The role of alginate lyases in the enzymatic saccharification of brown macroalgae, Macrocystis pyrifera and Saccharina latissima

In this work, we have compared the carbohydrate content and the enzymatic saccharification of the brown algae Macrocystis pyrifera from Chile and Saccharina latissima from Norway. M. pyrifera contained 40% mannitol, 31% uronic acids and 15% glucose, while S. latissima contained 37% glucose, 30% uronic acids and 25% mannitol. Thus, the ratio between mannitol and glucose was much higher for M. pyrifera. Acid pre-treated and untreated algae were enzymatically saccharified in two steps; first at pH 7.5, 25 °C for 12 h with a blend of recombinant alginate and oligoalginate lyases, then the pH was changed to 5.2, a commercial cellulase cocktail was added and saccharification continued at 50 °C for 4 h. These experiments showed that the use of recombinant alginate lyases and oligoalginate lyases in combination with cellulases increased the release of glucose from untreated seaweed. However, for saccharification of pretreated algae, only cellulases were needed to achieve high glucose yields. Finally, it was shown that brown algae hydrolysates could be used as a growth medium to produce microbial ingredients, such as Candida utilis yeast.