Microencapsulation of microbial cells

Microencapsulation involves coating or entrapping of a core material with a polymeric material to generate microspheres in the size range of 1–1000 μm. This versatile technology has been used to encapsulate a wide array of products such as pharmaceuticals, flavors, volatile oils, plant extracts, enzymes and others. In the recent decades, this technology has also been applied to the area of microbial cell immobilization owing to its numerous advantages over other cell immobilization techniques such as higher cell loading capacity, enhanced cell survival and increased production rate of the desired microbial products. The confinement of microbial cells within a semipermeable polymeric matrix enables the physical isolation of cells from the external environment while maintaining a hospitable internal micro-environment. It has found application in various biotechnological processes such as probiotic encapsulation in food industries, in biotransformation and fermentation processes producing antibiotics, organic acids, enzymes, and alcohols as well as environmental decontamination such as waste water treatment. The judicious selection of materials and methods for the production of microspheres is critical for ensuring minimum damage to the viability of the encapsulated microbial cells. The conventional methods used for microencapsulation of microbial cells are reviewed along with the recent advances in the respective methods. The effect of microencapsulation on the microbial cells, the stability of the microspheres as well as the techniques for enumeration of the encapsulated cells are also discussed, followed by a summary of recent applications of microencapsulation in different biotechnological processes.