Isolation and Growth Characterization of an Acrylamide-degrading Bacillus sp. strain UPM2021n Isolated from the Juru River

Abstract

Polyacrylamide, in which acrylamide is the primary component, degrades back into acrylamide over time. Major amounts of acrylamide can be found in soil. The bioremediation strategy of using microbes to break down acrylamide is gaining popularity in many parts of the world. Several acrylamide-degrading bacteria have been isolated from sediment from the Juru River’s bank. The best isolate was a bacterium identified tentatively as Bacillus sp. strain UPM2021n based on cultural, colony morphology and biochemical tests. According to early studies, ideal growth parameters included a pH range of 6.5 and 7.0 and a temperature range of 25 to 35 degrees Celsius. Both glucose and sucrose performed at a similar level in supporting the growth of this bacterium on acrylamide as the sole nitrogen source. The highest growth occurs in between 300 and 500 mg/L of acrylamide, resulting in a growth of nearly 7.7 log CFU/mL with a nett growth of about 4 Log CFU/mL as compared to the control. Growth was nearly tolerated at the highest concentrations tested, which was 1500 mg/L and growth completely ceased at higher concentrations Toxic heavy metals tested such as mercury, copper, chromium, and cadmium showed that mercury strongly hampered growth on acrylamide whilst other metal ions such as copper, lead, cadmium, and chromium showed from 30 to 60% inhibition. The relatively high tolerance of acrylamide makes this bacterium suitable for remediation of soil contaminated with acrylamide whilst its sensitivity to heavy metals chiefly mercury means metal-chelating or sequestering compounds must be added to soil contaminated with both acrylamide and heavy metals.