CAPES / Glutathione (GSH) is a tripeptide, soluble in water; it consists of three amino acids: L-glutamate, L-cysteine and glycine. It is the most efficient intracellular antioxidant present in the all biologics systems (animals and vegetables). Currently, it is reported many applications of GSH in different segments, like in food industries as food additive; in the sports segment, in the pharmaceutical field; it is used as food supplement; and is also used in the treatment of industrial effluents due to ability to absorb heavy metals. The application in magnetic fields (MF) inside the fermentative process can cause stimulants or inhibitory effects. However, it is not that reported in the literature. Thus, the main objective of this work is to study the influence of magnetic fields in the production of glutathione in reactor ?air-lift?? pressurized and the microorganism used was Saccharomyces cerevisiae ATCC 7754 During the fermentations were analyzed the pH, concentrations of cell (g/L), glucose (g/L) and GSH (mg/L). Firstly, it was evaluated at different pressures (0; 0.25; 0.50; 0.75; 1.00; 1.25 e 1.50 kgf/cm2). In this context, conditions fermentation were 20?C, total time of 96 h e pHinitial 5.0. The results showed that the best two pressures were 1.50 kgf/cm2, concentration of cell 17.25 g/L and 141.30 mg/L of GSH (72 h) and 0.50 kgf/cm2, with 13.51 g/L concentration of cell and 178.21 mg/L of GSH (96 h). Secondly, was realized experimental factorial design 22 with the two best results of pressures obtained in the first step. In the planning seven tests were done including three central points, in which the variables investigated were: pressure and velocity of cell recycling. The percent of variation of 90% (p < 0.1) was used to statistical analysis of results of concentration of cell and GSH. Therefore, according to the results of the second step, the highest concentration of cell (7.26 g/L) was obtained with 1.5 kgf/cm2 and recycle of 15 cm/s at 72 h of fermentation. In relation to production of GSH, the highest result was 67.24 mg/L at 0.50 kgf/cm2 and recycle of 3.0 m/s with 67.24 mg/L at 94 h. There was no significant response in both responses to the variables (concentration of cell and GSH), according to the table of estimated effects. The production of GSH by S. cerevisiae ATCC 7754 on a pressurized system presented as an efficient and promising technology. However the influence of MF and the velocity of cell recycling led to mechanisms that promoted particular synthesis inhibition leading to a decrease in its final concentration. / A glutationa (GSH) ? um tripept?deo hidrossol?vel composto por tr?s amino?cidos: ?cido glut?mico, ciste?na e glicina. ? o mais eficiente antioxidante intracelular presente em todos os sistemas biol?gicos (animais e vegetais). Atualmente, relatam-se in?meras aplica??es da GSH nas ind?strias em diferentes segmentos, sendo eles: nas ind?strias de alimentos como aditivo alimentar; no campo farmac?utico; no segmento desportivo como suplemento alimentar e ainda no tratamento de efluentes industriais, pois tem a capacidade de adsorver metais pesados. A aplica??o de campos magn?ticos (CM) em processos fermentativos pode causar efeitos estimulantes ou inibit?rios, or?m ainda ? pouco reportada na literatura. Desta forma o principal objetivo deste trabalho foi estudar a influ?ncia de CM na produ??o de glutationa em reator ?air-lift? pressurizado, o micro-organismo utilizado foi Saccharomyces cerevisiae ATCC 7754. Durante as fermenta??es foi feito o acompanhamento do pH, concentra??o celular (g/L), GSH (mg/L) e glicose (g/L). Na primeira etapa foi estudada apenas a varia??o da press?o no reator (0,00; 0,25; 0,50; 0,75; 1,00; 1,25 e 1,50 kgf/cm2). As condi??es das fermenta??es foram: 20?C, tempo total 96 h e pHinicial 5,0. De acordo com os resultados desta etapa, as duas melhores press?es em estudo foram 1,50 kgf/cm2, apresentando 17,25 g/L de concentra??o celular e 141,30 mg/L de GSH (72 h) e 0,50 kgf/cm2, com 13,51 g/L de concentra??o celular e 178,21 mg/L de GSH (96 h). Na segunda etapa, na qual se aplicou os CM, foi realizado um delineamento fatorial 22, onde foram realizados 7 ensaios, incluindo 3 pontos centrais, nos quais as vari?veis independentes testadas foram: press?o (kgf/cm2) e velocidade de reciclo celular (cm/s). O n?vel de signific?ncia de 90% (p < 0,1) foi utilizado na an?lise estat?stica dos dados de concentra??o celular e de GSH. De acordo com os resultados desta etapa, o maior resultado quanto ao crescimento celular (7,26 g/L) foi obtido a 1,50 kgf/cm2 e reciclo de 15 cm/s ap?s 72 h de fermenta??o. Em rela??o a concentra??o de GSH, o maior resultado foi a 0,50 kgf/cm2 e reciclo de 3,0 m/s com 67,24 mg/L a 94 h. A an?lise estat?stica mostrou que n?o houve vari?veis significativas em ambas as respostas (concentra??o celular e GSH). A produ??o de GSH a partir de S. cerevisiae ATCC 7754 em sistema pressurizado apresentou-se como uma tecnologia eficiente e promissora, por?m a influ?ncia de CM juntamente com a velocidade de reciclo celular, levou a mecanismos que promoveram determinada inibi??o em sua s?ntese, levando a diminui??o na sua concentra??o final.