A Procedure for High-Yield Spore Production by Bacillus s ubtilis

Abstract

Bacillus subtilis spores have a number of potential applications, which include their use as probiotics and competitive exclusion agents to control zoonotic pathogens in animal production. The effect of cultivation conditions on Bacillus subtilis growth and sporulation was investigated in batch bioreactions performed at a 2-L scale. Studies of the cultivation conditions (pH, dissolved oxygen concentration, and media composition) led to an increase of the maximum concentration of vegetative cell from 2.6 x 10(9) to 2.2 x 10(10) cells mL(-)(1) and the spore concentration from 4.2 x 10(8) to 5.6 x 10(9) spores mL(-)(1). A fed-batch bioprocess was developed with the addition of a nutrient feeding solution using an exponential feeding profile obtained from the mass balance equations. Using the developed feeding profile, starting at the middle of the exponential growth phase and finishing in the late exponential phase, an increase of the maximum vegetative cell concentration and spore concentration up to 3.6 x 10(10) cells mL(-)(1) and 7.4 x 10(9) spores mL(-)(1), respectively, was obtained. Using the developed fed-batch bioreaction a 14-fold increase in the concentration of the vegetative cells was achieved. Moreover, the efficiency of sporulation under fed-batch bioreaction was 21%, which permitted a 19-fold increase in the final spore concentration, to a final value of 7.4 x 10(9) spores mL(-)(1). This represents a 3-fold increase relative to the highest reported value for Bacillus subtilis spore production.

Identification and characterization of Bacillus subtilis from grass carp (Ctenopharynodon idellus) for use as probiotic additives in aquatic feed

“…In this study, the sporulation rates of GC-5 and GC-21 were almost 100% and that of GC-6 was more than 90% after 72 h incubation, which was coordinated with a recent report [29]. However, the sporulation rate of GC-22 was much weaker, which might be correlated with the medium, aeration or temperature [32] or because that GC-22 has different mechanism in sporulation process. It is worth mentioning that the commercial probiotic B. subtilis C-3102 also showed poor sporulation, which could be improved through optimizing the culture conditions, such as aeration and cell density, in industrial bioreactors [32].…”

“…However, the sporulation rate of GC-22 was much weaker, which might be correlated with the medium, aeration or temperature [32] or because that GC-22 has different mechanism in sporulation process. It is worth mentioning that the commercial probiotic B. subtilis C-3102 also showed poor sporulation, which could be improved through optimizing the culture conditions, such as aeration and cell density, in industrial bioreactors [32]. From another point of view, GC-22 may also be used as a new model to study the mechanism of sporulation.…”

Bet hedging or not? A guide to proper classification of microbial survival strategies

“…Characteristics of the selection environment, such as the magnitude and frequency of changes, determine the mean, the variance as well as other distributional characteristics of the phenotype distribution [32,33]. For instance, isogenic B. subtilis MB24 cells have been shown to sporulate with an efficiency of about 15% in a noncontrolled batch culture [34]. The observed sporulation efficiency might be the result of a selection process that favours this efficiency not only over a sporulation efficiency of 0 or 100% (non-sporulating vs. non-reproducing population), but also over an isogenic population with a sporulation efficiency of 20%.…”

Bacillus-Based Biological Control of Plant Diseases

“…They are produced by the bacteria when environmental conditions are unfavorable which probably helps these microorganisms to survive in the phytosphere. The phenomenon can also be exploited in industrial production as sporulation can be induced at the end of cultures (Monteiro et al, 2005). This greatly facilitates post-culture conditioning as bacterial suspensions can be converted to easy to handle powder formulations without the impressive bacterial mortality observed with non-sporulating bacteria (Lolloo et al, 2010).…”