Biodiversité des actinomycètes halophiles et halotolérants isolés à partir de trois sites Ramsar situés au niveau de la Wilaya d’Oum El Bouaghi.

Abstract

This work represents a first study of the biodiversity of the actinomycetes inhabitants three Sebkhas protected by the Ramsar-Algeria convention. The physicochemical analyzes of the soil samples revealed extremely high salinities, basic or very basic pH, low percentages of moisture, moderate or very high percentages of organic matter. These results also showed that samples of sebkha Annk Djemel belong to the ""clay"" and ""Clay loam"" classes, samples of sebkha Guellif belong to the ""clay loam"" and ""sandy-clay loam"" classes and samples of sebkha Et Taref belong to the ""clay"" class. An isolation of actinomycetes from the soil has been achieved by the use of conventional methods and / or Culturomics. The enumeration results revealed that the number of actinomycetes could reach to 2.105 CFU/g of soil. Based on the enumeration results, a statistical analysis, carried out by the application of non-parametric tests of Kruskal-Wallis and Mann-Whitney, revealed that culture media relatively poor in nutrients and the concentration 5% of NaCl are the most favorable in the isolation of actinomycetes. The competitive effect of bacterial and fungal flora has also been highlighted. Following the isolation protocols adopted, we were able to purify and store a total of 204 isolates, all Gram (+), of which 108 isolates were derived from conventional isolation techniques and 96 isolates were obtained by the Culturomics method. Identification by the MALDITOF MS and sequencing of the 16S rDNA methods allowed us to identify a new species that we named Streptomyces massilialgeriensis sp. nov. and to assign certain other isolates to the genera Streptomyces, Nocardiopsis and Actinomyces. Other isolates have been identified as Bacillus, Virgibacillus, Gracilibacillus, Staphylococcus, Flavonifactor and Halobacillus. The activity test, carried out by the agar plug diffusion method, of 13 selected isolates belonging to the genera Streptomyces and Nocardiopsis against multidrug-resistant bacteria reveal interesting zones of inhibition of the isolate S20 against K. pneumoniae CSUR P1596 (coli R), E. coli CSUR P4969 (coli R, HLP), E. coli CSUR P5139 (carba R) and P. mirabilis CSUR P2049 (oxa-48), and isolate S112 against S. aureus CSUR P1943 (MRSA, KTG, inducible MLSB), E. coli CSUR P4969 (coli R, HLP) and P. mirabilis CSUR P2049 (oxa-48).