Dilsea Carnosa Research Articles

Biochemical composition of red, green and brown seaweeds on the Swedish west coast

Seaweed biomass has the potential to become an important raw material for bio-based production. The aim of this study was to screen the overall composition of several seaweed species on the Swedish west coast, including some scarcely studied species, to provide fundamentals for evaluation of biorefining potential and to benchmark with already potentially industrially relevant species and commercially important land-based biomasses. Twenty-two common seaweed species (green, red, brown) were collected and the carbohydrate, ash, protein, water and metal contents were measured. Carbohydrate content varied between 237 and 557 g kg−1 dry weight (dw), making it the largest constituent, on a dry weight basis, of most species in the study. Ash, which is considered unwanted in biorefining, ranged between 118 and 419 g kg−1 dw and was the largest constituent in several seaweeds, which were therefore considered unsuitable for biorefining. Protein content was most abundant in the red seaweeds but was generally low in all species (59–201 g kg−1 dw). High contents of several unwanted metals for processing or human consumption were found (e.g. aluminium, arsenic, copper, chromium and nickel), which need to be considered when utilizing seaweeds for certain applications. Potential targets for further biorefinery development mostly include species already known for their potential (Saccharina latissima, Laminaria digitata and Chondrus crispus) while some, such as Halidrys siliquosa and Dilsea carnosa, have not been previously noted. However, more detailed studies are required to explore biorefinery processes for these seaweeds, as well as how to potentially cultivate them.

Bioethanol Production from UK Seaweeds: Investigating Variable Pre-treatment and Enzyme Hydrolysis Parameters

This study describes the method development for bioethanol production from three species of seaweed. Laminaria digitata, Ulva lactuca and for the first time Dilsea carnosa were used as representatives of brown, green and red species of seaweed, respectively. Acid thermo-chemical and entirely aqueous (water) based pre-treatments were evaluated, using a range of sulphuric acid concentrations (0.125–2.5 M) and solids loading contents (5–25 % [w/v]; biomass: reactant) and different reaction times (5–30 min), with the aim of maximising the release of glucose following enzyme hydrolysis. A pre-treatment step for each of the three seaweeds was required and pre-treatment conditions were found to be specific to each seaweed species. Dilsea carnosa and U. lactuca were more suited with an aqueous (water-based) pre-treatment (yielding 125.0 and 360.0 mg of glucose/g of pre-treated seaweed, respectively), yet interestingly non pre-treated D. carnosa yielded 106.4 g g−1 glucose. Laminaria digitata required a dilute acid thermo-chemical pre-treatment in order to liberate maximal glucose yields (218.9 mg glucose/g pre-treated seaweed). Fermentations with S. cerevisiae NCYC2592 of the generated hydrolysates gave ethanol yields of 5.4 g L−1, 7.8 g L−1 and 3.2 g L−1 from D. carnosa, U. lactuca and L. digitata, respectively. This study highlighted that entirely aqueous based pre-treatments are effective for seaweed biomass, yet bioethanol production alone may not make such bio-processes economically viable at large scale.

X-ray structure of a sodium salt of digeneaside isolated from red alga Ceramium botryocarpum

X-ray diffraction analysis has been recently used to determine the crystal structure of the floridoside (2- O-α- d-galactopyranosylglycerol) isolated from red alga Palmaria palmata and Dilsea carnosa, respectively [Simon-Colin, C.; Michaud, F.; Léger, J.-M.; Deslandes, E. Carbohydr. Res. 2003, 338, 2413–2416; Vonthron-Senechau, C.; Sopkova-de Oliveira Santos. J.; Mussio, I.; Rusig, A. M. Carbohydr. Res. 2008, 343, 2697–2698]. In this present study, a similar analysis was performed on another compound belonging to the glycopyranosyl–glycerols family present in red algae, digeneaside. The crystal structure of a hydrated sodium salt of digeneaside (sodium 2- O-α- d-mannopyranosyl- d-glycerate monohydrate) was determined by single-crystal X-ray diffraction analysis at 110 ± 3 K. The space group is C2 with Z = 4, a = 17.9315(12), b = 6.2693(4), c = 10.7805(7) Å, beta = 90.746(7)°.

X-ray structure of floridoside isolated from the marine red algae Dilsea carnosa

The natural floridoside (2- O-α- d-galactopyranosylglycerol) was isolated from Dilsea carnosa, and its structure has been determined by single-crystal X-ray diffraction analysis. The solved structure is in agreement with the previously solved crystal structure of floridoside [Simon-Colin, C.; Michaud, F.; Léger, J.-M.; Deslandes E. Carbohydr. Res. 2003, 338, 2413–2416] and demonstrates for the first time the presence of floridoside in the red algae Dilsea carnosa.

Evolutionary relationships of Mycaureola dilseae (Agaricales), a basidiomycete pathogen of a subtidal rhodophyte

Mushroom-forming fungi (homobasidiomycetes) are major examples of morphological and ecological diversification in terrestrial habitats. Homobasidiomycetes includes only nine described species that are known from marine environments. Morphological traits that have concealed the ancestry of these fungi include reduced fruiting bodies with hairy surfaces and extremely modified spores, both of which may function as floating devices to aid successful dispersal and adhesion to various substrates such as driftwood. Our previous results suggested that all marine forms as yet investigated are placed in the Nia clade (euagarics) and that they have primarily evolved from cypelloid forms (minute, cup-shaped, terrestrial saprotrophs) via transitions through mangroves to fully marine habitats. We show here that Mycaureola dilseae, which parasitizes the red alga Dilsea carnosa, is a second independent lineage of marine fungi in the euagarics clade that is not related to cyphelloid forms. Phylogenetic reconstructions were based on two data sets: a partial four-region rDNA data set (nuc-ssu, nuc-lsu, mt-ssu, and mt-lsu) with inclusive sampling of 249 taxa and a densely sampled ITS data set including 32 taxa, which formed a clade with Mycaureola in the four-region rDNA analyses. Inferences using constrained and unconstrained six-parameter weighted parsimony, Bayesian Markov chain Monte Carlo methods, and maximum likelihood approaches place M. dilseae in the morphologically diverse /physalacriaceae clade next to Gloiocephala spp., a group of highly reduced stipitate-pileate saprotrophs.

Chemical versus mechanical inhibition of fouling in the red alga Dilsea carnosa

In this study, we used field experiments in natural populations to test whether the low degree of fouling found naturally on the red alga Dilsea carnosa (Schmidel) O. Kuntze (1893) is due to chemical inhibition by antifouling metabolites. Extracts with concentrations volumetrically equiva- lent to whole algal tissue were incorporated into stable gels, which served as settlement substrata for potential fouling organisms. The gels were placed in the field during several time periods, covering all seasons. We also investigated the fouling intensity on living D. carnosa plants to be able to compare fouling on algae with fouling on gels. The extracts inhibited recruitment of a few fouling organisms, but they were not effective against the dominant bryozoan fouling species Electra pilosa and Membranipora membranacea. Furthermore, a relatively high number of these species occasion- ally recruited onto D. carnosa plants. Hence, chemical inhibition of fouling could not explain the low degree of fouling of bryozoan species found naturally on D. carnosa. Instead, based on field observa- tions showing that D. carnosa is able to shed its epidermis, we hypothesised that the low degree of fouling is primarily due to cuticle peeling, whereby the alga sloughs off the outermost cell layer in order to remove associated fouling organisms. This hypothesis was tested in a field survey in which D. carnosa plants were marked and surveyed for about 5 mo. The results show that individual algae that experienced a radical drop in their fouling cover had distinct traces of cuticle peeling. Hence, this study suggests that the dominant fouling organisms are not chemically inhibited by D. carnosa. Instead, the low degree of fouling found naturally on D. carnosa is probably a consequence of a mechanical defence, whereby the alga sloughs off the outermost cell layer in order to remove associ- ated epibiota.

The use of FTIR microspectrometry as a new tool for the identification in situ of polygalactanes in red seaweeds

FTIR microspectrometry method has been applied on sections of different red algae, their cell wall is mainly constituted by polygalactanes such as agar and carrageenans. The former has previously been identified in the red algae Gracilaria verrucosa, whereas in Dilsea carnosa, Chondrus crispus and Hypnea musciformis, different kinds of carrageenans were present. The comparison of the obtained spectra with those previously reported for the extracts from the same seaweeds allowed the confirmation of the nature of each carrageenan. For example, in the obtained infrared spectrum from the cell wall of Chondrus crispus, an intense band at about 1250cm −1 indicates the presence of considerable amounts of sulfate groups, likewise the band at 845 cm −1 which is characteristic of the C-O-S vibration demonstrates that the half ester-sulfate group is substituted on the C4·of the 1,3 linked galactopyranosyl. Thus it was concluded that κ-carrageenan is the main constituent of this algae.

Observations on the seasonal occurrence of marine endophytic and parasitic fungi

Information is presented on three fungal–algal associations on intertidal marine algae. They comprise two members of the Ascomycotina, Lautitia danica parasitic on Chondrus crispus, and Mycosphaerella ascophylli, an obligate endophyte of Ascophyllum nodosum, and a member of the Basidiomycotina, Mycaureola dilseae, that is parasitic on Dilsea carnosa. Details are given of life cycles and seasonal periodicity. The reproductive cycles of Mycosphaerella ascophylli and Ascophyllum nodosum are synchronised, with the fungal sporocarps being confined to the algal receptacles. Lautitia danica occurs on cystocarpic Chondrus crispus throughout the year, with older fronds being more likely to have fungal sporocarps on them. Mycaureola dilseae infecting Dilsea carnosa was only found during September and October. The systemic nature of the association between Mycosphaerella ascophylli and Ascophyllum nodosum is compared with the apparently localized occurrence of Lautitia danica and Mycaureola dilseae. Key words: marine algicolous fungi, seasonality, Ascomycetes, Basidiomycetes.

Antifungal activity in crude extracts of marine red algae

Extracts of Dilsea carnosa, Laurencia pinnatifida, Odonthalia dentata and Polysiphonia lanosa reduced the rate of colony extension in Microsporum canis and Trichophyton verrucosum , with seasonal variations in the levels of inhibitory activity. Antifungal activity was not detected in any extract of Chondrus crispus , although some stimulation of colony extension in M. canis was recorded. None of the algal extracts exhibited antifungal activity against Aspergillus flavus, A. fumigatus or Candida albicans .

Mycaureola dilseae, a marine basidiomycete parasite of the red alga, Dilsea carnosa

Mycaureola dilseae , originally described as a pyrenomycetous ascomycete, is shown to be a basidiomycete with sigmoid, sessile basidiospores. The fungus is a parasite of the marine, subtidal red alga, Dilsea carnosa , on which it produces circular necrotic lesions. Dolipore septa have been observed in the fungal hyphae which penetrate and destroy the cortical cells of the algal host. A revised description is given for M. dilseae , the first aquatic basidiomycete to be described as an algal parasite.

The production of antimicrobial compounds by British marine algae III. Distribution of antimicrobial activity within the algal thallus

The distribution of antibiotics within the thalli of six known antibiotic-producing marine algae was investigated by collecting standard samples at various distances from their growing points and then assaying their antibiotic content. The results showed that out of the six species examined only Ulva lactuca contained a uniform distribution of antibiotic(s). Three species; Chondrus crispus, Dilsea carnosa and Codium fragile exhibited increased activity in the younger regions of their thalli whilst the frond of Laminaria saccharina was least active around its meristematic region. Laminaria digitata appears to have a more complicated distribution of activity within its thallus. The experiments were repeated at quarterly intervals but no significant seasonal variation in antibiotic distribution within these six plants could be detected.

The production of antimicrobial compounds by British marine algae II. Seasonal variation in production of antibiotics

Eleven known antibiotic-producing species of British marine algae were quantitatively screened at monthly intervals for the presence of antibacterial compounds. The antibacterial components of the algae were extracted with acetone and then assayed against Staphylococcus aureus. The results indicate that seasonal variation in antibiotic production occurs in some marine algae and also that four main patterns of production can be discerned. These are, (a) the Polysiphonia type, in which antibiotic production occurs iniformly throughout the year; (b) the Laminaria type, which is characterised by maximum antibiotic production occurring during the winter months, this is also found in Chondrus crispus, Laurencia pinnatifida and Ulva lactuca; (c) the Dictyota type, possessing a summer peak of activity, which also occurs in Dilsea carnosa and Ascophyllum nodosum; (d) the Codium type, where there is a spring peak of activity, this is also exhibited by Halidrys siliquosa.

The production of antimicrobial compounds by British marine algae I. Antibiotic-producing marine algae

Using five species of bacteria as the test organisms, 151 species of British marine algae have been screened for the production of antibiotics. Of these, Asparagopsis armata, Bonnemaisonia asparagoides, Bonnemaisonia hamifera, Chondrus crispus, Dilsea carnosa, Gloiosiphonia capillaris, Sphondylothamnion multifidum, Desmarestia aculeata, Desmarestia ligulata, Laminaria digitata, Dictyopteris membranacea, Dictyota dichotoma, Halidrys siliquosa and most members of the family Rhodomelaceae appear to possess outstanding antibacterial properties. Although the production of antibiotics would appear to be a characteristic of several families, it has not been possible to establish any major correlation between taxonomy and antibiotic production. In the case of two closely related and morphologically similar species, Chondrus crispus and Gigartina stellata, the former possesses considerable degrees of antimicrobial activity whilst the latter exhibits no such activity. The results also indicate that the production of antibiotics by the algae is affected by the season of the year.