Continuous cultivation of a thermophilic bacterium Aeribacillus pallidus 418 for production of an exopolysaccharide applicable in cosmetic creams.

AIMS: The aim of this study was to evaluate the effectiveness of continuous cultivation approach for exopolysaccharide (EPS) production by a thermophilic micro-organism and the potential of the synthesized EPS for application in cosmetic industry. METHODS AND RESULTS: Study on the ability of Aeribacillus pallidus 418, isolated as a good EPS producer, to synthesize the polymer in continuous cultures showed higher production in comparison with batch cultures. The degree of the EPS in the precipitate after continuous cultivation significantly increased. Non-Newtonian pseudoplastic and thixotropic behaviour of EPS determines the ability of the received cream to become more fluid after increasing time of application on the skin. CONCLUSIONS: This study demonstrates a highly efficient way for production of EPS from a continuous growth culture of A. pallidus 418 that have many advantages and can outperform batch culture by eliminating time for cleaning and sterilization of the vessel and the comparatively long lag phases before the organisms enter a brief period of high productivity. The valuable physico-chemical properties of the synthesized EPS influenced positively the properties of a commercial cream. SIGNIFICANCE AND IMPACT OF THE STUDY: EPSs from thermophilic micro-organisms are of special interest due to the advantages of the thermophilic processes and nonpathogenic nature of the polymer molecules. However, their industrial application is hindered by the comparatively low biomass and correspondingly EPS yield. Suggested continuous approach for EPS could have an enormous economic potential for an industrial scale production of thermophilic EPSs.

Brevibacillus themoruber: a promising microbial cell factory for exopolysaccharide production.

AIMS: This study aims to identify a high level exopolysaccharide (EPS) producer thermophile that in turn could be used as a model organism to study the biological mechanisms and whole genome organization of EPS-producing thermophilic bacteria. METHODS AND RESULTS: Thermophilic isolates were screened, and then growth and EPS production of the best producer Brevibacillus thermoruber strain 423 were investigated under different carbon and nitrogen sources, temperature, pH and agitation rates. Rheological characterization revealed that the EPS behaved like a typical Newtonian fluid and viscosity of the EPS solution increased with increasing Ca(2+) ion concentration. Chemical characterization by TLC, GC-MS, FT-IR and NMR suggested a heteropolymer structure with glucose as major monomer unit. High biocompatibility of pure EPS fractions suggested their potential use in biomedical applications. CONCLUSIONS: This study reports on the comprehensive description of microbial production conditions as well as chemical, rheological and biological characterization of the EPS produced by B. thermoruber strain 423. The bioreactor cultures were found to reach two times higher yields and three times higher productivities when compared with literature. SIGNIFICANCE AND IMPACT OF THE STUDY: Brevibacillus thermoruber strain 423 combined the advantages of its nonpathogenicity with the advantages of fast productivity and hence proved to be a very promising model organism and cell factory for microbial EPS production.