Bold Basal Medium Research Articles

Scenedesnus rotundus isolated from the petroleum effluent employs alternate mechanisms of tolerance to elevated levels of Cadmium and Zinc

Scenedesmus rotundus was isolated from metal contaminated petroleum industry effluent and its tolerance to Cadmium and Zinc was tested using different concentrations of CdCl2 and ZnCl2 ranging from 0.001 mM to 1.0 mM of Cd and 0.03 mM to 1.21 mM of Zn amended in Bolds Basal medium. The changes in cell count recorded at regular intervals upto a period of 24 days revealed a concentration dependent inhibition in growth. Concentration of the metal, at which 50% of the cells are live and metabolically active referred to as EC50 was calculated as 0.04 mM for Cd and 0.2 mM for Zn. Further, the effect of EC50 of the metals on the protein content, uptake of metals at varying pH, oxidative stress markers including lipid peroxidation, protein oxidation andnd oxygen uptake, levels of enzymatic antioxidants such as catalase and superoxide dismutase and non-enzymatic antioxidants namely, GSH and PC4 were determined. Though a direct correlation could not be drawn between pH and metal uptake, the compartmentalization of the metal during the lag phase and exponential phase was evident, most of the metal was present in extracellular fractions in the former, while in the later it was internalized. Our study shows a clear correlation between toxicity of Cd and the ability of the algae to synthesize PC4 from GSH and chelate it leading to detoxification, while Zn treatment led to an increase in the activity of catalase and superoxide dismutase and replete GSH pools. Further the changes in the cell wall structure at EC50 of Cd and Zn were studied. This is the first report on effect of heavy metals on the structural modifications of the cell wall of Scenedesmus in general and Scenedesmus rotundus in particular, indicating appearance of granules on the entire cell surface in both Cd and Zn treatments, with the degree of granulation increasing in the order of pH 12 > 10 > 8 in Cd treatment. Further structures of higher order resembling minute wheels are observed in Cd treated cells are also reported.

Phycoremediation of cassava wastewater by Desmodesmus armatus and the concomitant accumulation of lipids for biodiesel production

The present study investigated the coupling of phycoremediation of harmful and malodorous cassava wastewater by Desmodesmus armatus with the biosynthesis of fatty acid methyl esters (FAMEs). Cultivation of the microalga on hydrolysed cassava wastewater + Bold's basal medium led to a reduction of total dissolved solids (TDS) by 72% (548.8 mg L−1), electrical conductivity (EC) by 73% (998.1 μs cm−1), biochemical oxygen demand (BOD) by 76% (136.20 mg L−1) and chemical oxygen demand (COD) by 74% (407.73 mg L−1) under heterotrophic mode. Mixotrophic growth mode showed a reduction in TDS by 83% (352.8 mg L−1), EC by 83% (621.92 s m−1), BOD by 87% (73.56 mg L−1) and COD by 92% (121.83 mg L−1). Biomass productivity of 70.83 mg L−1d−1 (mixotrophy) was significantly (p < 0.05) higher than 52.14 mg L−1d−1 (heterotrophy). Overall, the FAMEs produced were of C17 – C19 types, and of excellent quality for biodiesel production.

Feasibility of Biohydrogen Purification from Carbon Dioxide Mixture via Integrated Microalgae-Membrane Contactor Towards Zero Carbon Emission

Biohydrogen (H2) mixed with carbon dioxide (CO2) produced from the fermentation of Palm Oil Mill Effluent (POME) could be a potential renewable energy source. However, an effective technique to treat both gases towards zero carbon emission has become a major concern. In this study, a new approach was introduced to treat H2/CO2 mixture from POME fermentation by an integrated microalgae-membrane contactor system. Polyvinylidine fluoride (PVDF) hollow fibre membrane used in the integrated membrane contactor system abled to give the highest purified H2% from mixed H2/CO2 in the microalgae liquid absorbent (Chlorella Vulgaris) (69.4%) followed by Bold Basal Medium (BBM) (59.1%) and distilled water (55.9%). This initial result showed that the microalgae possessed better ability to absorb CO2 into the liquid stream via the PVDF membrane contactor. Next, investigation on optimizing the system’s operational parameters using BBM as liquid absorbent showed the highest CO2 absorption flux and efficiency were obtained at initial solution pH of 10. Further investigation showed that the absorption efficiency was enhanced as the liquid flow rate increased up to 0.4 L/min and the gas flow rate was at 0.1 L/min. Upon utilizing 0.6 g/L microalgae, the purified H2% found to remarkably increase up to 83.2%. In conclusion, the use of the developed integrated microalgae-membrane contactor system to purify the bio-H2 from CO2 mixture is a promising alternative method for zero carbon emission especially in palm oil industry.

Screening of growth phases of Antarctic algae and cyanobacteria cultivated on agar plates by chlorophyll fluorescence imaging

Recently, chlorophyll fluorescence imaging is frequently used non-invasive method to monitor the metabolic state and photosynthetic activities of vascular plants and other autotrophic organisms. In our study, we used the measurements of chlorophyll fluorescence kinetics to follow the development of culture of Antarctic algae (Macrochloris rubrioleum, Zygnema sp.) and cyanobacteria (Hassalia antarctica, Nostoc commune). On the cultures grown on agar plates, Bold´s Basal Medium (BBM), slow Kautsky kinetics supplemented with saturation pulses were measured repeatedly in a week interval. On the kinetics, typical points (OPSMT) were distinguished and species-specific and time of cultivation-dependent differences in shape of the OPSMT kinetics evaluated. We tested sensitivity of various chlorophyll fluorescence parameters to cultivation time on agar plates. In the algae, the most pronounced changes were the decrease in maximum quantum yield of photosystem II (FV/FM) and quenching of basal chlorophyll fluorescence qF0 (M. rubrioleum, Zygnema sp.). In cyanobacteria, chlorophyll fluorescence parameters did not show clear trends with the time of cultivation. F0 quenching (qF0) reached positive values in H. antarctica, while it was negative in N. commune. In both cases, however, qF0 showed an increase with cultivation time. The differences are discussed as well as the potential of the emerging area of the application of chlorophyll fluorescence imaging for evaluation of photosynthetic performance of algal/cyanobacterial cultures on agar plates.

A scale-up evaluation of a semicontinuous culture of Scenedesmus sp. in a raceway under greenhouse conditions using a commercial fertilizer as culture medium

In the present work, Scenedesmus sp. was grown under a semicontinuous regime in fertilizer (Bayfolan® Forte, 1 mL L−1) medium, and Bold’s Basal Medium (BBM) as control, in raceways of 200 and 2000 L under greenhouse conditions. The biomass, lipid, protein, carbohydrate and total pigment production was determined. The culture under the semicontinuous regime allowed an increase in the productivities in each consecutive cycle, reaching a lipid productivity of 20.00 ± 6.29 mg L−1 d−1 in Bayfolan medium. The biomass productivity in the medium supplemented with fertilizer was significantly higher than in the BBM. The protein productivity was significantly higher in Bayfolan (1.93 ± 0.28 L−1 d−1). The average carbohydrate productivity of the cycles was 10.10 ± 2.01 mg L−1 d−1. The fertilizer allowed an increase of up to 3-fold in total pigment productivity compared to the BBM. The fatty acids obtained were mainly composed of C16:0, C18:3n3 (α-linolenic) and C18:0. Palmitic acid (C16:0) was the main fatty acids methyl ester accumulated along with stearic (C18:0) and myristic (C14:0) acids. It was shown that the utilization of the liquid fertilizer Bayfolan is a potential alternative to replace conventional media.

Influence of agriculture fertilizer for the enhanced growth and astaxanthin production from Haematococcus lacustris RRGK isolated from Himachal Pradesh, India

In the present study, Haematococcus lacustris RRGK which is the former name of H. lacustris HPI-001 isolated from Himachal Pradesh, India, and another strain H. lacustris SAG-19a retrieved from Gottingen Culture Collection, Germany, were used. The H. lacustris SAG-19a served as a control. The both strains were grown in a Bold basal medium in which the components of NaNO3, K2HPO4∙3H2O and KH2PO4 were replaced with agriculture fertilizers such as NPK (17:17:17), urea (CH4N2O) and DAP (diammonium phosphate; (NH4)2HPO4 + potash (K2CO3) in different concentrations. The isolate of H. lacustris HPI-001 showed maximum growth at 1.2 mM NPK, while the H. lacustris SAG-19a showed maximum growth at 1.5 mM. However, both the strains showed maximum astaxanthin content at 0.6 mM NPK. The H. lacustris HPI-001 showed a maximum growth and astaxanthin content with 3.3 mM and 4.9 mM of urea, respectively, while H. lacustris SAG-19a showed maximum growth and astaxanthin accumulation with 3.3 mM and 6.6 mM of urea, respectively. The H. lacustris HPI-001 showed maximum growth at 250 mg/L (NH4)2HPO4 + 200 mg/L K2CO3 and maximum astaxanthin content at 150 mg/L (NH4)2HPO4 + 100 mg/L K2CO3, while the maximum growth in H. lacustris SAG-19a was observed at 200 mg/L (NH4)2HPO4 + 150 mg/L K2CO3, and the maximum astaxanthin content at 150 mg/L (NH4)2HPO4 + 100 mg/L K2CO3. The basal medium was also amended with the addition of commercial NaHCO3 wherein the maximum growth and content of astaxanthin in H. lacustris HPI-001 was at 0.6 mM and 1.5 mM of NaHCO3, respectively. The H. lacustris SAG-19a showed maximum growth and astaxanthin content at 1.5 mM and 0.6 mM, respectively. Based on the investigation, a medium was formulated and named as modified HPI-001 medium. The results of the present study suggest that commercial agricultural fertilizers may be used as excellent substitutes to enhance cell growth and astaxanthin production in H. lacustris.

Long-term maintenance of 23 strains of freshwater microalgae on solid microbiological culture media: A preliminary study

In this work, the ability of 23 strains of freshwater microalgae to be maintained on 10 different solid culture media was evaluated. Depending on the type of media, it was found that all strains of microalgae could be recovered after 19–24 months of culture in the dark. Bold's basal medium (BBM), BBM + 5% (v/v) coconut milk (CMA) and BBM + 5% (w/v) powdered skim milk (SMA) solidified with 1.5% (w/v) agar were good choices for growth and maintenance of freshwater microalgae strains in this study. Out of 23 strains of microalgae, 21 samples maintained on BBM, 21 from CMA and 12 from SMA were viable and successfully recovered on solid BBM. Strains which were maintained on nutrient agar (NA), luria-bertani agar (LB), potato dextrose agar (PDA) and trypticase soy agar (TSA) required pre-culture on solid BBM or CMA supplemented with glucose, sucrose or both, prior to final recovery on plain BBM. Four samples from NA, 2 from LB, 2 from PDA and 1 from TSA were successfully recovered. Findings from this study suggests that long-term maintenance of freshwater microalgae on solid media in the dark could be used as a possible alternative to cryopreservation.

Growth medium and nitrogen stress sparked biochemical and carotenogenic alterations in Scenedesmus sp. CCNM 1028

Microalgae are a spring of valuable compounds finding its wide applicability as cosmo-nutraceuticals, a renewable substitute for bioenergy and bioremediation. The present study utilizes Scenedesmus sp. CCNM 1028, freshwater microalgae, to understand the influence of various microalgal growth media, like BG-11, Chu's 10, Bold's basal medium (BBM) and Zarrouk's media (ZM), on the growth and lutein production. Furthermore, two-stage nitrogen starvation studies were carried out using the selected BG-11 media and its effect on the lutein and biochemical parameters of Scenedesmus sp. CCNM 1028 after 0, 6, 9, 15 and 21 days (d) of nitrogen starvation were recorded. Lutein was accumulated till 6d of nitrogen starvation. Additionally, ~3-fold increase of carbohydrate content (%w/w) was observed after 21d of nitrogen starvation with respect to the control. Thus, this study proposes two-stage nitrogen starvation as a capable strategy to cultivate Scenedesmus sp. CCNM 1028 for lutein (6d) and carbohydrate production (21d).

Evidence of the production of galactooligosaccharide from whey permeate by the microalgae Tetradesmus obliquus

Galactooligosaccharides (GOS) are prebiotics commonly produced from lactose via an enzymatic reaction catalyzed by β-galactosidase (β-gal) which is present in many organisms, including microalgae. Whey permeate (WP), a major byproduct of the dairy industry rich in lactose, represents an interesting medium for producing GOS as high value-added ingredients. Using the microalgae Tetradesmus obliquus as the enzyme source could be an interesting alternative due to its lower nutritional requirements for growth and its applicability in industry. Therefore, this study investigates the growth of T. obliquus and its potential to produce GOS in WP compared to modified Bold's Basal medium (BBM). The growth kinetics, β-gal activity, and medium composition, such as minerals, lactose, glucose, galactose and GOS concentrations, were evaluated during algal cultivation for up to 21 days. The growth rate of T. obliquus was significantly higher in WP, reaching a biomass concentration 4.5 times higher than when growing in BBM. The growth stimulation in WP is directly proportional to the concentration of minerals and ionic species in WP compared to BBM, except for nitrate. The lactose concentration decreased significantly (by 21%) in WP only, with substantial production of the simple carbohydrates, glucose (3.1 g/L) and galactose (4.1 g/L). The higher degree of lactose hydrolysis in WP was supported by significantly higher β-gal specific activity and volumetric productivity. In addition, we detected, for the first time, the production of a trisaccharide GOS in WP whose concentration increased with time, reaching 4.4 g/L and conversion yield of 8.4% (w/w of initial lactose) after 21 days. Overall, these results hold promise for developing a novel bioprocess for the production of value-added products from WP, but the microalgal enzyme must first be characterized and optimized.

Recovery of landfill leachate as culture medium for two microalgae: Chlorella sp. and Scenedesmus sp.

The microalgae culture medium should contain essential nutrients for their optimal growth. However, landfill leachate contains these nutrients; merely, the use of leachate in the cultivation of microalgae is not conceivable because of its high toxicity. This survey proposes to demonstrate the growth performance in terms of biomass production, chlorophyll contents and cell morphology of two microalgae, namely Chlorella sp. and Scenedesmus sp., in different concentrations of leachate (10%, 30%, 50%, 80% and 100% (v/v) crude leachate). Changes in chemical oxygen demand (COD), ammoniacal nitrogen (NH4+–N) and salinity content were also monitored. Results showed that when the two algae were mixed, the culture medium containing 10% (v/v) of leachate caused an optimal and selective growth of Chlorella and a total mortality for Scenedesmus cells. Also, this culture medium containing 10% (v/v) of leachate promoted the cell growth of Chlorella sp., of around 2 times in terms of cell density and 10 times in terms of chlorophyll content as compared to the result obtained for the standard culture medium “Bold’s Basal Medium (BBM).” Abatement rates of COD, NH4+–N and salinity of 60%, 100% and 10% were, respectively, achieved by pure cultures of Chlorella sp. Therefore, the strain of Chlorella sp. appeared resistant in this unfriendly environment as compared to the strain of Scenedesmus sp. As a perspective, the tested landfill leachate could be convenient for culturing Chlorella sp. for leachate purification and biofuel production.

Biomass productivity, synthetic seed preparation, oil extraction and chemical profiling of Scenedesmus obliquus

Microalgae are the quickly growing thalloid organisms and can be used as a renewable source of green energy. The present study focused on the uni-algal culturing, biomass productivity, viability testing of synthetic seed, oil extraction and chemical profiling of the micro-alga, Scenedesmus obliquus. Alga was isolated from leaves and cultured in the Bolds Basal Medium (BBM). The uni-algal culture of the species was developed by serial dilution method. The present study confirmed that BBM was the most successful culture medium for cultivating Scenedesmus obliquus. In the preliminary study, it was found that the biomass productivity of alga was higher in the log stage and later it was decreasing. Synthetic seed test proved that algal beads had more storage viability than pure culture and extend up to years. The percentage of oil in S. obliquus was 54.2 ± 0.0.49%. The GC–MS analysis established that algal oil consists of altogether 37 chemical components with a variety of properties.

Manipulating Nutritional Conditions and Salinity-Gradient Stress for Enhanced Lutein Production in Marine Microalga Chlamydomonas sp.

Marine microalgae has great potential for lutein production with the advantage of saving fresh water resource. Thus, marine microalga Chlamydomonas sp. JSC4 is investigated as a potential lutein producer in this study. The medium types, nitrate-N and sea salt concentration are individually investigated to promote the cell growth rate and lutein production of JSC4. In Modified Bold Basal 3N medium, cell growth and lutein content are optimal at the nitrate-N concentration of 1000 mg L-1 and sea salt concentration of 2%. In addition, an innovative salinity-gradient strategy is operated to dramatically enhance biomass productivity (560 mg/L/d) and lutein content (3.42 mg g-1 ), resulting in the optimal lutein productivity (1.92 mg/L/d). Overall, this study clearly demonstrates that salinity is a significant inducer of lutein accumulation by strain JSC4 and that lutein production can be successfully optimized using the salinity-gradient strategy, which is beneficial for the outdoor large-scale lutein production in the future.

Carbon sequestration potential of Scenedesmus quadricauda (Turpin) and evaluation on Zebra fish (Danio rerio)

Carbon dioxide sequestration by microalgae is receiving increased attention in alternative impact of increasing CO2 in the atmosphere. For this study, we have chosen three different microalgae such as Chlorococcum humicola, Chlorella vulgaris and Scenedesmus quadricauda were treated with 3 W/m2 UV-B radiation in different time durations (10, 15, 30, 45 and 60 min) and supplemented with bold basal medium. Parameters such as Total Chlorophyll, protein, Carbohydrate, and CO2 fixation rate were determined. Based on the parameters Scenedesmus quadricauda is used for carbon sequestration study. Different concentrations of sodium bicarbonate (0.2%–1%) were supplemented to bold basal medium for carbon utilization it can act as an alternative source of atmospheric CO2. In this maximum amount of chlorophyll content were observed in 0.6% of Sodium bicarbonate. The uttermost amount of CO2 fixation rate and lipid content was recorded at 0.4% sodium bicarbonate concentration. Finally, the result indicated that Scenedesmus quadricauda could be used for CO2 mitigation and having a rich source of polyunsaturated fatty acid. Further urea and glucose in the media positively influence growth and CO2 fixation rate of micro algae. These carbon and PUFA rich microalgae can be used as dietary feed fish usually obtain necessary nutrients via bioaccumulation through the food chain. Thus, this study proves to be an encouraging source of discovery of alternating the dietary source for fish and also helping in carbon utilization process in a natural way.

Bioremediation of minkery wastewater and astaxanthin production by &lt;i&gt;Haematococcus pluvialis&lt;/i&gt;

A two-stage system was designed for culturing and induction processes of H. pluvialis. H. pluvialis was cultivated in minkery wastewater and compared with the conventional Bold's basal medium, and grew better in diluted (1.5%) minkery wastewater, yielding a biomass production of 906.3 ± 34.0 mg L−1. Total nitrogen and total phosphorus were also removed successfully. In the following induction stage, nitrogen-deprived vegetative cells were exposed to high light intensity for astaxanthin production, and the resultant production was 39.72 ± 1.69 mg L−1. Employing the diluted wastewater, a mixotrophic induction strategy was also tested by using a series of acetate and NaCl concentrations. The findings indicated that the optimal combination for astaxanthin production was 38.14 mM acetate and 0.58% (w/v) NaCl. And the optimal astaxanthin concentration was 67.95 ± 3.93 mg L−1 after a 12-day induction period. This study concludes that H. pluvialis offers a potential opportunity for treating minkery wastewater and producing high-value astaxanthin.

Effects of various abiotic factors on biomass growth and lipid yield of Chlorella minutissima for sustainable biodiesel production.

In this study, effects of different abiotic factors were studied on biomass and lipid yield of green microalga Chlorella minutissima (C. minutissima) Various concentrations of abiotic factors like nitrogen, phosphorus, glucose, iron, zinc, different values of pH, temperature, light intensity and different photoperiods were observed on the biomass growth and lipid yield of C. minutissima cultivated with modified CHU-13 medium. Initially, three cultivation media namely, Bold's basal medium (BBM), modified CHU-13 and blue-green-11 (BG-11) were used to culture C. minutissima in batch mode. Microalga cultivated with modified CHU-13 medium resulted in maximum biomass and lipid yield of 970 ± 0.21 and 356.63 ± 0.51 mg/L, respectively. To maximize biomass and lipid yield of microalga further, it was cultivated with modified CHU-13 medium and variation of above mentioned abiotic factors was done. Different biomass and lipid yields were achieved for different abiotic factors varied. Highest biomass of 1840.49 ± 0.62mg/Lwas achieved with 12g of glucose containing medium and highest lipid yield of 579.86 ± 0.76 mg/Lwas achieved with 0.3g of nitrogen containing medium. GC-MS analysis of biodiesel obtained from C. minutissima biomass cultivated with modified CHU-13 medium shown the presence of C14:0, C16:0, C16:1,C18:0, C18:1, C18:2, C18:3, C20:0, C20:1 and C22:0. Properties of biodiesel obtained from C. minutissima were found in compliance with ASTM-6751-02 and European biodiesel standards EN14214. These results suggest that C. minutissima can be used as a potential biodiesel feedstock for microalgal biodiesel production.

CULTIVATION OF Chlorella vulgaris IN MEDIUM SUPPLEMENTED WITH DESALINATION CONCENTRATE GROWN IN A PILOT-SCALE OPEN RACEWAY

ABSTRACT In this study, we investigated the outdoor production of a microalga C. vulgaris cultured in two different media under autotrophic cultivation: Bold Basal Medium (BBM) as the control and BBM supplemented with desalination concentrate (BBM + DC) using open raceway ponds (8 m2). Data were collected on the growth, biomass productivity and biochemical composition. The culture developed in BBM + DC showed a biomass productivity of 6.8 g m-2 day-1, while for the BBM control it was 8.5 g m-2 day-1. Intracellular protein was the main algal component (~28.6%), followed by carbohydrate + fiber (~26.0%) and lipids (~5.0%). The predominant fatty acids were mainly α-linolenic (~19.5%), palmitic (~16.5%) and linoleic (~10.0%) acids. This study demonstrates the feasibility of culturing C. vulgaris in an alternative medium based on DC in order to valorize the desalination wastewater through its application to algal mass production.

Successive production of biodiesel and bioethanol feedstock from the Cosmarium sp

Cosmarium sp is unicellular microalga which was grown in bold basal medium with the controlled condition and investigated biochemical characterizations for biodiesel production and evaluated standardization of ethanol production. Once microalgae were reaches the proper growth stage total lipid was analyzed and these lipids were used for the production of biodiesel by transesterification process using Calcium oxide (0.66%) as a catalyst. Bioethanol production was done by using the defatted residues of Cosmarium sp. with Saccharomyces cerevisiae (10%). In view of the above-mentioned facts, the present study has been designed to enhance the production of biodiesel and bioethanol.

STUDY AND CHARACTERIZATION GROWTH OF FOUR MICROALGAE SPECIES AND TEST ANTIMICROBIAL ACTIVITY

Abstract&#x0D; In this study to the growth characteristics of microalgae (Dunaliella salina, Nannochloropsis oculata, Tetrasel mis chuii &amp; Chaetoceros calcitrans), in different mediums, namely Bold’s Basal Medium (BBM) and BBM modification of sea water. The results obtained from microalgae (N.oculata, T.chuii, C.calcitrans) are better grown on BBM media while microlaga D.salina grows well on BBM modification of sea water. Microalgae biomass is extracted by maceration method in hexane and methanol solvents. Test bacteria used gram positive (Staphylococcus aureus) and gram negative (Escherichia coli). Inhibitory zone diameter results were compared with antimicrobial sensitivity tests according to Clinical and Laboratory Standards Institute (CLSI). From the results of microalgae hexane and methanol extract antibacterial activity tests (D.salina, N.oculata, T.chuii, C.calcitrans) showed that the extract was not too sensitive to inhibit bacterial growth.&#x0D; &#x0D; Keywords: microalgae, medium, antimicrobial

Growth Media Affects Microalgae Susceptibility to Disruption by Low-Frequency Power Ultrasound

The effect of microalgae growth medium on power ultrasound treatment of microalgal biomass was investigated. Chlorella vulgaris was grown in Bold's basal medium (BBM), Bristol's medium, sueoka medium, and MiracleGro All Purpose Water Soluble Plant Food. These media showed statistically indistinguishable intrinsic growth rates, averaging 0.052/day. Power ultrasound treatment was applied at 9.5 W for 5 min. MiracleGro showed chemical oxygen demand (COD) solvation post-sonication of 66%, twice that of other growth media per cell ruptured; which was unexpected based on observed consistent biomass quality. Media differences do not appear to have an effect on ultrasound power transfer; thus, C. vulgaris grown in MiracleGro medium has a decreased strength in terms of resistance to rupture by ultrasound. These results suggest that while biomass productivity and composition are important for the efficiency of extraction, media effects on the susceptibility of cells to pretreatment should not be ignored in overall process design.

Enhancement of lipid production from algal biomass through various growth parameters

Algal lipids are prospective sustainable and economic resources for biodiesel. In this study, growth parameters i.e. lipid, biomass, and total chlorophyll contents of the two algal consortia S1 and S16 were optimized at varied pH microenvironment, different nutrient media and NaNO3 concentrations. Results obtained from the present study revealed that optimum growth of the consortia S1 in terms of lipid, biomass, and total chlorophyll was observed at pH 7 while for S16 it was at pH 8. Optimum protein contents for S1 and S16 were obtained at pH 6 and 5, respectively. For both the consortia, BG-11 was found to be the best-suited medium for biomass, total chlorophyll and protein contents, whereas the highest lipid accumulation was favored by the Bold Basal Medium. The present study demonstrated that nitrogen deprivation in the medium would favor high lipid accumulation. About 1.0 g L−1 of sodium nitrate (NaNO3) was found to be suitable for enhancing the biomass yield and total chlorophyll while the concentration required for optimum lipid and protein content was observed to be 10 folds lower at 0.1 g L−1. Consequently, under nitrate stress, the lipid content of S1 was observed to increase by 55.5% as compared to control. Surface morphology of algal cells was explored with the help of Scanning Electron Microscopy (SEM) under normal as well as stress conditions (0.1 g L−1 NaNO3). Nitrate stress was found to exert significant effects on cell morphologies of both the algal consortia. Fourier Transform Infrared (FTIR) spectra of both the consortia revealed the presence of various functional groups corresponding to lipid, carbohydrate, and protein under normal and stress conditions.