Phycology International

Comparative characteristics of cytosolic and chloroplastidial D/L- myo-inositol-1-phosphate phosphatase partially purified from Enteromorpha intestinalis (L.) Nees (a marine macro alga) grown under high salinity niche

Sautrik Basu — 2021-10-19

The present investigation describes a protocol for partial purification and basic characterization of one of the key enzymes of myo-inositol biosynthesis, D/L- myo- Inositol-1-phosphate phosphatase (MIPP), from a marine macro alga (Enteromorpha intestinalis) growing under varying salinity conditions of Chilika lagoon (Odisha, India). Cytosolic and chloroplastidial forms of MIPP were partially purified to about 55- and 16- folds respectively following lowspeed centrifugation, high-speed centrifugation, 0-80% ammonium sulfate precipitation, successive chromatography through CM-cellulose, Sephadex G-200 and UltrogelAcA 34 columns. The apparent molecular weights of the native cytosolic and plastidial forms of MIPP were determined to be 146 and 148 kDa respectively. Cytosolic and plastidial MIPP were remarkably active within the temperature range of 20-40°C and function within a narrow pH range (7.0-7.5). Using nonlinear regression kinetics, the Km value for D-MIP of the cytosolic MIPP and its plastidial iso-form were 0.07277 mM and 0.07332 mM respectively. Different monovalent as well as divalent cations exhibited variable effects on enzyme activity of either preparation. The activity of MIPP was remarkably found to increase proportionately with the salinity of Chilika lagoon.

Marine cyanobacteria from Mauritian waters

Rajni Sooroojebally — 2021-12-08

Cyanobacteria are phototrophic gram negative prokaryotes which include more than 150 genera and 200 species. Tropical marine ecosystems harbor a specific cyanobacterial flora while those forming the benthic community are known for their profilic source of natural products as well as their toxin production. Since no recent research had been entertained in determining the diversity of benthic cyanobacteria in Mauritius, this study aimed at identifying the benthic mat-forming cyanobacteria which inhabit the Mauritian lagoons. Samples were collected around the coastal areas of the Island during the summer season from Blue Bay, Albion, Balaclava and Grand River South East. Based on phenotypic and genotypic characters, 11 cyanobacterial strains were successfully identified to genus level, out of 12 samples collected. DNA extraction was performed using a Chelex-100 method which resulted in amplifications products when PCR was carried out. These cyanobacteria belong to the filamentous group of Lyngbya, Leptolynbya, Oscillatoria and Anabaena genera and the non-filamentous group of Merismopedia genera. Phylogenetic inferences based on 16s rRNA sequences revealed that the cyanobacterial strains evolved from a common ancestor, forming monophyletic clades. The identification of cyanobacterial strains up to the species level was not successful using both morphological and molecular characterization, suggesting the need for other important information such as ultrastructural morphology, ecophysiological characters or whole genome sequencing to ascertain their identity.

Tolerance and metabolic responses of Cyanidiophytina (Rhodophyta) towards exposition to Cl4K2Pd and AuCl4K

Maria Sirakov — 2021-11-08

Polyextremophilic algae, such as unicellular red algae known as Cyanidiophyceae, have the intrinsic capacity to selectively mobilize and adsorb metals, since they are adapted to live in geothermal and volcanic sites characterized by elevated concentration of heavy and rare metals. In this work we evaluated the ability of 3 strains of the genus Galdieria (G. maxima, G. sulphuraria, G. phlegrea) along with one strain of Cyanidium caldarium to tolerate different concentrations of rare metal as Cl₄K₂Pd and AuCl₄K by monitoring changes in algal growth in culture exposed to different concentration of each metal and investigating algae metabolic response and possible oxidative stress induced by these metals.