An investigation onto Cd toxicity to freshwater microalga Chlorella sorokiniana in mixotrophy and photoautotrophy: A Bayesian approach

Autor(es)

Marchello, Adriano Evandir ^{[1, 2]} ; Oliveira, Natalia Lombardi ^[3] ; Lombardi, Ana Teresa ^[1] ; Polpo, Adriano ^[4]

Afiliação do(s) autor(es)

^[1] Univ Fed Sao Carlos, Dept Bot, Lab Algal Biotechnol, Sao Carlos, SP - Brazil

^[2] Univ Fed Sao Carlos, Ctr Biol & Hlth Sci, Postgrad Ecol & Nat Resources, Sao Carlos, SP - Brazil

^[3] Carnegie Mellon Univ, Dept Stat & Data Sci, Pittsburgh, PA 15213 - USA

^[4] Univ Fed Sao Carlos, Ctr Exact Sci & Technol, Dept Stat, Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Chemosphere; v. 211, p. 794-803, NOV 2018.
• Citações Web of Science: 2

Resumo

Aquatic ecosystems are composed by a myriad of dissolved organic materials that can be assimilated by microalgae, while they can perform photosynthesis, this is refereed as mixotrophy. However, ecotoxicological tests usually consider only the photoautotrophic metabolism. This research investigated the ecotoxicological differences between photoautotrophy and mixotrophy in Chlorella sorokiniana exposed to cadmium (Cd). Chlorophyll a, photosynthetic efficiency (Fv/Fm), cell viability, biochemical composition and pH were used to monitor possible toxic effects at 72 h cultures. Glucose (1 g.L-1) was used as organic carbon source. To evaluate the probability of the photoautotrophic culture being more affected by Cc than the mixotrophic one, Bayesian statistical analysis was performed. The photoautotrophic cultures were more affected by Cd than the mixotrophic ones, with reduction of all evaluated parameters, excep for protein concentration. However, in mixotrophic cultures, no changes in protein concentration and proteins:carbohydrates ratio were observed, and chlorophyll a, Fv/Fm and cell viability were only affected at the high Cd concentrations (range In -11.5 to -9.4). However, both mixotrophy and photoautotrophy had the same probability of having the carbohydrates concentration affected by Cd. We conclude that the microalgae in mixotrophy were more resistant to the Cd than in photoautotrophy. In addition, we showed that under photoautotrophy Fv/Fm decreased linearly as Cd concentration increased, but in mixotrophy no effect was observed up to 10-5 molL(-1) Cd, after which it decreased. We rationale that the reduced photosynthetic capacity under mixotrophy can end up reducing the release of oxygen gas, which can compromise the entire aquatic ecosystem. (C) 2018 Elsevier Ltd. All rights reserved (AU)

• Processo FAPESP: 14/15894-0 - Fixação do CO2 em microalgas Chlorophyceae: estudo da fotossíntese e composição bioquímica em diferentes concentrações de CO2
• Beneficiário: Ana Teresa Lombardi
• Modalidade de apoio: Auxílio à Pesquisa - Regular