Statistical optimization of culture medium composition for enhanced zeaxanthin production by Cyanophycean microalgae Trichodesmium thiebautii (NIOT 152)

Background/Objectives: Zeaxanthin is a xanthophyll carotenoid revered for its role in the prevention of age related macular degeneration. The study evaluated the zeaxanthin accumulation of the marine Cyanophycean alga Trichodesmium thiebautii (NIOT 152). A sequential statistical technique was applied to optimize the Artificial Sea Water nutrient medium (ASN-III) components for enhancing the zeaxanthin accumulation in T. thiebautii. Methods: A two-level statistical approach involving Plackett-Burman (PB) design to screen the most important nutrients influencing the zeaxanthin accumulation followed by Response surface methodology (RSM) was employed. The results of PB design revealed sodium nitrate, disodium EDTA, magnesium sulphate and sodium carbonate as the crucial medium components for increasing zeaxanthin accumulation. Further, RSM was employed to study the interaction between these factors and identified an optimum concentration of the ingredients for higher zeaxanthin production. Findings: The optimized medium components resulted in 2.33 fold increase in zeaxanthin accumulation (4.3 ± 1.29 mg L-1) as compared to ASN III medium (1.84 ± 0.12 mg L-1). Novelty: There are only few studies on laboratory cultured Trichodesmium and only very few reports are available regarding pigment production from Trichodesmium sp. The present study successfully demonstrated the statistical optimization of ASN III medium to improve zeaxanthin accumulation by Trichodesmium thiebautii. Keywords: ASN III medium; zeaxanthin; Trichodesmium thiebautii; Plackett-Burman; response surface methodology REFERENCE

Vertical and horizontal distribution of phytoplankton around an oceanic archipelago of the Equatorial Atlantic

The surrounding area of the St. Peter and St. Paul Archipelago (SPSPA) (0°55′10″N 29°20′33″W) was investigated in order to verify the physical and chemical influences in species composition and abundance, and the patterns of distribution of phytoplankton in the water column, especially in the thermocline depths. The expedition was held on board the Cruzeiro do Sul Hydro-oceanographic ship, from 21 to 23 July 2010 in two perpendicular and opposite transects. A cylinder-conical net and Niskin bottles were used. Two water masses were identified (Tropical Water and South Atlantic Central Water), and the thermocline depths varied from 40 to 110 m. A total of 128 species of phytoplanktonic organisms were identified, belonging to four phyla. The most conspicuous species was the cyanobacteriaTrichodesmium thiebautii; nevertheless, 22 species were considered new registers for the region. The total phytoplanktonic density (1 × 103to 183 × 103 cells l−1) was low and typical of oligotrophic regions, decreasing slightly with depth. Among the 35 species identified in the vertical distribution, 22 were present in the thermocline depth. The total density ofTrichodesmium thiebautii, Oxytoxum longicepsandProtoperidinium minimumhad significant correlations with the physical and chemical parameters. These data indicate that SPSPA can be associated to an island mass effect in the local oceanic circulation that mainly affects the physical and chemical characteristics of the surrounding waters. Consequently, these interactions influence the phytoplanktonic community, mainly those located at the end of the photic zone and those that are under the influence of thermocline oscillation.

Distribution and annual variation of Trichodesmium thiebautii Gomont ex Gomont (Oscillatoriales - Cyanophyta) in tropical waters of Northeastern Brazil (Western Atlantic)

Estudos sobre Trichodesmium thiebautii Gomont ex Gomont e as relações de sua distribuição espacial e temporal com as condições hidrológicas, foram desenvolvidos na plataforma continental do litoral de Pernambuco, Brasil. As amostras foram coletadas durante as estações chuvosa (julho/2005) e seca (novembro/2006) na superfície e no fundo, em seis pontos de amostragem, distribuídos ao longo de dois perfis perpendiculares à costa das praias de Gaíbu e Serrambi. Os pontos de coleta localizaram-se aproximadamente a 5, 10 e 20 km da costa, correspondente às isobatas de 10, 20 e 30 metros. T. thiebautii ocorreu nos dois períodos estudados, com menor densidade em áreas mais próximas da costa e maior densidade em áreas mais afastadas da costa. A correlação de T. thiebautii foi positiva com pH e oxigênio dissolvido durante a estação chuvosa e com salinidade e oxigênio dissolvido durante a estação seca. Nenhuma correlação foi observada com os sais nutrientes. Palavras-chave: hidrologia, densidade, variação espacial

BLOOMS OF Trichodesmium erythraeum AND T. thiebautii (CYANOBACTERIA, OSCILLATORIALES) IN THE BAHÍA DE LA PAZ, GULF OF CALIFORNIA

Florecimientos de Trichodesmium erythraeum y T. thiebautii (Cyanobacteria, Oscillatoriales) en la Bahía de La Paz, Golfo de California Se hicieron muestreos de siete florecimientos de Trichodesmium en la Bahía de La Paz entre 2005 y 2011. Trichodesmium erythraeum y T. thiebautii fueron las especies responsables; esta ultima especie es registrada por primera vez en el Golfo de California. Los florecimientos de T. erythraeum presentaron concentraciones entre 0.75 y 4.5 × 106 céls L–1 mientras que Trichodesmium thiebautii alcanzó densidades entre 1.86 y 2.34 × 106 céls L–17sup. Los florecimientos ocurrieron dentro de un intervalo de temperatura de 20 y 30 °C y no causaron ningún efecto negativo sobre la biota marina de la zona.

New record of Trichodesmium thiebautii Gomont ex Gomont (Oscillatoriales - Cyanophyta) for the continental shelf of northeastern Brazil

This study reports the first occurrence of Trichodesmiumthiebautii Gomont ex Gomont on the coast of northeastern Brazil. Samples were gathered during the rainy season (July 2005) and the dry season (November 2006) at six stations distributed along two perpendicular profiles of the coast of Pernambuco (8º18'S - 34º56'W and 8º32'S - 35º00'W). T. thiebautii was found during both periods of the year and at the six collection stations, forming colonies in the form of clusters or more rarely, bundles, with straight cylindrical trichomes, quadratic or slightly longer cells, with widths between 5-10 µm and heights of 3-15 µm. The hydrological variables presented small variations, contributing to wide distribution of the species.