Characterization of Rhodopseudomonas palustris strain 2C as a potential probiotic

Photosynthetic bacteria (PSB) are prokaryotes that first appeared on the earth 2 billion years ago. Being rich in nutrients and having unique biological transformational function, PSB have been used as medicinal ingredients and healthcare products. However, there is insufficient information about the probiotic properties of PSB. The aim of this study was to characterize the potential probiotic properties of Rhodopseudomonas palustris strain 2C. The tolerance of strain 2C to low pH, high bile salt and simulated gastrointestinal conditions was determined. The susceptibility of strain 2C to 11 antibiotics was screened. The in vitro antioxidative activity and acute toxicity of strain 2C were performed. The survival duration of strain 2C after it had been repeatedly ingested by Wistar rats was determined. Strain 2C was tolerant to low pH, high bile salt concentration, and simulated gastrointestinal conditions. Strain 2C was only resistant to two of the 11 tested antibiotics (penicillin and ampicillin), and it showed antioxidative activity in vitro. When ingested by rats, strain 2C did not cause any bacteria translocation or tissue damage. The survival duration of strain 2C depending on doses ingested by the rats, 3 days after the termination of intake, it could no longer be enriched from the feces. Taken together, these findings indicate that strain 2C may be a potential probiotic strain.