The study evaluated the safety and colonisation properties of four lactic acid bacteria (LAB), by determining their cell hydrophobicity and aggregation abilities. In addition, the presence of virulence and resistance genes was assayed in these probiotic candidates. Lactobacillus reuteri ZJ625, Lactobacillus reuteri VB4, Lactobacillus salivarius ZJ614 and Streptococcus salivarius NBRC13956 were tested for cell surface hydrophobicity abilities against xylene, chloroform and ethyl acetate. The isolates were also tested for auto-aggregation and co-aggregation abilities; the optical densities of cell growth were measured after 1, 2, 3 and 4 h of experimental set-up. DNA was extracted from all the four isolates and amplified using PCR with specific primers to detect virulence genes of adhesion collagen protein (ace) and aggregation substances (agg and asa); also, resistance genes of Vancomycin vanA, Vancomycin vanC1 and Vancomycin vanC2/3 were assayed in the four isolates. The isolates showed high hydrophobicity to all solvents: xylene (78-84%), chloroform (68-75%) and ethyl acetate (52-60%). High auto- and co-aggregations ranging from 60 to 70% and from 45 to 56% respectively were observed in the isolates after 4 h of incubation at 37 °C. Some of the tested isolates showed the presence of virulence and resistance genes; however, this does not indicate that these genes are unsafe because their transmission and expression abilities are unknown. Therefore, in this study, the isolates studied are considered safe for use as future probiotics, as revealed from results presented, which generally represents the scanned safety evaluations of the isolates as promising probiotics.

The study investigated the effects of probiotic bacteria (Lactobacillus reuteri ZJ625, Lactobacillus reuteri VB4, Lactobacillus salivarius ZJ614, and Streptococcus salivarius NBRC13956) administered as direct-fed microorganisms on growth performance and blood parameters of weaned piglets. Forty-five weaned piglets were divided into five treatments: antibiotic (PC), no antibiotic and no probiotic (NC), probiotic (P1), probiotic (P2), and combination of probiotics (P3). Fecal and ileum samples were collected for microbial count analysis. Blood samples were also collected from the animals at the end of the trial for the hematological and biochemical analysis and the ability of the probiotics to stimulate immunoglobulin G (IgG). Supplementation of probiotics had no effect on feed intake (FI). However, average daily weight gained (ADG) in the P3 treatment was higher than in other treatments and lowered the value of feed conversion ratio (FCR) of weaned piglets. Microbial count of fecal samples did not differ in all the treatments while ileum samples had lower enteric bacteria in P3 treatment when compared to other treatments. Concentration of albumin, globulin, neutrophils and basophils were higher in the NC treatment when compared to other treatment groups. The IgG concentration was highest in P3 compared to other treatments. Results suggested that probiotics have beneficial effects on growth performances, blood parameters, and IgG stimulation of weaned piglets. This advocates that probiotics will offer a significant benefit in pig farming by reducing the risk of post weaning diarrheal syndromes, and therefore enhance pig industry's economy. ______________________________________________________________________________________