Isolation and characterization of vaginal <i>Lactobacillus</i> spp. in dromedary camels (<i>Camelus dromedarius</i>): in vitro evaluation of probiotic potential of selected isolates

Abstract

<i>Lactobacillus</i> spp. is one of the beneficial lactic acid producing microbiota in the vagina, which is important for a healthy vaginal environment. However, little is known about vaginal <i>Lactobacillus</i> in dromedary camels (<i>Camelus dromedarius</i>). Therefore, this study aimed to isolate vaginal lactic acid bacteria (LAB) in dromedary camels and to study the probiotic potential of selected isolates. A total of 75 vaginal swabs were collected from pluriparous, non-pregnant, non-lactating dromedary camels. The LAB were isolated using deMan, Rogosa and Sharpe broth and agar media. Suspected LAB isolates were subjected to catalase testing and Gram staining and examined for indole production, nitrate reduction, hemolytic activity, cell surface hydrophobicity, auto- and coaggregation, antibacterial activity and characterized by 16S rRNA amplification and sequencing. Eighteen LABs were isolated from the 75 vaginal swabs. Among the 18 LAB isolates, six were <i>Lactobacillus plantarum</i>, eight were <i>Lactobacillus fermentum</i>, and four were <i>Lactobacillus rhamnosus</i>. None of the LAB isolates was hemolytic and only four LAB were H₂O₂ producing. The percentage of hydrophobicity ranged from 0% to 49.6%, 0% to 44.3% and 0% to 41.6% for hexadecane, xylene and toluene, respectively. All isolates showed higher (<i>P</i> < 0.05) autoaggregation after 24 h of incubation compared to 4 h. Furthermore, all LAB showed higher coaggregation (<i>P</i> < 0.05) and antimicrobial activity toward <i>Staphylococcus aureus</i> than to <i>Escherichia coli</i>. All LAB isolates were vancomycin resistant and sensitive to streptomycin, erythromycin, kanamycin and chloramphenicol. Only, three LAB isolates were resistant to tetracycline. The dromedary camel vaginal LAB isolates exhibited varying degrees of in vitro probiotic properties tested in this study and showed promising activity against the most common bacterial causes of endometritis in dromedary camels. Further investigation of the in vivo effect of these isolates is warranted.