Abstract
A marine Alternaria alternata was tested for its ability to produce amylase by solid state fermentation (SSF) and submerged fermentation (SMF). Various lignocellulosic wastes such as corn cobs, wheat bran, potato shells, wheat straw and rice straw were used as solid substrates. The highest titer of amylase activity was obtained on potato shells by SSF (46.47 U/g solid substrate) compared to 41.19 U/g solid substrate by SMF after 14 day of fermentation. The highest extraction yield of alpha-amylase (183.57 U/g solid substrate) was obtained with acetate buffer (0.05 M, pH 5) as a leaching agent, 75% sea water concentration and pre-treatment of the waste by boiling in water for 60 min. Repeated washes under the optimum conditions showed that most of the enzyme (about 90.31%) was recovered in four repeated extractions. The calculated values of the half life for the crude amylase at 50, 55 and 60 degrees C were 189.86, 99.82 and 93.77 min, respectively. Optimum alpha-amylase enzyme activity was observed at 40 degrees C and active at wide range of pH. The calculated Km and Vmax for a-amylase were 1.90 mg/ml and 0.33 U/mg protein, respectively. Presence of Na+ enhanced amylase activity by 2-fold. Moreover, the enzyme was able to hydrolyze corn starch under optimized conditions with efficiency 85%.