Bold Basal Medium Research Articles

Comparison of the Photoautotrophic Growth Regimens of Chlorella sorokiniana in a Photobioreactor for Enhanced Biomass Productivity

Microalgae have a wide industrial potential because of their high metabolic diversity and plasticity. Selection of optimal cultivation methods is important to optimize multi-purpose microalgal biotechnologies. In this research, Chlorella sorokiniana AM-02 that was isolated from a freshwater lake was cultured under various high photosynthetic photon flux density (PPFD) conditions and CO2 gas levels in standard Bold’s basal medium (BBM). Furthermore, a wide range of nitrate levels (180–1440 mg L−1) was tested on the growth of C. sorokiniana. Microalgae growth, pigment concentration, medium pH, exit gas composition, as well as nitrate, phosphate, and sulfate levels were measured during an experimental period. The preferred high PPFD and optimal CO2 levels were found to be 1000–1400 μmol photons m−2 s−1 and 0.5–2.0% (v/v), respectively. The addition of nitrate ions (up to 1440 mg L−1) to the standard growth medium increased final optical density (OD750), cell count, pigment concentration, and total biomass yield but decreased the initial growth rate at high nitrate levels. Our findings can serve as the basis for a robust photoautotrophic cultivation system to maximize the productivity of large-scale microalgal cultures.

Effects of chemical interaction of nutrients and EDTA on metals toxicity to Pseudokirckneriella subcapitata

We studied the effect of the chemical interaction of nutrients and the ethylenediamine tetraacetic acid (EDTA) on metals toxicity. Growth inhibition tests of Pseudokirchneriella subcapitata by nutrient metals copper (Cu) and zinc (Zn), and the non-nutrient metal lead (Pb), were performed. The high-enriched Bold's Basal medium (BBm) and two low-enriched standard media, recommended by the Organization for Economic Cooperation and Development (OECDm) and Environmental Protection Agency-algal assay procedure medium (AAPm), were used in this study. The metals toxicity was affected by the interaction of nutrients and EDTA. Cu+2 was more toxic in the OECDm (EC50 20.3 μg/L), while Pb+2 (EC50 23.1 μg/L) and Zn+2 (EC50 99.4 μg/L) in the AAPm. Non-toxic effect of these metals was observed in BBm, but the exclusion of EDTA shifted it into a toxic medium. Finally, we found that the toxicity of the studied nutrient metals is mainly influenced by EDTA, which reduced the concentration of ionized metals, while the toxicity of the non-nutrient metal is affected by EDTA and phosphates.

Performance evaluation of different harvesting methods and cultivation media on the harvesting efficiency of microalga and their fatty acids profile

Harvesting techniques directly affect the quality and quantity of microalgal biomass as well as the total cost of final products. In this study, the harvesting efficiency of freshwater microalga, Scenedesmus quadricauda, from synthetic medium (Bold's Basal Medium, BBM) and real wastewater (dairy wastewater, DWW) was studied using ferric chloride (FeCl3). For this purpose, the effects of three variables namely solution pHs (3, 7, and 11), coagulant concentrations (100, 400, and 700 mg/L), and reaction times (5, 10 and, 15 min) on the harvesting efficiency of microalgae were evaluated. The highest harvesting efficiencies from BBM and DWW media were achieved as 95.75% (pH 11, 700 mg/L coagulant concentration, and 10 min reaction time) and 87.11% (pH 7, 700 mg/L coagulant concentration, and 15 min reaction time). The harvested microalgal biomasses were subsequently used for the lipid extraction. The analysis of lipids profile showed that the cultivation media (BBM and DWW), harvesting methods (coagulation and centrifugation), and biomass storage time (one day and two months) significantly affected the percentages of saturated fatty acids (SFAs) and poly unsaturated fatty acids (PUFAs) in microalgal lipids. The findings of this study revealed that the harvesting methods and cultivation media are two major factors that remarkably influenced the harvesting efficiency of microalga and the fatty acids of microalgal lipids as well.

Enhancement of targeted microalgae species growth using aquaculture sludge extracts

Natural growth-promoting nutrients extracted from aquaculture sludge waste can be used to maximise microalgal growth. This study identified the influence of aquaculture sludge extract (SE) on four microalgae species. Conway or Bold's Basal Media (BBM) was supplemented with SE collected from a Sabak Bernam shrimp pond (SB) and Kota Puteri fish pond (KP), and tested using a novel microplate-incubation technique. Five different autoclave extraction treatment parameters were assessed for both collected SE, i.e., 1-h at 105 °C, 2-h at 105 °C, 1-h at 121 °C, 2-h at 121 °C, and 24-h at room temperature (natural extraction). Microalgae culture in the microplates containing control (media) and enriched (media + SE) samples were incubated for nine days, at 25 °C with the light intensity of 33.75 μmol photons m−2 s−1 at 12-h light/dark cycle. The total dissolved nitrogen (TDN) and total dissolved phosphorus (TDP) in KP SE were 44.0–82.0 mg L−1 and 0.96–8.60 mg L−1. TDN (8.0%–515.0%) and TDP (105%–186 %) were relatively higher in KP SE compared to SB SE. The growth of microalgae species Nannochloropsis ocenica showed significant differences (p < 0.05) between the five extraction treatments from SB and the control. However, Chlorella vulgaris, Neochloris conjuncta, and Nephroclamys subsolitaria showed no significant differences (p > 0.05) in SB SE. N. ocenica, C. vulgaris, and N. conjuncta showed significant differences (p < 0.05) between five extraction treatments from KP and the control while N. subsolitaria showed no significant difference (p > 0.05). The specific growth rate (SGR) in the exponential phase of all microalgae species were relatively higher in SB SE compared to KP SE. While the organic matter content of KP SE was relatively higher, there were no significant differences in microalgae growth compared to SB SE. Nonetheless, modified SE did influence microalgae growth compared to the control. This study shows that modified SE could be used as enrichment media for microalgae cultivation.

Macro algae based adsorption for treatment of cotton processing wastewater

In the recent advances in treatment of different industrial wastewater, an attempt is made to treat the wastewater produced in demand of dyes and is used to make bandages and surgical cotton using freshwater macro algae. In the treatment method adopted here is focused on reducing the organic and inorganic pollutants present in the wastewater in the form of COD, BOD, Nitrate, Ammonia, Phosphate and Sulphate. Cotton processing wastewater contains high level of tCOD and sCOD in the order of 15000. Initially, Fresh water Green Macro algae is grown in freshwater Bolds Basal Medium (BBM). Tests were conducted with different dilution of Medium, Wastewater and Macro algae. The concentration of COD, NO3, NH4, PO4, and SO4in the real wastewater found to be 4800mg/l, 60.236mg/l, 4.110mg/l, 19.132mg/l, and 2.239mg/l respectively. Finally, after 10 days of continuous treatment of cotton wastewater using macro algae was found to be 1600mg/l, 7.30mg/l, 1.970mg/l, 4.800mg/l, and 1.009mg/l respectively. COD concentration of 1600 mg/l was still not a safe value to be finalized for a safe disposal, it has been observed that due to the high toxicity of the wastewater, macro algae are unable to treat the wastewater further. Solids like Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Fixed Solids (FS) and Total solids (TS) are also noted and studied during the treatment.

Evaluation of toxic effects of platinum-based antineoplastic drugs (cisplatin, carboplatin and oxaliplatin) on green alga Chlorella vulgaris

Platinum-based antineoplastic drugs (PBADs) enter the environment via hospital and municipal wastes as reactive and highly toxic molecules. Chlorella vulgaris is a freshwater microalgae and is used as an excellent aquatic model for toxicity assessment. In the present study, the toxicity of PBADs to C. vulgaris was investigated for better understanding of PBADs environmental toxicity. The algae were cultured in Bold´s Basal Medium (BBM) and exposed to different concentrations of PBADs for 48, 72 and 96 h. Then, cell proliferation, the synthesis of photosynthetic pigments, protein content, malondialdehyde (MDA) release and antioxidant potential were determined. IC50 s of cisplatin, carboplatin and oxaliplatin for 96 h of exposure were 106.2, 124.3 and 153.9 mg/L respectively. Cell proliferation, synthesis of chlorophyll a, chlorophyll b and algal protein content significantly decreased in a time and dose-dependent manner. The release of MDA to culture media significantly increased and antioxidant potential decreased.Cisplatin showed more toxic effects on C. vulgaris compared to carboplatin and oxaliplatin indicating its severe toxicity for marine organisms. PBADs induce their toxic effects in algal cells via the interaction with DNA, production of free radicals (such as reactive oxygen species), lipid peroxidation and cell wall damages. Due to these toxic effects of PBADs for various environmental organisms, there must be severe restriction on their release into the environment.

Microalga Scenedesmus acuminatus em meios de cultivo visando à produção de biodiesel

O biodiesel tem-se destacado como uma das opções mais viáveis para promover a gradativa redução do consumo de combustíveis fósseis. Neste contexto, as microalgas surgem como matéria-prima promissora, uma vez que apresentam produtividade de lipídios superior à das oleaginosas utilizadas na produção deste biocombustível, além da capacidade de biorremediação de águas residuárias e de grande absorção de CO2. Contudo, o elevado custo dos nutrientes empregados na preparação dos meios de cultivos dificulta a implementação em escala real. Este estudo teve como objetivo avaliar o crescimento da microalga Scenedesmus acuminatus em três meios de cultura: dois sintéticos, Bold´s Basal Medium (BBM) e Wright’s Cryptophyte (WC), e um alternativo, com efluente de tratamento anaeróbio de esgoto doméstico do reator tipo Upflow Anaerobic Sludge Blanket (UASB), a fim de minimizar os custos e viabilizar a produção de biodiesel. De acordo com os resultados obtidos, o cultivo com efluente de UASB obteve a maior densidade celular e não apresentou diferenças estatisticamente significativas em relação aos meios sintéticos, o que revela uma alternativa viável de cultivo. Diante disso, concluiu-se que a utilização de resíduos líquidos oriundos do tratamento anaeróbio de esgoto doméstico pode aumentar a viabilidade dos cultivos com vistas à produção de biodiesel, uma vez que permitem redução de custos ao substituir os meios sintéticos.

Remediation of Nitrate in Drinking Water and Accumulation of Lipids using Microalgae

The use of fertilizers in agriculture, and especially nitrogen to improve crop yield has resulted in the accumulation of high levels of nitrates in the groundwater (wells) throughout the mid‐western US states. This can lead to high levels of nitrates in drinking water, which exceeds the Safe Drinking Water Act, which the EPA limits at 10 mg/L. Drinking water containing nitrate levels above 10 mg/L is associated with significant health risks, particularly to unborn infants, as it can cause blue‐baby syndrome, a condition caused reduced capacity of hemoglobin to carry oxygen. Our laboratory has been employing microalgae to remediate nitrates to reduce this burden on water supplies. Two of the algal strains we have used were able to reduce Bold Basal Media (BBM) level nitrate (42mg/L) down to below 1 mg/L in 4 days, with an optical density (OD550) absorbance of around 3.0. In addition to remediating nitrate from contaminated sources, these microorganisms also accumulate lipids (triglycerides) under certain nutrient conditions and have been promoted as a feedstock for biofuels. Our lab has discovered several small compounds including WD30030 and WD20067 that induce lipid accumulation in algae without reducing growth and biomass in Chlamydomonas reinhardtii. In the present studies, we evaluated the impact of the compounds on several algal strains that have shown good growth in large bioreactors, Coccomyxia subellipsoidea – C169, Scenedesmus acutus f. alternans (UTEX B72), Chlorella kessleri (UTEX 2229) and Bumilleriopsis filiformis. Both nitrate removal and lipid accumulation during growth were monitored to assess whether or not these organisms can be used to couple nitrate remediation to production of high value lipid products.Support or Funding InformationNebraska Department of Economic Development and Vestal W2O, LLC

Effects of alternate nutrient medium on microalgae biomass and lipid production as a bioenergy source for fuel production

Over last three decades, worldwide researchers are researching on biomass feedstock, as it is a promising renewable and zero-carbon source of energy. Fuels produced from biomass are called as biofuels; biofuels can play an important role in meeting the energy demand and can help to reduce global warming. As compared to other biomass feed stocks (terrestrial plants) microalgae is considered as a promising source due to its high potential to produce lipids by absorbing nutrients from the wastewater, without affecting the usage of arable land and fresh water resources. Among the different microalgae strains, green microalgae have higher growth rate with more lipid content. Biomass production and lipid accumulation of microalgae are limited by various factors, such as CO2 supply, temperature, aeration, salinity and concentration of nutrients in the medium. Nutrient concentration and its limitation is one of the effective limiting factor to increase the lipid accumulation in microalgae.During the present study, three various alternate nutrient concentration experiments viz. higher strength, full strength and half strength, and one standard Bold’s Basal Medium (BBM) with full strength have been prepared to investigate the effects of alternate nutrient medium and different nutrient concentrations on biomass and oil productivity of green microalgae Chlorella Sorokiniana-5673. The cultivation was carried in a semi-controlled open pond environment and all experiments were conducted in duplicate. The alternate nutrient medium was prepared by using agriculture fertilizers, as source of major nutrients and tap water as a substrate. The growth performance of microalgae was observed by UV–visible spectrophotometer and the oil extraction was carried by Bligh–Dyer Method. The growth performance, biomass productivity and oil productivity of all experiments were observed. These findings indicate that alternate nutrient medium gives better performance than the standard BBM and low nutrients concentration medium showed high oil productivity. Thus the open pond cultivation of microalgae with alternate nutrient medium viz. agriculture fertilizer medium is an efficient cultivation method to produce more biomass and oil.

Two-phase method of cultivating Coelastrella species for increased production of lipids and carotenoids

Cultivation of Coelastrella sp. on Bold's basal medium (BBM) and Bold's triple nitrogen medium (B3N) over 12 days was performed for production of lipids and carotenoids by adjusting photoperiod and light intensity. The highest lipid content (30%) and maximum lipid productivity (77.83 mg/L/d) were attained on the 5th day of stage 2 in B3N media supplemented with 1% NaCl under light intensity of 4200 ± 100 Lux for 24 h. With the addition of 1% NaCl in B3N under light intensity of 4200 ± 100 Lux for 24 h (without any period of darkness) in stage 2, the biomass and lutein productivity were 1.8 and 1.6 folds of those under stage 1 in same medium. As judged by fatty acid profiles, the product, namely oil, met all the criteria stipulated for biodiesel in the international standard. We hypothesized that development of two phase cultivation may provide additional advantages which confirmed from the results obtained.

Isolation and selection of growth medium for freshwater microalgae Asterarcys quadricellulare for maximum biomass production.

The use of microalgae biomass as a suitable alternative feedstock for biofuel production has been promoted in the field of green biotechnology. In this present study, the microalgae were isolated from freshwater samples. The predominant strain was screened from the samples and grown in four different growth media, including modified Bold's Basal Medium (BBM), modified CFTRI medium, BG11 medium and CHU medium, to find the suitable growth medium to enrich biomass production. In total three microalgae colonies were identified based on their colony morphology microscopically by using a light microscope. The predominant strain was confirmed as Asterarcys quadricellulare using 18S rRNA sequencing. The growth of microalgae was investigated based on parameters like dry weight, pigment composition such as chlorophyll a, chlorophyll b, carotenoid and lipid content in the microalgae. Among the four different media, modified BBM medium showed maximum dry weight (1.44 ± 0.015 g/L), chlorophyll a (23.07 ± 0.049 mg/L), chlorophyll b (16.76 ± 0.010 mg/L), carotenoid (8.92 ± 0.031 mg/L) and lipid content (375 ± 0.020 mg/L) on the 25th day of culture. The gas chromatography mass spectrometry (GC/MS) analysis showed the presence of major fatty acids stearic acid, palmitic acid and oleyl alcohol in the microalgae. Therefore the high lipid content and fatty acid profiles of Asterarcys quadricellulare are becoming a promising suitable strain for biofuel production with modified BBM medium.

Microwave-Assisted Biodiesel Production from Microalgae, Scenedesmus Species, Using Goat Bone-Made Nano-catalyst.

The production of biodiesel from Scenedesmus algal oil is one of the best alternative forms of liquid fuel production from biomass to petrol diesel. Biodiesel plays a significant role in the carbon sequestration process during cultivation. Scenedesmus algal species was isolated and cultured in a bold basal medium by using nonheat releasing white florescence (2500lx) for a 12:12-h dark and light cycle. Algae oil was extracted from dried microalgae biomass through a microwave digester-assisted solvent extraction method. Consequently, about 20.8% algal oil per gram was obtained. A waste-based calcium oxide (CaO) nano-catalyst prepared from goat bone was used in the transesterification process. The catalyst was calcinated at 900°C and characterized using FTIR, SEM, EDX, and XRD techniques. The results revealed a mean particle size of 43.96nm with an irregular shape, porous structure, and possession of many active sites. The optimized transesterification process offers an optimum biodiesel yield of 92% at the experimental conditions, i.e., at a reaction temperature of 60°C, 2% (Wt.) catalyst loading and 11:1 methanol to algal oil molar ratio, 1500rpm stirring speed, and 3h reaction duration. The physicochemical properties of the produced biodiesel were tested according to ASTM D6751 standards and are in good agreement.

A simple method for the cultivation of algae Chlorella vulgaris Bejerinck

Chlorella vulgaris Beijerinck stimulates the growth of agricultural plants and suppress the development of pathogenic microorganisms. Original data about on development of culture medium and selection of optimal cultivation conditions for the alga Chlorella vulgaris are presented. The most favorable conditions for algae growth were daylight, temperature 25° C and rotation at the speed 100 rpm. The most effective culture medium was of the Bold basal medium with the addition of vitamins thiamine, cyanocobalamin and soil extract. This method may used for creation the biopesticide and growth stimulators on the basis Chlorella biomass.

Pengaruh Variasi Fotoperiodisitas terhadap Pertumbuhan Chlorella dalam Medium Basal Bold

The research of photoperiodicity effect on the cell densities of genus Chlorella grown in Bold’s Basal Medium (BBM) had been done. Observations were done for 14 days. Research was experimental study with full random design to 8 varieties of photoperiodicity i.e. 6 h light/18 h dark (L/D) cycles, 8 h light/16 h dark (L/D) cycles, 10 h light/14 h dark (L/D) cycles, 12 h light/12 h dark (L/D) cycles, 14 h light/10 h dark (L/D) cycles, 16 h light/8 h dark (L/D) cycles, 18 h light/6 h dark (L/D) cycles, and 24 h light/0 h dark (L/D) cycles. On peak culture, 24 h light/0 h dark (L/D) cycles produced the highest cell numbers (204.680.000 cell/ml) and the lowest cell numbers were achieved by culture with 6 h light/18 h dark (L/D) cycles. Kruskall-Wallis test showed that there were some effects of photoperiodicity variations on cell numbers of Chlorella (cell/ml) in culture (p&gt;0.05). Multiple comparison tests showed that mean of cell numbers of Chlorella (cell/ml) differ (p&gt;0.01) on every photoperiodicity. Relationship between photoperiodicity and cell numbers of Chlorella was determined by regression equation Ŷ = 24634821,214 + 21977643,869 X.

Experimental evaluation of the culture parameters for optimum yield of lipids and other nutraceutically valuable compounds in Chloroidium saccharophillum (Kruger) comb. Nov

The progress of algal-based biofuel industry depends on the identification of high lipid-yielding algal species from diverse environments. Laboratory-scale standardization of culture requirements for optimum yield of lipids and other desirable chemicals are highly important in the industrial utilization of an algal species. The major objectives of the present study were such an evaluation of the industrial potentials of a fast-growing native green microalga isolated from eutrophicated water bodies of Kerala, South India, morphologically and molecularly identified as Chloroidium saccharophilum. Biomass productivity and biochemical composition of the alga in relation to culture parameters such as total carbohydrates, proteins, pigments and lipids were learned. At an increased pH (8) or salinity (50 mM) and at a deprived nitrate (0 mM) or decreased phosphate (0.5 mM) in the medium, the alga was found producing lipids that have good biodiesel properties such as low iodine value and high cetane number. Optimum culture parameters such as pH, salinity, nitrate and phosphate conditions for maximum biomass yield of the alga are discovered. It was found that an increase in salinity or phosphates and a decrease in nitrate from that of the normal Bold's Basal Medium are favourable for an increase in omega-3 fatty acid content in the lipid.

High production of carotenoids by the green microalga Asterarcys quadricellulare PUMCC 5.1.1 under optimized culture conditions.

Since carotenoids are important as natural colorants, antioxidants, neutraceutics and pharmaceutics, the aim of the present study was to find a new good source of these pigments. We hereby report a green microalga Asterarcys quadricellulare PUMCC 5.1.1 as a new and good producer of carotenoids. The organism produced 35±1.75 μg carotenoids mg−1 dry biomass during stationary phase in control cultures. The growth and carotenoids production by the test microalga were optimized by varying nutrient growth media, pH, nitrogen and phosphate source, salinity, light quality, intensity and duration. The optimized conditions for carotenoid production were: Bold basal (BB) medium with pH 8.5, containing with10 mM nitrate, 3.5 mM phosphate and 0.17 mM salinity and illuminated with blue light with 60 μmol m-2 s-1 photon flux light intensity. Cultivation of cultures in the above mentioned optimized conditions resulted in nearly 3.0 fold increase in carotenoid production compared to the control cultures grown in unmodified BB medium. Using HPTLC, four carotenoids have been identified as β-carotene, lutein, astaxanthin and canthaxanthin. Further, carotenoids were also separated and purified by flash chromatography and the amounts of purified carotenoids were determined by HPLC. The organism produced 47.0, 28.7, 15.5 and 14.0 μg β-carotene, lutein, astaxanthin and canthaxanthin mg−1 dry biomass, respectively, under optimized conditions. The amount of total carotenoids (118 μg mg-1 dry biomass) produced by Asterarcys quadricellulare PUMCC 5.1.1 under optimized culture conditions was significantly higher than control cultures. Thus, this microalgal strain is a promising candidate for carotenoid production at commercial level.

The Effect of Mixed Wastewaters on the Biomass Production and Biochemical Content of Microalgae

The effect of ammonia and iron concentration in Bold Basal Medium and mixed wastewater (including pretreated piggery wastewater and acid mine drainage) on biomass production and biochemical content (lipid and ß-carotene) of microalgae (Uronema sp. KGE 3) was investigated. Addition of iron to the Bold Basal Medium enhanced the growth, lipid, and ß-carotene of Uronema sp. KGE 3. The highest dry cell weight, lipid content, and lipid productivity of KGE 3 were 0.551 g L-1, 46% and 0.249 g L-1 d-1, respectively, at 15 mg L-1 of Fe. The highest ß-carotene was obtained at 30 mg L-1 of Fe. The biomass production of KGE 3 was ranged between 0.18 to 0.37 g L-1. The microalgal growth was significantly improved by addition of acid mine drainage to pretreated piggery wastewater by membrane. The highest dry cell weight of 0.51 g L-1 was obtained at 1:9 of pretreated piggery wastewater by membrane and acid mine drainage for KGE 3. The removal efficiencies of total nitrogen and total phosphate was ranged from 20 to 100%. The highest lipid and ß-carotene content was found to be 1:9. Application of this system to wastewater treatment plant could provide cost effective technology for the microalgae-based industries and biofuel production field, and also provide the recycling way for pretreated piggery wastewater and acid mine drainage.

Potential use of a thermal water cyanobacterium as raw material to produce biodiesel and pigments.

Global energy demand is increasing every day and most is still derived from non-renewable sources. Therefore, sustainable alternatives are sought to produce biofuels, such as biodiesel. Several studies have demonstrated the potential of microalgae and cyanobacteria to produce biodiesel and pigments. These pigments, such as lutein and astaxanthin, have a high commercial value and can economically support the production of biodiesel. However, few studies have explored the potential of cyanobacteria collected in thermal water. In these microorganisms, both biomass and metabolites production can be altered by the culture form. Thus, a cosmopolitan filamentous cyanobacterium (Geitlerinema amphibium) from thermal water was collected and isolated to evaluate its potential to produce fatty acids, biodiesel, and pigments in two culture media. G. amphibium was cultured in WC (Wright's Cryptophyte) and BBM (Bold's Basal Medium) media. Thermal stress (40°C for 48h) was applied to the medium, which generated higher productivity of the biomass in BBM. The cyanobacterium contained higher biodiesel content in the WC medium and higher pigment content in the BBM medium. Thermal stress increased the biodiesel content by 350%, but decreased pigment content. Two pigments with high commercial value (astaxanthin and lutein) were identified. G. amphibium produced up to 2.74mgg-1 of astaxanthin and 5.49mgg-1 of lutein, which is seven times more lutein than Marigold, currently the main raw material used commercially. Therefore, G. amphibium has the potential to produce biodiesel, astaxanthin, and lutein concomitantly.

Two pronounced Chlorella strains for efficient biodiesel feedstock production

In this study, two indigenous Chlorella strains were evaluated for triacylglycerol (TAG) production and related parameters during 10 days of N-deprivation. The strains were identified based on morphological characteristics and genomic information, named as Chlorella sp. IMU12 and Chlorella sp. IMU17. Time-dependent reduction of growth was accompanied by decreased chlorophyll content, reduced oxygen evolution ratio, and elevated carotenoid content of both strains cultivated in N-free Bold's basal medium. Nitrogen deprivation induced total lipid and neutral lipid content in both strains, supported by FTIR measurement of TAGs. Chlorella sp. IMU17 showed higher production of TAGs as a response to N-deprivation. Strikingly, relative polysaccharide content showed a rapid increase on the first days and a noticeable reduction was recorded especially after 5 days of N-deprivation while TAG production showed a gradual increase during the whole period of N-deprivation in both strains. Starch might be a predominant form of carbon storage in the short term and the continuous increase of TAG production might be supported by degradation of starch in a longer period of N-deprivation. FAME analysis of lipids showed that the saturation level of the fatty acids of both strains meets the European standard EN 14214 requirements. Lastly, N-deprivation stimulated a significant reduction of PUFA production in Chlorella sp. IMU17. Thus, Chlorella sp. IMU17 might stand as a promising candidate for biodiesel feedstock production with its low PUFA content and a concomitant induction of saturation of fatty acids as a clear response to N-deprivation.

Growth optimization, free radical scavenging and antibacterial potential of Chlorella sp. SRD3 extracts against clinical isolates.

The aim of present work was to explore the potential of Chlorella sp. SRD3 extracts for antioxidant and antibacterial activity along with the evaluation of minimum inhibitory concentration (MIC) and haemolytic activity to detect RBC cell damage. Screening and isolation of microalgae was performed using bold basal medium under normal illuminance (at 27°C) and microscopic observation. Growth of the microalgae was optimized using a different medium and light source. The isolated microalgae incubated under fluorescent light when cultured in F/2 medium showed a highest dry biomass yield of 3·77±0·1gl-1 , when compared to the growth under direct sunlight (2·74±0·07gdwtl-1 ). The quantitative analysis of extracts revealed higher phenols, flavonoids and proanthocyanidins in ethyl acetate and hexane extracts followed by methanol. The antioxidant activity of extracts was tested against 1-diphenyl-2-picrylhydrazyl and ABTS radical, its reducing power assay was performed. From antibacterial activity, the two extracts showed better inhibition against Gram-negative bacteria. Also, they resulted in very low MIC values with effective activity against pathogens. In haemolytic activity, no haemolysis occurred, when the concentration (µgml-1 ) was below 64 for methanol and 32 for ethyl acetate extract. In addition, Chlorella sp. extracts were characterized by GC-MS analysis to detect the major compounds. The polar extracts revealed satisfactory results against the clinical isolates and the compounds responsible were reflected in the GC-MS spectrum. The present study revealed significant biological potentials of the green alga, Chlorella sp. such as antioxidant, antibacterial and hemolytic activities. Therefore, this vital source might serve as a cost-effective, alternative choice to the pharmaceutical and food industries in the near future.