Kinetic Study of Lasiodiplodan Production by Lasiodiplodia theobromae MMPI in a Low-Shear Aerated and Agitated Bioreactor

Abstract

Little information is available in the literature concerning the kinetics of the production of exopolysaccharides (EPS). The kinetics of growth, substrate consumption and lasiodiplodan (LAS) production by the filamentous fungus Lasiodiplodia theobromae MMPI were studied in a new bioreactor design (Low-Shear Aerated and Agitated Bioreactor; LSAAB) using media based on glucose and glycerol. The kinetic parameters of cultivation were compared with fermentations conducted in a stirred tank bioreactor (STR) and in shake flasks. Cultivation in LSAAB using glucose resulted in 3.17 ± 0.16 g.L−1 of LAS, a value lower than that obtained in shake-flasks (6.49 ± 0.03 g.L−1), but somewhat higher than obtained in STR (0.70 ± 0.12 g.L−1). When glycerol was used as substrate, the production of LAS was less effective than glucose. From the fungal biomass produced, as well as the related growth kinetic parameters (YX/S and QX), fungal growth was more efficient in LSAAB. Lasiodiplodan production by L. theobromae MMPI from glycerol was accelerated by an increase in broth pH during cultivation, and the behavior was opposite (decreased pH) when using glucose. LSAAB proved to be promising for the production of LAS by the fungus studied. Although glucose was shown to be the better substrate for the production of LAS, glycerol, as a fermentation substrate, has potential of a less-expensive medium for cultivating the fungus.