Extra and intracelular activities of carbonic anhydrase of the marine microalga Tetraselmis gracilis (Chlorophyta)

Abstract

The activities of extra and intracellular carbonic anhydrases (CA) were studied in the microalgae Tetraselmis gracilis (Kylin) Butcher (Chlorophyta, Prasinophyceae) growing in laboratory cultivation. During ten days of batch cultivation, daily determinations of pH, cell number, enzymatic activity, and total dissolved inorganic carbon (DIC), as well as its main species, CO2 and HCO3 -, were performed. Enzymatic activity increased as the growing cell population depleted inorganic carbon from the medium. Carbon dioxide concentration decreased quickly, especially in the third day of cultivation, when a significant increase of the intracellular enzymatic activity was observed. Bicarbonate concentration had its largest decrease in the cultivation medium in the fourth day, when the activity of the extracellular enzyme had its largest increase, suggesting its use by the alga through CA activity. After the fourth cultivation day, half of the cultures were aerated with CO2-free atmospheric air, which caused an increase in the total and external activity of the enzyme, although, in this condition, the stationary growth phase began earlier than in cultures aerated with atmospheric air. The pH of the media was measured daily, increasing from the first to the fourth day, and remaining almost constant until the end of the cultivation. Algal material transferred to the dark lost all enzymatic activity.

An investigation into producing Botryococcus braunii in a tubular photobioreactor

“…Nonetheless, many species of microalgae can actively transport bicarbonate ions across the plasma membrane to the cytosol, where the intracellular activity of carbonic anhydrase maintains a steady flux of CO 2 to ribulose bisphosphate carboxylase oxygenase (RuBisCo) for photosynthesis. Alternatively, extracellular carbonic anhydrase (CA) can also catalyze the interconversion between HCO 3 − and CO 2 , which has been evidenced for photosynthetic microorganisms . With pH in the culture medium maintained at 7.3 ± 0.5, the dynamic equilibrium between bicarbonate and CO 2 also provides this gas to the cell.…”

The effect of carbon dioxide rich environment on carbonic anhydrase activity, growth and metabolite production in indigenous freshwater microalgae

“…Assay of CA activity was carried out electrometrically using a modified procedure of Wilbur and Anderson [45] as described by Rigobello-Masini et al [46]. For the preparation of the algal extract, the optical density of microalgal culture was measured spectrophotometrically at 560 nm and a culture aliquot of 2ml was centrifuged at 5708 RCF.…”

“…The preparation of algal extract and reaction was performed at low temperature (0-2 o C). The carbonic anhydrase enzyme activity was calculated by using the following equation [46].…”

Extracellular carbonic anhydrase: Method development and its application to natural seawater

“…eCA is constitutive in most of the marine phytoplankton, whereas the expression was regulated by the concentration of inorganic carbon (Nimer et al ; Elzenga et al ). Previous studies have shown that the activity of eCA in marine phytoplankton depends on the availability of inorganic carbon, light and the pH (Moroney et al ; Rigobello‐Masini et al ). Expression of eCA increased at low partial pressure of CO 2 (pCO 2 ) and light availability, but essentially the expression was reduced at conditions with higher pCO 2 .…”