Saccharification of Ulva lactuca via Pseudoalteromonas piscicida for biofuel production

摘要

Pseudoalteromonas piscicida WM21 was isolated from seawater at Hurghada, Red Sea, Egypt. It was promising to hydrolyze the polysaccharides of Ulva lactuca. Ulva lactuca contained 44% carbohydrates, 5% lipids, 16% proteins, 12% Fibers and 23% ash. Optimization of reducing sugars production by P. piscicida WM21 was investigated using PlackettBurmman design. The main effect data as well as the t-test results suggested that the beef extract and inoculum size are the most effective variables that controlled the reducing sugar produced by P. piscicida. Considerable positive effects of the high levels of substrate concentration and low levels of incubation period were also suggested. On the other hand, variations within the examined levels of pH levels, NaCl and peptone recorded slight effects. While the main effect data as well as the t-test results suggested that the substrate concentration and incubation period were the most effective variables that controlled amylase activity produced by P. piscicida. To evaluate the accuracy of the applied Plackett-Burman statistical design, a verification experiment was carried out. The predicted near optimum and far from optimum levels of the independent variables were examined and compared to the basal condition settings. The applied near optimum condition, resulted in approximately 56 mg/g increase in reducing sugar with 6 mm amylase activity by P. piscicida when compared to the basal medium formulation, while the conditions predicted to be far from optimal recorded approximately 45 mg/g decreases in reducing sugar with 3 mm amylase activity. These results supported the predictions of the applied Plackett-Burman experiment for enhancement of reducing sugar production by marine microorganisms.