Botany and Microbiology

Nannochloropsis salina was cultured batch-wise to evaluate the potential of the alga to produce biodiesel. The cells were harvested at the end of the exponential growth phase when the concentration was 18 • 10 6 cells/mL culture. The growth estimated as dry weight from this cell number was (3.8  0.7) mg/L. The lipid and triglyceride contents were 40% and 12% on a dry weight basis, respectively. The amount of the ratio triglycerides/total lipids was approximately 0.3. The composition of triglyceride fatty acid methyl esters (biodiesel) was analysed by gasliquid chromatography and identifi ed as:

Total, free and conjugated forms (steryl esters, steryl glycosides and acyl steryl glycosides) of sterols from three microalgae that are extensively used in mariculture (Tetraselmis chuii, Nannochloropsis salina and Skeletonema costatum) were examined. The results revealed that cholesterol is the only common fraction detected in all investigated species and distributed in free and all conjugated forms. However, the total sterol content of T. chuii was about 325 μg/g dry wt, most of it was concentrated amongst 24-methylcholesta-5,24-diene-3β-ol and 24-methylcholest-5-en-3β-ol. On the other hand, the majority of the fractions were distributed in the free form. The total sterol content of N. salina was about 180 μg/g dry wt, cholesterol was the major fraction that was detected. Nevertheless, the dominant distribution forms were esterified. While in S. costatum, the total sterol content was 76 μg/g dry wt, approximately most fractions are quantitatively alike and dominated in the free f...

The marine eustigmatophycean microalga Nannochloropsis (Monallantus) salina Hibberd was cultivated in a batch culture in the presence of various concentrations (0, 25, 50, 75 and 100%) of an aqueous extract of diesel fuel oil in order to assess the influence of the pollutant on the growth and certain physiological responses of the microalga. The growth data revealed a significant negative effect of the various pollutant concentrations on the algal cell number (p ≤ 0.05). However, at the midlogarithmic growth phase (day 8), the algal cells were analysed for chlorophyll a, β-glucan, amino acid pool, C/N ratio and elemental composition. According to our results, N. salina was significantly affected by the pollution with regard to the different physiological parameters examined, and this significance may be negative, positive or variable. The effect of the pollutant on cellular β-glucan and the total

In this work some major marine green algal taxa and the fresh water Chara species were selected and subjected to sterols and fatty acid analyses. Fatty acid analyses indicated that most of the extracted acid fractions were of the polyunsaturated ones (C16, C18 and C20) with some unusual fractions of C17 and C19. Fatty acids as a taxonomic tool gave a particular picture for each investigated taxa that characterized each member. High similarity matrices were observed between Dunaliella salina, Chlorella salina and Enteromorpha compressa. Sterol data indicated that most of the tested algae contained Δ 5 , Δ 5,22 , Δ 7 sterols, peptosterol and the saturated nucleus campestanol. Sterol analyses showed clear variations between genera of the different orders: spinasterol was detected only in Ulvales while 5 β cholestanol and 5 β cholest-7-en-β-ol in Chlorococcales and 5, 22, 24 cholestatrien-3 β-ol was detected only in Charales. In general view, data of sterols and fatty acids indicated that Chara species could be placed among green algae.

A series of batch culture experiments of two marine microalgae Dunaliella salina Teodoresco and Nannochloropsis salina Hibberd was conducted at various humic acid (HA) concentrations (0.0, 0.1, 0.2, 0.3, 0.4, 0.5 mgL-1) to evaluate the stimulatory potential of HA on the growth (expressed as a biomass concentration), pigment production (chlorophyll a and carotenoids) and C/N ratio. The impact of HA on the proximate composition (moisture, ashes, dietary fiber, crude lipid, available carbohydrates, crude protein and the energy content) was also considered. Results demonstrated a highly significant positive effect of HA on growth, pigment production and proximate analysis (P≤ 0.01). The response of both investigated microalgae to HA show optima in the range of concentration studied, which makes it a low cost-high yield investment. However, C/N ratio in D. salina showed a gradual decrease upon addition of HA. On the other hand a slight increase in the ratio was observed in N. salina.

Seasonal biomass variation, agar yield and some agar properties of Pterocladia capillacea and Hypnea musciformis were examined during the period from July 2003 to June 2004. The maximum biomass values of both studied algae were recorded during winter and the minimum values were obtained during spring and summer. Agar yield of P. capillacea varied from a minimum of 26.6% (dry weight) in August, to a maximum value of 35.6% in October, while that of H. musciformis varied from a minimum of 15.3% at June, to a maximum of 24% at December. The maximum agar gel strengths were recorded at July (being 225 and 158 gcm-2 of P. capillacea and H. musciformis, respectively). Gelling and melting temperatures showed significant seasonal variation for both studied algal species. Agar yield and quality of P. capillacea and H. musciformis were within the range of accepted commercial values. Yield and gel properties of agar extracted from H. musciformis were comparable with those obtained from P. capillacea. Results also indicated that H. musciformis can be considered as a good candidate for commercial agar use.

The marine eustigmatophycean microalga Nannochloropsis (Monallantus) salina Hibberd was cultivated in a batch culture in the presence of various concentrations (0, 25, 50, 75 and 100%) of an aqueous extract of diesel fuel oil in order to assess the influence of the pollutant on the growth and certain physiological responses of the microalga. The growth data revealed a significant negative effect of the various pollutant concentrations on the algal cell number (p≤ 0.05). However, at the midlogarithmic growth phase (day 8), the algal cells were analysed for chlorophylla, β-glucan, amino acid pool, C/N ratio and elemental composition. According to our results, N. salina was significantly affected by the pollution with regard to the different physiological parameters examined, and this significance may be negative, positive or variable. The effect of the pollutant on cellular β-glucan and the total The complete text of the paper is available at http://www.iopan.gda.pl/oceanologia/ 76 N....

This paper describes a preliminary analysis of the possibility to use different algae species for biodiesel production. A lab scale cultivation of five Chlorella spp. was conducted to evaluate their potential for biodiesel production, with respect to their growth and fatty acids characterization, as an initial step to transferring them into the outdoor open ponds. The results of algal dry wt (mg/l), arranged in descending order, were Chlorella salina, 200 ± 0.02; Chlorella vulgaris , 192.28 ± 0.00; Chlorella stigmatophora , 162 ± 13.06; Chlorella capsulata , 101.08 ± 7.54; Chlorella marina , 86 ± 6.99, while the growth rates (mg/d) were Chlorella marina , 2 ± 0.17; Chlorella vulgaris , 1.78 ± 0.14; Chlorella stigmatophora , 1.52 ± 0.11; Chlorella capsulata , 1.51 ± 0.13; Chlorella salina , 1.16 ± 0.09. The highest lipid content (dry wt based) was recorded for Chlorella capsulata (446 ± 0.33 mg/g), while Chlorella vulgaris showed the lowest content (255 ± 2.5 mg/g). The amounts of th...

The marine eustigmatophycean microalga Nannochloropsis (Monallantus) salina Hibberd was cultivated in a batch culture in the presence of various concentrations (0, 25, 50, 75 and 100%) of an aqueous extract of diesel fuel oil in order to assess the influence of the pollutant on the growth and certain physiological responses of the microalga. The growth data revealed a significant negative effect of the various pollutant concentrations on the algal cell number (p ≤ 0.05). However, at the midlogarithmic growth phase (day 8), the algal cells were analysed for chlorophyll a, β-glucan, amino acid pool, C/N ratio and elemental composition. According to our results, N. salina was significantly affected by the pollution with regard to the different physiological parameters examined, and this significance may be negative, positive or variable. The effect of the pollutant on cellular β-glucan and the total

The marine micro-alga Nannochloropsis oculata was batch-wise grown under different salinities ranged from 0 to 40 g up to the stationary phase. The aim was to identify the best salinity that could enhance the maximum cell mass and oil for biodiesel production. Growth data showed an increase in cell number and dry weight of microalga as a function of salinities up to 30 g, while the amounts of algal oil continually increased over all experimental salinity range. In order to get a maximum oil yield whilst maintaining a high cells concentration of the alga, the cells at stationary-phase were transferred from the preferred growth medium with salinity of 30 to salinity of 32 g. The cells have been re-inoculated in the up-next concentrations of 34, 36, 38, and 40 g in the same step-wise fashion. By this trend of cultivation, algal cell division showed a good adaptation to the highest salinities and the cells would not go into osmotic shock and die. On the other hand, the composition of fa...

A laboratory study was carried out to enhance biofuel yield of marine microalgae Tetraselmis chuii, Chaetoceros muelleri and Isochrysis sp. (clone c Iso), using an aqueous extract of secondary recovered sewage sludge (SS). In this respect, we compared the intracellular lipid accumulation in cells grown on controlled to the treated with SS cultures, both quality and quantity. The gravimetric data showed an obvious increase of total lipids in the treated cells 13.16, 1.65 and 1.8 times for T. chuii, C. muelleri and Iso. sp. respectively. In addition, the algal oil increased 16, 1.73 and 5 times in the same order. Fatty acid methyl esters of the controlled growth cultures are dominated by C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, C18:3, C18:4 and C22:6. However, the treated ones showed a significant variation in the concentration of both total lipids and oil fatty acids. Moreover, some fractions are disappeared, while others are newly synthesized. The results suggest that the applicati...

Biodiesel has become an attractive diesel fuel substitute to its environmental benefits since it can be made from renewable resource. A technological assessment of biodiesel production from chlorella marine was carried out to evaluate their technical benefits and limitations. The main issue with algal oil is the high level of free fatty acids found in it. Economic analysis is a powerful tool that can be used to both evaluate the production cost of algae bio-fuels and help to identify the major factors which contribute most to the production cost - thereby helping to focus future engineering research. This investigation examines how economic assessment has been used to estimate the future cost of transport fuels produced from algal biomass. The acid-catalyzed process using algal oil proved to be technically feasible with less complexity than the alkali-catalyzed process, thereby making it a competitive alternative to commercial biodiesel production by the alkali-catalyzed process. It...

Nannochloropsis salina was cultured batch-wise to evaluate the potential of the alga to produce biodiesel. The cells were harvested at the end of the exponential growth phase when the concentration was 18 x 10(6) cells/mL culture. The growth estimated as dry weight from this cell number was (3.8 +/- 0.7) mg/L. The lipid and triglyceride contents were 40% and 12% on a dry weight basis, respectively. The amount of the ratio triglycerides/total lipids was approximately 0.3. The composition of triglyceride fatty acid methyl esters (biodiesel) was analysed by gas-liquid chromatography and identified as: C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, C18:3, C20:1, and C20:5. The ratio of unsaturated to saturated fatty acid contents was approximately 4.4. Additionally, the characterization of each individual fatty acid ester was discussed with regard to the fuel properties of biodiesel produced by the alga.

The marine eustigmatophycean microalga <i>Nannochloropsis</i>(<i>Monallantus</i>) <i>salina</i> Hibberd was cultivated in a batchculture in the presence of various concentrations (0, 25, 50, 75 and 100%)of an aqueous extract of diesel fuel oil in order to assess the influenceof the pollutant on the growth and certain physiological responses of themicroalga. The growth data revealed a significant negative effect of thevarious pollutant concentrations on the algal cell number(<i>p</i> ≤ 0.05). However, at the mid-logarithmic growth phase (day 8),the algal cells were analysed for chlorophyll <i>a</i>, <i>β</i>-glucan,amino acid pool, C/N ratio and elemental composition. According to ourresults, <i>N. salina</i> was significantly affected by the pollution withregard to the different physiological parameters examined, and thissignificance may be negative, positive or variable. The effect of ...

This work aims at culturing different Chlorella species, monitoring growth and estimating the nutritional quality for further application of complete cells and lipid extracted biomass in Artemia franciscana feeding. We conducted experiments using C. marina, C. salina, C. capsulata, C. stigmatophora and C. vulgaris that were batch cultured for 14 days. C. salina showed the maximal count on the sixth day while C. marina recorded the maximum growth rate (2 ± 0.177). However, C. capsulata and C. stigmatophora recorded the minimum rate (1.5 ± 0.11). Analyses of algal biomass showed that C. capsulata contains maximal lipids and carbohydrates, but the minimal protein (22.8 ± 1.4 %). However, C. salina contained the highest protein (33.1 ± 1.4 %). After oil extraction, there were no significant losses in the other biochemical constituents of the studied Chlorella species. Considering algae metabolites, saturated fatty acids were the main constituent in the fatty acids methyl esters (FAMEs). Palmitic and stearic acids were dominant. Amino acid pools of the experimental marine Chlorella species were found to contain lysine, methionine and histidine; but were deficient in cysteine. The present investigation showed that lipids, proteins and protein to lipid ratio of A. franciscana napulli enriched with mixed cells of Chlorella species were enhanced by (22 %); 1.96 and 1.33 folds, respectively. Furthermore, the growth and survival of A. franciscana showed significant increases when fed on lipid extracted algae residuals, especially that of a mixed diet; which is considered as an important achievement and confirms that the residual algae biomass can be significantly used for aquaculture feeding.