Assessing the salt tolerance of Spirulina platensis freshwater strains and examining cheap culture media for cultivation of the potential strain

Spirulina cyanobacteria have been widely cultivated to exploit products such as crude protein, vitamins, phycocyanin pigment... with high nutritional and pharmacological values. However, the commercialization of these products is still a challenging issue due to high biomass cost, which is mainly caused by expensive nutrients in the culture medium. In this study, from 11 freshwater S. platensis strains, by culture screening, we found 7 strains being capable of profitable growth on inexpensive seawater with salinity ranging from 5 - 30‰, and selected ST strain as the potential strain for further study. Natural seawater must be pretreated to remove ions that easily cause precipitation of nutrients in the culture medium such as Mg2+, Ca2+, SO42-… before using. The ST strain showed the best growth in the natural seawater medium with 30‰ salinity containing 3 g/L NaNO3, 0.5 g/L K2HPO4, 0.05 g/L FeSO4. This strain reached the highest biomass yield at 0.487 g/L and the specific growth rate (µ) of 0.12 x day-1; protein and phycocyanin contents reached 48.6% and 127 mg/g of dry biomass, respectively. There was no difference in the mentioned above values with biological statistical significance between this medium and SOT medium in distilled water. The ST strain biomass was qualified to be used for the production of functional foods. Results of this study provided scientific basis for the use of marine and brackish waters to produce biomass of this highly economic cyanobacterium.

Labyrinthulomycota from Brazilian mangrove swamps and coastal waters

The phylum Labyrinthulomycota is composed of three distinct groups of fungus-like organisms: the labyrinthulids, the thraustochytrids and the aplanochytrids. They are present in marine and brackish waters as saprobes and/or parasites. In recent years, there was an increased interest in studying these organisms due to the ability that some have to produce large amounts of lipids, particularly polyunsaturated fatty acids. However, in spite of their importance and diversity, in Brazil only four species were reported in the 1970s. Due to their ecological and economic importance globally and the limited knowledge of them in the country, this study aimed to evaluate the diversity of the Labyrinthulomycota in mangrove swamps and coastal waters of São Paulo State, Brazil. The specimens were isolated from water and leaf samples using different methodologies, and purified in an agar medium prepared with half-strength sterile seawater, peptone, yeast extract and glucose. After purification, they were identified by means of morphology and phylogenetic analysis of the SSU rDNA region. A total of 193 specimens representing five genera were observed, 26 specimens were incorporated into the culture collections and 29 sequences of the SSU rDNA region were deposited in GenBank.Labyrinthulasp.,Aurantiochytriumsp.,Parietichytrium sarkarianumandThraustochytrium striatumare new records for Brazil, contributing to our knowledge of the diversity of fungus-like organisms in the country.

Diversidad y afinidades biogeográficas de los tiburones, rayas y quimeras (Chondrichthyes: Elasmobranchii, Holocephali) de México

The diversity of chondrychthyans in Mexico is described. The fauna is composed by 214 species (111 sharks, 95 rays and 8 chimaeras) and represents 17.3 % of the total number of species recorded worldwide. The families with the highest diversity comprise: Rajidae (14.5 %), Carcharhinidae (12.1 %), Pentanchidae, Triakidae, and Urotrygonidae (5.1 %). In terms of geographical distribution, the diversity on the Mexican Pacific slope reaches up to 56.1 % of those species inhabiting Mexican marine and brackish waters (120 species, 62 genera, 37 families and 14 orders); the diversity in the Atlantic slope resulted similar to that on the Mexican Pacific with 55.1 % of the species (118 species, 59 genera, 35 families and 13 orders). The biogeographical affinities of the Mexican chondrychthyan fauna are complex with 19.7 % of the species being circumglobal, 9.9 % transatlantic, 1.9 % transpacific, and 9.4 % endemic to the exclusive economic zone. Additionally, 36.6 % of the species recorded so far are endemic to the Eastern Pacific coast where the species are similar to those found in the Cortez biogeographic province (27.7 %), followed by the Californian (20.7 %), Panamanian (19.3 %), Galapagos (5.6 %) and Peruvian-Chilean (8.9 %). Likewise, 33.3 % are endemic of the Atlantic coast, where species are similar to those found in the Caribbean province (31.9 %), followed by the Carolinean (24.4 %) and the Brazilian (6.6 %).