Experimental Designs see Note

3.2.1. Complete 2 x 3 x 3 Factorial Design

1. To test the growth and bacteriocin production of L. salivarius CRL 1328, three factors are evaluated: culture media (LAPTg and MRS broth), temperature (30, 37, and 44°C), and initial pH (5.0, 6.5, and 8.0).

2. Ten curves were performed experimentally per day, two corresponding to the central points and eight to the remaining combinations (Table 1).

3. The experiments are repeated twice.

4. The complete design can be finished in 4 d (blocks). A total of 40 curves with 18 different combinations are made. The day number (block) in which each one of the culture conditions is tested is indicated in each cell of Table 1.

3.2.2. Fractional Factorial Design

1. To test the growth and H2O2 production by vaginal lactobacilli, five factors were evaluated: Lactobacillus strains (L. crispatus CRL 1266 and L. paracasei CRL 1289), culture media (LAPTg and MRS broth), temperature (30, 37, and 44°C), initial pH (5.0, 6.5, and 8.0), and agitation (nonagitated and agitated cultures).

2. This design was obtained by using the menu DOE (Design of Experiments) of the MINITAB software.

3. The experiments corresponding to the central points are repeated four times, and the vertex points (conditions of the 25-1 design) are carried out once.

4. Six curves are experimentally performed per day, corresponding to two vertex points and four central points of the design.

5. The complete design can be finished in 8 d (blocks). A total of 48 curves with 24 different combinations are made, 16 of them corresponding to the factorial design of two levels and 8 to the central points (Table 2). The day number (blocks) in which each one of the culture condition is tested is indicated in each cell of Table 2.

Was this article helpful?

0 0

Post a comment