Chlorella Vulgaris Cultures Research Articles

Photobioreactor design utilizing procedural three-dimensional modelling and ray tracing.

The design of photobioreactors for microalgae cultivation aims to achieve an architecture that allows the most efficient photosynthetic growth. The availability of light at wavelengths that are important for photosynthesis is therefore particularly crucial for reactor design. While testing different reactor types in practice is expensive, simulations could effectively limit the range of material and reactor design options. In this study, procedural three-dimensional modelling together with ray tracing was used to create virtual models of a conventional glass photobioreactor lit from the outside and a steel photobioreactor with embedded light sources. The measured transmittance and reflectance of Chlorella vulgaris culture were used as a basis for light interaction simulation, and spectral images of the same species were used to validate the simulation results. This type of simulation could have the potential for comparing different reactor architectures, geometries and light attenuation to facilitate the transition to large-scale cultivation. Our results show that the proposed simulator is usable in photobioreactor geometry design as well as in the estimation of available illumination on wavelengths where microalgae have strong absorption peaks, but the handling of light scattering still needs improvement. To the authors' best knowledge, this is the first attempt, not focused on a specific use case, to build a general photobioreactor design tool capable of estimating hyperspectral light attenuation in microalgae suspension. All software code and used datasets are made available for the reader as open source.

Effect of Acids on Biomass Growth and Development of Chlorella vulgaris Culture

Background. Influence of dissolved nitrogen and sulfur oxides, as components of flue gases, on the cultivation of microalgae Chlorella vulgaris. Objective. To study biomass production and changes in cells of the microalgae Chlorella vulgaris with the introduction of nitrogen and sulfate acids tor simulate the effects of dissolved nitrogen and sulfur oxides, aiming to develop biotechnology for the utilization of gas emissions by microalgae. Methods. The effect of the constant introduction of small concentrations of nitrogen (up to 0.47%) and sulfate (up to 1.5%) acids on the development of Chlorella vulgaris cultures, pH changes in the cultural envi­ronment, and biomass growth were studied. Results. The utilization of gaseous emissions by Chlorella vulgaris depends on the content of nitrogen and sulfur oxides that are constantly supplied to the cultivation medium, the initial biomass concentration, and pH. It was determined that for an initial cells concentration of (85 ± 5)×104 cells/ml in the culture medium, the threshold values of acids that do not cause significant changes in the cultivation process are 0.1% H₂SO₄ and 0.19% HNO₃. At a sulfuric acid concentration of 0.2%, the culture cells become discolored. Conclusions. It is shown that with a constant supply of sulfuric or nitric acids above the threshold values of 0.1% H2SO4 and 0.19% HNO3, the pH of the culture medium decreases, leading to the suspension of deve­lopment and the death of the Chlorella vulgaris culture. Therefore, controling these parameters will improve the ecological state of the environment and form the basis for developing biotechnology for the utilization of gas emissions by microalgae.

Growth and Biochemical Characteristics of Microalgae Chlorella vulgaris Grown on Various Combinations of Fish Waste Hydrolysate and Seaweed Hydrolysate

Background: to utilize the fish waste and seaweed as a media for the growth of microalgae Chlorella vulgaris and carbon sequestration. Methods: Culture of Chlorella vulgaris in the fish waste and seaweed hydrolysate, analysed the cell density, biomass, chlorophyll, carotenoid content, carbon-di-oxide sequestration and proximate of microalgae (Protein, Carbohydrate, Lipid and Ash). Result: In the combination of fish acid hydrolysate and sargassum sp., acidhydrolysate, the respective peak values of cell density, average specific growth rate, biomass, chlorophyll a and b, carotenoid contentand carbon-di-oxide sequestrated recorded are 4.26±0.06×106 cells/ml, 0.58 µ/day, 1.98±0.04 g/l, 5.59±0.09 µg/ml and 3.69±0.04 µg/ml, 3.64±0.05 µg/ml, 3.73±0.07 g/l/d in 3:6 combination. Corresponding protein, carbohydrate, lipid and ash content observed in the resultant algae are 51.77±0.6%, 15.4±0.2%, 10±0.53 and 7.08±0.4% respectively.

Cultivation of microalgae Chlorella vulgaris, Monoraphidium sp and Scenedesmus obliquus in wastewater from the household appliance industry for bioremediation and biofuel production.

Microalgae Chlorella vulgaris, Scenedesmus obliquus, and Monoraphidium sp were cultivated in effluent from the household appliance industry as an alternative medium for bioremediation due to the high variability of chemical and biological substances in wastewater. The experiments were carried out using biological effluent (BE), chemical effluent (CE), and a combination of the two (MIX). The results showed a maximum biomass yield of 1056mg/L (± 0.216) in the BE cultivation of the microalga Scenedesmus obliquus, 969mg/L (± 0.20) in the BE of the microalga Monoraphidium sp. and 468mg/L (± 0.46) in the CE of Chlorella vulgaris. In addition, they showed removal (100%) in the CE and MIX for cultivation with Chlorella vulgaris and 100% BE and 75% MIX with Monoraphidium sp. For the (75.3%, 99% e 97.9%) in the cultures with C. vulgaris BE, CE, and MIX respectively, with Monoraphidium sp. 58% in BE and 42% in CE and MIX. With S. obliquus, 100% removal was observed in all 3 treatments. Metal removal was also observed. The C. vulgaris culture showed lipid contents of 16%, 12%, and 17% for BE, CE, and MIX, respectively. For Monoraphidium sp., 14.5% for BE, 16% for CE, and 14% for MIX. In the culture of S. obliquus, 17%, 15.5%, and 16.5% for BE, CE, and MIX, respectively.

Adaptation of Chlorella vulgaris immobilization on rice straw with liquid manure to create a sustainable feedstock for biogas production and potential feed applications

Rice straw (RS) is a widely available agricultural residue with significant potential for biogas production and feed applications; however, its poor digestibility and nutritional value limit its utilization. This study explores an innovative approach to enhance the digestibility and nutritional value of RS by cultivating Chlorella vulgaris through immobilization technology on RS, using liquid manure (LM) as an alternative to the traditional BG11 medium. The results showed an increase in chlorophyll a (Chl a) after 12 days for both the BG11 medium and LM-based treatments, from 0.13 to 0.34 and 0.24 mg Chl a/g product (DM), respectively. Additionally, the immobilized microalgal biomass increased to 284.18 and 170.14 mg algal biomass/g product (DM), respectively. Soaking under microaerobic conditions during cultivation led to the partial degradation of RS. This, combined with the formed microalgal biofilm, contributed to an improved digestibility of the dry matter, reaching 69.1% and 65.9% for the final products based on the BG11 medium and LM mediums, respectively, compared to 52.1% for the raw RS. Furthermore, the crude protein and lipids contents were significantly improved with the potential for applications in feed, reaching 21.4% and 4.1% for the BG11 medium-based product, while they were observed to be 12.8% and 3.0%, respectively, for the LM-based product. Additionally, carbon-to-nitrogen ratio was significantly reduced compared to the raw RS. The higher digestibility and improved nutritional value contributed to increased biogas production, reaching 129.3 and 118.7 mL/g (TS) for the products based on the traditional medium and LM medium, respectively, compared to 86.7 mL/g (TS) for the raw RS. The immobilization mechanism and biofilm development could be attributed to the roughness of the RS and extracellular polymer substances. This study demonstrates that integrating C. vulgaris cultivation on RS with LM as a nutrient source not only enhances the digestibility and nutritional value of RS but also offers a sustainable waste management solution with potential applications in biogas production and animal feed.

Physiological Effects and Mechanisms of Chlorella vulgaris as a Biostimulant on the Growth and Drought Tolerance of Arabidopsis thaliana.

Microalgae have demonstrated biostimulant potential owing to their ability to produce various plant growth-promoting substances, such as amino acids, phytohormones, polysaccharides, and vitamins. Most previous studies have primarily focused on the effects of microalgal biostimulants on plant growth. While biomass extracts are commonly used as biostimulants, research on the use of culture supernatant, a byproduct of microalgal culture, is scarce. In this study, we aimed to evaluate the potential of Chlorella vulgaris culture as a biostimulant and assess its effects on the growth and drought tolerance of Arabidopsis thaliana, addressing the gap in current knowledge. Our results demonstrated that the Chlorella cell-free supernatant (CFS) significantly enhanced root growth and shoot development in both seedlings and mature Arabidopsis plants, suggesting the presence of specific growth-promoting compounds in CFS. Notably, CFS appeared to improve drought tolerance in Arabidopsis plants by increasing glucosinolate biosynthesis, inducing stomatal closure, and reducing water loss. Gene expression analysis revealed considerable changes in the expression of drought-responsive genes, such as IAA5, which is involved in auxin signaling, as well as glucosinolate biosynthetic genes, including WRKY63, MYB28, and MYB29. Overall, C. vulgaris culture-derived CFS could serve as a biostimulant alternative to chemical products, enhancing plant growth and drought tolerance.

Carbon and energy metabolism for the mixotrophic culture of Chlorella vulgaris using sodium acetate as a carbon source.

There has been an emergence of a diversity of microalgal mixotrophic synergistic mechanisms due to substrate differences. In this study, the effects of the mixotrophic culture of Chlorella vulgaris were examined. The maximum values of cell density, specific growth rate, and cell dry weight of Chlorella vulgaris were 3.52*107 cells/mL, 0.75 d-1, and 3.48 g/L in the mixotrophic mode, respectively. These were higher than the corresponding values of photoautotrophic or heterotrophic modes. Moreover, it was found that the concentrations of sodium bicarbonate consumed by the Chlorella vulgaris under mixotrophic and photoautotrophic modes were 635 mg/L/d and 505 mg/L/d, respectively; the concentrations of sodium acetate consumed by the Chlorella vulgaris under mixotrophic and heterotrophic modes were 614 mg/L/d and 645 mg/L/d, respectively. The activity of Rubisco was 9.36 U/mL in the mixotrophic culture, which was 3.09 and 4.85 times higher than that of the photoautotrophic and heterotrophic modes, respectively. This indicated that the differences for the carbon source absorption efficiency of Chlorella vulgaris in the mixotrophy led to different internal metabolic efficiencies when compared to photoautotroph or heterotrophy. Additionally, Chlorella vulgaris exhibits a more rapid energy metabolism efficiency when operating in the mixotrophic mode.

Cultivation of chlorella vulgaris using aquaculture wastewater: Assessing its viability as a promising resource for biodiesel production

This study investigates the viability of utilizing Chlorella vulgaris cultivated in aquaculture wastewater as a feedstock for biodiesel production. The research involved scaling up the algal culture from 10 ml to 10 liters in a photobioreactor, optimizing growth conditions, and analyzing the water parameters of the aquaculture wastewater medium. The results showed successful growth of the algal culture, with the highest growth rate achieved on day 15 in the 10-liter reactor. The harvested biomass was converted into biodiesel through direct transesterification, and the produced biodiesel was characterized using Fourier-transform infrared spectroscopy (FTIR) and fuel property tests. The FTIR analysis confirmed the presence of functional groups indicative of esterification, validating the successful conversion of the wet biomass into biodiesel. The fuel property tests revealed that the algal biodiesel exhibited marginally higher kinematic viscosity but a favourable flash point compared to established standards. Emission tests demonstrated an increase in CO2 and hydrocarbon emissions with higher engine loads, aligning with combustion principles. The findings highlight the potential of utilizing aquaculture wastewater as a sustainable medium for cultivating Chlorella vulgaris and producing biodiesel, contributing to the development of more resource-efficient and environmentally friendly biofuel production methods.

Investigating the impacts of a recirculation sedimentation application on microalgae biomass cultivation in wastewater treatment

Commercial microalgae production is often interrupted by contamination, leading to short production cycles, reinoculation needs, and culture collapses, significantly increasing costs. This study focuses on investigating Recirculated Sedimentation Application (RSA) to control contamination in microalgae culture systems used for wastewater treatment. Chlorella vulgaris culture was grown in an unsterilized mixture of tertiary treatment effluent and centrate of anaerobic digestion wastewater sludge over a 90-day experimental period. 60 L raceway reactor was operated under a light intensity of 275 μM m−2.s−1 with a 16:8 h light-dark photoperiod. To evaluate the effect of RSA on biological-based problems, the experiment was conducted in three phases. The benefits of utilizing RSA were established through the following observations: effective removal of contaminants at an acceptable level without releasing the culture; extension of the biofilm formation time on the inner walls; inhibition of heterotrophic bacteria and nitrification; enhancement of the suspended solids retention capacity of the raceway tank (up to 770 mg.L−1); and improvement in ammonium removal rate to approximately 30 mg.L−1d−1. The ideal salinity level for both ammonium removal and biomass concentration in RSA should be below 0.02%. These findings demonstrate the potential of phycoremediation for sustainable wastewater treatment and contribute to environmental bioremediation strategies.

Effect of Fermented Mother Liquor (FML) Substitution Enriched with NaNO3 as a Chlorella vulgaris Culture Media

Effect of Fermented Mother Liquor (FML) Substitution Enriched with NaNO3 as a Chlorella vulgaris Culture Media

Optimizing Chlorella vulgaris Cultivation to Enhance Biomass and Lutein Production.

Lutein is widely used in medicine, health care, and food processing due to its antioxidant effects; however, it is difficult for the traditional extraction of lutein using marigolds to meet the increasing market demand for lutein. To achieve high-efficiency lutein production, we investigated the effects of different conditions on the biomass accumulation and lutein yield of Chlorella vulgaris. The optimized cultivation conditions include mixotrophic cultivation using sodium nitrate as a nitrogen source, maintaining a total-organic-carbon-to-total-nitrogen ratio of 12:1, a total-nitrogen-to-total-phosphorus ratio of 10:1, and lighting duration of 24 h. The results of the study indicated that under these specific conditions, Chlorella vulgaris attained a final biomass concentration, biomass productivity, and growth yield of 6.08 g·L-1, 1.00 g·L-1·d-1, and 1.67 g biomass/g TOC, respectively. Additionally, the concentrations of total chlorophyll, carotenoid, lutein, and protein reached 139.20 mg·L-1, 31.87 mg·L-1, 15.02 mg·L-1, and 2.17 g·L-1, respectively, and the content of lutein reached 2.47 mg·g-1. This study supplies a theoretical basis for the industrial application of lutein production using Chlorella vulgaris.

Source separation and anaerobic co-digestion of blackwater and food waste for biogas production and nutrient recovery.

Anaerobic co-digestion of source-separated blackwater (BW) and food and kitchen waste (FW) offers decentralized circular economy solutions by enabling local production of biogas and nutrient-rich byproducts. In this study, a 2 m3 pilot-scale continuously stirred tank reactor (CSTR) operated under mesophilic conditions was utilized for co-digestion of BW and FW. The process obtained a CH4 yield of 0.7 ± 0.2 m3/kg influent-volatile solid (VS), reaching a maximum yield of 1.1 ± 0.1 m3/kg influent-VS, with an average organic loading rate of 0.6 ± 0.1 kg-VS/m3/d and HRT of 25 days. The CH4 production rate averaged 0.4 ± 0.1 m3/m3/d, peaking at 0.6 ± 0.1 m3/m3/d. Treatment of digestate through flocculation followed by sedimentation recovered over 90% of ammonium nitrogen and potassium, and 80-85% of total phosphorus in the liquid fraction. This nutrient-rich liquid was used to cultivate Chlorella vulgaris, achieving a biomass concentration of 1.2 ± 0.1 g/L and 85 ± 3% and 78 ± 5% ammonium nitrogen and phosphorus removal efficiency, respectively. These findings not only highlight the feasibility of anaerobic co-digestion of source-separated BW and FW in local biogas production but also demonstrate the potential of microalgae cultivation as a sustainable approach to converting digestate into nutrient-rich algae biomass.

Towards a circular economy - Repurposing side streams from the potato processing industry by Chlorella vulgaris

Common wastewater treatment strategies in the food industry do not include efficient remediation strategies for nitrogen, phosphorous and organic carbon. Incorporating microalgae in water treatment plants is rising in popularity because of their high nutrient and trace element uptake driven by light. In this study, four different side streams from an Austrian potato processing company have been screened for their applicability of microalgal cultivation. The side streams were assessed for Chlorella vulgaris growth and their requirement of any additional pretreatment or media supplementation. One side stream specifically, called blanching water II, a stream generated by boiling the potatoes for ease of peeling, turned out very useful to cultivate Chlorella vulgaris and concomitantly remedy the wastewater. Compared to a state-of-the-art cultivation in BG11, cultivating Chlorella vulgaris in blanching water II led to a 45 % increase in specific growth rate of 1.29 day−1 and a 48% increase in biomass productivity to 294.6 mg/L/day, while all nitrogen and phosphate present in the side stream were metabolized. Overall, the results demonstrate that the water remediation process for blanching water II shows vast potential in regard to water purification and waste to value approaches.

Hydrogel-based photobioreactor for Solid-State cultivation of Chlorella vulgaris

Solid-state cultivation is a promising technology for algal biomass production, achieving high productivities without the need for dewatering. However, such systems have suffered from high evaporation, and capital costs. Here is described a hydrogel photobioreactor (hPBR) with the aim of reducing water demand in solid-state cultivations. Two designs are described with “Design A” offering better humidity control overgrowth conditions. A biomass productivity of 2.41gm-2d-1, and 2.87gm-2d-1 when using physically crosslinked poly(vinyl alcohol) (pPVA) and chemically crosslinked PVA (cPVA) respectively were achieved with Chlorella vulgaris with a water demand around 0.44 kg g−1 of biomass. Over the 23 days of growth, the lipid content increased from 18.9 % to 56.6 % and 13.8 % to 43.2 % for pPVA and cPVA respectively, and the chlorophyll content decreased by more than 81 %. However, cell viability stayed high at over 98 % and surface coverage analysis showed good coverage of the gel surface.

Cultivation of Chlorella vulgaris in wastewater: biodiesel potential and wastewater remediation.

The present investigation has evaluated the use of effluents from a secondary municipal wastewater treatment plant for biomass production and potential of the biomass for biodiesel production. Cultivations of Chlorella vulgaris using wastewater, wastewater with supplementation, and WC medium were carried out. Effect of wastewater collected in different months on biomass productivity (BP) and lipid composition was studied. Methods based on NMR and GC-MS techniques were applied for determining the composition of the lipids and their fatty acid profile including poly unsaturated fatty acids (PUFAs). Lipids extracted are comprised of both neutral (tri acyl glycerides, TAG; free fatty acids, FFA) and polar (glyco glycero/phospho) lipids. The TAG content of the extracted lipids was determined in the range of 22.5-41.3% w/w. The NMR and GC-MS compositional results of microalgal lipids of biomasses cultivated in wastewater without nutrient supplementation, collected in different months, showed potential for biodiesel production. The fatty acid profiles of neutral and polar lipids, which are mainly comprised of saturated and unsaturated long alkyl chain (C16-C22) fatty acids, are potential sources for the biodiesel and food industry. The concentration of nitrates (45-78mg L-1) in wastewater without supplementation, collected in different months, was found to be optimum to enable cultivation of biomasses with reasonably good BP of 21.5-28.1mg L-1day-1. Similar results have been obtained in the present work as well as reported in the literature in the case of WC medium (nitrate, 69mg L-1) with BP of 25.5-28.2mg L-1day-1, thus highlighted the significance of the presented work.

Cultivation and nutritional characteristics of Chlorella vulgaris cultivated using Martian regolith and synthetic urine

Long-term spatial missions will require sustainable methods for biomass production using locally available resources. This study investigates the feasibility of cultivating Chlorella vulgaris, a high value microalgal specie, using a leachate of Martian regolith and synthetic human urine as nutrient sources. The microalga was grown in a standard medium (BBM) mixed with 0, 20, 40, 60, or 100 % Martian medium (MM). MM did not significantly affect final biomass concentrations. Total carbohydrate and protein contents decreased with increasing MM fractions between 0 % and 60 %, but biomass in the 100% MM showed the highest levels of carbohydrates and proteins (25.2 ± 0.9 % and 37.1 ± 1.4 % of the dry weight, respectively, against 19.0 ± 1.7 % and 32.0 ± 2.7 % in the absence of MM). In all MM-containing media, the fraction of the biomass represented by total lipids was lower (by 3.2 to 4.5%) when compared to BBM. Conversely, total carotenoids increased, with the highest value (97.3 ± 1.5 mg/100 g) measured with 20% MM. In a three-dimensional principal component analysis of triacylglycerols, samples clustered according to growth media; a strong impact of growth media on triacylglycerol profiles was observed. Overall, our findings suggest that microalgal biomass produced using regolith and urine can be used as a valuable component of astronauts’ diet during missions to Mars.

Microalgae cultivation trials in a membrane bioreactor operated in heterotrophic, mixotrophic, and phototrophic modes using ammonium-rich wastewater: The study of fouling.

In this work, microalgae cultivation trials were carried out in a membrane bioreactor to investigate fouling when the cultures of Chlorellavulgaris were grown under mixotrophic, heterotrophic, and phototrophic cultivation regimes. The Chlorella cultures were cultivated in wastewater as a source of nutrients that contained a high concentration of ammonium. In mixotrophic cultivation trials, the results showed that the elevated contents of carbohydrates in the soluble microbial product and proteins in extracellular polymeric substances probably initiated membrane fouling. In this case, the highest protein content was also found in extracellular polymeric substances due to the high nitrogen removal rate. Consequently, transmembrane pressure significantly increased compared to the phototrophic and heterotrophic regimes. The data indicated that cake resistance was the main cause of fouling in all cultivations. Higher protein content in the cake layer made the membrane surface more hydrophobic, while carbohydrates had the opposite effect. Compared to a mixotrophic culture, a phototrophic culture had a larger cell size and higher hydrophobicity, leading to less membrane fouling. Based on our previous data, the highest ammonia removal rate was reached in the mixotrophic cultures; nevertheless, membrane fouling appeared to be the fundamental problem.

Development of alginate beads loaded with bioactive ingredients from Chlorella vulgaris cultivated in food industry wastewaters

Microalgae are increasingly recognized for their potential in the food sector due to their rapid growth and rich content in proteins, carbohydrates, and pigments. The extraction of pigments from microalgal biomass holds promise for their utilization as natural colorants and antioxidants. To address the economic challenges associated with microalgae cultivation, particularly high nutrient costs, this study focused on cultivating Chlorella vulgaris in a mixture of food industry wastewaters (brewery wastewater, expired orange juice and cheese whey). This resulted in a microalgae-bacteria consortium with a concentration of 2.2 g·L−1 dry weight after 5 days of cultivation. The wastewater bioremediation ranged between 23 and 77 %, and the produced microalgae biomass contained 21.68 ppm lutein, 36.47 ppm a-chlorophyll and 11.19 ppm b-chlorophyll. The extraction process employed a solvent screening strategy with food industry-accepted solvents used to extract high-value compounds efficiently. Ethanol was the most effective solvent, outperforming acetone, ethyl acetate, and hexane. An upscaled extraction process was conducted using 10 g lyophilized microalgae. After ethanol evaporation, the microalgal extract was re-diluted in sunflower oil and encapsulated in alginate beads, achieving an encapsulation yield of 93.3 %. Lutein, identified as one of the main compounds in the extract, exhibited a satisfactory encapsulation efficiency of 55 %. The efficient encapsulation of the microalgae components in alginate beads was verified by the alteration of the colorimetric parameters of these alginate beads compared to those loaded with pure sunflower oil as well as empty beads. These findings highlight the potential of microalgae as a valuable tool for transforming food industry wastewater into high-value products, especially when microalgal extract is encapsulated in alginate beads. This strategy presents substantial prospects for the food industry, merging effective wastewater valorization with biomass production and bioactive compound extraction. It exemplifies a circular bioeconomy, showcasing sustainable resource management and value creation.

Optimization of a Chlorella–Saccharomyces co–culture system for enhanced metabolite productivity

Microalgae and yeast co–culture systems are gaining interest as a promising method for higher production of biomass and metabolites. However, because these organisms have particular cultivation requirements, optimization of culture conditions is needed for suitable growth and productivity of the co–culture. This work examines the effects of cultivation media macronutrient composition on the growth and metabolite production of co–cultures of either Chlorella vulgaris or Chlorella sorokiniana with a strain of Saccharomyces cerevisiae. Specifically, the consequence of glucose, yeast extract and peptone supplementation on the physiological responses of the co–culture system was investigated. The co–culture responses were equivalent for both Chlorella species, although C. sorokiniana could maintain a more stable population ratio with yeast. The addition of glucose with peptone significantly enhanced biomass production of the co–culture by approximately 2–fold in comparison to microalgae or yeast monocultures, while the addition of glucose alone or in combination with yeast extract did not exhibit the same effect. An approximately 3–fold increase in lipid content was observed in the co–culture samples under glucose–only supplementation, where yeast growth was restricted. The addition of glucose and yeast extract enhanced the growth of yeast monocultures, but this did not benefit the co–culture. Fourier transform infrared spectroscopy analysis revealed different metabolic fingerprints of the monoculture and the co–culture samples grown in glucose and peptone containing medium, which indicated higher abundance of metabolites including lipids, proteins, carbohydrates in the co–culture samples. Specifically, total protein yields in the co–cultures were increased by 1.6– to 1.7–fold in comparison to microalgae monoculture while total lipid yields were increased by 3.6– to 5.1–fold in the co–cultures. This work highlights the importance of organic carbon and nitrogen availability for microalgae–yeast co–culture growth and their potential for a wide range of valuable applications including nutritional and bioenergy uses.

Temperature and photoperiods optimization for the cultivation of Chlorella vulgaris for growth and biomass production from cassava wastes

Microalgae biomass is widely being used as a third generation biofuel because they are the most promising renewable feedstock for biofuel production. Its use is greatly considered as it has high growth rate, photosynthetic efficient, not competing for arable land, efficient carbon dioxide fixation and potential to accumulate high amount of carbohydrate. Microalgae carbohydrates are contained in their cell wall mainly as cellulose and plastids as starch which are readily converted into fermentable sugars. The cultivation of Chlorella vulgaris on cassava wastes for growth and biomass production depends on factors such as temperature and photoperiods. Cassava waste mixtures were cultivated on Chlorella vulgaris stock culture at different concentration ratio at pH of 6.5 and salinity of 10mg/l, cultivation ratio of 160:40 for cassava peel water to cassava waste water CP:CW at 670nm absorbance for 7 days. Temperature variations of 200C, 300C and 350C were checked to determine the optimum temperature for the growth and biomass production of Chlorella vulgaris on the optimum cassava waste mixture concentration. Photoperiod variation of 12:12, 6:18 and 18:6 were checked to determine optimum photoperiod for the growth and biomass production of Chlorella vulgaris on the optimum cassava waste mixture concentration. From the results obtained in this optimization study, optimum growth and biomass was recorded at temperature of 30 ℃. Photoperiod of 12:12 was responsible for optimum growth while photoperiod of 18:6 light and dark conditions gave high biomass production. This study shows that optimized conditions are necessary high growth and biomass production of the microalgae on cassava waste.