Effect of heavy metals on the induction of arsenate reductase of Bacillus megaterium

Abstract

Throughout the world, millions of people are affected by arsenic as they drink contaminated water. Almost all the districts in Bangladesh are under the alarming incursion of arsenic due to its ubiquitous underground presence. Arsenic is responsible for triggering many diseases, such as kidney failure, vertigo, diarrhoea, even cancer in the lung and skin and so on. Widespread arsenic has made it impossible to remove it from the environment. However, management measures can be taken to withstand its effect. Therefore, bioremediation can be one of the ways to remove arsenic from contaminated water. Bacillus megaterium was isolated from the arsenic-contaminated soil. This bacterium produces an arsenate reductase enzyme that can convert arsenate [As(V)] to arsenite [As(III)]. Arsenate reductase enzyme was induced by arsenate. Pretreatment with other heavy metals, like lead and bismuth, also induced this enzyme. Induction also took place in both moving and static culture conditions. In static culture, biofilm was formed, and the most significant amount of enzyme induction occurred in this condition compared to any other culture condition. Enzymatic treatment to separate the cells in biofilm released more enzymes in the medium than mechanical treatment. This strain was able to grow aerobically and anaerobically as well. This strain can be used to further study the effect of various circumstances on the induction of the arsenate reductase enzyme. The results of this research will help the detoxification of arsenic contamination to protect the water, soil, aquaculture, agriculture and global ecosystem. Subsequently, a more meaningful way of bioremediation can be attained.

Jahangirnagar University J. Biol. Sci. 14(1 & 2): 29-40, 2025 (June & December)