Bacteria versus parasites: Effect of Lactobacillus rhamnosus cell- free supernatant on the sporulation of coccidian oocysts in vitro and in vivo

The purpose of this study was to determine if the probiotic bacterium, Lactobacillus rhamnosus, generates compounds that affect the sporulation of the oocysts of three species of Eimeria using an in vitro assay. In addition, anticoccidial effects of L. rhamnosus cell-free supernatant (CFS)-based diets were evaluated in chickens following experimental infection with Eimeria tenella and the anticoccidial effect was assessed using fecal oocyst shedding and the sporulation process. L. rhamnosus was grown in Mann-Rogosa-Sharpe (MRS) broth for 48 h at 37 o C anaerobically and the cells were removed from the broth by centrifugation to get the CFS. Exposure of the oocysts of the 3 species of Eimeria, namely E. acervulina , E. tenella and E. maxima, to 4-fold diluted CFS resulted in 37%, 33% and 46% inhibition of sporulation, respectively while exposure to undiluted CFS resulted in 100% inhibition of sporulation in all species. Chickens fed 1% or 3% CFSsupplemented diets in E. tenella-infected groups shed significantly less (P < 0.0001) oocysts than their counterparts fed the control diet. More importantly, the sporulation rate of the oocysts recovered from the CFSsupplemented birds was significantly lower than that of the oocysts recovered from the infected birds fed the control diet (P < 0.0001). The results showed for the first time that CFS from L. rhamnosus cultures has anticoccidial activity.