Enzymes from marine phycophages that degrade cell walls of seaweeds

Agarase, cellulase and alginate lyase activities from crude extracts of Aplysia dactylomela Rang, Haliotis coccinea canariensis Nordsieck, Littorina striata King et Broderip and Diadema antillarum Phillipi were measured in vitro to compare digestive efficiencies against several components of complex seaweed cell walls. Commercial abalone acetone powder (AAP, an extract from Haliotis sp.; Sigma, Ref. A-7514) and purified (Sigma, Ref. A-6306) and non-purified agarases from Pseudomonas atlantica were used with the same objective. Optimum conditions for agarase and cellulase activities were 40°C and pH 6.0. For alginate lyase, optimum temperature and pH were species-dependent. Highest reducing sugar release was shown by crude extracts from A. dactylomela. These crude extracts displayed high agarase activity compared with bacterial agarases at 40°C, and were significantly higher at 25°C. AAP and crude extracts from L. striata and D. antillarum exhibited high specific activities on all the substrates. Cold extract from Gracilaria spp. was the best substrate with which to measure agarase activity.