Isolation and identification of bacterial strains
Bacterial strains associated with Artemia cysts were
isolated according the following procedure: 0.01 g of Artemia
cysts recovered from Sebkhat El Adhibet in the South East of
Tunisia (33°44 N – 10°46 E) were incubated in 60 ml sterile
falcons containing 30 ml of filtered and autoclaved sea water
(FASW) (salinity 34 g l-1 and pH 7.99) at Shaker incubator
(28°C, 120 rpm) and exposed to constant incandescent light of
Shaker (Lab-Line Orbit Environ-Shaker). Under these
conditions, hatched larvae appeared after 18 to 20 hours of
incubation. Water samples (1 ml) were enriched 24 h at 30° C
in nutrient broth sea water (NBSW) (salinity 34 g l-1 and pH
7.99) and speared on nutrient agar plate and incubated at 30 °C.
The most appeared colonies were reisolated on Petri plates
with nutrient agar. Gram negative rods were identified using
Rapid NF Plus strips (Remel. USA) according the
manufacture’s recommendation.
Isolation and identification of yeast strain (Candida utilis)
Pure culture of Candida utilis used in this study was
isolated on Sabuoraud agar plate from the American biomass
known as “Kambautcha” in our Laboratory. Biochemical
characterization of Candida utilis was carried out by Api 20 C
Aux (Bio Merieux, France) test.
Well diffusion agar assay (WDAA)
Potential probiotic strains were tested for their antagonistic
activity using the well diffusion agar assay (WDAA) (34)
against three target strains: Vibrio parahemolitycus
ATCC17802, Vibrio alginolyticus ATCC17749, and Vibrio
alginolyticus (S1) isolated from infected fish previously
described by Ben Kahla-Nakbi et al.(2). The pathogenic
bacteria were grown in 10 ml of nutrient broth and cultured for
24 hours on nutrient agar at 30°C. The common colonies from
pure culture were suspended in 10 ml of physiological medium
and well mixed during 5 min. One ml was spread over the agar
plates. Potential probiotic strains were cultured in 10 ml
nutrient broth for 24 hours, 100 μl of the supernatant were
introduced into the wells of the MH agar medium and
incubated for a period of 24 h at 30 °C. Antibacterial activity
was defined as the diameter (mm) of the clear inhibitory zone
formed around the well.
Isolation and identification of bacterial strainsBacterial strains associated with Artemia cysts wereisolated according the following procedure: 0.01 g of Artemiacysts recovered from Sebkhat El Adhibet in the South East ofTunisia (33°44 N – 10°46 E) were incubated in 60 ml sterilefalcons containing 30 ml of filtered and autoclaved sea water(FASW) (salinity 34 g l-1 and pH 7.99) at Shaker incubator(28°C, 120 rpm) and exposed to constant incandescent light ofShaker (Lab-Line Orbit Environ-Shaker). Under theseconditions, hatched larvae appeared after 18 to 20 hours ofincubation. Water samples (1 ml) were enriched 24 h at 30° Cin nutrient broth sea water (NBSW) (salinity 34 g l-1 and pH7.99) and speared on nutrient agar plate and incubated at 30 °C.The most appeared colonies were reisolated on Petri plateswith nutrient agar. Gram negative rods were identified usingRapid NF Plus strips (Remel. USA) according themanufacture’s recommendation.Isolation and identification of yeast strain (Candida utilis)Pure culture of Candida utilis used in this study wasisolated on Sabuoraud agar plate from the American biomassknown as “Kambautcha” in our Laboratory. Biochemicalcharacterization of Candida utilis was carried out by Api 20 CAux (Bio Merieux, France) test.Well diffusion agar assay (WDAA)Potential probiotic strains were tested for their antagonisticactivity using the well diffusion agar assay (WDAA) (34)against three target strains: Vibrio parahemolitycus
ATCC17802, Vibrio alginolyticus ATCC17749, and Vibrio
alginolyticus (S1) isolated from infected fish previously
described by Ben Kahla-Nakbi et al.(2). The pathogenic
bacteria were grown in 10 ml of nutrient broth and cultured for
24 hours on nutrient agar at 30°C. The common colonies from
pure culture were suspended in 10 ml of physiological medium
and well mixed during 5 min. One ml was spread over the agar
plates. Potential probiotic strains were cultured in 10 ml
nutrient broth for 24 hours, 100 μl of the supernatant were
introduced into the wells of the MH agar medium and
incubated for a period of 24 h at 30 °C. Antibacterial activity
was defined as the diameter (mm) of the clear inhibitory zone
formed around the well.
การแปล กรุณารอสักครู่..
