Variation of Extracellular Polymeric Substances (EPS) of Chlamydomonas reinhardtii under arsenic stress

Extracellular Polymeric Substances (EPS) are an important component of microorganisms. In this paper, we first compared the effectiveness of EPS extraction methods for amodel green algae (Chlamydomonas reinhardtii), and then investigated variations of EPS under arsenic (As) stress. Components of the algal EPS with or without arsenite and arsenate treatments were analyzed. The results showed that the different EPS extraction methods ranked as follows: NaOH > heating > cation exchange resin > EDTA > centrifugation. However, NaOH extraction caused more cell disruption than the heating approach. The optimal extraction was heating at 50 degrees C, under which the amount of EPS was 40.06 +/- 0.297 mg g(-1). Under 20 mu g L-1 As(V) and 200 mu g L-1 As(III), the amounts of EPS were 41.35 mg g(-1) and 38.63 mg g(-1) respectively, compared to control (46.4 mg g(-1)), indicating that the EPS production of C. reinhardtii was not affected by As.