Optimization of a new medium of whey water and sweet potato extract for different lactobacillus species by plackett-burman statistical design using mini –tab16 software

Anotace: An attempt is made to use cheese whey water (Ww) and sweet potato extract (SPE) separately or in combination to manipulate a cheap and economical media component for large scale production of lactobacilli. Primarily, lactobacilli species were cultivated on de-Man Rogosa and Sharp medium (MRS) then, these strains were grown in (SPE) and (Ww) using a flask fermentation technique at 37°C, followed by applying a statistical experimental design (Plackett- Burman (PB)) via a statistical software MiniTab16 to optimize the media constituents for achieving a large scale production of lactobacilli; with studying the main effect of medium components referring to the most critical nutritional factors in the newly organized medium. Generally, our results indicated that both sweet potato and whey water extract (SPWE); could be used for the growth of lactobacilli instead of (MRS) medium. Further, other experiments were done to show how lactobacilli growth will be affected by pH and various types of whey; using standard plate count method. Highest counts for Lactobacillus acidophilus (2r) and Lactobacillus rhamnosus (190RZFAAU) were at pH 6 and pH 6.5 in (SPWE) medium. Depending on the above investigations; (SPWE) medium including the addition of different types; whey water can be used as an alternative growth medium for lactobacilli instead of MRS which was traditionally used for growing these kinds of Lactic acid bacteria (LAB). Additionally, findings in this study can help in cleaning our environment from the huge disposal quantities of whey resulted as byproduct from cheese industries.