Toxicity of Carbon Tetrachloride to Dunaliella salina, an Environmentally Tolerant Alga

Abstract

Carbon tetrachloride (CCl₄), a water disinfection by-product, at low environmentally relevant concentrations exerts adverse effects on mammals.The unicellular microalga Dunaliella salina possessing a remarkable degree of environmental adaptation was selected as test organism to investigate low-level exposure to CCl₄. With incubation with less than 0.13% CCl₄, algae responses were similar to control as evidenced by cell growth and levels of β-carotene, a marker of adaptation. The maximal concentration of CCl₄ that D. salina could tolerate was 0.2%. Algae incubated with more than 0.32% CCl₄ showed decreased growth and reduced β-carotene levels, which were nondetected after a few days. However, after 98 d, D. salina seemed to revive as evidenced by growth and returned to the biomass similar to control in another 25 d. Randomly amplified polymorphic DNA (RAPD) method was used to compare the genomic DNA difference between control and recovered cells. Polymorphic and repeatable RAPD bands indicated that chronic effects of CCl₄ to D. salina led generation of altered genomic DNA, which may enable the microalga to adapt to survival in an apparently toxic substance environment.

The project is partly supported by the National Science Foundation of China (20676041).

Notes

IARC. Carbon Tetrachloride. In Re-evaluation of some organic chemicals, hydrazine and hydrogen peroxide (part two) (IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, Vol. 71), pp. 401–432. Lyon: International Agency for Research on Cancer.