The Early Diagenetic Formation of Organic Sulfur in the Sediments of Mangrove Lake, Bermuda

Due to a low mineral content, the sapropelic sediments depositing in Mangrove Lake, Bermuda, provide an excellent opportunity to explore for possible additions of sulfur to organic matter during the early stages of diagenesis. We evaluated early diagenetic organic sulfur transformations by monitoring the concentrations and stable isotopic compositions of a number of inorganic and organic sulfur pools, thereby accounting for all of the sulfur in the sediments. We have identified and quantified the following sulfur pools: porewater sulfate, porewater sulfide, elemental sulfur, pyrite sulfur, hydrolyzable organic sulfur (HYOS), chromium-reducible organic sulfur (CROS), and nonchromium-reducible organic sulfur (Non-CROS). Of the organic sulfur pools, the Non-CROS pool is by far the largest, followed by CROS, and finally HYOS. By 60 cm depth these pools contribute, respectively, to 85, 7.9, and 3.6% of the total solid phase sulfur. The HYOS pool is probably of biological origin and shows no interaction with the sulfur compounds produced during diagenesis. By contrast, CROS is produced, most likely, from the diagenetic addition of polysulfides to functionalized lipids in the upper, H2S-poor, elemental sulfur-rich, region of the sediment. A portion of this sulfur pool is unstable and decomposes on contact with the H2S-rich porewaters. The portion of CROS that remains in the sulfidic waters appears to readily exchange sulfur isotopes with H2S. While some of the Non-CROS pool is of biological origin, some is also formed by the diagenetic addition of sulfur to organic compounds in the upper H2S-poor region of the sediment. By contrast with CROS, Non-CROS is not diagenetically active in the H2S-rich porewaters. Overall, somewhere between 27 and 53 % of the organic sulfur buried in Mangrove Lake sediments is of diagenetic origin, with the remaining organic sulfur derived from biosynthesis. We extrapolate our Mangrove Lake results and calculate that in typical coastal marine sediments between 11 and 29 μmol g−1 of organic sulfur will form during early diagenesis, of which 2–5 μmol g−1 will be chromium reducible.

Benzaldehyde derivatives from Eurotium rubrum, an endophytic fungus derived from the mangrove plant Hibiscus tiliaceus

Four new (1-4) and seven known (5-11) benzaldehyde derivatives were characterized from the liquid fermentation cultures of Eurotium rubrum, an endophytic fungus that was isolated from the inner tissue of stems of the mangrove plant Hibiscus tiliaceus. The structures of these compounds were determined by extensive analysis of their spectroscopic data. Among these metabolites, compound 1, which was named as eurotirumin, possesses a new carbon skeleton with a cyclopentabenzopyran ring system.

Isolation and characterization of microsatellite loci from mangrove red snapper Lutjanus argentimaculatus

Lutjanus argentimaculatus, also called mangrove red snapper, is a commercially important fish in East Asia. A proper understanding of population structure is primarily linked with the management of genetic resources in exploiting marine fisheries. Herein, seven microsatellite loci, which showed high polymorphism (observed heterozygosity per locus ranging from 0.3571 to 0.7857 and expected heterozygosity per locus ranging from 0.6236 to 0.8821), were isolated and characterized from L. argentimaculatus. Cross-species amplifications also indicate that primers designed for these loci may be useful for further studies about other closely phylogenetic species of the family Lutjanidae.

Natural Anthraquinone Derivatives from a Marine Mangrove Plant-Derived Endophytic Fungus Eurotium rubrum: Structural Elucidation and DPPH Radical Scavenging Activity

There is considerable interest in the isolation of potent radical scavenging compounds from natural resources to treat diseases involving oxidative stress. In this report, four new fungal metabolites including one new bisdihydroanthracenone derivative (1, eurorubrin), two new seco-anthraquinone derivatives [3, 2-O-methyl-9-dehydroxyeurotinone and 4, 2-O-methyl4-O-(alpha-D-ribofuranosyl)-9-dehydroxyeurotinone], and one new anthraquinone glycoside [6,3-O-(alpha-D-ribofuranosyl)questin], were isolated and identified from Eurotium rubrum, an endophytic fungal strain that was isolated from the inner tissue of the stem of the marine mangrove plant Hibiscus tiliaceus. In addition, three known compounds including asperflavin (2), 2-O-methyleurotinone (5), and questin (7) were also isolated and identified. Their structures were elucidated on the basis of spectroscopic analysis. All of the isolated compounds were evaluated for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity.

Chemical constituents of marine medicinal mangrove plant Sonneratia caseolaris

Twenty-four compounds including eight steroids (1-8), nine triterpenoids (9-16, 24), three flavonoids (20-22), and four benzenecarboxylic derivatives (17-19, 23) were isolated and identified from stems and twigs of medicinal mangrove plant Sonneratia caseolaris. The structures of the isolated compounds were determined by extensive analysis of their spectroscopic data. Among these metabolites, compounds 1, 4-20 and 22-24 were isolated and identified for the first time from S. caseolaris. In the in vitro cytotoxic assay against SMMC-7721 human hepatoma cells, compound 21 (3',4',5,7-tetrahydroxyflavone) exhibited significant activity with IC50 2.8 mu g/mL, while oleanolic acid (14), 3,3'-di-O-methyl ether ellagic acid (18), and 3,3',4-O-tri-O-methyl ether ellagic acid (19) showed weak activity. None of these compounds displayed significant antibacterial activites.

Fermentative hydrogen production by the new marine Pantoea agglomerans isolated from the mangrove sludge

A new fermentative hydrogen-producing bacterium was isolated from mangrove sludge and identified as Pantoea agglomerans using light microscopic examination, Biolog test and 16S rRNA gene sequence analysis. The isolated bacterium, designated as P. agglomerans BH-18, is a new strain that has never been optimized as a potential hydrogen-producing bacterium. In this study, the culture conditions and the hydrogen-producing ability of P. agglomerans BH-18 were examined. The strain was a salt-tolerant facultative anaerobe with the initial optimum pH value at 8.0-9.0 and temperature at 30 degrees C on cell growth. During fermentation, hydrogen started to evolve when cell growth entered late-exponential phase and was mainly produced in the stationary phase. The strain was able to produce hydrogen over a wide range of initial pH from 5 to 10, with an optimum initial pH of 6. The level of hydrogen production was affected by the initial glucose concentration, and the optimum value was found to be 10 g glucose/l. The maximum hydrogen-producing yield (2246 ml/l) and overall hydrogen production rate (160 ml/l/h) were obtained at an initial glucose concentration of 10 g/l and an initial pH value of 7.2 in marine culture conditions. In particular, the level of hydrogen production was also affected by the salt concentration. Hydrogen production reached a higher level in fresh culture conditions than in marine ones. In marine conditions, hydrogen productivity was 108 ml/l/h at an initial glucose concentration of 20 g/l and pH value of 7.2, whereas, it increased by 27% in fresh conditions. In addition, this strain could produce hydrogen using glucose and many other carbon sources such as fructose, sucrose, sorbitol and so on. As a result, it is possible that P. agglomerans BH-18 is used for biohydrogen production and biological treatment of mariculture wastewater and marine organic waste. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

Composition, Abundance, and Diversity of the Peracarida on Different Vegetation Types in the Qi'ao-Dan'gan Island Mangrove Nature Reserve on Qi'ao Island in the Pearl River Estuary, China

Chang-Fu Wang, Xian-Qiu Ren, and Run-Lin Xu (2010) Composition, abundance, and diversity of the Peracarida on different vegetation types in the Qi'ao-Dan'gan Island Mangrove Nature Reserve on Qi'ao Island in the Pearl River estuary, China. Zoological Studies 49(5): 608-615. Almost nothing is known about the Peracarida in the Pearl River estuary. This is the 1st report to study the composition, abundance, and diversity of the Peracarida in the Qi'ao-Dan'gan I. Mangrove Nature Reserve on Qi'ao I., in the Pearl River estuary, southern China. Bimonthly samplings were carried out in 3 representative vegetation types (mangrove arbor, emergent plants, and seaweed) for 2 yr. Using a Peterson grab, 1940 individuals (id.) were collected in total, including 11 species of 6 genera, 5 families, and 3 orders (Amphipoda, Isopoda, and Tanaidacean). Discapseudes mackiei Bamber 1997 was the dominant species with the highest density of 1,432 incl./m(2). The effect of temperature on the abundance of Peracarida was significant (p < 0.01), and the optimum temperature was 22-23 degrees C in both the mangrove arbor and seaweed. The results showed that the abundance of the Peracarida was higher in the mangrove arbor, while the diversity, especially Amphipoda diversity, was higher in the seaweed. In contrast, emergent plants provided no suitable habitats for the Peracarida. http://zoolstud.sinica.edu.tw/Journals/49.5/608.pdf

Triterpenoids from the mangrove plant Hibiscus tiliaceus

Three new triterpenoids with the rarely occurring nigrum skeleton, namely (20E)-22-hydroxynigrum-20-en-3-one (1), 21 beta-hydroxynigrum-22(29)-en-3-one (2), and 21 alpha-hydroxynigrum-22(29)-en-3-one (3), were isolated from the mangrove plant Hibiscus tiliaceus. Additionally, five known triterpenoids including friedelin (4),12-oleanen-3 beta-ol (5), 3 beta-hydroxy-12-oleanen-28-oic acid (6),20(29)-lupen-3 beta,28-diol (7). and cucurbita-5,23-dien-3 beta,25-diol (8) were also isolated and identified. The latter structures were elucidated by a detailed NMR and MS analyses, as well as by comparison with reported literature data.

Dioxopiperazine Alkaloids Produced by the Marine Mangrove Derived Endophytic Fungus Eurotium rubrum

Cultivation of the fungal strain Eurotium rubrum, an endophytic fungus that was isolated from the inner tissue of stems of the mangrove plant Hibiscus tiliaceus, resulted in the isolation of two new dioxopiperazine derivatives, namely, dehydrovariecolorin L (1) and dehydroechinulin (2), together with eight known dioxopiperazine compounds including variecolorin L (3), echinulin (4), isoechinulin A (5), dihydroxyisoechinulin A (6), preechinulin (7), neoechinulin A (8), neoechinulin E (9), and cryptoechinuline D (10). The structures of the isolated compounds were determined by extensive analysis of their spectroscopic data as well as by comparison with literature. Compounds 1, 2, 9, and 10 were investigated for their a,a-diphenyl-beta-picrylhydrazyl (DPPH) radical-scavenging activity. In addition, the new compounds, 1 and 2, were evaluated for their cytotoxic activity against the P-388, HL-60, and A549 cell lines.

Nutrient enrichment effects on mangrove sediments from differing tree height zones in Bocas del Toro, Panama

Red mangrove (Rhizophora mangle L.) forests have distinct tree-height zones, with tall trees fringing the ocean and shorter trees in interior stands. A long-term nitrogen (N) and phosphorus (P) fertilization experiment in Almirante Bay, Bocas del Toro Province, Panama has shown that tree-height zonation is primarily related to nutrient limitation. This experiment was used to test the effects of in-situ nutrient additions and tree zonation on mangrove sediments. The sediments underlying the experimental R. mangle trees were sampled and N₂ fixation, ¹⁵N, chlorophyll a, percent N and P, and percent organic biomass were quantified. Both N and P additions significantly affected almost every parameter measured in both zones within this experiment. These results are likely to have implications for management since N and P inputs are predicted to increase throughout the tropics and subtropics worldwide.