Assay for Determination of α-Amylase Activity in Activated Sludge Mixed Bacterial Communities

In municipal wastewater a significant fraction of the biodegradable material is comprised of macromolecular carbohydrates. This complex material must be hydrolyzed enzymatically prior to bacterial uptake and utilization. An assay method was developed to monitor the overall rate of α-amylase hydrolytic activity in a mixed culture of activated sludge. The method is based on the tracer material amylose azure, a potato starch covalently labelled with Remazol Brilliant Blue R dye. Results of batch experiments under aerobic, anoxic and anaerobic conditions indicate marked differences in the rate of cleavage of α(1–4) glucan bonds. The hydrolysis rate of the complex carbohydrate material in activated sludge was found to be highest under anaerobic conditions and lowest under aerobic conditions, with an intermediate value under anoxic conditions.