Nitrate-ammonium utilisation for the green alga species Desmodesmus armatus reared in laboratory batch culture conditions

Monoclonal 1.2 L batch cultures of the green microalga Desmodesmus armatus (R. Chod.) Hegev. (culture accession: NQAIF301, sourced from the North Queensland Algal Culturing and Identification Facility at James Cook University, Townsville, QLD) were reared in standard Bold Basal Medium (BBM). Cultures were kept in a temperature-controlled room at 27 ± 3°C with a 14-10 day-night cycle at a light intensity of 70 µmol photons m2 s-1. Nitrogen was set as the limiting factor for growth in all experimental cultures, supplied between 4 to 8 times below the recommended BBM concentration with either sodium nitrate (NaNO3) for nitrate-BBM, or ammonium chloride (NH4Cl) for ammonium-BBM, or both. Phosphorous, iron, and all other nutrients were supplied at non-limiting concentrations.