Résumé:
Halophilic and halotolerant microorganisms in hypersaline environments have
developed strategies to adapt to environmental constraints. They thus present original
biomolecules, in particular enzymes which enable them to develop optimally in their biotopes.
The exploitation of these microorganisms and their molecules is a boon for biotechnology.
The objective of this study is to demonstrate extracellular hydrolytic activities in halophilic
and halotolerant microorganisms of sebkha Melghir and chott Merouane (wilaya of El Oued), and chott Aïn El Beida (wilaya of Ouargla).
This work resulted in the isolation of seventy-two strains from brine and sediment samples.
A preliminary characterization based on cultural, morphological, biochemical and
physiological aspects is carried out. 29 pigmented, Gram-negative and extreme halophilic
strains (optimum at 20% (w/v) salt) possess the properties of haloarchaea. The remainder of the isolates are distributed between moderate halophiles and halotolerants, and often Grampositive. The spherical cellular form is predominant. All strains have a broad growth
temperature range with an optimum at 37°C or 45°C; They are moderate mesophiles or
thermophiles. About 50 strains have extracellular hydrolases, dominated by the hydrolysis
capacity of gelatin. However, amylolytic activity appears to be more important in strains of
Archaea. In addition, many isolates produce up to four types of hydrolases.
