Purification and characterization of cold-adapted beta-agarase from an Antarctic psychrophilic strain

An extracellular β-agarase was purified from Pseudoalteromonas sp. NJ21, a Psychrophilic agar-degrading bacterium isolated from Antarctic Prydz Bay sediments. The purified agarase (Aga21) revealed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with an apparent molecular weight of 80 kDa. The optimum pH and temperature of the agarase were 8.0 and 30 °C, respectively. However, it maintained as much as 85% of the maximum activities at 10 °C. Significant activation of the agarase was observed in the presence of Mg²⁺, Mn²⁺, K⁺; Ca²⁺, Na⁺, Ba²⁺, Zn²⁺, Cu²⁺, Co²⁺, Fe²⁺, Sr²⁺ and EDTA inhibited the enzyme activity. The enzymatic hydrolyzed product of agar was characterized as neoagarobiose. Furthermore, this work is the first evidence of cold-adapted agarase in Antarctic psychrophilic bacteria and these results indicate the potential for the Antarctic agarase as a catalyst in medicine, food and cosmetic industries.

Catabolite inactivation of trehalose synthesis during growth of yeast on maltose

1. The effects of catbolite inactivation upon the trehalose pathway linked to maltose utilization were investigated in Saccharomyces cerevisiae. Mutant strains devoid of UDPG-trehalose synthase activity were used in this study. 2. Trehalose accumulation was also susceptible to catabolite inactivation as has been reported for the carrier protein, one of the components of the maltose system. Reversibility was only achieved when incubation with glucose did not exceed 5 min and was dependent upon protein sunthesis