TITLE:
Enhanced Spore Production of Bacillus subtilis Grown in a Chemically Defined Medium
AUTHORS:
S. M. S. Monteiro, J. J. Clemente, M. J. T. Carrondo, A. E. Cunha
KEYWORDS:
Bacillus subtilis, Spores, Probiotics, Bioreaction, Fed-Batch
JOURNAL NAME:
Advances in Microbiology,
Vol.4 No.8,
June
17,
2014
ABSTRACT: Spores of Bacillus subtilis are being used as probiotics and
competitive exclusion agents for animal consumption. Commercial production
media often include relatively expensive components of animal origin that are a
potential source for the presence of adventious agents, therefore undesirable
for use in production scale. In this study a new animal-free component,
chemically defined medium, was tested for B.
subtilis spore production. Medium composition was optimized with respect to
vitamin composition, carbon, nitrogen and calcium concentrations. A fed-batch
bioprocess was developed, being the effect on sporulation of the carbon to
nitrogen ratio at the end of the exponential growth phase studied. The
developed strategy consisted of an initial and a final batch phase and an
intermediate fed-batch phase with the addition of a feeding solution containing
glucose and calcium and the addition of a feeding solution of ammonium
sulphate, using an exponential and a constant feeding profile, respectively.
Using the fed-batch strategy, it was possible to achieve a maximum spore
production of 3.6 × 1010 spores/mL, corresponding to a 5 folds
increase when compared to the preliminary batch experiments.