Growth and carrageenan quality of <Emphasis Type="Italic">Kappaphycus striatum</Emphasis> var. <Emphasis Type="Italic">sacol</Emphasis> grown at different stocking densities,duration of culture and depth

Kappaphycus striatum var. sacol was grown in two separate studies: (1) at two stocking densities, and (2) at four different depths, each for three different durations of culture (30, 45 and 60 days) in order to determine the growth rate of the seaweed and evaluate the carrageenan content and its molecular weight. The results demonstrated that stocking density, duration of culture and depth significantly (P < 0.01) affected the growth rate, carrageenan content and molecular weight of K. striatum var. sacol. Decreasing growth rate was observed at both stocking densities and at four depths as duration of culture increased. A lower stocking density (500 g m⁻¹line⁻¹) showed a higher growth rate for the shortest durations, i.e. 30 days, as compared to those grown at a higher density. Likewise, decreasing growth rate was observed as depth increased, except at 50 cm after 60 days of culture. A 45-day culture period produced the highest molecular weight at both stocking densities (500 g m⁻¹line⁻¹ = 1,079.5 ± 31.8 kDa, 1,000 g m⁻¹line⁻¹ = 1,167 ± 270.6 kDa). ‘Sacol’ grown for 30 days at 50 cm (1,178 kDa) to 100 cm (1,200 kDa) depth showed the highest values of molecular weight of carrageenan extracted. The results suggested that K. striatum var. sacol is best grown at a stocking density of 500 g m⁻¹line⁻¹, at a depth of 50–100 cm, and for a duration of 30 days in order to provide the highest growth rate, carrageenan content and molecular weight.     

Superior quality agar from <Emphasis Type="Italic">Gracilaria</Emphasis> species (Gracilariales,Rhodophyta) collected from the Gulf of Mannar,India

Gracilaria edulis, G. crassa, G. foliifera, and G. corticata are naturally occurring agarophytes of Indian waters. These agarophytes were evaluated for their agar contents using an improved process recently reported by us (US Patent 2005/0267296A1). The effect of different concentrations of NaOH in the alkali treatment was studied for optimizing the extraction conditions. These Gracilaria species of Indian waters produced agars, both native and alkali treated, with different properties confirming the heterogeneity of the agar polymers in this genera, as one would expect. Among these, G. edulis and G. crassa produced agar polymers having high gel strengths of 490 ± 8.16 and 800 ± 15.4 g cm⁻², respectively, with 8% NaOH treatment as opposed the low gel strength agars that have been reported in the literature to date.     

Characterization of Carrageenan Extracted from <Emphasis Type="Italic">Hypnea bryoides</Emphasis> in Oman

Carrageenophyte red seaweed from Oman, Hypnea bryoides, extracted using three different processes: an aqueous, a mild alkaline, and a more vigorous alkaline extraction was investigated. The resulting extract precipitated by alcohol was subject to chemical and rheological measurements. The total carbohydrate [ranged from 36.78 to 41.65 g/100 g], and ash [39.04 to 43.11 g/100 g] were the most abundant components in H. bryoides and contrary to the two, lipid content was found at a minimum [ranging from 2.95 to 3.38 g/100 g]. Alkali treatment with NaOH allowed complete conversion of kappa (κ) carrageenan form as detected by FTIR analysis. Total yield by alkali treatments gave higher yields (33%) compared with aqueous treatments (12%). However, subsequent aqueous treatment produced mixed carrageenan (μ and κ) with higher molecular weight compared with the alkali treatments which produced single carrageenan form (κ) with molecular weight of 4.1 × 10⁵ Da. The effects of thermal history on gel–sol and sol–gel transition were investigated by differential scanning calorimeter (DSC) and rheology on a pure sample and 1.5% κ-carrageenan mixture added with 30 mM KCl. Transition temperatures from DSC and rheology showed comparable results and were in good agreement with those previously reported.     

Effect of alkali treatment time and extraction time on agar from <Emphasis Type="Italic">Gracilaria vermiculophylla</Emphasis>

The effects of alkali treatment time and extraction time of native agar and alkali treated agar obtained from Gracilaria vermiculophylla were studied. The response characteristics were mainly agar yield and gel strength. Alkali treatment was carried out at 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 h. Agar yield and gel strength decreased with the increase in the time of the alkali treatment. The highest yield (15.3%) and highest gel strength (1,064 g cm⁻²) were obtained at 0.5 h, and therefore this time was used for the next experiment. The extraction of both native and alkali treated agars was carried out at 1.5, 2.0, 2.5, and 3.0 h. The best extraction time for alkali treated agar was 1.5 h, and for native agar 2.5 h. The alkali treated agar obtained with the different alkali treatment and extraction times showed higher melting (92.4–99.7°C) and gelling (35.7–39.6°C) temperatures. Native agar was lower in melting (60.2–64.1°C) and gelling (20.4–23.4°C) temperatures. The 3,6-anhydrogalactose content decreased with increasing alkali treatment time, with the opposite effect during the extraction of native and alkali treated agars.     

Alginate,mannitol, phenolic compounds and biological activities of two range-extending brown algae, <Emphasis Type="Italic">Sargassum mangarevense</Emphasis> and <Emphasis Type="Italic">Turbinaria ornata</Emphasis> (Phaeophyta: Fucales), from Tahiti (French Polynesia)

This study deals with two range-extending brown algae from Tahitian coral reefs, Sargassum mangarevense and Turbinaria ornata; their alginate properties, mannitol and phenolic contents, antioxidant and antimicrobial activities were determined. Turbinaria ornata showed the richest alginate content with the highest extraction yield (19.2 ± 1.3% dw). Their alginates also exhibited the highest viscosity (50 ± 18 mPa.s), but the M:G ratios (mannuronic acid to glucuronic acid) of alginates (1.25–1.42) were similar in both species. Alginate yield displayed spatial variations, but no significant seasonal changes. The highest mannitol content was found in S. mangarevense (12.2 ± 2.1% dw) during the austral winter. With respect to other tropical Fucales, both algae exhibited also a high phenolic content (2.45–2.85% dw) with significant spatio-temporal variations. Furthermore, high antioxidant activity and activity against Staphylococcus aureus were also detected in extracts. According to these preliminary results, these two range-extending algae are of key interest in numerous industrial areas.     

Seasonal variation of agar from <Emphasis Type="Italic">Gracilaria vermiculophylla,</Emphasis> effect of alkali treatment time,and stability of its Colagar

Gracilaria vermiculophylla, from Baja California Sur, Mexico, was studied in order to determine the seasonal variation of yield and quality of native and alkaline agar during 2007–2008. The highest alkaline agar yield was obtained in summer (17%) and the highest gel strength in spring (1,132 g cm⁻²). The highest melting temperature was 98°C (winter). The highest gelling temperature was 68°C (summer). The values obtained are within the range of the most important Gracilaria species harvested worldwide. During the agar extraction step, the best results were obtained after 30 min of alkali treatment with sodium hydroxide (7%), after which the quality decreased significantly. We produced Colagar from G. vermiculophylla which consists of the seaweeds treated with sodium hydroxide and dried. The yield and quality of the agar obtained from the Colagar shows stability in both yield and quality during 1 year of storage, suggesting that alkali treatment is a good method of avoiding agar hydrolysis during storage.     

Heavy metal pollution monitoring using the brown seaweed Padina durvillaei in the coastal zone of the Santa Rosalía mining region, Baja California Peninsula, Mexico

The coastal marine sediments near Santa Rosalía on the eastern coast of the Baja California Peninsula (Mexico) are heavily polluted by metals due to copper mining and smelting over the past century (up to 1984). The present study compares the accumulation of metals in the brown seaweed Padina durvillaei from the central segment of the coast of Santa Rosalía (polluted by Co, Cu, Mn and Zn) and from two segments north and south of the known “hot spot”. The seaweed samples were collected in May and August 2004 and June 2005 at 13 stations located along the Santa Rosalía mining region. Heavy metal concentrations were measured by instrumental neutron activation analysis (Co and Fe) directly in dried homogenized subsamples or by flame atomic absorption spectrophotometry (Cd, Cu, Mn, Ni, Pb and Zn) after complete strong acid digestion of sub-samples. The means and standard deviations of the concentrations in dry tissues of Padina durvillaei specimens for all the studied metals and stations lie in the following sequence: Cd (3.6 ± 1.6 mg kg⁻¹) < Co (6.5 ± 6.1 mg kg⁻¹) < Pb (7.8 ± 6.2) < Ni (9.96 ± 5.28 mg kg⁻¹) < Cu (53 ± 38 mg kg⁻¹) < Zn (63 ± 43 mg kg⁻¹) < Mn (295 ± 269 mg kg⁻¹) < Fe (2243 ± 2325 mg kg⁻¹). This increase of the average concentrations was statistically significant. Principal Component Analysis showed that Factor 1 (36.46%) displays high positive loadings for Co, Cu, Mn and Zn, reflecting the influence of local anthropogenic pollution on the seaweed composition, while Factor 2 (26.91%) is important for Co, Fe and Ni and probably corresponds to the adsorption or accumulation of terrigenous elements of the regional origin, while Factor 3, with a high positive loading for Pb and a high negative loading for Cd, is probably controlled by local and regional anthropogenic input of Pb and episodic supply of Cd by local upwellings. The results of ANOVA for each element do not show any significant differences between the average concentrations for Cd, Fe, Ni and Pb in the seaweed of the three segments, or between the central and southern segments for Cu, Mn and Zn. Cobalt contents in the seaweed from the northern and central segments are, however, significantly different from the southern segment. This indicates that element concentrations in Padina durvillaei generally do not follow the drastic increases and gradients of Cu, Co, Mn and Zn contents detected in surface sediments. The apparent contradiction could be explained by a low geochemical mobility of these metals in the polluted sediments, composed mainly of stable residues of smelter wastes, with very low content of organic matter usually driving diagenetic mobilization of some metals into interstitial waters and then to the overlying water.     

An initial comparison of tubular netting versus tie–tie methods of cultivation for Kappaphycus alvarezii (Rhodophyta, Solieriaceae) on the south coast of Rio de Janeiro State, Brazil

A new cultivation technique for Kappaphycus alvarezii was used in the Brazilian southeastern coast (23°02′25″ S and 43°53′39″ W), the tubular netting on floating rafts. The tubular net technique (TN) was compared with the current method of tie–tie (TT). After 47 days, the daily growth rate (mean ± SD of TN and TT = 3.4 ± 0.7% day⁻¹), carrageenan yield (mean ± SD of TN and TT = 36 ± 1.3%), gel strength (mean ± SD of TN and TT = 730 ± 114.5 g cm2), and viscosity (mean ± SD of TN and TT = 350 ± 60.4 cP) did not differ between the two techniques (p > 0.05). The amount of time used to plant (TT = 30.2 ± 2.3 min and TN = 13.3 ± 3.4 min) and to harvest the seedlings (TT = 36.2 ± 2.7 min and TN = 17.8 ± 3.7 min) were lower in TN (p < 0.001). It is concluded that TN was more effective than TT, the cultivation management (time rates used to plant and harvest the seedlings) was 53.6% faster, no seedlings were lost, the cost was lower, and an estimated return in 1 year of nearly 20% more than that of the TT technique.     

Growth and survival performance of the gametophyte of Gigartina skottsbergii (Rhodophyta, Gigartinales) under defined nutrient conditions in laboratory culture

Gigartina skottsbergii is a commercially important carrageenan producer that has been suffering severe extraction pressure in Chile’s Magellan Region and Cape Horn Archipelago since 1998. In order to create baseline information for its cultivation and repopulation, we studied the effects of agricultural fertilizers on growth of G. skottsbergii early developmental stages. The culture media utilized were: a) seawater + Bayfoland, b) seawater + Superphosphate, c) seawater + Urea, d) seawater + Provasoli and e) seawater as a control. The culture conditions were: a) 12L:12D photoperiod; b) temperature 8 ± 1°C and c) irradiance at 45 μmol photons m⁻² s⁻¹. After 60 days, higher relative growth rates between treatments were observed; the treatments that included Bayfoland and Provasoli showed greater growth (382 ± 55 and 378 ± 50 μm, respectively,) compared to Superphosphate (88 ± 16 μm), control (78 ± 10 μm) and Urea (70 ± 11 μm) treatments, after 81 days. The Urea treatment and the control had inhibitory effects on G. skottsbergii germlings growth and survival, as evidenced by progressive loss of pigmentation and death after 60 days. These results showed that Bayfoland was an excellent alternative to develop cultures.     

Enhancement of polysaccharides production in <Emphasis Type="Italic">Ganoderma lucidum</Emphasis> by the addition of ethyl acetate extracts from <Emphasis Type="Italic">Eupolyphaga sinensis</Emphasis> and <Emphasis Type="Italic">Catharsius molossus</Emphasis>

To screen stimulators from Chinese medicinal insects for mycelial growth and polysaccharides production of Ganoderma lucidum, G. lucidum was inoculated into the media with and without supplementation of medicinal insect extracts. The ethyl acetate extract of Eupolyphaga sinensis at 55 mg l⁻¹ lead to significant increase in both biomass and intracellular polysaccharides (IPS) concentration from 8.53 ± 0.41 to 14.16 ± 0.43 and 1.28 ± 0.09 to 2.13 ± 0.11 g l⁻¹, respectively. In addition, the ethyl acetate extract of Catharsius molossus at 55 mg l⁻¹ significantly enhanced extracellular polysaccharides (EPS) production; the EPS yield increased from 350.9 ± 14.1 to 475.1 ± 15.3 mg l⁻¹. There were no new components in the two types of polysaccharides obtained by the addition of the insect extracts.     

Preparation of superior quality products from two Indian agarophytes

The effect of alkali pre-treatments on the properties of agar obtained from Gelidiella acerosa and Gelidium pusillum growing along the West and South coast of India was studied in order to evaluate its potential for industrial use. Agar samples were extracted by hot water extraction and termed native agar, and alkali pre-treatment was carried out with various NaOH concentrations e.g. 4%, 6%, 8%, 10% and 15%, to optimise the alkali concentration for preparation of alkali-treated agar. Gelidiella acerosa and Gelidium pusillum produced superior quality agar polymers having greater gel strengths 2,000 ± 50 and 1,400 ± 50 g cm⁻² and lower sulphate contents ≤0.30% and ≤0.50%, respectively, as opposed the low gel strength and high sulphate content agars reported in the literature. Furthermore, the physicochemical properties of agars were identical with the commercially available agars. The results of this study revealed that Indian agarophytes may be used for production of superior quality agar and agaroses, which may be used for food and biological applications.     

Continuous cultures of <Emphasis Type="Italic">Pseudomonas putida</Emphasis> mt-2 overcome catabolic function loss under real case operating conditions

The long-term performance and stability of Pseudomonas putida mt-2 cultures, a toluene-sensitive strain harboring the genes responsible for toluene biodegradation in the archetypal plasmid pWW0, was investigated in a chemostat bioreactor functioning under real case operating conditions. The process was operated at a dilution rate of 0.1 h⁻¹ under toluene loading rates of 259 ± 23 and 801 ± 78 g m⁻³ h⁻¹ (inlet toluene concentrations of 3.5 and 10.9 g m⁻³, respectively). Despite the deleterious effects of toluene and its degradation intermediates, the phenotype of this sensitive P. putida culture rapidly recovered from a 95% Tol⁻ population at day 4 to approx. 100% Tol⁺ cells from day 13 onward, sustaining elimination capacities of 232 ± 10 g m⁻³ h⁻¹ at 3.5 g Tol m⁻³ and 377 ± 13 g m⁻³ h⁻¹ at 10.9 g Tol m⁻³, which were comparable to those achieved by highly tolerant strains such as P. putida DOT T1E and P. putida F1 under identical experimental conditions. Only one type of Tol⁻ variant, harboring a TOL-like plasmid with a 38.5 kb deletion (containing the upper and meta operons for toluene biodegradation), was identified.     

Permeabilization of <Emphasis Type="Italic">Microbacterium oxylans</Emphasis> shifts the conversion of puerarin from puerarin-7-<Emphasis Type="Italic">O</Emphasis>-glucoside to puerarin-7-<Emphasis Type="Italic">O</Emphasis>-fructoside

The main product of the conversion of puerarin by unpermeabilized cells of bacterium Microbacterium oxydans CGMCC 1788 was puerarin-7-O-glucoside (241 ± 31.9 μM). Permeabilization with 40% ethanol could not increase conversion yield, whereas it resulted in change of main product; a previous trace product became a main product (213 ± 48.0 μM) which was identified as a novel puerarin-7-O-fructoside by electrospray ionization time-of-flight MS, ¹³C NMR, ¹H NMR, and GC-MS analysis of sugar composition, and puerarin-7-O-glucoside became a trace product (14.8 ± 5.4 μM). However, the extract from cells of M. oxydans CGMCC 1788 permeabilized with ethanol converted puerarin to form 113.9 ± 27.7 μM puerarin-7-O-glucoside and 187.8 ± 29.5 μM puerarin-7-O-fructoside under the same conditions. When unpermeabilized intact cells were recovered and used repeatedly for the conversion of puerarin, with increase of reuse times, the yield of puerarin-7-O-glucoside gradually decreased, whereas the yield of puerarin-7-O-fructoside increased gradually in the conversion mixture. The main product of the conversion of puerarin by the tenth recycled unpremerbilized cells was puerarin-7-O-fructoside (288.4 ± 24.0 μM). Therefore, the change of permeability of cell membrane of bacterium M. oxydans CGMCC 1788 contributed to the change of conversion of the product’s composition.     

Hyper production of cellulase-free xylanase by <Emphasis Type="Italic">Thermomyces lanuginosus</Emphasis> SSBP on bagasse pulp and its application in biobleaching

A cellulase-free xylanase production by Thermomyces lanuginosus SSBP using bagasse pulp was examined under submerged (SmC) and solid-state cultivation (SSC). Higher level of xylanase activity (19,320 ± 37 U g⁻¹ dried carbon source) was obtained in SSC cultures than in SmC (1,772 ± 15 U g⁻¹ dried carbon source) after 120 h with 10% inoculum. The biobleaching efficacy of crude xylanase was tested on bagasse pulp, and the maximum brightness of 46.1 ± 0.06% was observed with 50 U of crude xylanase per gram of pulp, which was 3.8 points higher than the brightness of untreated samples. Reducing sugars (26 ± 0.1 mg g⁻¹) and UV-absorbing lignin-derived compounds in the pulp filtrates were observed as maximum in 50 U of crude xylanase-treated samples. T. lanuginosus SSBP has potential applications due to its high productivity of xylanase and its efficiency in pulp bleaching.     

Effect of eight benthic diatoms as feed on the growth of red abalone (Haliotis rufescens) postlarvae

The growth rate of abalone post larvae of Haliotis rufescens fed ad libitum with a benthic monoalgal diatom culture maintained as monocultures on a semi-commercial scale, was evaluated and correlated with the biochemical composition of the diatoms. The cell size (7.0 × 4.0 μm to 21.0 × 7.5 μm), protein percentage (7.42% to 13.66%), and ash content (49.03% to 59.61%) were different among diatom strains; lipid percentage, nitrogen free extract, and energy content (Kcal g⁻¹) were similar among diatom strains. The values of essential and non-essential amino and fatty acids composition differed among diatom strains. Differences in the abalone shell length and orthogonal analyses revealed postlarval growth was dependent on the quality of the food source. Postlarvae abalone displaying the longest shell lengths were fed Nitzschia thermalis var. minor and Amphiprora paludosa var. hyalina (1,712.0 ± 61 μm and 1,709 ± 67 μm, respectively), followed by Navicula incerta (1,413.3 ± 43 μm). The fatty acid content of benthic diatoms and abalone growth rate were not correlated.     

Effects of reduced diameter of bag cultures on content of essential fatty acids and cell density in a continuous algal production system

Cell density and fatty acid (FA) content of Pavlova lutheri and Chaetoceros muelleri were analysed in a continuous algal production system (250-L bags) with reduced diameter. The cell density and FA content and composition in the algal production system were determined in replicate bags over a period of 5 weeks. The results showed that the cell density and essential FAs increased during the experiment for both species. After 5 weeks the mean cell numbers had increased to 6.0 ± 0.3 × 10⁶ cells mL⁻¹ in the P. lutheri bags and 6.0 ± 0.4 × 10⁶ cells mL⁻¹ in the C. muelleri bags. The content of total FAs increased significantly (p < 0.05) in all of the bags during the experiment. At the end of the experiment the mean total FA content were 2.7 ± 0.3 pg cell⁻¹ in the P. lutheri bags and 1.8 ± 0.1 pg cell⁻¹ in the C. muelleri bags. Maximum total FA content registered was 3.0 pg cell⁻¹ in one of the P. lutheri bags. The content of the essential FAs (ARA, EPA, DHA) increased over time in both of the species. At the end of the experiment the content of EPA (0.6 ± 0.1 pg cell⁻¹) and DHA (0.3 ± 0.0 pg cell⁻¹) were highest in the P. lutheri bags, while ARA (0.1 ± 0.0 pg cell⁻¹) was highest in C. muelleri. EPA and DHA constituted 22% and 11%, respectively, of total FA content in P. lutheri, while ARA constituted 6% of total FA content in C. muelleri. The results from this experiment indicate that flagellates such as P. lutheri perform better in narrow bags with improved light conditions, while diatoms like C. muelleri perform better in wider bags under light limitation. Implications for bivalve hatcheries are discussed.     

Chemical and physical characteristics of carrageenan extracted from Eucheuma spinosum harvested from three different Indonesian coastal sea regions

Carrageenan extracted from Eucheuma spinosum harvested from three different coastal sea regions, where this alga has been mainly cultivated, were determined for their chemical and physical characteristics. The carrageenan was extracted from the seaweed using hot alkali followed by precipitation, drying, and milling. The carrageenan properties were determined in terms of yield, ash, mineral, sulfate content, functional group, molecular weight, and viscosity profile. Physical characteristics of carrageenan were evaluated by a texture analyzer for gel strength and a rapid visco analyzer for viscosity. The yield of carrageenan from Sumenep (34.81 ± 5.83%) and Takalar (37.16 ± 3.26%) was found to be relatively higher than that of Nusa Penida (25.81 ± 1.93%). The calcium content was higher than magnesium, potassium and sodium content, and no cadmium, lead, mercury, and arsenic detected in all carrageenan. The ash content was around 29%; while, the sulfate content was in the range of 30–32%, and those were not different in all carrageenan. The presence of sulfate content was identified by FTIR at absorption band of 1373 cm^?1. It was found that the molecular weight of carrageenan from Takalar were relatively higher and the gel strength of carrageenan from Takalar were significantly higher than that of carrageenan from Nusa Penida and Sumenep. Likewise, upon cooling from 80 to 20°C, the viscosity profile of carrageenan from Takalar characterized by higher viscosity compared to that of carrageenan from Sumenep and Nusa Penida. These results indicated that carrageenan from Nusa Penida, Sumenep, and Takalar were identified as iota‐carrageenan with similar physico‐chemical characteristics except for the gel strength, viscosity profile upon cooling from 80 to 20°C and the yield.     

Effect of seawater temperature on the productivity of <Emphasis Type="Italic">Laminaria japonica</Emphasis> in the Uwa Sea,southern Japan

Recent studies on global climate change report that increase in seawater temperature leads to coastal ecosystem change, including coral bleaching in the tropic. In order to assess the effect of increased seawater temperature on a temperate coastal ecosystem, we studied the inter-annual variation in productivity of Laminaria japonica using long-term oceanographic observations for the Uwa Sea, southern Japan. The annual productivity estimates for L. japonica were 2.7 ± 2.5 (mean ± SD) kg wet wt. m⁻¹ (length of rope) (2003/2004), 1.0 ± 0.6 kg wet wt. m⁻¹ (2004/2005) and 12.1 ± 12.5 kg wet wt. m⁻¹ (2005/2006). Our previous study using the same methodology at the same locality reported that the productivity was estimated for the 2001/2002 (33.3 ± 15.2 kg wet wt. m⁻¹) and 2002/2003 (34.0 ± 8.7 kg wet wt. m⁻¹) seasons. Productivity in 2003/2004 and 2004/2005 was significantly lower than in years 2001/2002, 2002/2003 and 2005/2006. A comparison of oceanographic conditions among the 5 years revealed the presence of threshold seawater temperature effects. When the average seawater temperature during the first 45 days of each experiment exceeded 15.5°C, productivity was reduced to about 10 % of that in cooler years. Moreover the analysis of growth and erosion rates indicates that when the seawater temperature was over 17.5°C, erosion rate exceeded growth rate. Thus, an increase of seawater temperature of just 1°C during winter drastically reduces the productivity of L. japonica in the Uwa Sea.     

Chemopreventive effect of <Emphasis Type="BoldItalic">Padina boergesenii</Emphasis> extracts on ferric nitrilotriacetate (Fe-NTA)-induced oxidative damage in Wistar rats

The present study was designed to investigate the prophylactic effect of extracts of the brown alga Padina boergesenii against potent nephrotoxic agent ferric nitrilotriacetate (Fe-NTA), in blood circulation of rats. Administration of Fe-NTA for seven consecutive days significantly enhanced lipid peroxidation accompanied with reduction in glutathione content. Together with this, the level of antioxidant enzymes, glutathione peroxidase, superoxide dismutase, and catalase was significantly (P < 0.05) diminished. Pretreatment of rats with P. boergesenii (150 mg kg⁻¹ body weight) reversed Fe-NTA-induced oxidative damage in lipid peroxidation and glutathione content significantly (P < 0.05). Further, the activity of antioxidant enzymes was also restored significantly. In order to assess the role of polyphenolic components in the relevant activity, phenolic contents of the extract was found to be 1.78 ± 0.02% in the methanol extract and 1.30 ± 0.30% in the diethyl ether extract. Hence, the present results confirm that the brown alga P. boergesenii preclude its role in Fe-NTA-induced oxidative damage and hyperproliferative response in circulation.     

Optimization of protoplast yields from the red algae <Emphasis Type="Italic">Gracilaria dura</Emphasis> (C. Agardh) J. Agardh and G. <Emphasis Type="Italic">verrucosa</Emphasis> (Huds.) Papenfuss

This study reports on the optimization of protoplast yield from two important tropical agarophytes Gracilaria dura and Gracilaria verrucosa using different cell-wall-degrading enzymes obtained from commercial sources. The conditions for achieving the highest protoplast yield was investigated by optimizing key parameters such as enzyme combinations and their concentrations, duration of enzyme treatment, enzyme pH, mannitol concentration, and temperature. The significance of each key parameter was also further validated using the statistical central composite design. The enzyme composition with 4% cellulase Onozuka R-10, 2% macerozyme R-10, 0.5% pectolyase, and 100 U agarase, 0.4 M mannitol in seawater (30‰) adjusted to pH 7.5 produced the highest protoplast yields of 3.7 ± 0.7 × 10⁶ cells g⁻¹ fresh wt for G. dura and 1.2 ± 0.78 × 10⁶ cells g⁻¹ fresh wt for G. verrucosa when incubated at 25°C for 4–6 h duration. The young growing tips maximally released the protoplasts having a size of 7–15 μm in G. dura and 15–25 μm in G. verrucosa, mostly from epidermal and upper cortical regions. A few large-size protoplasts of 25–35 μm, presumably from cortical region, were also observed in G. verrucosa.