The Function of CBM32 in Alginate Lyase VxAly7B on the Activity on Both Soluble Sodium Alginate and Alginate Gel

Carbohydrate-binding modules (CBMs), as an important auxiliary module, play a key role in degrading soluble alginate by alginate lyase, but the function on alginate gel has not been elucidated. Recently, we reported alginate lyase VxAly7B containing a CBM32 and a polysaccharide lyase family 7 (PL7). To investigate the specific function of CBM32, we characterized the full-length alginate lyase VxAly7B (VxAly7B-FL) and truncated mutants VxAly7B-CM (PL7) and VxAly7B-CBM (CBM32). Both VxAly7B-FL and native VxAly7B can spontaneously cleavage between CBM32 and PL7. The substrate-binding capacity and activity of VxAly7B-CM to soluble alginate were 0.86- and 1.97-fold those of VxAly7B-FL, respectively. Moreover, CBM32 could accelerate the expansion and cleavage of alginate gel beads, and the degradation rate of VxAly7B-FL to alginate gel beads was threefold that of VxAly7B-CM. Results showed that CBM32 is not conducive to the degradation of soluble alginate by VxAly7B but is helpful for binding and degradation of insoluble alginate gel. This study provides new insights into the function of CBM32 on alginate gel, which may inspire the application strategy of CBMs in insoluble substrates.

Weakening of the Transdermal Effect of p-Phenylenediamine Pigments by the Temperature-Sensitive Poloxamer Sodium Alginate Gel

A temperature-sensitive hair dye was prepared with a poloxamer-sodium alginate mixture. When the hair dye was applied to the hair (< 32 °C), it retained its flow dynamics. The hair dye was able to undergo a phase change and formed a solid as soon as it touched the scalp (32°C), which reduced the transdermal amount of p-phenylenediamine (PPD) and also adverse effects and toxicity. Compared to a conventional hair dye, the temperature-sensitive hair dye achieved a reduction of the transdermal amount of p-phenylenediamine by almost 65% at different concentrations. At the same time, the colouring effect was not significantly reduced. The poloxamer alginate hydrogel can be used as a novel colouring material to reduce the harm of the dye intermediate to the human body when colouring hair.

Addition of disaccharides and dimethyl sulfoxide to sodium alginate gel improves viability of immobilized Saccharomyces boulardii after cryopreservation

Gel-immobilized microorganisms are increasingly used in microbiological industries. Currently, the problem of developing technologies for long-term storage of microorganisms immobilized in gel carriers remains urgent. Low-temperature storage is the most effective method of preserving microorganisms. The viability of immobilized cells is affected by cryoprotective properties of gel matrix as well as cooling regimes. Therefore, the effects of incorporation of cryoprotective agents in alginate gel and cooling regimes on the viability of immobilized Saccharomyces boulardii cells after cryopreservation were studied. Incorporation of non-permeable cryoprotectants (sucrose, lactose, and trehalose) and permeable one dimethyl sulfoxide (DMSO) in alginate gel beads promoted an increase in the viability of immobilized cells after freeze-thawing. The highest viability rates of the gel-immobilized cells were observed in the alginate gel beads incorporating combinations of DMSO (5 – 10 % v/v) and one of the disaccharides (10 – 20 % w/v). In all experiments, slow cooling provided significantly higher viability if compared to the rapid immersion of the samples into liquid nitrogen.