ABSTRACT

To study As bioaccumulation and the production of volatile As compounds, 100 mL Erlenmeyer flasks containing 40 mL of Sabouraud broth were inoculated with 5a mL spore suspension of S. brevicaulis strain. The medium was then enriched with 5 mL of 0.25 mg and 2.50 mg of As(III) and 0.19 mg and 1.90 mg of As(V) to reach

1 INTRODUCTION

Arsenic (As) species are widely distributed in nature. Dis tribution of As can be greatly affected by various microbial mechanisms such as oxidation, reduction or alkylation resulting in changes of its speciation, mobility, bioavailability and toxicity. Aerobic and anaerobic microorganisms such as bacteria and filamentous fungi are particularly re sponsible for the evolution of volatile As compounds (Cullen & Reimer 1989). Volatile As compounds such as arsines, methylarsines and arsenic oxides as the results of microbial volatilization are more mobile, bioavailable and often more toxic compared with inorganic trivalent and pentavalent As species. On the contrary, biosorption and bioaccumulation of As by microscopic filamentous fungi and other microbes can led to its immobilization and lower migration in the environment. Moreover, both processes are considered to be an effective bioremediation tool (Chojnacka 2009).