Effects of salinity on anatomical features and physiology of a semi-mangrove plant Myoporum bontioides.

The effect of different concentrations of NaCl, 0, 100, 200, 300 and 400 mM, on the anatomical features and physiology of Myoporum bontioides was investigated. The photosynthetic rates (Pn) were significantly reduced by salt stress, with the lowest values at 400 mM NaCl. The content of malondialdehyde (MDA), proline and soluble sugar, as well as the activities of peroxidase (POD) and catalase (CAT) increased at the beginning, but became similar to the control as the experiment proceeded. The NaCl effect on superoxide dismutase (SOD) was different from the other parameters, with a significant reduction at 400 mM NaCl at Day 7. Salt glands were found in both upper and lower epidermis, and the ratios of the thickness of palisade to spongy mesophyll tissues increased with NaCl concentrations. The medullary ray was clearly damaged by NaCl at levels of 200 and 300 mM. These results demonstrated that M. bontioides could adapt to a relatively low salinity, and was not a halophilous species.

Degradation of Phthalate Esters by Fusarium sp. DMT-5-3 and Trichosporon sp. DMI-5-1 Isolated from Mangrove Sediments.

Phthalate esters (PAEs) are important industrial compounds mainly used as plasticizers to increase flexibility and softness of plastic products. PAEs are of major concern because of their widespread use, ubiquity in the environment, and endocrine-disrupting toxicity. In this study, two fungal strains, Fusarium sp. DMT-5-3 and Trichosporon sp. DMI-5-1 which had the capability to degrade dimethyl phthalate esters (DMPEs), were isolated from mangrove sediments in the Futian Nature Reserve of Shenzhen, China, by enrichment culture technique. These fungi were identified on the basis of spore morphology and molecular typing using 18S rDNA sequence. Comparative investigations on the biodegradation of three isomers of DMPEs, namely dimethyl phthalate (DMP), dimethyl isophthalate (DMI), and dimethyl terephthalate (DMT), were carried out with these two fungi. It was found that both fungi could not completely mineralize DMPEs but transform them to the respective monomethyl phthalate or phthalate acid. Biochemical degradation pathways for different DMPE isomers by both fungi were different. Both fungi could transform DMT to monomethyl terephthalate (MMT) and further to terephthalic acid (TA) by stepwise hydrolysis of two ester bonds. However, they could only carry out one-step ester hydrolysis to transform DMI to monomethyl isophthalate (MMI). Further metabolism of MMI did not proceed. Only Trichosporon sp. was able to transform DMP to monomethyl phthalate (MMP) but not Fusarium sp. The optimal pH for DMI and DMT degradation by Fusarium sp. was 6.0 and 4.5, respectively, whereas for Trichosporon sp., the optimal pH for the degradation of all the three DMPE isomers was at 6.0. These results suggest that the fungal esterases responsible for hydrolysis of the two ester bonds of PAEs are highly substrate specific.

Biodegradation of anthracene and benz[a]anthracene by two Fusarium solani strains isolated from mangrove sediments.

An investigation was undertaken on the biodegradation of two kinds of polycyclic aromatic hydrocarbons (PAHs), anthracene (ANT) and benz[a]anthracene (BAA), by fungi isolated from PAH-contaminated mangrove sediments environment in Ma Wan, Hong Kong. ANT (50mg l(-1)) and BAA (20mg l(-1)), respectively, were added to mineral salt medium initially for screening of PAH-degrading fungi, and finally two fungal species capable of using ANT or BAA as the sole carbon source were isolated and identified as Fusariumsolani species. Removal of ANT and BAA reached 40% and 60% of the added amount, respectively, after 40 days of incubation. A total of six metabolites were isolated and characterized by solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC/MS), which indicate that F.solani degraded both ANT and BAA via their respective quinone molecules to generate phthalic acid. Free extracellular laccase was detected during the degradation process without detectable lignin peroxidase (LiP) and manganese-dependent peroxidase (MnP), suggesting that laccase might play an important role in the transformation of PAHs compounds.

Purification and characterization of an extracellular laccase from the anthracene-degrading fungus Fusarium solani MAS2.

An extracellular laccase was purified from the culture medium of the non-white rot, anthracene-degrading fungal strain Fusarium solani MAS2. Both native PAGE and SDS-PAGE revealed one single band corresponding to a molecular weight of about 72 kDa. Treatment with endoglycosidase H reduced the molecular weight by 12%. The purified laccase maintained stable at pH 3-11 and up to 50 degrees C. The highest activity was detected at pH 3.0 and at 70 degrees C. The enzyme retained 46.2-97.2% of it activity in the presence of 20mM Pb(2+), Ni(2+), Cr(3+), and its activity was enhanced in the presence of 20mM Hg(2+). The laccase retained more than 50% of its activity in the presence of 5% acetone, acetonitrile, dimethyl sulphoxide (DMSO), ethanol and methanol. The kinetic constants (K(m) and k(cat)) showed that 2,6-dimethoxyphenol (DMOP) and 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt (ABTS) were the more effective substrates rather than catechol and guaiacol. The novel properties of this laccase suggest its potential for biotechnological and environmental applications.

Three metabolites from the mangrove endophytic fungus Sporothrix sp. (#4335) from the South China Sea.

Three metabolites, sporothrins A, B, and C (1-3), were isolated from the mangrove endophytic fungus Sporothrix sp. (#4335). Their structures were identified by the spectral data and X-ray diffractive techniques, with compound 1 showing strong inhibition of acetylcholine esterase. 1,3,6,8-Tetrahydroxynaphthalene (T4HN) was deduced as one of the precursors in the biosynthesis of 1 and 2. In a primary biosynthesis gene study, the partial gene fragment obtained with the LC1-Im/2c-Im primer pair was shown to be closely related to genes encoding T4HN synthase. The deduced protein sequences were highly homologous to the ketosynthase domains of other fungal PKS genes involved in T4HN biosynthesis.

Benzofuran derivatives from the mangrove endophytic Fungus Xylaria sp. (#2508).

Three metabolites, named xyloketal J (1), xyloester A (2), and xyloallenolide B (3), together with the known substituted dihydrobenzofuran (4) were isolated from the mangrove endophytic fungus Xylaria sp. (#2508). Structures were determined by spectroscopic methods, mainly 1D and 2D NMR.

1H and 13C NMR assignments for 6-demethylvermistatin and two penicillide derivatives from the mangrove fungus Guignardia sp. (No. 4382) from the South China Sea.

One new compound 6-demethylvermistatin (1), together with two known compounds, the penicillide derivatives (2) and (3) were isolated from the mangrove fungus Guignardia sp. No. 4382 obtained from the South China Sea. Their structures were assigned using high-resolution electron ionization mass spectrometry(HREIMS), (1)H and (13)C NMR spectra, DEPT, and by 2D COSY, HMQC, and HMBC experiments. The absolute configuration of 1 was established by comparison of its CD with that of vermistatin.

Cyclic peptides from an endophytic fungus obtained from a mangrove leaf (Kandelia candel).

Two new cyclic depsipeptides, 1962A (1) and 1962B (2), along with the three known cyclodipeptides cyclo-(Leu-Tyr) (3), cyclo-(Phe-Gly) (4), and cyclo-(Leu-Leu) (5) were isolated from the fermentation broth of the mangrove endophytic fungus (No. 1962) isolated from an old leaf of Kandelia candel collected in Hong Kong. Through spectroscopic experimentation, X-ray crystallographic analysis, and acid hydrolysis followed by chiral HPLC analysis, their structures were established to be 1962A, cyclo-(D-Leu-Gly-L-Tyr-L-Val-Gly-S-O-Leu) (1), and 1962B, cyclo-(D-Leu-Gly-L-Phe-L-Val-Gly-S-O-Leu) (2), respectively. Both of these new cyclo-depsipeptides were found to contain one d-amino acid. In the MTT bioassay, 1962A (1) showed weak activity against human breast cancer MCF-7 cells.

(1)H and (13)C NMR assignments for five anthraquinones from the mangrove endophytic fungus Halorosellinia sp. (No. 1403).

We report the unambiguous assignments of the (1)H and (13)C NMR spectra of two new natural products, namely, 1,4,5,6,7,9-hexahydroxy-2-methoxy-7-methyl-5beta,9beta,8abeta, 6alpha,10aalpha-hexahydroanthracen-10 (10aH)-one (1) and 1,4,6-trihydroxy-2-methoxy-7-methylanthracene-9, 10-dione (2), together with three known anthraquinones. These compounds were all isolated from the marine endophytic fungus No. 1403 collected from the South China Sea. Compounds 3 and 4 were isolated from the marine fungus for the first time. The structures were elucidated by the spectroscopic methods 1D and 2D NMR including COSY, HMQC, HMBC and NOE, and HREIMS. In our cytotoxicity assays, compound 5 showed cytotoxicity toward KB and KBv-200 cells with IC(50) of 1.40 and 2.58 microg/ml, respectively. In addition, the plausible biogenic relationship of compounds 1, 2, 3 and 4 is discussed.

A new chloro-monoterpene from the mangrove endophytic fungus Tryblidiopycnis sp. (4275).

A new chloro-monoterpene (compound 1) and three known compounds, peroxyergosterol, uracil and methylisocoumarin, were isolated from the ethyl acetate extract of the fermentation broth of the mangrove endophytic fungus Tryblidiopycnis sp. (4275) obtained from Kandelia woody tissue from Mai Po, Hong Kong. Its structure was determined spectroscopically and by X-ray crystallographic analysis.

A comparison of airborne ergosterol, glucan and Air-O-Cell data in relation to physical assessments of mold damage and some other parameters.

UNLABELLED: We report here a comparison of long duration air samples in 110 homes where the material collected on open faced filter cassettes was analyzed for beta 1,3-d glucan, ergosterol, cholesterol and endotoxin. These data were then compared to careful estimates of visible mold and Air-O-Cell data. All the values found except cholesterol were of a similar magnitude to values reported in the limited number of studies available. Glucan was measured with a factor G based assay of the Limulus Amebocyte Lysate followed by size exclusion chromatography. This showed that the majority of airborne glucan found in these houses was fungal in origin arising from both yeasts and intact spores, as well as hyphal and spore fragments. Hyphal and spore fragments together represented 16% of the intact spore counts but over a broad range. Correlations between airborne glucan were strong for ergosterol and visible mold. However, airborne ergosterol was more highly correlated to visible mold than glucan. Endotoxin and Air-O-Cell measurements were poorly or not related to the other measures in the study. This study provides confidence that long duration air samples of the toxin glucan and ergosterol are related to building damage. PRACTICAL IMPLICATIONS: Some studies of damp buildings have shown a relationship between extent of water/mold damage and symptoms. This study compared long duration air samples for glucan and ergosterol to extent of visible mold in houses measuring also the nature of the glucans present. Both measures were highly correlated to extent of visible mold damage in the houses; ergosterol was somewhat superior. Spore counts or prevalence of Asp/Pen in Air-O-Cell samples was not related to extent of visible mold damage but the observation of hyphal fragments was more likely when mold damage was present. This indicates that rigorous assessment of mold damage is a useful measure.

The metabolites of the mangrove fungus Verruculina enalia No. 2606 from a salt lake in the Bahamas.

Two metabolites enalin A (1) and B (2), together with hydroxymethyl furfural (3) and three cyclodipeptides (4, 5 and 6), were isolated from the mangrove fungus Verruculina enaria from a salt lake in the Bahamas. Their structures were determined by spectroscopic methods, mainly by 2D NMR spectroscopic analyses. A possible biosynthetic scheme to 1 and 2 is presented.

Zoospore chemotaxis of mangrove thraustochytrids from Hong Kong.

Zoospores of mangrove isolates of Schizochytrium mangrovei KF6, KF7, KF12 (three strains), Thraustochytrium striatum KF9 and Ulkenia sp. KF13 were examined for their chemotactic responses to amino acids, carbohydrates, ethanol, and leaf extracts using a capillary root model. Most leaf extracts of mangrove plants and a marsh grass tested were shown to induce moderate chemotactic responses in zoospores of both S. mangrovei KF6 and Ulkenia sp. KF13. Of the remaining amino acids and carbohydrates evaluated, glutamic acid and pectin induced strong attraction in zoospores of S. mangrovei KF6 and Ulkenia sp. KF13, suggesting these are the major components in leaves which may be responsible for the chemotactic response of thraustochytrid zoospores in nature. Zoospores of T. striatum KF9, in general, showed a weak chemotactic response to all the tested compounds and extracts except cellulose, which elicited a moderate response. The ecological significance of the data presented is discussed.