title: Combined nitrogen limitation and cadmium stress stimulate total carbohydrates, lipids, protein and amino acid accumulation in Chlorella vulgaris (Trebouxiophyceae).
abstract: Metals have interactive effects on the uptake and metabolism of nutrients in microalgae. However, the effect of trace metal toxicity on amino acid composition of Chlorella vulgaris as a function of varying nitrogen concentrations is not known. In this research, C. vulgaris was used to investigate the influence of cadmium (10(-7) and 2.0×10(-8)molL(-1) Cd) under varying nitrogen (2.9×10(-6), 1.1×10(-5) and 1.1×10(-3)molL(-1)N) concentrations on its growth rate, biomass and biochemical composition. Total carbohydrates, total proteins, total lipids, as well as individual amino acid proportions were determined. The combination of Cd stress and N limitation significantly inhibited growth rate and cell density of C. vulgaris. However, increasing N limitation and Cd stress stimulated higher dry weight and chlorophyll a production per cell. Furthermore, biomolecules like total proteins, carbohydrates and lipids increased with increasing N limitation and Cd stress. Ketogenic and glucogenic amino acids were accumulated under the stress conditions investigated in the present study. Amino acids involved in metal chelation like proline, histidine and glutamine were significantly increased after exposure to combined Cd stress and N limitation. We conclude that N limitation and Cd stress affects the physiology of C. vulgaris by not only decreasing its growth but also stimulating biomolecule production.
authors.affiliation: Department of Botany, Federal University of São Carlos, Rodovia Washington Luis km 235, São Carlos, SP Cep 13565905, Brazil. Electronic address: chia28us@yahoo.com.
authors.forename: Mathias Ahii
authors.initials: MA
authors.lastname: Chia
authors.affiliation: Department of Botany, Federal University of São Carlos, Rodovia Washington Luis km 235, São Carlos, SP Cep 13565905, Brazil.
authors.forename: Ana Teresa
authors.initials: AT
authors.lastname: Lombardi
authors.affiliation: Department of Hydrobiology, Federal University of São Carlos, Rodovia Washington Luis km 235, São Carlos, SP Cep 13565905, Brazil.
authors.forename: Maria
authors.initials: M
authors.lastname: da Graça Gama Melão
authors.affiliation: Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, Newfoundland A1C 5S7, Canada.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Parrish
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D018533:Biomass; D002104:Cadmium / Q000633:toxicity*; D050260:Carbohydrate Metabolism / Q000187:drug effects; D048408:Chlorella vulgaris / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D050356:Lipid Metabolism / Q000187:drug effects; D009584:Nitrogen / Q000378:metabolism / Q000494:pharmacology*; D010758:Phosphorus / Q000494:pharmacology; D010940:Plant Proteins / Q000378:metabolism; D025341:Principal Component Analysis; D013312:Stress, Physiological / Q000187:drug effects*; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D000596:Amino Acids; D010940:Plant Proteins; D014874:Water Pollutants, Chemical; D002104:Cadmium; D002734:Chlorophyll; D010758:Phosphorus; D009584:Nitrogen; D000077194:Chlorophyll A
keywords: Amino acids; Biochemical composition; Microalgae; Nutrients; Physiology; Trace metals