[Statistical methods to optimize immobilization and bacteriocin production by Lactobacillus paracasei HD1.7].

OBJECTIVE

To enhance bacteriocin production by Lactobacillus paracasei HD1.7 immobilized with calcium alginate gel by statistical methods.

METHODS

A 2(6-2) two-level fractional factorial design was employed first where 6 variables were studied for their influence on bacteriocin production. The concentration of sodium alginate, inoculation volume and culture time were the most significant variables to improve bacteriocin production. The greatest response area was estimated by the design of steepest ascent approach. A three-level Box-Behnken factorial design was employed for maximizing the bacteriocin production and the number of cell cycle. The repeated batch fermentation using immobilized cells was done.

RESULTS

The optimal condition for bacteriocin production and the number of cell cycle was with sodium alginate 2.8%, CaCl2 5%, immobilization time 4 h, the density of entrapped cells 1/20, culture time 63 h and inoculation volume 8.2%. The period of fermentation was 24 h of a batch fermentation after 63 h and bacteriocin production was 70% of free-cell fermentation.

CONCLUSION

After optimizing, the total production of bacteriocin was increased by 19% using the batch fermentation during 327 hours, the beads were intact with little cell leakage and repeatedly used, which laid foundation for the high study of bacteriocin and finally extracted.