Evaluation of the enzymatic activity of immobilized Lysobacter sp. microorganisms

The specific enzymatic activity of bacterial cultures illustrates the key applications of a studied strain of bacteria and the biological products based on it. The aim of this study was to determine the enzymatic activity of immobilized Lysobacter sp. cells on inorganic matrices. The proteolytic activity of extracellular enzymes in the temperature range 20-40 and the activity of β-1,4-glucanase were studied, and the influence of pH and temperature on the activity and stability of the enzyme was revealed. Optimal cultivation conditions for the Lysobacter strain were selected for the highest production of β-1,4-glucanase: glucose, 1% by weight; yeast extract, 0.2% by weight; CMC, 0.75% by weight; pH 7; amount of inoculum, 3.5% by volume; and optimal temperature for incubation, 30°C. Enzyme stability results showed that the enzyme retained 90% of its activity after minimal preincubation at pH 5.5 and more than 60% of its maximum activity at pH 4–10, demonstrating stability over a wide pH range. Therefore, it can be considered as an acid/alkali-resistant enzyme. It was found that the greatest activity of the enzyme occurs at 50 °C. When the temperature is increased to 50 °C, the enzyme activity increases and then decreases linearly. More than 60% of β-1,4-glucanase's enzymatic activity is observed in the range of 20-60 °C. Consequently, biocompositions based on Lysobacter sp. can be used in a wide range of temperatures and pH, which represents its promising use as a probiotic drug.