Biology of a terrestrial green alga, Chlorococcum sp (Chlorococcales, Chlorophyta), collected from the Miruksazi stupa in Korea

A terrestrial chlorophyte, Chlorococcum sp., was isolated from the stone walls of Miruksazi stupa, which is a national treasure of Korea. The alga was one of the dominant organisms contributing to biodeterioration of the monument and it grew extensively on the walls of the inner room of the stupa, which had been sealed for more than 5 yr before we started this experiment. Chlorococcum survived in darkness during that time as dormant, warty, thick-walled spores. The resting spores revived in freshwater medium and released numerous unicellular progeny, which were isolated into a unialgal culture. The isolate was subjected to 18S rDNA phylogenetic analysis as well its ultrastructure and life cycle studies. In addition, the effect of salinity stress was investigated using sterile enriched seawater as a medium. Chlorococcum sp. grew in seawater culture medium for more than 5 mo and reproduced by aplanospores.