Abstract: In one embodiment, the present invention provides a method for characterizing a first composition comprising a fecal-derived bacterial population, comprising the steps of: obtaining a live culture of the first composition comprising a fecal-derived bacterial population, supplying factors that selectively expand the at least one bacterial strain at a level below a threshold for detection above the threshold level by seeding a chemostat containing culture medium with a second composition comprising a fecal-derived bacterial population; adding the live culture of the first composition comprising a fecal-derived bacterial population to the seeded chemostat, and culturing the first composition comprising a fecal-derived bacterial population with the second composition comprising a fecal-derived bacterial population in the chemostat for a time sufficient to expand the at least one bacterial strain; removing a sample of the chemostat culture; and identifying the at least one bacterial strain.

Abstract: A method includes reconstituting a lyophilized microbial community. Ribonucleic acid (RNA) is extracted from at least one targeted microbe in the reconstituted microbial community at a plurality of selected time periods. The RNA as extracted at the selected time period is subjected to a multiplex analyzer and determining RNA concentrations at the plurality of selected time periods. An increase in the RNA concentration from a first of the plurality of selected time periods to a second of the plurality of time periods indicates RNA expression from the at least one targeted microbe. RNA expression from the at least one targeted microbe indicates that the at least one targeted microbe is a living microbe.