New Insights into a Conceptual Bionic Colonic Bioreactor: A Model, 'Probiotics in Human Colon', Showing How Probiotics Alleviate Constipation from a Bioprocess Engineering Perspective.

Constipation is a common problem which often causes negative impacts on the patient's quality of life. Apart from the pharmacologic and diet approaches, the use of probiotics has gradually shown promising efficacy to alleviate constipation. However, an exact understanding of the underlying mechanisms of probiotic actions on alleviating constipation is still unclear and need to be explored. In this review, we propose a model, 'probiotics in human colon', from a bioprocess engineering perspective. This model can be interpreted as a new concept of bionic colonic bioreactor design of a human colon in vitro, in which the transport phenomena during the fermentation of chyme by probiotics can be detected. By reviewing the anatomy structure and peristalsis mode of the human colon, we have focused on the influence by probiotics on the physical properties of colonic contents during the fermentation process. We relate physical properties such as shape, water content, density, hardness, viscosity, and elasticity to constipation symptoms directly. The influences on the physical properties of colon contents triggered by probiotics can be a potential key to understand the mechanisms for alleviating constipation.