Optimization of medium components and physicochemical parameters to simultaneously enhance microbial growth and production of lypolitic enzymes by Stenotrophomonas sp
Cintia Anabela Mazzucotelli, María Victoria Agüero, María del Rosario Moreira and María Roberta Ansorena
Grupo de Investigación en Ingeniería en Alimentos, Departamento de Ingeniería Química y en Alimentos, Facultad de Ingeniería, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina.
The optimization of lipase and esterase production and bacterial growth of a Stenotrophomonas sp strain was developed. For this purpose, the effect of five different medium components and three physicochemical parameters were evaluated using a Plackett-Burman statistical design. Among eight variables, stirring speed, pH and peptone concentration were found to be the most effective factors on the three responses under evaluation. An optimization study applying Box-Benhken response surface methodology was used to study the interactive effects of the three selected variables on lipase/esterase production and microorganism growth. Predicted models were found to be significant with high regression coefficients (90–99%). By using the desirability function approach, the optimum condition applying simultaneous optimization of the three responses under study resulted to be: stirring speed of 100 rpm, pH of 7.5 and a peptone concentration of 10 g/L, with a desirability value of 0.977. Under these optimal conditions, it is possible to achieve in the optimized medium a 15-fold increase in esterase productivity, a 117-fold increase in lipase production, and a 9-log CFU/ml increase in bacterial growth, compared to the basal medium without agitation.
Keywords: Lipase;Medium optimization;Plackett-Burman design;Response surface methodology;Stenotrophomonas sp.