Huh C., Yeo S., Lee S.
Institute of Green-Bio Science & Technology, Seoul National University, South Korea

Since it was revealed the growth-promoting effect of sub-therapeutic levels of antibiotics in 1940s, antibiotics have been widely used in livestock production. However, the extensive use of antibiotics caused the occurrence of antibiotic-resistant pathogenic bacteria and the risk of transference of antibiotic-resistance genes from animal to human. Consequently, antibiotics as growth promoters (AGPs) in animal production has been banned in the European Union since 2006, and the development of alternatives to AGPs as feed additives has increased.
Pig is a very influential livestock in the world food market and economy as 2 billion of pigs are supplied per every year. The pig industry was a representative farming influenced by the AGPs, however, after the prohibition, the world average loss and its ratio to the total distribution has been decreased even without AGPs. To the consequence, many of nutritional strategies and additives have been suggested as alternative. Probiotic lactic acid bacteria (LAB) which is currently a major alternative feed additive for livestock has been reported to be able to inhibit non-commensal microbes and modulate the microbiota in the human gastrointestinal tract (GIT). With several reports about that the gastrointestinal flora is related to animal health and growth performance, LAB has scientific basis for treatment of various disease of animals such as diarrhea caused by pathogen colonization.
However, many of the previous probiotic strains applied for AGPs alternative were isolated from human, and verified by human-based in vitro screening methods which are not enough to reflect the physiology, immune system, and gastrointestinal microbial community of the host animal. Therefore, it is necessary to consider and develop a host target-specific probiotics and its adaptive in vitro screening, thereby the compatibility of the characterized strain is expected to show enhanced in vivo efficacy when it is administered to livestock as feed additives.

In the present study, we have developed a pig host target probiotic strain. We confirmed the availability of two conventional methods for selecting putative probiotic strain as feed additives, using Lactobacillus salivarius strains isolated from fed-pig feces and Lactobacillus rhamnosus GG commercial-probiotics originated from human intestine. We compared the viability of the strains during passage through the in vitro human and porcine GIT models. We also observed the different adhesion ability of each strain on a porcine intestine cell line (PSI) and a human intestine cell line (Caco-2).

The results showed significant differences in GIT survival and adhesion ability when comparing the probiotic strains for human and porcine with target different in vitro model conditions. We suggest that the target-specific screening and validation are important to develop probiotic feed additives, and this approach may support future-oriented agriculture.

In conclusion, although our suggested in vitro models are not enough to represent the physiology of human and pig, but it may be postulated that it is needed to develop target-specific validation method for screening probiotic candidates depending on the host of application. The applicability of our suggested models may provide a basis for the selection of pig probiotic candidates to be tested in vivo.

Keywords: Probiotics, Feed additives, Porcine, Gastrointestinal tract, Adhesion ability

Huh C., Yeo S., Lee S. (2016). Development of putative probiotics with target - specific validation. Conference Proceedings of IPC2016. Paper presented at the International Scientific Conference on Probiotics and Prebiotics, Budapest (p. 99.). IPC2016

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