dakhla Bay with the Atlantic Ocean, characterized by hydrological dynamics that impede the deposition and accumulation of cysts in the bay's sediments. This study reaffirms the importance of investigating dinoflagellate cysts in assessing the diversity of HAB species and evaluating associated sanitary risks.

Characterization of Salmonella Enteritidis isolated from foods and patients in northern Morocco.

OBJECTIVES: This study aimed to investigate Salmonella Enteritidis strains isolated from human and food sources in the north of Morocco by means of phenotypic and genotypic methods. METHODOLOGY: Fifteen isolates from humans and food were submitted to phage typing, XbaI-macrorestriction (pulsed field gel electrophoresis [PFGE]), enterobacterial repetitive intergenic consensus (ERIC-PCR), antimicrobial susceptibility testing, and PCR assay targeting the spvR and invA genes. RESULTS: Six fingerprinting profiles were obtained with the ERIC-PCR method, four with PFGE profiling, five with antimicrobial resistance, three with phage typing, and only one with plasmid profiling. spvR gene was detected in six strains, which did not harbour plasmids of 90 kb. CONCLUSIONS: The conclusions of this study are drawn from a limited number of isolates. It would be desirable to investigate a greater and more diverse population of Salmonella isolates. S. Enteritidis was genotyped and showed four different patterns by PFGE and six by ERIC-PCR. Accordingly, high genetic similarity and limited genetic diversity were found for these strains from north of Morocco.

Isolation, drug resistance and molecular characterization of Salmonella isolates in northern Morocco.

OBJECTIVES: The objective of this investigation was to assess the methods for the characterization of Salmonella isolates and to identify relationships of Salmonella isolates from human and food sources in northern Morocco. METHODOLOGY: Several Salmonella serotypes were isolated from human and food samples and were characterized using conventional culture methods, biochemical, serological, antimicrobial testing, and phage typing. Molecular analyses such as enterobacterial repetitive intergenic consensus (ERIC)-PCR, macrorestriction profiling by pulsed-field gel electrophoresis (PFGE), and virulence gene analysis were also performed. RESULTS: Sixteen Salmonella strains were isolated in our laboratory, serotyped and identified as S. Kottbus, S. Indiana, S. London, S. Typhi, S. Hadar, S. Corvallis, S. Mbandaka, S. Ouakam, S. Tm var. cop., S. Virchow, and S. Altona. The most common resistance profiles for the isolates was ATCFATSCGKSSS, belonging to phage type PT20, ATASCSS associated with strains DT104L/ad and ATATSS for isolates that were not typeable. The PFGE patterns were different for each Salmonella serotype. All strains were negative for the virulence gene spvR. CONCLUSIONS: To our knowledge, this is the first molecular characterization of Salmonella in food and humans from Morocco. Comparison of molecular techniques for differentiating between human and food isolates of Salmonella in north of Morocco shows that ERIC typing and PFGE were more discriminating than the other techniques used in this study.

Isolation, drug resistance and molecular characterization of Salmonella isolates in northern Morocco

Objectives: The objective of this investigation was to assess the methods for the characterization of Salmonella isolates and to identify relationships of Salmonella isolates from human and food sources in northern Morocco. Methodology: Several Salmonella serotypes were isolated from human and food samples and were characterized using conventional culture methods, biochemical, serological, antimicrobial testing, and phage typing. Molecular analyses such as enterobacterial repetitive intergenic consensus(ERIC) - PCR, macrorestriction profiling by pulsed - field gel electrophoresis (PFGE), and virulence gene analysis were also performed. Results: Sixteen Salmonella strains were isolated in our laboratory, serotyped and identified as S. Kottbus, S. Indiana, S. London, S. Typhi, S. Hadar, S. Corvallis, S. Mbandaka, S. Ouakam, S. Tm var. cop., S. Virchow, and S. Altona. The most common resistance profiles for the isolates was ATCFATSCGKSSS, belonging to phage type PT20, ATASCSS associated with strains DT104L/ad and ATATSS for isolates that were not type able. The PFGE patterns were different for each Salmonella serotype. All strains were negative for the virulence gene spvR. Conclusions: To our knowledge, this is the first molecular characterization of Salmonella in food and humans from Morocco. Comparison of molecular techniques for differentiating between human and food isolates of Salmonella in north of Morocco shows that ERIC typing and PFGE were more discriminating than the other techniques used in this study