In Vitro Evaluation of the Probiotic and Safety Properties of Bacteriocinogenic and Non-Bacteriocinogenic Lactic Acid Bacteria from the Intestines of Nile Tilapia and Common Carp for Their Use as Probiotics in Aquaculture

Abstract

In this study, seven bacteriocinogenic and non-bacteriocinogenic LAB strains previously isolated from the intestines of Nile tilapia and common carp and that showed potent antibacterial activity against host-derived and non-host-derived fish pathogens were assayed for their probiotic and safety properties so as to select promising candidates for in vivo application as probiotic in aquaculture. All the strains were investigated for acid and bile tolerances, transit tolerance in simulated gastrointestinal conditions, for cell surface characteristics including hydrophobicity, co-aggregation and auto-aggregation, and for bile salt hydrolase activity. Moreover, haemolytic, gelatinase and biogenic amine-producing abilities were investigated for safety assessment. The strains were found to be tolerant at low pH (two strains at pH 2.0 and all the strains at pH 3.0). All of them could also survive in the presence of bile salts (0.3% oxgall) and in simulated gastric and intestinal juices conditions. Besides, three of them were found to harbour the gtf gene involved in pH and bile salt survival. The strains also showed remarkable cell surface characteristics, and 57.14% exhibited the ability to deconjugate bile salts. When assayed for their safety properties, the strains prove to be free from haemolytic activity, gelatinase activity and they could neither produce biogenic amines nor harbour the hdc gene. They did not also show antibiotic resistance, thus confirming to be safe for application as probiotics. Among them, Lactobacillus brevis 1BT and Lactobacillus plantarum 1KMT exhibited the best probiotic potentials, making them the most promising candidates.

Safety and Antioxidant Properties of Five Probiotic <i>Lactobacillus plantarum</i> Strains Isolated from the Digestive Tract of Honey Bees

“…Auto-aggregation of the same probiotic strains appeared to be essential for their adhesion to intestinal epithelial cells and is correlated with the colonization of gastrointestinal tract via adhesion to this tissue [36,40]. The results of this study have shown that all the strains exhibited variables auto-aggregation percentage varying between 38.57% and 63.29% after 5 h. The detected auto-aggregation can be linked to cell surface component.…”

Improvement of the Growth Performance, Innate Immunity and Disease Resistance of Nile Tilapia (Oreochromis niloticus) against Vibrio parahaemolyticus 1T1 following Dietary Application of the Probiotic Strain Lactobacillus plantarum 1KMT

“…However, the aquaculture environment of most sub-Saharan countries showed rarity of probiotic lactic acid bacteria strains adapted to tropical ecological conditions. Nevertheless, in our previous studies [25], the strain Lactobacillus plantarum 1KMT isolated from the gut contents of Nile tilapia showed interesting probiotic potential in-vitro. Indeed, this strain demonstrate high ability of auto-aggregation and co-aggregation [25], high antimicrobial activity against many spoilage and pathogens bacteria [26].…”

“…Nevertheless, in our previous studies [25], the strain Lactobacillus plantarum 1KMT isolated from the gut contents of Nile tilapia showed interesting probiotic potential in-vitro. Indeed, this strain demonstrate high ability of auto-aggregation and co-aggregation [25], high antimicrobial activity against many spoilage and pathogens bacteria [26]. Lactobacillus plantarum 1KMT showed also no resistance to antibiotics, hemolytic and gelatinase activities, or biogenic amines production [25].…”

“…Probiotic strain Lactobacillus plantarum 1KMT, used in this study was isolated from the gut content of Oreochromis niloticus, identified and its probiotics properties were evaluated in -vitro in our previous studies [25,26]. To obtain the probiotic strain suspension, Lactobacillus plantarum 1KMT was activated in MRS broth (Oxoïd Ltd, Basingstoke, Hampshire, England), incubated for 24 h at 30°C.…”

“…Indeed, this strain demonstrate high ability of auto-aggregation and co-aggregation [25], high antimicrobial activity against many spoilage and pathogens bacteria [26]. Lactobacillus plantarum 1KMT showed also no resistance to antibiotics, hemolytic and gelatinase activities, or biogenic amines production [25]. However, this probiotic has not yet been used in aquaculture to evaluate their effects in-vivo.…”