Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8850338 | Chemosphere | 2018 | 35 Pages |
Abstract
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 72â¯h cultures. Glucose (1â¯g.Lâ1) was used as organic carbon source. To evaluate the probability of the photoautotrophic culture being more affected by Cd 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, except 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 ln â11.5 to â9.4). 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 10â5 molLâ1 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.
Related Topics
Life Sciences
Environmental Science
Environmental Chemistry
Authors
Adriano Evandir Marchello, Natalia Lombardi Oliveira, Ana Teresa Lombardi, Adriano Polpo,