Gelidium Pusillum Research Articles

Comparative assessment of pre-treatment techniques and process economics on marine seaweed, Gelidium pusillum, for enhanced bioethanol production

Many researchers are actively investigating different pre-treatment methods on alternative energy sources for sustainable production of bioethanol. With abundant carbohydrates and ease of cultivation, Gelidium pusillum, seaweed biomass has gained attention as a bioethanol feedstock. In the present study, various combinatorial pre-treatment methods like ultrasonic-acid treatment, microwave-alkali treatment, and steam-organic solvent treatment were carried out on seaweed biomass and compared for their efficiency in bioethanol production. Physico-chemical changes of biomass were characterized using Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and X-ray Diffraction. Among all pre-treatment methods, microwave-alkali treatment was found to be the most effective one and yielding fermentable sugars, sugar utilization efficiency, and ethanol concentration of 395 mg/g, 78.33 ± 0.98%, and 5.7 ± 0.19 g/L, respectively. Additionally, the process-economic analysis showed that Gelidium pusillum and microwave-alkali treatment could be scaled up to the industrial level with a production cost of $1.40 per liter of ethanol with minimal ecological impact.

Benthic Algal Assemblages Associated with Damselfi sh Territories in The Gulf of Thailand

Territorial damselfi sh are herbivorous fi sh that help maintain algal diversity and abundance by aggressive territorial defense and algal farming. We investigated the effect of territorial damselfi sh on algal diversity and abundance on a reef at Ko Taen, Surat Thani Province, Thailand. Ten permanent patches (20 × 20 cm2) were set up inside and ten outside damselfi sh territory and monitored bimonthly. We found 22 macroalgal species with fi ve dominant species: Polysiphonia sp., Padina minor, Ulva compressa, Gelidium pusillum, and Lobophora variegata. The abundance of Polysiphonia sp. was signifi cantly higher inside damselfi sh territory than outside. In contrast, the abundances of Gelidium pusillum, Padina minor, and Ulva compressa were slightly higher outside the territory. It might be perhaps because their feeding behavior, territorial defense, and farming activities altered the benthic community. These damselfi shes exclude other herbivorous fi shes from their territories and remove unpalatable algae and maintain their algal food crop. For species diversity, there was no signifi cant difference between algal species diversity outside and inside damselfi sh territories. Our results indicated that damselfi shes have a strong effect on algal abundance and composition.

Assessment of the macroalgal diversity of Kuwait by using the Germling Emergence Method

Cryptic stages of diverse macroalgae present in natural substrata, “the bank of microscopic forms”, were isolated into clonal cultures and identified based on both morphological characteristics and DNA barcoding. Approximately 120 clonal isolates from 308 natural substratum samples were collected from the entire coastline of Kuwait. Amongst these isolates, 77 (64%) were identified through DNA barcoding using the nuclear ribosomal small subunit, RuBisCO spacer (ITS2, <i>tufa</i>, <i>rbc</i>L, <i>psa</i>A, and <i>psb</i>A) and sequencing. Twenty-six isolates (34%) were identified in the division Chlorophyta, 18 (23%) as Phaeophyceae, and 33 (43%) as Rhodophyta. For all DNA sequences in this study, species-level cut off applied was ≥98% homology which depend entirely on the markers used. Three putative new records of Chlorophyta new for the Arabian Gulf were made: <i>Cladophora laetevirens</i> (Dillwyn) Kützing, <i>Ulva torta</i> (Mertens) Trevisan and <i>Ulvella leptochaete</i> (Huber) R. Nielsen, C. J. O′Kelly & B. Wysor in Nielsen, while <i>Cladophora gracilis</i> Kützing and <i>Ulva ohnoi</i> M. Hiraoka & <i>S. Shimada</i> are new records for Kuwait. For Phaeophyceae, Ectocarpus subulatus Kützing and <i>Elachista stellaris</i> Areschoug were new records for the Gulf and Kuwait. In the Rhodophyta, <i>Acrochaetium secundatum</i> (Lyngbye) Nägeli in Nägeli & Cramer, <i>Ceramium affine</i> Setchell & N. L. Gardner, <i>Gelidium pusillum</i> var. <i>pakistanicum</i> Afaq-Husain & Shameel and <i>Dasya caraibica</i> Børgesen are new records for the Gulf and Kuwait, while the red alga <i>Stylonema alsidii</i> (Zanardini) K. Drew is a new record for Kuwait. Several isolates identified corresponded to genera not previously reported in Kuwait and / or the Arabian Gulf, such as <i>Porphyrostromium</i> Trevisan, a new genus from the Bangiales, and two unidentified species for the Planophilaceae Škaloud & Leliaert. The isolates cultivated from substrata enhance understanding of the marine macroalgal diversity in the region and confirmed that the Germling Emergence Method is suitable for determining the actual diversity of a given study area through isolation from cryptic life-history phases.

Biopigments (Phycoerythrin, Fucoxanthin and Siphonaxanthin) from Seaweeds and Their Potential Applications as Ingredients in Cosmeceutical Industries: A Review

Green seaweed, red seaweed, and brown seaweed are the three main kinds of seaweeds, which are also categorized as macroalgae. The color represents chemical compounds known as photosynthetic pigments (biopigments) including carotenoids, chlorophylls, and phycobiliproteins. This review is focused on three biopigments, such as phycoerythrin (PE), fucoxanthin (FX), siphonaxanthin (SX), and their potential application as ingredients in cosmeceuticals industries. PE is a form of a marine bioactive protein called phycobiliprotein, which is primarily present in red seaweed, such as Halymenia sp., Euchema sp., Gelidium pusillum, Gracilaria verrucose, etc. The main xanthophyll carotenoid found in brown seaweed, such as Padina australis, Sargassum horneri, Undaria pinnativida, etc., is FX. Following that, SX is a rare xanthophyll carotenoid that is prevalent in green seaweed, including Codium fragile, Halimeda sp., etc. An epoxide and a bond of allenic are both present in the structure of FX, whereas these moieties are absent in the SPX structure. Generally, there are two main techniques to extract these biopigments: the conventional method (liquid solvent extraction), and the non-conventional. Furthermore, due to their antioxidant, antiaging, anti-inflammatory, anti-tyrosinase, etc. activities, PE, FX, and SX demonstrated strong potential as cosmetic activities. These biopigments are being explored as possible components for cutting-edge cosmeceuticals. There is still a need for additional research to assess the safety, effectiveness, and actual possible alternatives of using biopigments from seaweeds in the cosmeceutical business, despite the challenges of developing environmentally safer extraction techniques.

Trace element bioaccumulation in edible red seaweeds (Rhodophyta): A risk assessment for consumers

As a precursor to risk assessment and risk management through consuming contaminated seafood, food safety needs to be quantified and assured. Seaweed is an increasing dietary component, especially in developing countries, but there are few studies assessing uptake rates of contaminants from this route. As such, the present study determined likely human uptake due to the trace elemental (Fe, Mn, Ni, Cu, Zn, Se, Hg, and As) concentrations in the edible red seaweeds (Rhodophyta) Gelidium pusillum and Hypnea musciformis, growing in the industrialised Cox's Bazar coastal area of Bangladesh. Metal and metalloid concentrations in G. pusillum were in the order (mg/kg): Fe (797 ± 67) > Mn (69 ± 4) > Ni (12 ± 5) > Zn (9 ± 4) > Cu (9 ± 4) >Se (0.1 ± 0.1) > Hg (0.1 ± 0.01), and in H. musciformis: Fe (668 ± 58) > Mn (28 ± 5) > Ni (14 ± 2) > Zn (11 ± 5) > Cu (6 ± 4) >Se (0.2 ± 0.03) > Hg (0.04 ± 0.01). Despite the industrial activities in the area, and based on 10 g. day−1 seaweed consumption, it is concluded that these concentrations pose no risk to human health as part of a normal diet according to the targeted hazard quotient and hazard index (THQ and HI) (values < 1). In addition, and as a novel aspect for seaweeds, Selenium Health Benefit Values (Se-HBV) were determined and found to have positive values. Seaweed can be used as an absorber of inorganic metals for removing contamination in coastal waters. The results are a precursor to further research regarding the efficiency and rate at which seaweeds can sequester metal contamination in water. In addition, management techniques need to be developed thereby to control the contaminant inputs.

Novel adsorption approach for the enrichment of R-Phycoerythrin from marine macroalga Gelidium pusillum

R-Phycoerythrin is a fluorescent and commercially valuable pigment protein present in algae. The extraction, purification and concentration of such biomolecules is a challenge for processing industries. In the present work, enrichment of R-Phycoerythrin was attempted by selective adsorption of other contaminant biomolecules from extract of algal biomass. Different adsorbents (zeolite, molecular sieve, ammonium Y zeolite, silver-exchanged zeolite, mesoporous carbon) and nanoparticles (zinc oxide, graphene oxide, gold and silver) were explored for this purpose. Process conditions such as buffer pH (5, 6, 7 and 8), ionic strength (0.1, 0.35, 0.6, 0.85 and 1.1) and adsorbent levels (w/w) were optimized. Optimization resulted in enrichment of pre-treated R-Phycoerythrin by 3.31 fold with 73.36% yield using zeolite and 2.10 fold with 98.91% yield using gold nanoparticles. This work demonstrates the efficacy of adsorbents and nanoparticles as possible alternatives for enrichment and purification of R-Phycoerythrin with appreciable yield.

Morphological and molecular characterization of two species of Gelidium (Gelidiales, Rhodophyta) from Mexico: G. nayaritense sp. nov. and the new record of G. sanyaense

Gelidium pusillum is a species reported from the northern Gulf of California to the tropical region of the Mexican Pacific, but there is wide morphological variation among populations. The objective of this research was to evaluate of the Mexican species using morphological and molecular approaches, with the markers rbcL and COI-5P. This study examined 12 samples from four sites in the Mexican tropical Pacific. Phylogenetic analyses resolved these specimens within two clades separated from the topotype material of G. pusillum. The main morphological differences with other Mexican and phylogenetic closely related species were size, branching pattern, branching order, distribution of internal rhizoidal filaments, and shape of the tetrasporangial sori. The sequence divergences between these clades and the morphological differences support their representing distinct species so that Gelidium nayaritense sp. nov. is proposed for tropical specimens of the Mexican Pacific, whose diagnostic characteristics are the little or absent branching, its small size, as well as the presence of internal rhizoidal filaments concentrated in the subcortex, further G. sanyaense is register for first time from Mexico and Eastern Pacific.

Comparative assessment of bioactive compounds, antioxidant capacity and nutritional quality of red seaweeds and water spinach

Each food form is considered to have greater affinity if enriched with nutritional and bioactive compounds. This study was undertaken to evaluate the bioactive compounds, antioxidant properties, and proximate composition of two seaweeds i.e., Hypnea musciformis and Gelidium pusillum and a freshwater weed i.e., Ipomoea aquatica, in search of potential plant food sources with greater medicinal values. Bioactive compounds, e.g., total phenolic content (TPC), carotenoid, total flavonoids, ascorbic acid, tannin, and antioxidant activity by means of total antioxidant content (TAC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, and Ferric reducing antioxidant power (FRAP) were measured. The proximate compositions (e.g., protein, carbohydrate, etc.) of these study samples were also determined. Ipomoea exhibited 36.19% less antioxidant activity than seaweed samples (ranging from 19 to 22 mg AAE/g). The samples TPC (mg GAE/g) followed the order Gelidium (48.37 ± 0.96) > Hypnea (11.37 ± 0.92) > Ipomoea (9.4 ± 0.36). The DPPH radical scavenging activity of I. aquatica was 4 times less than the seaweed. Nevertheless, freshwater weed’s total carotenoids content was one and a half times higher than seaweed samples. The amount of ascorbic acid, tannin, and FRAP were also found higher in seaweeds. However, flavonoid content was higher (8.09 ± 1.4 mg QE/g) in freshwater weed. However, proximate compositions were about 1.5 times higher in seaweed. The non-parametric statistical analysis showed a significant difference between Hypnea versus Ipomoea and Gelidium versus Ipomoea (α=0.05; p<0.05) in each of the antioxidant and bioactive compound parameters. The study results suggested that red seaweeds are verily more compatible in contrast with freshwater weed for most of the parameters and could be used as a prospective source of human diets.

Antioxidant and antibacterial activity of Gelidium pusillum (Stackhouse) against Aeromonas caviae and its applications in aquaculture

Over the past two decades, intensive work has been conducted on antioxidants as they have great potential to prevent diseases and complications associated with age. Seaweeds are rich natural sources of bioactive metabolites with antioxidant and antimicrobial characteristics. In the present study, bioactive metabolites were extracted from the seaweed Gelidium pusillum by maceration in aqueous and ethanolic medium. The dried weed powder was analyzed by GC-MS and FTIR. The macerated products were assayed for antioxidant and antibacterial activity by in vitro and in vivo methods. Antibacterial activity against the marine pathogen Aeromonas caviae was observed. Giant freshwater prawns (Macrobrachium rosenbergii) were used as models for in vivo assays by inducing pathogenicity by intramuscular injection of pathogen. The present study revealed that G. pusillum is a rich source of antioxidant and antibacterial compounds. The data obtained from the present study substantiates the potential of G. pusillum as an ideal antioxidant and antibacterial in the aquaculture industry. The animals treated with the ethanolic extract of G. pusillum (35 μl of 1mg/ml extract) survived even after 3 weeks, compared to the untreated in which 100% mortality was observed within 120 h. Relative percentage survival (RPS) of 90% was observed in the group treated with the seaweed extract. GC-MS analysis revealed the presence of several compounds previously reported for antibacterial activity. In the present work, a total of seven compounds were identified by GC-MS analysis, out of which two compounds are reported to have antimicrobial activity. High sustained survival of the infected prawns post-administration of the extract revealed that this sea weed has potential in the biopharmaceutical, aquaculture, and food sectors.

Membrane processing for purification of R-Phycoerythrin from marine macro-alga, Gelidium pusillum and process integration

Ultrafiltration is widely used for separation and purification of several biomolecules from various sources. However, the performance of ultrafiltration in terms of transmembrane flux, yield and purity vary with biomolecule and process parameters. In the present study, ultrafiltration was employed for the purification of R-Phycoerythrin from marine macroalga Gelidium pusillum. Parameters such as molecular weight cut-off (30, 50, 100 and 300 kDa), transmembrane pressure (1, 2 and 4 bar), pH (4, 5, 6 and 7), and ionic strength (control, 0.5 and 1.0 M) were standardised. Ultrafiltration in diafiltration mode and its integration with ammonium sulphate precipitation and aqueous two-phase extraction was also carried out to maximise R-PE purity. In-situ ultrasonication was employed to enhance the transmembrane (permeate) flux. Permeate flux was evaluated employing Hermia’s model to have insight and understand membrane fouling that occurs during ultrafiltration. Integration of ammonium sulphate precipitation followed by diafiltration and aqueous two-phase extraction has resulted in 17 fold enrichment in R-PE purity with 61% yield and removal of more than 95% of soluble sugars. In-situ ultrasonication has resulted in increase of transmembrane flux by 10% to 47 L/m2/h. Hermia’s model based analysis of permeate flux has revealed that cake formation is the predominant type of fouling.

Biomimetic gold nanoparticles for its cytotoxicity and biocompatibility evidenced by fluorescence-based assays in cancer (MDA-MB-231) and non-cancerous (HEK-293) cells

Biomimetic gold nanoparticles of biological origin have created a significant impact on the field of biomedicine due to the great expectations of its applications. Because of this, the influences of biomimetic gold nanoparticles have been immensely studied, targeting various cancer cells. However, the impact of biomimetic gold nanoparticles against normal non-cancerous cells is scanty, which impose several limitations in their utility. Taking this as a challenge, we in this study report the biomimetic gold nanoparticles from marine seaweed Gelidium pusillum (G. pusillum) to evaluate its cytotoxic and biocompatible ability evidenced by fluorescence-based assays in cultured cells. The gold nanoparticles obtained in the study were spherical shaped with a mean diameter of 12 ± 4.2 nm. The seaweed extract plays a crucial role in stabilizing the gold nanoparticles to avoid aggregation and coalescence. At an IC50 concentration of 43.09 ± 1.6 μgmL−1, the biomimetic gold nanoparticles were found to be toxic to cancerous cells (MDA-MB-231). Whereas, biomimetic gold nanoparticles exhibit significant biocompatibility with human embryonic kidney cells even at a higher concentration of 150 μgmL−1. The morphological based fluorescence assays confirmed the ability of biomimetic gold nanoparticles in inducing apoptosis and thereby kills cancer cells. Altogether, the gold nanoparticles were safe to normal cells and did not show a significant impact. Hence, the novel biomimetic gold nanoparticles hold potential as multifaceted agent and can further be taken up to various biomedical applications.

Gelidium adriaticum sp. nov. and Gelidium carolinianum sp. nov. (Gelidiales, Rhodophyta) from the Mediterranean Sea

ABSTRACTIdentification of small Gelidium species based on morphology is difficult; as a consequence, the name Gelidium pusillum has been used for many small gelidiacean taxa throughout the world. Molecular-assisted identifications, however, are demonstrating that G. pusillum has a more restricted distribution than previously recognised. We used detailed morphological analyses combined with rbcL and cox1 sequence analyses to identify and assess the phylogenetic relationships of small Mediterranean Gelidium species. These analyses revealed the presence of two new species, G. adriaticum sp. nov. and G. carolinianum sp. nov. Gelidium adriaticum is a closely related sister species to G. pusillum, which was not found amongst our Mediterranean specimens. Gelidium carolinianum has been previously collected outside the Mediterranean, but it was misidentified as G. americanum. Morphological observations and sequence data generated from G. americanum types and other historical specimens clarified the status and distribution of this species. Phylogenetic analyses resolved G. carolinianum as a species in the Mediterranean and warm-temperate northwest Atlantic; whereas, G. americanum occurs in the Caribbean and tropical western Atlantic, and is sister to G. calidum from Brazil and closely related to G. crinale.

Phylogenetic relationships of Pakistan Gelidium (Gelidiales, Rhodophyta) species with recognition of Gelidium pakistanicum stat. nov.

Abstract Two species of Gelidium, Gelidium usmanghanii and Gelidium pusillum var. pakistanicum are reported only from Pakistan, but their taxonomic status, phylogenetic relationships, and distributions have not been assessed with molecular data. Analysis of rbcL sequences revealed that G. usmanghanii was a distinct species with a distribution extending at least to the coast of Oman. This analysis also resolved G. pusillum var. pakistanicum within a Gelidium millariana species complex that was distantly related to G. pusillum. Further analyses of rbcL and COI-5P sequences showed that G. pusillum var. pakistanicum was a distinct species in this complex, and based on these molecular, and previous morphological results, this variety is elevated to the rank of species as Gelidium pakistanicum stat. nov.

Aqueous two-phase extraction of R-Phycoerythrin from marine macro-algae, Gelidium pusillum

Aqueous two-phase extraction (ATPE) of R-Phycoerythrin (R-PE), a fluorescent and commercially valuable protein, was carried out in two parallel schemes. In scheme-1, ATPE alone was employed, and in scheme-2, process-integration was attempted, where primary extract was subjected to precipitation before standardization of process parameters of ATPE. Scheme-1 with polyethylene glycol (PEG)-3350/potassium phosphate system has resulted in very low R-PE yield (26% w/w) without much enrichment in purity (0.3). In scheme-2, PEG-1450/potassium phosphate system (pH 6, tie-line length 12.26% and lower volume-ratio) has resulted in higher R-PE purity (0.74) with 72% yield. R-PE containing PEG-rich (top) phase was subjected to ultrafiltration, to remove phase forming components, resulting in further increase in R-PE purity (1.1). Overall enrichment in R-PE purity of 11-fold with 57% (w/w) yield and removal of about 95% of total sugars was achieved in scheme-2. Intactness of R-PE after processing was confirmed by absorbance and emission spectrum analysis.

Extraction of R-Phycoerythrin from marine macro-algae, Gelidium pusillum, employing consortia of enzymes

Extraction of phycobiliproteins (R-phycoerythrin, R-PE) from macroalgae is difficult due to the presence of complex matrix of polysaccharides (agar, cellulose etc.) present in the cell wall which offers major hindrance for cell disruption. The present study is focused on the identification of suitable process conditions for the extraction of R-phycoerythrin (R-PE) from marine macroalgae, Gelidium pusillum (Stackhouse) Le Jolis., by enzymatic hydrolysis of polysaccharide-complex present in the macroalgal cell wall. Identification of optimum process conditions like incubation duration (2,4,6 h), incubation temperature (25, 30, 35, 40 °C) and enzyme to biomass ratio (0,20,40,60, 80 U/g biomass, fw) was carried out for agarase, cellulase and xylanase. Different relative proportions of these enzymes in a mixture at different pH (5.8, 6.8, 7.8) values were employed at the most suitable set of conditions. When employed alone, cellulase resulted in a minimum improvement (6%), agarase (14%) and xylanase the maximum (16%) on R-PE yield. Presence of cellulase in consortia has resulted in maximum improvement in R-PE yield (26%) at 25 °C and pH 5.8. Consortia of enzymes were more effective in improving the yield of biomolecules over the individual enzymes due to efficient hydrolysis of complex cell wall structure of biomass of Gelidium pusillum macroalgae and can be employed for the extraction of biomolecules also from other macroalgae.

Comparative study on the pyrolysis behaviour and kinetics of two macroalgae biomass (Gracilaria changii and Gelidium pusillum) by thermogravimetric analysis

Macroalgae are often referred as seaweed and could be significant biomass resource for the production of numerous energy carriers including biofuels. In this study, the chemical composition of Gracilaria changii (G. changii) and Gelidium pusillum (G. pusillum) were determined through proximate and ultimate analysis and the thermal degradation behaviour of G. changii and G. pusillum were investigated via thermogravimetric analysis (TGA) in determining the important main composition to be considered as biomass fuels. It has found the pyrolysis of G. changii and G. pusillum consists of three stages and stage II is the main decomposition stage with major mass loss of around 52.16% and 44.42%, respectively. The TGA data were then used for determination of kinetic parameters of the pyrolysis process using three model-free methods: Kissinger, Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The apparent activation energy calculated by using Kissinger method for G. changii was lower than G. Pusillum, i.e.173.12 kJ/mol and 193.22 kJ/mol, respectively. The activation energies calculated from KAS and FWO methods were increased with increasing the pyrolysis conversion with average activation energies of 172.32 kJ/mol and 181.19 kJ/mol for G. changii while for G. pusillum (177.42 kJ/mol and 187.4 kJ/mol). G. pusillum has lower and wider distribution of activation energy and revealed that the pyrolysis process for G. changii was easier than G. pusillum. These data provide information for further application for designing and modelling in thermochemical conversion system of macroalgae biomass.

Marine macroalgal resources from nine beaches along the Kerala coast, India

Estimates of number, density and wet biomass of seaweed resources and their availability for exploitation for phycocolloid extraction along the Kerala coast in relation to water quality were studied using the data collected at quarterly intervals from nine stations during 1998 and 1999. A total of 37 species of seaweeds were collected and out of these, 13 were grouped under Class Chlorophyceae (green seaweeds), 7 under Phaeophyceae (brown seaweeds) and 17 under Rhodophyceae (red seaweeds). Agar yielding seaweeds were represented by seven species and the major resources were Gracilaria corticata, G. foliifera, Gelidiopsis variabilis and Gelidium pusillum during 1998 and 1999 besides the species of Pterocladia during 1999. Alginophytes were represented by Sargassum wightii, S. duplicatum, S. tenerimum, Stoechospermum marginatum, Dictyota dichotoma and Padina spp. The carrageenan yielding red seaweeds were more in number (nine species) belonging to seven Genera. Out of them, Hypnea musciformis, H. valentiae, Grateloupia filicina, G. lithophila and a new resource Gracilariopsis lemaneiformis, from Dhalavapuram and Kannur stations were available in considerable quantities. The richest diversity of seaweeds was observed at Mullur (Vizhinjam) and Thikkodi (Calicut) followed by Thirumallavaram (Quilon).

Antifungal activity of crude extracts from brown and red seaweeds by a supercritical carbon dioxide technique against fruit postharvest fungal diseases

Fungal infections are the main cause of decay on fresh fruit during postharvest phase determining severe losses. Postharvest control is performed by fungicides, but their intense use have aroused issue relating to environmental protection and human health prompting to search alternative control means. The use of biofuel-used seaweed extracts by a supercritical carbon dioxide technique could be a valid alternative during postharvest handling of fresh fruit. The aim of this work was to assess the in vitro and in vivo activity of extracts from two brown seaweeds (Laminaria digitata and Undaria pinnatifida) and three red seaweeds (Porphyra umbilicalis, Eucheuma denticulatum and Gelidium pusillum) against three postharvest pathogens (Botrytis cinerea, Monilinia laxa and Penicillium digitatum) using three concentrations of extract (10, 20 and 30gL−1). The total content of fatty acids of the extracts was determined by CG-MS, those of polysaccharides by HIC, and phenolic compounds (phlorotannins) by HPLC-DAD. Twenty fatty acids were quantified in the extracts, while three polysaccharides categories and three phlorotannins classes were identified only in brown seaweed extracts. L. digitata, U. pinnatifida and P. umbilicalis showed the highest antifungal efficacy on in vitro cultures of the pathogens. L. digitata and U. pinnatifida completely inhibited mycelia growing and conidial germination of B. cinerea and M. laxa at the highest dose tested and strongly reduced those of P. digitatum. P. umbilicalis extract strongly inhibited mycelia and conidia growth on all the fungi. E. denticulatum and G. pusillum showed a lower but still significant reduction of mycelia growing and conidia germination on all the pathogens. In trials performed in vivo on wounded fruit, L. digitata, U. pinnatifida and P. umbilicalis extracts strongly suppressed grey mould on strawberries, brown rot on peaches, and green mould on lemons at 30gL−1 dose both in preventive and curative treatments; E. denticulatum and G. pusillum poorly reduced disease development. In all cases, a dose-effect of the treatments was observed with an increase of fruit decay inhibition and reduction of disease severity as the dose of extract applied over the wound increased. Moreover, an increased peroxidase activity in the strawberries/B. cinerea and peaches/M. laxa systems by preventive treatment with 30gL−1 extract was observed. The antifungal activity could be mainly ascribed to a direct toxicity of fatty acids found at the highest concentrations in L. digitata, U. pinnatifida and P. umbilicalis rather than to those of phenolic compounds and phlorotannins; but it could be related to possible peroxidase-mediated systemic resistance mechanisms elicited by the polysaccharides.

Ultrasound assisted methods for enhanced extraction of phycobiliproteins from marine macro-algae, Gelidium pusillum (Rhodophyta)

Extraction of phycobiliproteins (R-phycoerythrin, R-PE and R-phycocyanin, R-PC) from macro-algae is difficult due to the presence of large polysaccharides (agar, cellulose etc.) present in the cell wall which offer major hindrance for cell disruption. The present study is aimed at developing most suitable methodology for the primary extraction of R-PE and R-PC from marine macro-algae, Gelidium pusillum(Stackhouse) Le Jolis. Such extraction of phycobiliproteins by using ultrasonication and other conventional methods such as maceration, maceration in presence of liquid nitrogen, homogenization, and freezing and thawing (alone and in combinations) is reported for the first time. Standardization of ultrasonication for different parameters such as ultrasonication amplitude (60, 90 and 120µm) and ultrasonication time (1, 2, 4, 6, 8 and 10mins) at different temperatures (30, 35 and 40°C) was carried out. Kinetic parameters were estimated for extraction of phycobiliproteins by ultrasonication based on second order mass transfer kinetics. Based on calorimetric measurements, power, ultrasound intensity and acoustic power density were estimated to be 41.97W, 14.81W/cm2 and 0.419W/cm3, respectively. Synergistic effect of ultrasonication was observed when employed in combination with other conventional primary extraction methods. Homogenization in combination with ultrasonication resulted in an enhancement in efficiency by 9.3% over homogenization alone. Similarly, maceration in combination with ultrasonication resulted in an enhancement in efficiency by 31% over maceration alone. Among all the methods employed, maceration in combination with ultrasonication resulted in the highest extraction efficiency of 77 and 93% for R-PE and R-PC, respectively followed by homogenization in combination with ultrasonication (69.6% for R-PE and 74.1% for R-PC). HPLC analysis was carried out in order to ensure that R-PE was present in the extract and remained intact even after processing. Microscopic studies indicated a clear relation between the extraction efficiency of phycobiliproteins and degree of cell disruption in a given primary extraction method. These combination methods were found to be effective for extraction of phycobiliproteins from rigid biomass of Gelidium pusillum macro-algae and can be employed for downstream processing of biomolecules also from other macro-algae.

Marine Macrophytes and Plastics Consumed by Green Turtles (Chelonia mydas) in Hong Kong, South China Sea Region

Abstract This is the first identification of marine macrophytes consumed by green turtles in Hong Kong, South China Sea: 6 red algae species (Pterocladiella tenuis, Gelidium pusillum, Chondrus ocellatus, Gracilaria chorda, Grateloupia filicina, and Amansia glomerata), 1 brown alga species (Lobophora variegata), and 1 sea grass (Halophila ovalis) were identified. Plastics and other foreign materials were also found in the stomach contents of 2 of the 8 individuals sampled.