Producing Cu-loaded algae for feeding experiments: effects of copper on Parachlorella kessleri

Abstract

Microalgae require several essential metals for optimum growth, which at elevated concentrations may interfere with biochemical and physiological processes, one of them being copper (Cu). The aim of this study is to raise Cu-loaded Parachlorella kessleri as feed for mussels. In order to spike the algae with Cu without lowering their nutritional quality, it is important to know the highest Cu-concentration at which the main parameters remain unaffected, especially in respect to proteins and polysaccharides. The dependence of growth rate, biomass, chlorophyll-a and -b, pheophytin-a, protein, and polysaccharide contents on Cu concentrations are determined. The tests show that P. kessleri is largely unchanged in its nutritional value when exposed to Cu at levels of up to 6 µmol L⁻¹. Above 10 µmol L⁻¹, toxic effects become obvious, with chlorophyll contents and growth rate being the most sensitive indicators.

Keywords:

• copper
• Parachlorella kessleri
• growth rate
• biomass
• chlorophyll-a
• chlorophyll-b
• pheophytin-a
• proteins
• polysaccharides

Acknowledgments

We thank Dr Silke Gerstmann for facilitating helpful discussions. Financial support by Directorate General of Higher Education, Department of National Education of the Republic of Indonesia is highly appreciated.