title: Optimization of growth and bacteriocin production by Lactobacillus sakei subsp. sakei2a.
abstract: Lactobacillus sakei subsp. sakei 2a is a bacteriocinogenic lactic acid bacterium isolated from Brazilian pork sausage, capable of inhibiting the growth of microbial pathogens, mainly Listeria monocytogenes. In order to optimize bacteriocin production for industrial applications, this study evaluated the effect of supplementation of MRS broth with glucose, Tween 20, Tween 80, sodium citrate, potassium chloride and cysteine, and effect of the initial pH and temperature of incubation of the medium on production of bacteriocins by L. sakei 2a. Adding glucose and Tween 20 to the medium, an initial pH of 5.0 or 5.5, and incubation temperatures of 25 °C or 30 °C resulted to the highest bacteriocin yields. Thus, a 2(4) factorial design with the four variables was performed, and statistical analysis showed that it was an adequate model (R (2) = 0.8296). In the studied range, the four parameters significantly influenced bacteriocin production, with the maximum yield produced at an initial pH between 5.5 and 7.0, a temperature between 25 and 30 °C and supplementation of the MRS broth with glucose from 3.25 to 6.0 g L(-1) and Tween 20 from 0.575 to 1.15% (v/v). Response Surface Methodology analysis indicated that the highest bacteriocin production (12800 AU mL(-1)) occurred in the MRS broth supplemented with 5.5 g L(-1) glucose and 1.05% Tween 20 at an initial pH of 6.28 and an incubation temperature of 25 °C. The amount of bacteriocin produced in commercial MRS broths under the same conditions was only 5600AU mL(-1).
authors.affiliation: Departamento de Ciência de Alimentos, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil .
authors.forename: Patrícia S
authors.initials: PS
authors.lastname: Malheiros
authors.affiliation: Universidade Estadual do Rio Grande do Sul, Unidade de Encantado, Encantado, RS, Brazil .
authors.forename: Voltaire
authors.initials: V
authors.lastname: Sant'Anna
authors.affiliation: Departamento de Alimentos e Nutrição Experimental, Universidade de São Paulo, São Paulo, SP, Brazil .
authors.forename: Svetoslav D
authors.initials: SD
authors.lastname: Todorov
authors.affiliation: Departamento de Alimentos e Nutrição Experimental, Universidade de São Paulo, São Paulo, SP, Brazil .
authors.forename: Bernadette D G M
authors.initials: BD
authors.lastname: Franco
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism*; D001430:Bacteriocins / Q000378:metabolism*; D001938:Brazil; D003470:Culture Media / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D007778:Lactobacillus / Q000145:classification / Q000254:growth & development* / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D011136:Polysorbates / Q000378:metabolism; D000069466:Red Meat / Q000382:microbiology; D013499:Surface Properties; D013696:Temperature
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D003470:Culture Media; D011136:Polysorbates; D005947:Glucose
keywords: Lactobacillus sakei; bacteriocin; optimization; response surface methodology