Control of the specific growth rate of Bacillus subtilis for the production of biosurfactant lipopeptides in bioreactors with foam overflow

Abstract

International audienceThis paper formulates a feeding law for a bioprocess dedicated to the production of an antibiotic surfactant using Bacillus subtilis. The specificity of the process relies on the use of the surface active property of the product to extract it by foaming. The control law is designed to maintain a constant specific biomass growth rate while taking into account the particularity of the process. This law can be regarded as a generalization of the conventional exponential feeding strategy and is generic enough to encompass the case of continuous processes with partial recycling. Conventional exponential feeding strategies indeed fail to account for the loss of biomass induced by the foaming. Previous experiments have provided a model of the process and values for its parameters. From this information, a feeding rate law was computed using the feeding strategy proposed in this paper and applied to an experimental culture. This experiment allows discussion of the modeling of the biomass extraction method used in this study. The results on the estimated specific growth rate highlight the complete agreement between the expected and experimental features. Further process optimization studies can now be performed on the basis of the constant specific biomass growth rat

Purification and structural characterization of fengycin homologues produced by Bacillus subtilis LSFM-05 grown on raw glycerol

“…The most studied family is the surfactins, which may be the most powerful biosurfactants known and also exhibit antiviral and antifungal activity, and contain heptapeptides attached to a b-hydroxy fatty acid with carbon number in the range of 13-15 [13,19,37]. The mycosubtilin, iturin and bacillomycin family, contain heptapeptides attached to b-amino fatty acids and exhibit strong antifungal activity [7,33,44]. Fengycins represent the third family of Bacillus lipopeptide surfactants and, including the related plipastatin.…”

Real-time monitoring and control of microbial bioprocesses with focus on the specific growth rate: current state and perspectives

“…Feed-forward control by a priori calculation of an exponential feed trajectory, based on a simple combination of mass balances and Eq. 1, has been widely exploited to maintain μ constant throughout the culture (Pico-Marco et al 2005;Ren and Yuan 2005;Babaeipour et al 2007;Jungo et al 2007;Warth et al 2010;Chenikher et al 2010;Arnau et al 2010;Chen et al 2011). The mathematical description of the exponential feed trajectory is given in Eq.…”

Practical Solutions for Specific Growth Rate Control Systems in Industrial Bioreactors

“…where X = xV (g) is the cell (biomass) amount; x (g/L) is the cell (biomass) concentration; and V (L) is the cultivation broth volume. The SGR is the most important variable in biotechnological processes, which influences the physiological state of microbial culture, production of cell biomass and desired products, and quantity and quality of products [3][4][5][6][7][8].…”