Procedures for cultivation, observation, and conventional experiments in Cyanidioschyzon merolae

Abstract

Cyanidioschyzon merolae 10D was originally isolated from a mixture of hot spring water sampled in Naples, Italy. Currently, this strain is available in the Microbial Culture Collection at the National Institute of Environmental Studies in Japan. The strain has been cultured in 2×Allen's medium or its derivatives. The optimal growth conditions for this strain are as follows: pH 2.5, 42 °C, and ~100 μmol photons m -2 s -1, allowing the cell density to reach ~5×108 cells mL -1. C. merolae can also grow slowly at >20 °C. We generally store stock cultures at room temperature or at 30 °C under a low light condition (~20 μmol photons m -2 s -1) or as frozen stock in liquid nitrogen. Cell cycle progression can be synchronized by subjecting the culture to a 12-h light/12-h dark cycle. In addition, cells can be arrested at the S or M phases by adding relevant inhibitors. The shapes of cells and chloroplasts are clearly observed by phase-contrast or differential interference contrast microscopy. Because C. merolae lacks a cell wall, cellular contents (e.g., DNA, RNA, and proteins) are easily extracted.