Evaluation of survival and release of encapsulated bacteria in ex vivo porcine gastrointestinal contents using a green fluorescent protein gene-labelled E. coli.

摘要

Escherichia coli K-12 labelled with a green fluorescent protein (gfp) was used as a test strain to assess bacterial survival and release from capsules in ex vivo porcine gastrointestinal contents. Results showed that compared with non-encapsulated free bacterial cells, bacteria encapsulated with calcium alginate survived better in ex vivo porcine gastric conditions. After 3 h incubation in gastric contents, there was a 2 log decrease and 4 log decrease in viable encapsulated cells and free non-encapsulated cells, respectively. Within 1 h of incubation in small intestinal contents at 37癈, there was a complete release of encapsulated bacteria, whereas in colon contents under similar conditions, it took 8 h to almost completely release the encapsulated bacteria. After 10 h incubation in duodenal contents, there was only partial release of encapsulated bacteria. It is concluded that gfp-labelled bacteria was successfully used to evaluate the efficacy of the capsule in protecting and releasing the viable bacteria in animal intestinal contents. Microencapsulation was thus proved to be efficient in increasing the survival of encapsulated bacteria compared with non-encapsulated free cells.