Effects of Titanium Dioxide Nanoparticles in Different Metabolic Pathways in the Freshwater Microalga Chlorella sorokiniana (Trebouxiophyceae)

Author(s)

Marchello, Adriano Evandir ^{[1, 2]} ; Barreto, Daniela Mariano ^{[1, 2]} ; Lombardi, Ana Teresa ^[1]

Affiliation

^[1] Univ Fed Sao Carlos, Lab Algal Biotechnol, Dept Bot, Rodovia Washington Luis, Km 235, SP 310, BR-13565905 Sao Carlos, SP - Brazil

^[2] Univ Fed Sao Carlos, Postgrad Ecol & Nat Resources, Ctr Biol & Hlth Sci, Rodovia Washington Luis, Km 235, SP 310, BR-13565905 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: WATER AIR AND SOIL POLLUTION; v. 229, n. 2 FEB 2018.
• Web of Science Citations: 5

Abstract

The products that employ nanoparticles (NPs) in their composition have increased since the beginning of NP production; hence, their availability in the environment, especially in aquatic ecosystems, tends to increase. In these ecosystems, the phytoplankton is immersed in a complex matrix of nutrients, excreted materials, and other chemical compounds, which can influence the metabolic strategy of microalgae. One of the metabolic ways is mixotrophy, a situation whereby microalgae perform photosynthesis and use dissolved organic carbon at the same time. Most toxicity evaluations do not consider such a metabolic route, but this can represent a preferential metabolism in natural environments. The present study aimed at evaluating the effects of NP-TiO2 at a log concentration range of -3.10 to 0.89, on photosynthesis, growth, viability, and biochemical composition of the microalgae Chlorella sorokiniana during photoautotrophic and mixotrophic growth (glucose as the organic carbon source). The results showed lower chlorophyll a and photosynthetic activity in mixotrophy than in photoautotrophy, which can be due to a decreased need for photosynthesis in mixotrophy. Photoautotrophy cultures were sensitive to NPs, reaching 39% of viability at log 0.89, while in mixotrophy, cell viability was not affected by NPs. The biochemical composition and cell density changed as a function of NP concentrations, with increase in the protein/carbohydrate ratio in both treatments. The results showed that C. sorokiniana is more resistant to NPs during mixotrophic growth, but with changes in biochemical composition, whereas the photoautotrophic cultures were more sensitive to the increase in NP concentrations. (AU)

• FAPESP's process: 14/15894-0 - CO2 fixation by microalgae Chlorophyceae: photosynthesis and biochemical composition under different CO2 concentrations
• Grantee: Ana Teresa Lombardi
• Support Opportunities: Regular Research Grants