| Congresso Brasileiro de Microbiologia 2023 | Resumo: 1073-2 | ||||
Resumo:The emergence of antibiotic-resistant pathogens in poultry farms is increasing due to the misuse of antibiotics as growth promoters. This has brought a serious public health problem with the emergence of diseases such as difficult-to-treat Salmonellosis. This pathology is caused by Salmonella enterica, accounting for about 31% of foodborne illnesses (FBIs) worldwide. Because of this problem, innovative therapies have been studied, such as the use of bacteriophages (or phages) to control and treat contamination by this pathogen. Therefore, the objective was to isolate and characterize lytic bacteriophages for Salmonella enterica to control Salmonellosis. For this purpose, phages were isolated from environmental samples and subjected to physical-chemical and biological characterizations. Phage titers, UV-Vis spectra, and transmission electron microscopy (TEM) were performed and one-step growth curves, adsorption curves, inactivation curves, host range studies, and the influence of abiotic factors (pH, temperature, and solar radiation) on phages were determined. Two phages named SentP01T and SentP01L were isolated. After isolation, the phage titers were determined to be 1.42x10^12 PFU/mL and 1.82x10^12 PFU/mL, respectively. UV-Vis spectra showed maximum absorption at 251 nm (phage SentP01L) and 252 nm (phage SentP01T) with molar extinction coefficients of 6.463 × 10^−12 (PFU/mL)−1 ·cm−1 (SentP01L) and 9.986 x 10^-12 (PFU/mL)-1 .cm-1 (SentP01T). TEM images indicated that the phages belong to the order Caudoviricetes and the family Siphoviridae, with icosahedral heads and long, flexible, non-contractile tails. Biological tests demonstrated efficiency in the inactivation of the host bacteria, where the one-step growth curves showed a burst size of 466 virions per host cell and a latency period of 25 minutes, an eclipse period of 10 minutes, and an accumulation period of 15 minutes for phage SentP01L; and 132 virions per host cell, a latency period of 40 minutes, an eclipse period of 10 minutes, and an intracellular accumulation period of 30 minutes for phage SentP01T. The adsorption curves showed a rate of particle adsorption of 8.0 x 10^-10 Colony-Forming Units per mL per minute (CFU-1.mL.min-1) for phage SentP01L and 7.0 x 10^-10 CFU-1.mL.min-1 for phage SentP01T. During the inactivation curves, the best virus/bacteria ratios, i.e., multiplicity of infection (MOI) for free phages were, respectively, MOI 100 for phage SentP01L and MOI 1000 for phage SentP01T. However, in the cocktail, the most efficient result was achieved with MOI 1 and 10, with 87.6% bacterial inactivation in 6 hours of incubation, while MOI 1000 showed a control of inactivation lasting 12 hours. The host range study demonstrated efficiency against different strains of enteric bacteria, such as Escherichia coli and Klebsiella pneumoniae, as well as against other strain such as Pseudomonas syringae pv. garcae. The abiotic factors tests showed that phage SentP01L maintains viability in a pH range between 3 and 9, a temperature range between 25°C and 41°C, and loses efficiency when exposed to sunlight. Meanwhile, phage SentP01T maintains lytic viability between pH 3 and 6.5, retains efficiency between 25°C and 41°C, and loses its efficiency when exposed to solar radiation. Based on the obtained results, is possible to affirm that both bacteriophages are effective in controlling and treating Salmonella enterica, showing promising potential for combating Salmonellosis. Palavras-chave: Biotechnology, Characaterization, Infections, Phage, Salmonella Enterica | |||||