| Literature DB >> 28536556 |
Lamiaa A Al-Madboly1, Eman G Khedr2, Safaa M Ali3.
Abstract
In this work, we aim to optimize the production of reduced glutathione (GSH) synthesized intracellularly by a food-grade microorganism through a statistical approach. Using a colorimetric method, 25 Lactobacillus plantarum isolates were screened in an attempt to find a GSH-producing strain. It was found that 36% of the tested isolates showed positive result. Isolate (L7) was found to produce 152.61 μM glutathione per gram which was the highest amount produced intracellularly. Accordingly, the later isolate was selected for the optimization process using Plackett-Burman and Box-Behnken designs. Temperature, amino acids, and urea were found to be the most significant independent variables. Following data analysis, the composition of the optimized medium was De Man-Sharp-Rogosa broth as a basal medium supplemented with NaCl (5%), H2O2 (0.05%), sodium dodecyl sulfate (0.05%), amino acids (0.0281%), and urea (0.192%). The pH of the medium was adjusted to 8 and incubated for 24 h at 40°C. The GSH amount was increased by 10-fold (851%) using the optimized medium. Hence, our optimization design estimated the biotechnological potential of L. plantarum (L7) for the production of GSH in the industry.Entities:
Keywords: Box–Behnken; L. plantarum; Placket–Burman; glutathione; optimization
Year: 2017 PMID: 28536556 PMCID: PMC5422468 DOI: 10.3389/fmicb.2017.00772
Source DB: PubMed Journal: Front Microbiol ISSN: 1664-302X Impact factor: 5.640
Variables and levels used in Plackett–Burman design for screening of culture conditions affecting glutathione (GSH) production.
| Variables | -1 | +1 |
|---|---|---|
| - Osmotic stress: sodium chloride (%) | 1 | 5 |
| - Oxidative stress: | ||
| • Bile salt (%) | – | 0.5 |
| • Hydrogen peroxide (%) | – | 0.05 |
| • Urea (%) | – | 0.1 |
| - Detergent: SDS (%) | – | 0.05 |
| - Alcohols: | ||
| • Ethanol (%) | – | 2 |
| • Butanol (%) | – | 1 |
| - Salts: Potassium chloride (%) | – | 0.5 |
| - Incubation under aerobic conditions | – | + |
| - Precursor amino acids (equally mixed combination of glycine, | – | + |
| - pH | 6 | 8 |
| - Temperature (°C) | 30 | 40 |
| - Incubation time (h) | 18 | 24 |
| - Cooling after incubation at 4°C | – | 24 h |
Plackett–Burman experimental design for screening the significant variables affecting the production of glutathione.
| Trial no. | Sodium chloride | Bile salt | H2O2 | SDS | Ethanol | KCl | Urea | Butanol | Aerobic incubation | Amino acids | pH | Temperature | Incubation time | Cooling | GSH μM/g |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 1 | 1 | -1 | 1 | -1 | -1 | -1 | 1 | 1 | 1 | -1 | -1 | 1 | -1 | 260 |
| 2 | -1 | 1 | 1 | -1 | 1 | 1 | 1 | -1 | 1 | 1 | -1 | -1 | -1 | 1 | 245 |
| 3 | 1 | -1 | 1 | 1 | -1 | -1 | -1 | 1 | -1 | 1 | 1 | -1 | -1 | -1 | 1147 |
| 4 | -1 | 1 | -1 | 1 | 1 | 1 | 1 | -1 | 1 | -1 | 1 | 1 | -1 | -1 | 917 |
| 5 | -1 | -1 | 1 | -1 | 1 | 1 | -1 | 1 | -1 | 1 | 1 | 1 | 1 | -1 | 956 |
| 6 | -1 | -1 | -1 | 1 | -1 | -1 | 1 | -1 | 1 | -1 | -1 | 1 | 1 | 1 | 1147 |
| 7 | 1 | -1 | -1 | -1 | 1 | 1 | 1 | 1 | -1 | 1 | 1 | -1 | 1 | 1 | 260 |
| 8 | 1 | 1 | -1 | -1 | -1 | -1 | -1 | 1 | 1 | -1 | -1 | 1 | -1 | 1 | 275 |
| 9 | 1 | 1 | 1 | -1 | -1 | -1 | 1 | -1 | 1 | 1 | 1 | -1 | 1 | -1 | 860 |
| 10 | -1 | 1 | 1 | 1 | -1 | -1 | -1 | 1 | -1 | 1 | -1 | 1 | -1 | 1 | 443 |
| 11 | 1 | -1 | 1 | 1 | 1 | 1 | -1 | -1 | 1 | -1 | 1 | -1 | 1 | -1 | 199 |
| 12 | -1 | 1 | -1 | 1 | 1 | 1 | -1 | -1 | -1 | 1 | 1 | 1 | -1 | 1 | 153 |
| 13 | 1 | -1 | 1 | -1 | 1 | 1 | 1 | -1 | -1 | -1 | -1 | 1 | 1 | -1 | 1338 |
| 14 | -1 | 1 | -1 | 1 | -1 | -1 | 1 | 1 | -1 | -1 | 1 | -1 | 1 | 1 | 122 |
| 15 | 1 | -1 | 1 | -1 | 1 | 1 | 1 | 1 | 1 | -1 | -1 | 1 | -1 | 1 | 153 |
| 16 | -1 | -1 | -1 | -1 | -1 | -1 | -1 | -1 | -1 | -1 | -1 | -1 | -1 | -1 | 122 |
Levels of the selected variables used in Box–Behnken for optimization of GSH production.
| Variables | -1 | 0 | +1 |
|---|---|---|---|
| Amino acids (%) | 0.0125 | 0.025 | 0.05 |
| Temperature (°C) | 35 | 40 | 45 |
| Urea (%) | 0.02 | 0.1 | 0.5 |
Box–Behnken design of GSH production by L. plantarum as influenced by amino acids, temperature, and urea.
| Trail no. | Precursor amino acids | Temperature | Urea | Experimental GSH (μM/g) | Predicted GSH |
|---|---|---|---|---|---|
| 1 | 0 | -1 | -1 | 82.34 | 108.61 |
| 2 | 0 | 1 | -1 | 129.01 | 110.84 |
| 3 | 0 | -1 | 1 | 156.77 | 174.94 |
| 4 | 0 | 1 | 1 | 194.51 | 168.25 |
| 5 | -1 | -1 | 0 | 239.01 | 215.41 |
| 6 | -1 | 1 | 0 | 305.76 | 326.59 |
| 7 | 1 | -1 | 0 | 550.02 | 529.19 |
| 8 | 1 | 1 | 0 | 389.93 | 413.53 |
| 9 | -1 | 0 | -1 | 426.33 | 423.67 |
| 10 | -1 | 0 | 1 | 512 | 517.43 |
| 11 | 1 | 0 | -1 | 661.35 | 655.92 |
| 12 | 1 | 0 | 1 | 683.24 | 685.90 |
| 13 | 0 | 0 | 0 | 1599.06 | 1599.06 |