عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Replacement of animal proteins of fish diet with herbal proteins is one of the main method for decreasing the food cost. 70% of phosphorus in plants is in the form of phytate which is unavailable for fish because of lack of phytase enzymes. The aim of this study was evaluation of probiotic potential of phytase-producing bacteria from different sources. In this study, five bacterial species with the highest ability of phytase production including Raoultella terrigena, Klebsiella oxytoca, Citrobacter farmeri,Klebsiella pneumoniae and Enterobacter cloacae were isolated from agriculture and aquaculture origins, were evaluated for possessing the probiotic characterization. Probiotical indices including: acid resistance, bile salt resistance, bacterial antagonistic effects, hydrophobicity and lack of pathogenicity in fish, were evaluated in all isolates. Lactobacillus casei (confirmed fish probiotic) were chosen as positive control. Hydrophobicity and Antibiogram). All 5 isolates were more resistance against acid situation than L.casei, whereas the highest resistance in Fish 12 and Phas 32. All 5 phytase producer bacterias were resistance to 0.5 and 3 percent of bile salts concentrations (P> 0.05). All isolates have not antagonistic activity against Yersinia ruckeri and Aeromonas hydrophila but, Lactobacillus casei showed mild antagonistic activity. Resistance to different antibiotics was not significantly different (p> 0.05). But Fish11 showed the greatest resistance to the antibiotics. The hydrophobicity percentages were higher in all tested bacterias compare to the positive control. In this study all phytase producer bacterias had almost similar potential probiotic indices which were comparable to confirmed probiotic bacteria, L.casei. Then for choosing the best isolate possessing phytase producing ability and probiotic potential, more in vitro investigations as well as in-vivo study should be designed.