Determination of an economical medium for growth of Lactobacillus fermentum using response surface methodology

Lactobacillus fermentum is a widely utilized probiotic compound fed as an alternative to antibiotics for growth promotion in a wide variety of livestock species. The objective of this research is to develop an economical and practical fermentation medium for the growth of Lact. fermentum using response surface methodology.

A two-level Plackett-Burman design was used to determine which factors in the fermentation medium influence the growth of Lact. fermentum. Under our experimental conditions, peptone, urea and yeast extract were found to be major factors. Then, the steepest ascent method and the central composite design were applied to optimize the culture of Lact. fermentum. The following composition of the fermentation medium was estimated to be the most economical formula (per litre): 30 g corn syrup, 15 g glucose, 14.4 g peptone, 7 g (NH(4))(2)SO(4), 0.5 g urea, 3 g sodium acetate, 4 g sodium citrate, 0.1 g MnSO(4).4H(2)O, 0.5 g MgSO(4).7H(2)O, 7.3 g yeast extract, 0.5 g K(2)HPO(4).

Based on 10 side-by-side comparisons, we found that the yield of Lact. fermentum using our fermentation medium was 64% greater than those using modified de Man, Rogosa and Sharp broth (MRS) medium (1.8 x 10(9) CFU ml(-1)vs 1.1 x 10(9) CFU ml(-1), respectively), while the cost was 89% lower than MRS. This research indicates that it is possible to increase bacterial yield by using inexpensive materials.

It is more likely that the use of Lact. fermentum as a probiotic will increase. The low cost medium developed in this research can be used for large-scale, commercial application where economics are quite likely to be important.