Anti-Candida and anti-Cryptococcus antifungal produced by marine microorganisms.

In order to search for antifungal from biological origin, we performed a screening of marine microorganisms isolated from seawater, seaweed, sediment and marine invertebrates collected from different coastal areas of the Moroccan Atlantic Ocean. The antifungal activities of these isolates were investigated against the pathogenic yeasts involved in medical mycology. Whole cultures of 34 marine microorganisms were screened for antifungal activities using the method of agar diffusion against four yeasts. The results showed that among the 34 isolates studied, 13 (38%) strains have antifungal activity against at least one out of four yeast species, 11 isolates have anti-Candida albicans CIP 48.72 activity, 12 isolates have anti-C. albicans CIP 884.65 activity, 13 isolates have anti-Cryptococcus neoformans activity and only 6 isolates are actives against Candida tropicalis R2 resistant to nystatin and amphotericin B. Nine isolates showed strong fungicidal activity. Fourteen microorganisms were identified and assigned to the genera Acinetobacter, Aeromonas, Alcaligenes, Bacillus, Chromobacterium, Enterococcus, Pantoea, and Pseudomonas. Due to a competitive role for space and nutrient, the marine microorganisms could produce more antimicrobials; therefore these marine microorganisms were expected to be potential resources of natural products such as those we research: anti-Candida and anti-Cryptococcus fungicides.

Antifungal and antibacterial activity of marine microorganisms.

In order to explore marine microorganisms with pharmaceutical potential, marine bacteria, collected from different coastal areas of the Moroccan Atlantic Ocean, were previously isolated from seawater, sediment, marine invertebrates and seaweeds. The antimicrobial activities of these microorganisms were investigated against the pathogens involved in human pathologies. Whole cultures of 34 marine microorganisms were screened for antimicrobial activities using the method of agar diffusion against three Gram-positive bacteria, two Gram-negative bacteria, and against yeast. The results showed that among the 34 isolates studied, 28 (82%) strains have antimicrobial activity against at least one pathogen studied, 11 (32%) strains have antifungal activity and 24 (76%) strains are active against Gram-positive bacteria, while 21 (62%) strains are active against Gram-negative bacteria. Among isolates having antimicrobial activity, 14 were identified and were assigned to the genera Acinetobacter, Aeromonas, Alcaligenes, Bacillus, Chromobacterium, Enterococcus, Pantoea and Pseudomonas. Due to a competitive role for space and nutrient, the marine microorganisms can produce antibiotic substance; therefore, these marine microorganisms were expected to be potential resources of natural antibiotic products.

[Bio-guided isolation of an antifungal from Haliclona enamela collected from Jorf Lasfar port, Morocco]. / Isolement bio-dirigé d'un antifongique à partir de Haliclona enamela récoltée du port de Jorf Lasfar, Maroc.

In the context of our search for new biologically active secondary metabolites from marine invertebrates, we have isolated an antifungal from Haliclona enamela collected from Jorf Lasfar Port, El Jadida, Morocco. This has a strong antifungal activity against three yeasts (two Candida spp. and one Cryptococcus spp.) involved in human mycology and especially against Candida tropicalis resistant to nystatin and amphotericin B.

Detection of Shiga toxin-producing Escherichia coli in meat marketed in Casablanca (Morocco).

The contamination of meat and meat products with Shiga toxin-producing O157:H7 and non-O157 Escherichia coli (STEC), obtained from markets in Casablanca, Morocco, was investigated. A total of 460 meat and meat products were sampled between March 2004 and July 2006 analysed and 176 strains of E. coli were isolated from these samples. The presence of the stx1, stx2, eae and ehxA genes, recognized as major virulence factors of STEC, was tested in E. coli isolates by polymerase chain reaction (PCR). STEC was detected in 4 (0.9%) samples. The result of serotyping by molecular method showed that two of these STEC isolates corresponded to the serotype O157:H7. The others Shiga toxin-producing E. coli non-O157 corresponded to O6:H21 and O76:H19. The presence of O157:H7 and non-O157 STEC in meat and meat products marketed in Casablanca, Morocco, emphasizes the importance of implementing the Hazard Analysis and Critical Control Point (HACCP) system, as well as the need for implementing, evaluating, and validating antimicrobial interventions to reduce the presence of potential pathogenic microorganisms.

[Seasonal and geographical variation range of antifungal activity of sponge extracts from the Moroccan Atlantic coasts]. / Variation saisonnière et géographique de l'activité antifongique des extraits de deux éponges marines récoltées sur le littoral atlantique d'El Jadida, Maroc.

Currently, marine organisms have a very important source of new molecules in pharmacology and thus in the development of new bioactive products. The organic and aqueous extracts of two marine sponges, Cinachyrella tarentine collected during two different seasons, winter and summer, and Cliona viridis collected in two different zones on the coast of El Jadida (Morocco) were tested for their antifungal activity using the diffusion method. The C. tarentine sponge collected in January (winter) has a very important activity compared to that collected in August (summer). While the sponge C. viridis collected from Jorf Lasfar port (shallower and polluted area) has a very important activity compared to that collected from the coast of El Jadida (depth and unpolluted area).

Molecular typing of Escherichia coli strains isolated from food in Casablanca (Morocco).

Serotyping of O- and H- antigens is regarded as the gold standard in classification of E. coli for taxonomic and epidemiological purposes similar to the Kaufmann-White scheme for Salmonella enterica. Molecular methods to replace or to support the serotyping were recently applied. Using the molecular polymorphism of the somatic (O- antigen) gene rfb cluster and flagella (H- antigen) gene fliC, 74 E. coli strains carrying the virulent genes isolated from food were characterised by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results showed that 49 (66%) of the isolates revealed a reproducible and clear cut classification, with a very good correlation to the collection of reference strains, were found.

Identification of harman as the antibiotic compound produced by a tunicate-associated bacterium.

The alkaloid harman, previously reported from some marine invertebrates, was identified as the antibiotic substance of the tunicate-associated bacterium Enterococcus faecium. It exhibited antibacterial activity (MIC, 0.017 mM) against the ichthyopathogenic strain Vibrio anguillarum.

Screening of nonpolyenic antifungal metabolites produced by clinical isolates of actinomycetes.

The purpose of this work was to screen clinical isolates of actinomycetes producing nonpolyenic antifungals. This choice was made to limit the problem of rediscovery of well-known antifungal families, especially polyenic antifungals. One hundred and ten strains were tested, using two diffusion methods and two test media, against three yeast species and three filamentous fungi. Among 54 strains (49%) showing antifungal activity, five strains belonging to the genus Streptomyces were active against all test organisms and appeared promising. These results indicate that clinical and environmental isolates of actinomycetes could be an interesting source of antifungal bioactive substances. The production of nonpolyenic antifungal substances by these five active isolates was investigated using several criteria: antibacterial activity, ergosterol inhibition, and UV-visible spectra of active extracts. One active strain responded to all three selection criteria and produced potentially nonpolyenic antifungal metabolites. This strain was retained for further investigation, in particular, purification, structure elucidation, and mechanism of action of the active product.

Displacement of equilibrium in electroenzymatic reactor for acetaldehyde production using yeast alcohol dehydrogenase.

Electrochemical regeneration of NAD was performed in a bench scale reactor in which yeast alcohol dehydrogenase catalyzed the oxidation of ethanol. By recycling one of the products of the reaction, it was possible to displace the equilibrium and favor the production of acetaldehyde. The flow-through electrode was made of graphite felt and had a specific area of 275 cm(-1). A mathematical model taking into account the enzymatic and electrochemical reaction rates as well as the mass transfer to the electrode was used to analyze the results. The limiting steps in the reactor are the electrochemical reaction for low potentials and the cofactor mass transfer for high potentials.

Electrochemical regeneration of NAD in a plug-flow reactor.

Electrochemical regeneration of NAD was performed at a laboratory preparative scale to illustrate both the efficiency and intrinsic simplicity of the electrochemical method. A powerful plug-flow reactor was realized with a flow through graphite felt electrode, the ratio of the effective area of electrode/volume of reactor increased to 380 cm(2)/cm(3). This graphite-felt electrode was able to oxidize NADH coenzyme at a very low overvoltage. On the example of the gluconic acid production catalyzed by glucose dehydrogenase, current as high as 0.1 A was obtained in experience where enzymatic activity was the main limitation. In confirmation of our previous work, the results show that the yield of NADH electrochemical oxidation is better than 99.95%.