Effect of cryopreservation and microencapsulation of lactic acid bacterium Enterococcus faecium MC13 for long-term storage

The aim of this work was to investigate the effect of cryoprotectants on the survival of probiotic bacterium Enterococcus faecium MC13 during freeze drying and storage. The maximum relative cell viabilities were observed when cells were freeze dried and stored at −20 °C, which is optimum temperature for the preservation of E. faecium. At all storage temperatures, trehalose was found to be retaining the highest relative cell viability than other cryoprotectants. In addition, alginate–chitosan capsules were produced to encapsulate E. faecium with the aim of enhancing survival of probiotic cells and keeping the probiotic during exposure to the harsh gastro-intestinal conditions. Encapsulation of probiotic into alginate–chitosan capsules found to be retaining higher survival of probiotic cells (4.342 ± 0.26 Log CFU mL−1) at −20 °C for six months. Microencapsulated cells were resistant to simulated gastric (pH 2.0) and intestinal fluids (pH 7.5), resulting in significantly enhanced survival when compared with free cells. During in vivo treatment, capsules were broken and probiotic cells were directly released into the intestinal tract of rat. This result showed that microencapsulation of E. faecium MC13 with alginate and a chitosan coating offers an effective means of delivery of viable cells to the colon and maintains their survival during the adverse gastro-intestinal conditions.

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► This is the first report on the preservation of intestinal probiotic strain Enterococcus faecium MC13 from fish (Mugil cephalus).
► Various cryoprotective sugars and milk products were used as cryoprotectants for the preservation of probiotic E. faecium MC13.
► Maximum relative cell viability was obtained when cells were freeze dried with trehalose.
► Microencapsulation technique was used to improve the survival of probiotic cells during the course of long term storage and simulated gastric and intestinal fluid.
► In vivo analysis revealed that alginate–chitosan capsules facilitate the direct release of probiotic cells into the intestinal tract.