Red Algal Biomass Research Articles

갈락토스-글루코스 혼합당 수소 발효

Galactose, an isomer of glucose with an opposite hydroxyl group at the 4-carbon, is a major fermentable sugar in various promising feedstock for hydrogen production including red algal biomass. In this study, hydrogen production characteristics of galactose-glucose mixture were investigated using batch fermentation experiments with heat-treated digester sludge as inoclua. Galactose showed a hydogen yield compatible with glucose. However, more complicated metabolic steps for galactose utilization caused a slower hydrogen production rate. The existence of glucose aggravated the hydrogen production rate, which would result from the regulation of galactose-utilizing enzymes by glucose. Hydrogen produciton rate at galactose to glucose ratio of 8:2 or 6:4 was 67% of the production rate for galactose and 33% for glucose, which could need approximately 1.5 and 3 times longer hydraulic retention time than galacgtose only condition and glucose only condition, respectively, in continuous fermentation. Hydrogen production rate, Hydrogen yield, and organic acid production at galactose to glucose ratio of 8:2 or 6:4 were 0.14 mL H2/mL/hr, 0.78 mol <TEX>$H_2$</TEX>/mol sugar, and 11.89 g COD/L, respectively. Galactose-rich biomass could be usable for hydogen fermenation, however, the fermentation time should be allowed enough.

Bioremoval of heavy metals from industrial effluent by fixed-bed column of red macroalgae

Three different species of nonliving red algal biomass Laurancia obtusa, Geldiella acerosa and Hypnea sp. were used to build three types of fixed-bed column for the removal of toxic heavy metal ions such as Cu(2+), Zn(2+), Mn(2+) and Ni(2+) from industrial effluent. In general, the highest efficiency of metal ion bioremoval was recorded for algal column of L. obtusa followed by G. acerosa and the lowest one was recorded for Hypnea sp., with mean removal values of 94%, 85% and 71%, respectively. The obtained results showed that biological treatments of industrial effluents with these algal columns, using standard algal biotest, Pseudokirchneriella subcapitata, were capable of reducing effluent toxicities from 75% to 15%, respectively. Red algal column may be considered as an inexpensive and efficient alternative treatment for conventional removal technology, for sequestering heavy metal ions from industrial effluents.

Variação temporal do recrutamento e sucessão ecológica de macroalgas em recifes areníticos da Praia de Piedade – PE, Brasil

Two sites, in which Rhodophyta and Chlorophyta were the dominant algae, were selected in the intertidal zone of a sandstone reef at Piedade Beach to evaluate macroalgal recruitment and succession from March 2007 through January 2008. At each site, 2 meter transects were sampled using 20 x 20 cm quadrats in the midlittoral zone of the reefflat. The initial position of the quadrats was randomly chosen. Green algae (filamentousand foliose) showed a bloom at the end of the rainy season (approximately 250 grams of dry weight/m2 on October 2007), as indicated by the differences between the monthly average biomass values observed in the recruitment plots. The biomass measurements of control quadrats and in the succession treatments did not differ statistically during the rainy season for either Chlorophyta or Rhodophyta at Site 1 or during the dry season at Site 2. Green and red algae (filamentous and corticated) exhibited a pattern of alternating oscillations, as shown by the principal component analysis of recruitment, rainfall and air temperature. These results suggested a negative relationship between temperature and the recruitment of red algal biomass. Key words: Macroalgal Biomass, Benthic Ecology, Sandstone Reefs, Ecological Succession, Algal Recruitment.

Red algal cellular biomass lowers circulating cholesterol concentrations in Syrian golden hamsters consuming hypercholesterolaemic diets

Preliminary evidence suggests that consumption of Porphyridium cruentum (PC) biomass results in hypocholesterolaemic effects; however, mechanisms responsible have not been elucidated. The aim of the present study was to determine whether PC biomass lowers circulating cholesterol concentrations, dose dependently, in hamsters fed hypercholesterolaemic diets for 28 d and determine whether cholesterol biosynthesis is affected. Biomass added to diets at 2.5, 5 and 10% resulted in 14, 38 and 53% reductions (P < 0.001) in total plasma cholesterol, respectively, compared with a control diet. Similarly, non-HDL-cholesterol concentrations in the 5 and 10% PC groups were reduced (P < 0.001) 28 and 45%, respectively, v. controls. These effects were unrelated to cholesterol fractional synthesis rate (FSR), as this did not differ between either treatment or control animals. PC consumption had no effect on food intake, plasma glucose concentrations or energy expenditure, but percentage of body fat was lower (P < 0.001) in the 5 and 10% PC groups compared with controls. These data show that PC reduces total plasma cholesterol and non-HDL-cholesterol when incorporated into the diet at levels as low as 2.5%. The mechanism of action for this reduction may be related to increased excretion since food intakes and cholesterol FSR were not reduced in the animals receiving the PC. In conclusion, the use of PC biomass reduces circulating cholesterol, dose dependently, in hypercholesterolaemic hamsters but not via reductions in cholesterol FSR. There is potential for the use of this biomass as a functional ingredient to aid in the management of blood cholesterol concentrations.

Biochemical principles for phycoerythrin production from marine algae

Biochemical principles of the production process for obtaining phycoerythrin (a food dye) from marine alga gracilaria have been developed. Optimal conditions for destruction of algae and extraction of dye (composition of the extractant, its concentration, pH, temperature, and time of treatment) are determined. General recommendations are given for the creation of pilot production. The method for destruction of marine red algal biomass based on the principle of mechanical destruction of the cell wall of algae and on the freezing of the extracting agent with homogenization of algae is approved and recommended. To obtain and preliminarily purify the phycoerythrin extract, the successive filtration and centrifugation of the destroyed biomass of algae and extract of phycoerythrin are advanced. The membrane filtration and deposition using the 45−50% aqueous solution of ethyl alcohol or acetone is suggested for final purification and concentration of the extract. The suggested method for production of food dye from gracilaria allows us to obtain pure phycoerythrin of an intensive red-crimson color, which may be widely used in food and perfume industries as food supplements, dyes, in perfumes, as fluorescent markers for diagnostics in medical industries, and in radiobiology.

Spatial distribution and abundance of red snow algae on the Harding Icefield, Alaska derived from a satellite image

Red snow caused by algal bloom is common on glaciers and snowfields worldwide. Description of spatial distributions of snow algal blooms is important for understanding snow algae's unique life in an extremely cold environment and for determining the effect of algae through the reduction of surface albedo. Here we present the spatial distribution of red snow algae on the Harding Icefield, Alaska retrieved from a satellite image. Field observations on the icefield conducted in August 2001 revealed visible red snow, particularly near the snowline. Field measurements of spectral reflectance on the surface revealed the specific spectral absorption of algal pigments. We found a significant correlation between snow algal biomass and a reflectance ratio of SPOT (Satellite Probatoire d' Observation de la Terre) satellite band of wavelength 610–680 nm to band 500–590 nm. Using this relationship between the reflectance ratio and algal biomass, we estimated the distribution and abundance of red snow across the icefield using a SPOT satellite image. The spatial distribution of red snow on the icefield obtained by mapping the reflectance ratio matched field observations across the icefield with more red algal blooms on the continental than the maritime side of the icefield. Area averaged mean carbon content estimated from the red algal biomass for the icefield on the image was 1.2 kg km−2.

Chickens fed with biomass of the red microalga Porphyridium sp. have reduced blood cholesterol level and modified fatty acid composition in egg yolk.

The biomass of the red alga Porphyridium sp.constitutes a unique combination of soluble sulfatedpolysaccharide that accounts for about 70% of thealgal dry weight, and various polyunsaturatedfatty acids (PUFA) such as arachidonic andeicosapentaenoic acid (AA, 20:4 ω6 and EPA,20:5 ω3). In view of earlier results in ourlaboratory showing a reduction in serum cholesteroland triglyceride levels in rodents fed with red algalbiomass, we set out to examine the influence of algalbiomass as a feed additive on the metabolism ofchickens, with an emphasis on blood and eggcholesterol levels. For that purpose, lyophilizedalgal biomass was fed to 12–13, 30-week-old, WhiteLeghorn chickens for 10 days at a proportion of 5% or10% of the standard chicken diet. Twelve chickensfed with unsupplemented diet served as the control. No differences in body weight, egg number, and eggweight were found between the algal-fed chickens (atboth concentrations) and the control. However,chickens fed with algal biomass consumed 10% lessfood for both groups, and their serum cholesterollevels were significantly lower (by 11% and 28% forthe groups fed with 5% and 10% supplement,respectively) as compared with the respective valuesof the control group. Egg yolk of chickens fed withalgae tended to have reduced cholesterol levels (by10%) and increased linoleic acid and arachidonic acidlevels (by 29% and 24%, respectively). In addition,the color of the egg yolk was darker as a result ofthe higher carotenoid levels (2.4 fold higher) forchickens that fed with 5% supplement. Theseresults encourage the development of an improvedchicken feed having dietary fibers and polyunsaturatedfatty acids.

Degradation of agarophytic red algal cell wall components by new crude enzyme preparations

Several new crude enzyme preparations were isolated from a marine association of the agarolytic bacterium Cytophaga diffluens and the infusorium Uronema marinum, an axenic culture of Cytophaga diffluens, some species of land micro- and macromycetes adapted to assimilate red algal biomass and from the marine mollusc Littorina littorea. Fungal and mollusc enzyme preparations were shown to have cellulase, xylanase, protease and agarase activities. Fungal agarase activity was revealed only after 3–4 passages of the culture on the medium containing algal biomass. Enzyme preparations from the association and the pure bacterial culture growing on the medium with bactoagar as the sole carbon source contained only agarase activity. The maximum specific agarase activity was found in a preparation from the marine association. The preparations obtained can be used for isolating protoplasts and single cells from red seaweed thalli.