The Impact of Calcium Depletion on Proliferation of Chlorella sorokiniana Strain DSCG150

Abstract

This study analyzed the effects of Ca 2+ metal ions among culture medium components on the Chlorella sorokiniana strain DSCG150 strain cell growth. The C. sorokiniana strain DSCG150 grew based on a multiple fission cell cycle and growth became stagnant in the absence of metal ions in the medium, particularly Ca 2+ . Flow cytometry and confocal microscopic image analysis results showed that in the absence of Ca 2+ , cell growth became stagnant as the cells accumulated into four autospores and could not transform into daughter cells. Genetic analysis showed that the absence of Ca 2+ caused upregulation of calmodulin ( calA ) and cell division control protein 2 ( CDC2_1 ) genes, and downregulation of origin of replication complex subunit 6 ( ORC6 ) and dual specificity protein phosphatase CDC14A ( CDC14A ) genes. Analysis of gene expression patterns by qRT-PCR showed that the absence of Ca 2+ did not affect cell cycle progression up to 4n autospore, but it inhibited Chlorella cell fission (liberation of autospores). The addition of Ca 2+ to cells cultivated in the absence of Ca 2+ resulted in an increase in n cell population, leading to the resumption of C. sorokiniana growth. These findings suggest that Ca 2+ plays a crucial role in the fission process in Chlorella .