Lilian L.P. Vrijmoed

Role of fungi in marine ecosystems

Marine fungi are an ecological rather than a taxonomic group and comprise an estimated 1500 species, excluding those that form lichens. They occur in most marine habitats and generally have a pantropical or pantemperate distribution. Marine fungi are major decomposers of woody and herbaceous substrates in marine ecosystems. Their importance lies in their ability to aggressively degrade lignocellulose. They may be important in the degradation of dead animals and animal parts. Marine fungi are important pathogens of plants and animals and also form symbiotic relationships with other organisms. The effect of disturbances on marine fungi is poorly investigated. Keystone marine species may exist, especially in mutualistic symbioses. However, as many saprophytes appear to carry out the same function simultaneously, they may be functionally redundant. The need for a concerted effort to investigate the biodiversity and role of marine fungi globally and on as many substrata as possible is presented.

Optimization of laccase production by Pycnoporus sanguineus in submerged liquid culture

The white-rot fungus Pycnoporus sanguineus produces laccase under a range of C/N ratios in submerged liquid culture. Enzyme production was increased 50 fold in the presence of 20 μM xylidine to a m...

Degradability of the three dimethyl phthalate isomer esters (DMPEs) by a Fusarium species isolated from mangrove sediment

Dimethyl phthalate esters (DMPEs) are common plasticizersand additives to improve flexibility and softness of plastic products(Cartwright et al., 2000; Wang et al., 2004; Xu et al., 2005). ThreeDMPE-isomers, namely dimethyl phthalate (ortho-DMP; ortho-arrangement of the two carboxyl groups), dimethyl isophthalate(DMI; meta-) and dimethyl terephthalate (DMT; para-), display dif-ferent physical and chemical properties and are used in differentindustrial applications. DMP is used as a plasticizer in cellulose es-ter-based plastics (cellulose acetate and cellulose butyrate; Stapleset al., 1997). In polyester-based products, such as tape for VCR cas-settes, synthetic textile fibers etc., DMI and DMT are used as inter-mediates for their synthesis (Lee et al., 1999; Wang and Gu,2006a,b). Phthalate esters (PAEs) occur ubiquitously in both aqua-tic and terrestrial environments (Gu et al., 2005), and foods (Peter-sen and Breindahl, 2000). Because they do not bond covalentlywith the resin, leaching and migration of PAEs from plastic materi-als into the environment are of major concern for the potentialhealth problems associated with these chemicals. PAEs may actas endocrine disruptors affecting the normal function of the repro-ductive system and development of humans and animals at verylow concentrations (Jobling et al., 1995; Colon et al., 2000; Guet al., 2005; Xu et al., 2005). As a result, six PAEs including DMPare listed as priority pollutants by the United States EnvironmentalProtection Agency (Gu et al., 2005).It is suggested that complete degradation of PAEs in the envi-ronment is via microbial mineralization (Staples et al., 1997; Guet al., 2005). Degradation of PAEs has been well documented inbacteria. Various PAE-degrading bacteria have been isolated fromactivated sludge, mangroves, soils, rivers, and the marine environ-ment (Vegaand Bastide, 2003; Changet al., 2004; Gu et al., 2005; Liet al., 2005a,b; Xu et al., 2005; Wang and Gu 2006a,b; Fang et al.,2007). Both Gram-positive and Gram-negative bacteria are respon-sible for the aerobic degradation of phthalic acid (PA) via differentpathways (Chang and Zylstra, 1998; Stingley et al., 2004). Severalfunctional operons involved in the metabolism of PA have beenidentifiedand characterizedin Arthrobacter keyseri12B, Mycobacte-rium vanbaaleniiPYR-1, Burkholderia cepacia DBO1 and other bacte-rial strains (Chang and Zylstra, 1998; Eaton, 2001; Stingley et al.,2004). However, degradation of PAEs by fungi has rarely beenshown. Fungi have been demonstrated to be potential degradersof a wide range of recalcitrant compounds, including polycyclicaromatic hydrocarbons (PAHs), benzene–toluene–ethylbenzene–xylenes (BTEX), chlorophenols, polychlorinated biphenyl, muni-tions waste, and pesticides (Tortella et al., 2005). Nevertheless,degradation of PAEs by fungi has been studied only to a limited ex-tent with Aspergillus niger and Sclerotium rolfsii (Sivamurthy et al.,1991; Ganji et al., 1995; Pradeepkumar et al., 2000). The role offungi on the environmental fate of PAEs remains largely unknown.Coastal wetlands, such as mangroves, are usually sinks of pollu-tants from the aquatic system (Tam et al., 2001; Ke et al., 2005).Mangrove microorganisms may play an important role in the fateoforganicpollutantsinaquaticenvironments.Anumberofbacterialspecies capable of degrading PAEs have been isolated from man-grove sediments, such as Pseudomonas fluorescens, Rhodococcus ru-ber, Pasturella multocida, and Sphingomonas paucimobilis (Li et al.,2005a,b;Xuetal.,2005;LiandGu,2006).However,therearenore-ports concerned with the degradation of PAEs by mangrove fungi.The Futain Mangrove Nature Reserve of Shenzhen, China, is on thesouthern border of Shenzhen, one of the cities with the most rapideconomic development in China. The Reserve is under increasingpollution pressure derived from intense urbanization of the city,The objective of BASELINE is to publish short communications on different aspects of pollution of the marine environment. Only thosepapers which clearly identify the quality of the data will be considered for publication. Contributors to Baseline should refer to‘Baseline—The New Format and Content’ (Mar. Pollut. Bull. 42, 703–704).

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.

A qualitative assessment of lignocellulose degrading enzyme activity in marine fungi

Cellulolytic and ligninolytic activity in fifteen marine fungi was assessed. All displayed endoglucanase and cellobiohydrolase activity indicated by utilisation of carboxymethylcellulose and crystalline cellulose respectively. Variations in salinity appeared to have little effect on the extent of cellulolysis. Ligninolytic enzyme activity as indicated by dye decolorization was observed for several isolates, with intensity of reaction varying with respect to primary carbon source, pH and salinity. Generally peroxidase activity as indicated by PolyR478 dye decolorization favoured high salinities, whereas laccase activity as indicated by oxidation of ABTS dye was more pronounced at lower salinities.

Co-detection of three species of water-borne bacteria by multiplex PCR

Abstract Monitoring of water-borne pathogens is important to safeguard public health. In view of various limitations inherent in the traditional culture methods, the feasibility of using the polymerase chain reaction (PCR) to monitor water-borne pathogens was investigated. The STN enterotoxin gene of Salmonella typhimurium , the STO enterotoxin gene of Vibrio cholerae , the LTI and LTII enterotoxin genes of Escherichia coli , and the house-keeping genes, ARO-A and PHO-A of S. typhimurium and E. coli , respectively, were used as gene targets for PCR detection of toxigenic and general strains of these organisms. Six pairs of oligonucleotide primers were chosen to amplify internal fragments of the respective genes, and the identity of the PCR products was confirmed by restriction endonuclease digestion. The specificity of individual primer pairs in PCR was evaluated on DNA templates of 54 different bacterial isolates. The results showed that the LTI, LTII and STO primer sets were highly specific for toxigenic strains of E. coli H10407 (LTI+), E. coli SA53 (LTII+) and V. cholerae NRT (STO+), respectively. The PHO-A primers showed species-specific amplification products for all nine E. coli isolates examined, while the STN and ARO-A primer sets yielded species-specific amplification products for the 10 S. typhimurium isolates tested. Detection sensitivity of the ARO-A and PHO-A primer sets for S. typhimurium and E. coli , respectively, was estimated at 10 3 CFU. Using three different combinations of the above primer sets, multiplex PCR was performed to detect toxigenic and non-toxigenic strains of V. cholerae, S. typhimurium and E. coli in seawater samples artificially spiked with the organisms. The technique, which showed positive co-detection of the respective target genes in each case, only required a turnaround time of 5 h. Results of the present study indicate that the multiplex PCR is a potentially powerful technique for the rapid co-detection of enteropathogenic bacteria in routine water quality monitoring.

Fungal endophytes associated with Kandelia candel (Rhizophoraceae) in Mai Po Nature Reserve, Hong Kong

We examined the endophytic fungi associated with the dominant mangrove plant, Kandelia candel, in Mai Po Nature Reserve, Hong Kong. Bark, woody tissue and leaves from four mature healthy trees were sampled for fungal endophytes in April and June, 2001. A total of 880 isolates was obtained, 595 from the June sampling. The highest number of fungal endophytes was cultured from bark (674 isolates) with only 63 from leaves. Three taxa of ascomycetes, 18 of anamorphic fungi and 29 mycelial morphotypes were identified. These results indicate a degree of tissue recurrence with similar endophytic fungal assemblages in bark and wood, and a different assemblage in the leaf samples. Dominant sporulating fungi of K. candel were Phomopsis sp., Pestalotiopsis sp., Guignardia sp. and Xylaria sp., which are cosmopolitan and common endophytic species.

Metacognitive development and moving away

It is now largely accepted that social and cultural factors have a significant impact on cognitive development in children. Piaget acknowledged the impact of social factors and peer interaction on cognitive development. However, there has been relatively little work on the impact of social and cultural factors on the development of metacognition in first‐year university students. Using the Learning and study strategies inventory (LASSI) as a measure of metacognition, this study samples first‐year undergraduates in Hong Kong (N = 1815) and identifies significant differences in metacognitive abilities between students living in their home environment and those who have moved away from their family and, in some cases, culture, to pursue undergraduate education.

Observations on mangrove fungi from Macau and Hong Kong, with the description of two new ascomycetes: Diaporthe salsuginosa and Aniptodera haispora

Collections of mangrove fungi in Macau and Hong Kong yielded 45 species, with 28 new records for Macau and 21 new records for Hong Kong. Two new species: Diaporthe salsuginosa and Aniptodera haispora are described and a key to the genus Aniptodera is included.

Screening Mangrove Endophytic Fungi for Antimalarial Natural Products

We conducted a screening campaign to investigate fungi as a source for new antimalarial compounds. A subset of our fungal collection comprising Chinese mangrove endophytes provided over 5000 lipophilic extracts. We developed an accelerated discovery program based on small-scale cultivation for crude extract screening and a high-throughput malaria assay. Criteria for hits were developed and high priority hits were subjected to scale-up cultivation. Extracts from large scale cultivation were fractionated and these fractions subjected to both in vitro malaria and cytotoxicity screening. Criteria for advancing fractions to purification were developed, including the introduction of a selectivity index and by dereplication of known metabolites. From the Chinese mangrove endophytes, four new compounds (14–16, 18) were isolated including a new dimeric tetrahydroxanthone, dicerandrol D (14), which was found to display the most favorable bioactivity profile.