Water-soluble chitosan derivatives and pH-responsive hydrogels by selective C-6 oxidation mediated by TEMPO-laccase redox system.

Chitosan is a polysaccharide with recognized antioxidant, antimicrobial and wound healing activities. However, this polymer is soluble only in dilute acidic solutions, which restricts much of its applications. A usual strategy for improving the functionality of polysaccharides is the selective oxidation mediated by 2,2,6,6-tetra-methyl-1-piperidinidyloxy (TEMPO) using laccase as a co-oxidant.

Effects of metabolic pathway precursors and polydimethylsiloxane (PDMS) on poly-(gamma)-glutamic acid production by Bacillus subtilis BL53.

The aims of this study were to evaluate the effects of the addition of metabolic precursors and polydimethylsiloxane (PDMS) as an oxygen carrier to cultures of Bacillus subtilis BL53 during the production of γ-PGA. Kinetics analyses of cultivations of different media showed that B. subtilis BL53 is an exogenous glutamic acid-dependent strain.

Production and optimization of poly-γ-glutamic acid by Bacillus subtilis BL53 isolated from the Amazonian environment.

The aims of this research were to screen and characterize a new microbial source of γ-PGA, to optimize aspects of culture conditions and medium composition using central composite design and response surface methodologies. The influence of bioreactor stirring rates on the production of γ-PGA was also investigated and the oxygen volumetric mass transfer coefficients (k La) were established. The most productive strain was identified by 16S rDNA analysis as Bacillus subtilis, and its γ-PGA production in rotatory shaker was threefold increased under optimized conditions (37 °C, pH 6.