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Table 2 Central composite design for metal ion factors associated with spore density by the fluorometric assay

From: Rapid optimization of spore production from Bacillus amyloliquefaciens in submerged cultures based on dipicolinic acid fluorimetry assay

Run Models Metal ions concentration (mM) Fluorescence intensity (AU)
Mn2+ (x1) Fe2+ (x2) Ca2+ (x3) Mg2+ (x4) Experimental Predicted
1 0000 1 3 2 3 299.2 ± 44.7 299.1
2 0a00 1 1.52 2 3 292.1 ± 38.3 290.3
3 −−++ 0.5 2 3 4 280.8 ± 21.2 278.4
4 +−++ 1.5 2 3 4 284.4 ± 38.2 286.3
5 ++++ 1.5 4 3 4 282.3 ± 30.0 282.2
6 −+++ 0.5 4 3 4 268.2 ± 24.3 268.0
7 −−−+ 0.5 2 1 4 263.4 ± 20.2 265.1
8 ++−− 1.5 4 1 2 280.8 ± 28.6 282.0
9 ++−+ 1.5 4 1 4 281.5 ± 30.4 276.7
10 000A 1 3 2 4.48 288.5 ± 27.6 290.4
11 −−+− 0.5 2 3 2 280.5 ± 23.3 284.4
12 a000 0.26 3 2 3 278.8 ± 20.1 278.8
13 +−−+ 1.5 2 1 4 266.4 ± 17.4 265.8
14 0000 1 3 2 3 302.9 ± 33.1 299.1
15 −+−− 0.5 4 1 2 287.2 ± 25.7 284.4
16 +−+− 1.5 2 3 2 284.5 ± 24.0 283.1
17 +−−− 1.5 2 1 2 271.0 ± 18.4 270.4
18 +++− 1.5 4 3 2 282.2 ± 24.6 279.6
19 00a0 1 3 0.52 3 273.9 ± 23.6 277.6
20 0A00 1 4.48 2 3 285.5 ± 23.3 291.2
21 A000 1.74 3 2 3 279.1 ± 26.0 282.9
22 −−−− 0.5 2 1 2 280.1 ± 4.7 279.0
23 −++− 0.5 4 3 2 275.2 ± 17.4 274.6
24 00A0 1 3 3.48 3 285.4 ± 19.5 285.6
25 −+−+ 0.5 4 1 4 269.6 ± 15.3 269.8
26 000a 1 3 2 1.52 296.9 ± 24.5 298.8
27 0000 1 3 2 3 302.2 ± 26.6 299.1
  1. The experimental results are the means of two replicates of 1000-fold diluted spore samples. The symbols in the model column mean each factor at five different levels (−a, −, 0, +, A). The variables at a central coded value are considered at zero