Effect of Temperature and pH on Amylase and Cellulase Activities and Stability

To evaluate the effects of pH on the enzymatic activity and stability, each bacterial culture was incubated at different pH values of 5.0–9.0 using the following buffer reaction solution: Tris–HCl buffer (pH 6.0–8.0), citrate buffer (pH 3.0–5.0), and glycine-NaOH buffer (pH 9.0–10.0); 2.5% starch and 2.0% CMC were used as substrates, respectively. The temperature should be kept at 30°C. The pH value of the cellulase and amylase reaction mixture was adjusted by using the above specified buffers, while both enzymatic activities were quantified as per the standard assay method. The stability of both the enzymes was determined by pre-incubating the enzyme reaction mixture for 30 min at 30°C. Meanwhile, the effects of temperature on the enzymatic activity and stability were determined by incubating each reaction solution at a different temperature (30–70°C) and the pH value should be kept at 7.0 for 1 day and the relative enzymatic activities were measured by the use of 2.5% starch and 2.0% CMC as substrates. The thermal stability of both the enzymes were quantified by pre-incubating the reaction mixtures at 30–70°C temperature and constant pH value of 7.0 for 30 min. The amount of enzyme synthesized was then quantified to analyze the thermal stability of both of the specified enzymes (Awasthi et al., 2018).