Résumé:
The forms of life on earth are uncountable, as the environments which shelter them. Those
developing in hostile environments are globally qualified as extrêmophiles. The first
extrêmophilic organisms iso
lated are a member of halophilic organisms
, discovere
d in an
environment which we considered devoid of life, where its name: the Dead Sea. Their
resistance in high salinity confers them surprising characteristics, what reveals a real
biotechnological
trump
.
A st
udy having for objective, screenin
g and production of hydrolases of halophilic
microorganisms isolated from Algerian hypersalin
e
environments is realized. For that
purpose, a collection of 104 halophilic aerobic
prokaryotes
strains isolated from the samples
of water, salt and sediments tak
en from four different sites (Sebkha Ezzemoul, Chott Melghir,
Oued Righ and Sidi Mahdi) is constituted then phenotypical
l
y characterized and
systematically examined to detect the qualit
ative presence of four hydrolytic
activities
(amylase, protéase, cellul
ase and lipase). A
numerical
analysis was also made.
A dominance of short rods, Gram positive grouped in pairs or in small chains was recorded.
The whole of the strains presents opt
ima of pH and temperature at 7,0
-
7,5 and 37
-
40°C
,
respectively.
The optimu
m of salinity
while being varied from 0
% to 25%
(w/v)
made it
possible to reveal halotolerant, light halophilic,
moderate and
extreme halophil
ic
microorganisms
.
The amylolytic and protéolytic
activities were the major hydrolytic activities
revealed. Several strains present a combination of enzymatic activities. The numerical
analysis allowed to obtain
15
phenons, clustered on the basis of the percentage of similarity
between strains.
