Characterization of novel probiotics from gut microbiota of Chinese young adults

The microbiota of the human body represents a symbiosis of microbial networks spanning multiple organ systems, where the gut microbiota ecosystem is emerging as the preeminent one. The human microbiota has long been known to influence human health and disease, but recently researchers started to appreciate its interaction with the body systems. The bacterial composition is host specific and susceptible to genetic and other factors, such as environment, geographical location, lifestyle, diet and drug consumption. This biodiversity is an interesting source of novel potential probiotic strains. The aim of the present study was to isolate and characterize from human faeces of a specific population novel probiotic bacterial strains and to investigate subsequently in vitro probiotic properties. The faecal samples was from selected young healthy students from North East of China. A group of strains morphologically compatible with Lactobacillus spp. have been isolated from the faecal samples, using MRS selective agar (de Man, Rogosa, Sharpe). The isolated bacterial strains have been screened for their probiotic properties [1, 2, 3], performing some preliminary tests including survival to acidic conditions, survival to bile salts, antimicrobial activity. In particular the latter has been investigated on the bacterial cells, but also non-viable microbial cells, microbial fractions and cell free supernatant have been examined as bioactive compounds. The viability of the strains at pH 3.0, at different time points until 5 hours after the inoculum was investigated. The bile salts tolerance has been tested, using selective medium enriched with different concentration of bile salts. The antimicrobial activity of the potential probiotic bacteria was performed using disk-diffusion agar and well-diffusion agar assays, testing either live and heat and mechanically-inactivated bacterial cells. Eight bacterial strains out of twenty show promising properties, that encourages to complete their characterization profile with their identification and with further investigation on their potential probiotic properties.