SURVIVAL OF LAC-LUX MARKED PSEUDOMONAS-AERUGINOSA UG2LR CELLS ENCAPSULATED IN KAPPA-CARRAGEENAN AND ALGINATE

A milder method for encapsulating viable bacterial cells in kappa-carrageenan was developed. A 1% (w/v) kappa-carrageenan concentration amended with clay and skim milk was used as a lower-cost alternative to alginate for potential introductions of bacteria into soil. Survival of lac-lux marked Pseudomonas aeruginosa UG2Lr cells during long-term storage in dried K-carrageenan and alginate beads at 4 degrees C was compared. Survival of UG2Lr cells in the kappa-carrageenan formulated beads at Log 8.3 CFU/g dry beads was significantly better in the first 90 days than that in alginate at Log 7.8 CFU/g dry beads. After 360 days survival remained stable at Log 7.8 CFU/g dry beads and was not significantly different between the two carriers. Electron micrographs revealed bacterial cells in the K-carrageenan matrix, and degradation of the bead surface after 4 weeks incubation in non-sterile soil.