Biomethylation and Volatilization of Arsenic by Model Protozoan Tetrahymena pyriformis under Different Phosphate Regimes

Xixiang Yin, Lihong Wang, Zhanchao Zhang, Guolan Fan, Jianjun Liu, Kaizhen Sun and Guo-Xin Sun
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Xixiang Yin: Jinan Research Academy of Environmental Sciences, Jinan 250014, China
Lihong Wang: Shandong Analysis and Test Center, Shandong Academy of Sciences, Jinan 250014, China
Zhanchao Zhang: Jinan Research Academy of Environmental Sciences, Jinan 250014, China
Guolan Fan: Jinan Research Academy of Environmental Sciences, Jinan 250014, China
Jianjun Liu: Jinan Research Academy of Environmental Sciences, Jinan 250014, China
Kaizhen Sun: Jinan Research Academy of Environmental Sciences, Jinan 250014, China
Guo-Xin Sun: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China

IJERPH, 2017, vol. 14, issue 2, 1-9

Abstract: Tetrahymena pyriformis , a freshwater protozoan, is common in aquatic systems. Arsenic detoxification through biotransformation by T. pyriformis is important but poorly understood. Arsenic metabolic pathways (including cellular accumulation, effluxion, biomethylation, and volatilization) of T. pyriformis were investigated at various phosphate concentrations. The total intracellular As concentration increased markedly as the external phosphate concentration decreased. The highest concentration was 168.8 mg·kg ?1 dry weight, after exposure to As(V) for 20 h. Inorganic As was dominant at low phosphate concentrations (3, 6, and 15 mg·L ?1 ), but the concentration was much lower at 30 mg·L ?1 phosphate, and As(V) contributed only ~7% of total cellular As. Methylated As contributed 84% of total As at 30 mg·L ?1 phosphate, and dimethylarsenate (DMAs(V)) was dominant, contributing up to 48% of total As. Cellular As effluxion was detected, including inorganic As(III), methylarsenate (MAs(V)) and DMAs(V). Volatile As was determined at various phosphate concentrations in the medium. All methylated As concentrations (intracellular, extracellular, and volatilized) had significant linear positive relationships with the initial phosphate concentration. To the best of our knowledge, this is the first study of As biotransformation by protozoa at different phosphate concentrations.

Keywords: arsenic; accumulation; biotransformation; phosphate; protozoan; Tetrahymena pyriformis (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2017
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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