Magnetic stirrers attached to the microcosm lids were switched off during diatom addition and only turned on again 1 h after complete settlement of the diatoms.
A power adaptor is connected to the back outer surface of the unit to supply DC current to the magnetic stirrers from a 220 AC source.
Cells were grown at 30 °C in baffled shake flasks and sealed glass vials with magnetic stirrers and rubber stoppers to follow aerobic and anaerobic growth, respectively.
These mixing operations are difficult to accommodate with magnetic stirrers because the vast majority of such stirrers are designed not to entrain vapor.
Briefly, a 50 ml quantity of H2O was first added to a reaction vessel and stirred vigorously using magnetic stirrers.
The bottles were sealed with rubber lined caps to maintain the cultures anaerobically and stirred on magnetic stirrers for seven days.
Sixteen millimoles of the pure L-form of aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, valine, methionine, isoleucine, leucine, phenylaianine, iysine, tryptophan, histidine, and arginine were rinsed into 700 ml of H20, heated to 70°C in a water bath and stirred with magnetic Stirrers until all the amino acids were dissolved.
The diffusion cells were placed on multiple-site magnetic stirrers (RO 5 power, IKA-Werke GmbH and Co. KG, Staufen, Germany) to keep the receptor medium homogenous throughout the sampling period (magnetic cross stir bars, 5 × 10 mm, VWR International GmbH, Darmstadt, Germany).
Magnetic stirrers (JB-2A, Shanghai Rex Instrument Factory, China) were positioned under the flasks to stop the algal cells sticking.
Well-used magnetic stirrers harbour metal atoms that could bias the results of chemical and biochemical reactions.
