Arsenic (As) in natural waters mainly includes inorganic As and organoarsenicals. The widespread occurrence of As in the aquatic environment, especially in freshwater, has attracted extensive concern, because of its potential environmental risk to human health. Although previous studies has suggested that cyanobacteria and other microorganisms may play an important role in As biotransformation and metabolism in the environment, very little has been studied regarding the influences of environmental factors on arsenic biotransformation and release in algae.
The Scientists of IUE conducted a series of experiments using Taguchi methods to determine optimum conditions for As biotransformation. Arsenate (As(V)), dissolved inorganic nitrogen (N), phosphate (P), and ambient pH were selected as the principal effective factors in this study. The results suggested that N is the critical component for As(V) biotransformation in M. aeruginosa, specifically for As(III) transformation, because N can accelerate algal growth, subsequently improving As(III) accumulation and its efflux, which results in an As(V) to As(III) reduction. Following As(V), P was the primary impacting factor for As accumulation. Furthermore, low P concentrations in combination with high N concentrations promote As accumulation. In addition, small amounts of As accumulation under low concentrations of As and high P were securely stored in living algal cells and were easily released after cell death. Results from this study will help to assess practical applications and the overall control of key environmental factors, particularly those associated with algal bioremediation in As polluted water.
The research results have been published in the famous journal in the field of environment, Water Research 2017, 118: 167–176 (WANG Zhenhong, LUO Zhuanxi, YAN Changzhou, XING .Baoshan Impacts of environmental factors on arsenate biotransformation and release in Microcystis aeruginosa using the Taguchi experimental design approach). The study was supported by the National Natural Science Foundation of China (NSFC) and International Science & Technology Cooperation Program of China.

Mean S/N ratios for (a) intracellular As(V), (b) As(III), and (c) TAs in M. aeruginosa as affected by As, N, P, and pH.