Microalgal Consortia Research Articles

Evaluation of carbon capture in competent microalgal consortium for enhanced biomass, lipid, and carbohydrate production

Enrichment of carbon dioxide (CO2) in environment is a major factor for enhancement of global warming on Earth surface. Microalgal consortia play an important role in inhibiting the alarming fluxes of CO2 through sustainable mechanism of bioconversion of CO2 into biomass. In the present investigation, eight heterogeneous consortia of cyanobacteria and green algae such as MC1, MC2, MC3, MC4, MC5, MC6, MC7, and MC8 for the sustainable utilization of effective CO2 sequestration and biomass production were studied. Two factorial central composite designs (% CO2 and pH) were used for optimization of cellular morphology, growth, and development of consortia. The photosynthetic quantum yield of consortium MC8 was found to be maximum (0.61) in comparison with other consortia. The morphological and physiological behavior of the above consortium was analyzed under C, 5, 10, and 15% concentrations of CO2 resource capture in 250mL BG-11+ medium. We have identified that 10% CO2 concentrated medium maximally promoted the cellular growth in terms of cell dimension, dried biomass, carbohydrate, and lipid contents in this consortium. As such, the elemental composition of carbon and carbon capturing capability was high at 10% CO2 concentration. However, further CO2 enrichment (15%) led to decline in growth and morphology of cell size as compared to control. The results indicate that the optimum CO2 enrichment in consortia exhibits potent commercial utilization for rapid biomass production and plays a distinguished role in global carbon sequestration and mitigation agent.

Comparison of biodegradation of lubricant wastes by Scenedesmus vacuolatus vs a microalgal consortium

Locally, the petroleum, aluminum and steel milling industries have expressed considerable interest in the utilization of bioremediation as a means for reducing their lubricant waste. Since hydrocarbons accumulate within microalgae, the aim of this study was to determine the efficiency of Scenedesmus vacuolatus vs a microalgal consortium (Chlamydomonas pitschmannii, Trebouxia australis and Pectinodesmus pectinatus) in the biodegradation lubricant waste products; from which these indigenous microalgae were originally isolated. To determine the biodegradation capability of these microalgae, dehydrogenase activity tests were carried out and indicated by % TPF values. Samples that tested positive for dehydrogenase activity, were analyzed using gas chromatography/mass spectrometry, to track the biotransformation of hydrocarbons intracellularly and extracellularly. Results were analyzed statistically with SPSS, p < 0.05. Dehydrogenase activity for both the coolant rolling oil (0.058 ± 0.001 mg/mL), and the spent rolling emulsion (0.047 ± 0.002) was higher for the microbial consortium compared to S. vacuolatus, 0.046 ± 0.001 mg/mL. Weekly, gas chromatography/mass spectrometry biotransformations, indicated no hydrocarbons present after five weeks, confirming 100% biodegradation. Irrespective of the use of either a single isolate or a microalgal consortium; complete biodegradation after just five weeks, makes the use of microalgae for bioremediation a viable strategy.

The influence of microalgae on vegetable production and nutrient removal in greenhouse hydroponics

Abstract: The effect of microalgae on plant growth and nutrient removal was assessed for three vegetables (arugula, purple kohlrabi and lettuce) grown entirely using nitrate-rich synthetic wastewater in greenhouse hydroponics. Results showed that the response of the vegetables to microalgae varied. Microalgae had a negative effect on arugula growth, but in the purple kohlrabi and lettuce groups, there were no negative effects or even an increase in vegetable production. The dissolved oxygen (DO) and microalgae biomass concentrations in the group with microalgae added were relatively higher. pH increased because of microalgae photosynthesis and decreased due to NH3–N removal processes. The presence of microalgae, especially Chlorella vulgaris addition, can significantly improve the removal rate of total dissolved solids, total nitrogen (TN), and total phosphorus (TP), but not COD. The contribution of each vegetable and microalgal consortia on the N or P removal in greenhouse hydroponics was different. The P removal efficiency were satisfactory in all groups, especially in the natural microalgae treatment where P removal rate reached more than 98%. In some cases, vegetable hydroponics could be upgraded with microalgae co-cultivation which could be an ecofriendly and economically sustainable production system.

Treating anaerobically digested piggery effluent (ADPE) using microalgae in thin layer reactor and raceway pond

The successful cultivation of microalgae on anaerobically treated wastewaters would not only allow for the bioremediation of the waste stream but also the cost effective production of algal biomass. In this study, the growth and bioremediation ability of a microalgal consortium of Chlorella sp. and Scenedesmus sp. for treating anaerobically digested piggery effluent (ADPE) was assessed and compared using a thin layer reactor (TLR) (0.5-cm depth, 350 L) and a conventional raceway pond (15-cm depth, 1500 L) with an initial ammonium concentration of 110 ± 10 mg N-NH4+ L−1. The ammonium removal rate of microalgae grown in the TLR (19.23 mg N-NH4+ L−1 d−1) was 1.4 times higher than that grown in the raceway pond. The ash-free biomass yield (0.84 g L−1) and the average volumetric biomass productivity (60 mg L−1 d−1) of the algal consortium in the TLR were 2.5 and 2 times higher than that achieved in the raceway pond, respectively. However, considering four times higher culture volume in the raceway pond, the average areal biomass productivity in the raceway pond (4.2 g m−2 s−1) was more than two times higher than the productivity achieved in the TLR (1.9 g m−2 s−1). As a result of this, the areal lipid productivity of the microalgae grown in the raceway pond was also 2.7 times higher than that grown in the TLR. Our results indicated that under the operational conditions evaluated in this study and based on areal biomass productivity, raceway pond performed better than the thin layer reactor for treating ADPE.

Evaluation of the population dynamics of microalgae isolated from the state of Chiapas, Mexico with respect to the nutritional quality of water.

As Chiapas state, México, counts on an extensive hydrography with diverse nutrimental and climatic characteristics, it therefore allows isolating and identifying microalgae with bioenergetics potential.For this purpose, samples from 8 locations were collected, corresponding to 6 rivers, a wastewater and a springwater. The isolation of microalgae was developed for 4 weeks with 12:12 light/dark cycles. We demonstrated that the most efficient means for the isolation of microalgae of the hydrographic areas evaluated was the medium BG11 with 80.53% effectiveness. Of the microalgal consortium identified, 90% are composed of microalgae belonging to the class Chlorophycear. It was shown that another factor favouring the richness of morphotypes identified in the Santo Domingo River is associated with adequate concentrations of macroelements such as nitrates, nitrites, ammonium, phosphorus, sodium, potassium, magnesium and calcium at concentrations of 0.03 mg/l, 0.0006 mg/l, 0.08 mg/l, 0.03 mg/l, 62.93 mg/l, 5.46 mg/l, 34.52 mg/l and 48.78 mg/l respectively and microelements such as copper, zinc, iron, andmanganese at concentrations less than 0.2 mg/l in all microelements. The identified morphotypes, according to literature, have lipid contents ranging from 2 to 90%; this is of biotechnological importance for the production of biodiesel.

Valorization of waste micro-algal biomass - collected from coke oven effluent treatment plant and evaluation of sorption potential for fluoride removal.

Fluoride contamination in groundwater is now becoming a global concern. In the present study, removal of fluoride using dry biomass (DBM) of a micro-algal consortium of Chlorococcum infusionum and Leptolyngbya foveolaurum, collected from a coke-oven effluent treatment plant, Durgapur, India, has been investigated. The large volume of algal bloom in the industrial effluent has created serious disposal issues and caused severe environmental concerns. A biosorption technique has been carried out to valorize the waste algae biomass into a potential adsorbent. Response Surface Methodology (RSM) is used to model and optimize fluoride removal. Maximum fluoride removal (72%) is obtained at pH 4, 5 mg/L initial fluoride concentration, 0.5 g/L adsorbent dose (AD), and 25 °C temperature during one-factor-at-a-time (OFAT) analysis. The optimum condition of removal as specified by RSM is - initial concentration of fluoride: 30 mg/L, pH: 4.5, AD: 3.5 g/L and temperature: 30 °C. FESEM-EDX, FTIR and BET isotherm studies are done to characterize raw and fluoride treated biomass. Lagergren first order kinetic model and Freundlich isotherm model, are found to analyze best kinetic and equilibrium data, respectively. Adsorption capacity of DBM has been found to be 34.36 mg/g. The kinetics of fluoride removal have been well described by COMSOL Multiphysics.

Growth of microalgae on undiluted anaerobic digestate of piggery effluent with high ammonium concentrations

Anaerobic digestate of piggery effluent (ADPE) is extremely high in ammonia toxic to many microorganisms. Bioprospecting and nutrient enrichment of several freshwater and wastewater samples combined and further acclimation resulted in a mixed culture containing at least three microalgae species capable of growing on undiluted ADPE. Outdoor growth of the mixed culture using raceway ponds showed potential for up to 63.7±12.1mgN-NH4+L−1d−1 ammonium removal from the ADPE. The microalgal consortium was dominated by Chlorella sp. and was stable at between 800 and 1600mgN-NH4+L−1. Regulation of CO2 addition to the ponds to maintain a pH of 8 increased chlorophyll content of the microalgal consortium. Average microalgal biomass productivity of 800mgN-NH4+L−1 culture conditions during five weeks semicontinuous growth was 18.5mgash-freedryweightL−1d−1. Doubling the ammonium concentration from 800 to 1600mgN-NH4+L−1 resulted in a 21% reduction of productivity, however the culture grown at 1600mgN-NH4+L−1 with the addition of CO2 by keeping pH at pH=8 led to a 17% increase in biomass productivity.

Harvesting microalgae using ozoflotation releases surfactant proteins, facilitates biomass recovery and lipid extraction

In this paper, a mixed microalgal consortium (including cyanobacteria) was separated from treated wastewater by ozoflotation to evaluate the method's effect on protein excretion, lipids extraction, and cell recovery. Microalgae suspensions obtained from an artificial lake, Lake Nabor Carrillo, were subjected to different ozoflotation conditions (0.028–0.136 mg O3/mg biomass). During ozoflotation, proteins released exhibited surfactant activity in the water disrupting the surface tension of water to values of 42.73 mN/m. A critical micelle concentration (CMC) of at least 550 ± 17 mg protein/L was needed to produce foaming and biomass separation of the aqueous medium. The C-Phycocyanin beta chain was identified as one of the main proteins released during the ozoflotation process. Biomass recovery was found to be directly proportional to the ozone dose; best results (75% as TSS) were obtained at the highest dose used (0.14 mg O3/mg biomass). In contrast, the best lipid recovery (16% mg lipid/mg biomass) was achieved when using low ozone doses (0.047 mg O3/mg biomass).

Exploring the efficacy of wastewater-grown microalgal biomass as a biofertilizer for wheat.

Microalgae possess the ability to grow and glean nutrients from wastewater; such wastewater-grown biomass can be used as a biofertilizer for crops. The present investigation was undertaken to evaluate two formulations (formulation with unicellular microalgae (MC1) and formulation with filamentous microalgae (MC2); T4 and T5, respectively), prepared using wastewater-grown microalgal biomass, as a biofertilizer (after mixing with vermiculite/compost as a carrier) in wheat crop (Triticum aestivum L. HD2967) under controlled conditions. The highest values of available nitrogen (N), phosphorus (P), and potassium (K) in soil and nitrogen-fixing potential were recorded in treatment T5 (75% N + full-dose PK + formulation with filamentous microalgae (MC2). Microbial biomass carbon was significantly enhanced by 31.8-67.0% in both the inoculated treatments over control (recommended dose of fertilizers), with highest values in T4 (75% N + full-dose PK + formulation with unicellular microalgae (MC1)). Both the microalgal formulations significantly increased the N, P, and K content of roots, shoots, and grains, and the highest total N content of 3.56% in grains was observed in treatment T5. At harvest stage, the treatments inoculated with microalgal formulations (T4 and T5) recorded a 7.4-33% increase in plant dry weight and up to 10% in spike weight. The values of 1000-grain weight showed an enhancement of 5.6-8.4%, compared with T1 (recommended doses of fertilizers). A positive correlation was observed between soil nutrient availability at mid crop stage and plant biometrical parameters at harvest stage. This study revealed the promise of such microalgal consortia as a biofertilizer for 25% N savings and improved yields of wheat crop.

Meta-approaches to harvest natural products from harmful algae blooms

In 2009, Ross Youngs established the company Biosortia Pharmaceuticals based on a new harvesting technique utilizing microalgae natural products chemistry to overcome the lack of efficiency of drug discovery. This approach has focused on the micro-algal consortia using a meta-metabolomics and a mega-scale approach.

Carbon dioxide sequestration in wastewater by a consortium of elevated carbon dioxide-tolerant microalgae

The emission of the green house gas (GHG) carbon dioxide (CO2) in the atmosphere at an increasingly high rate is the primary cause of global warming. A study was performed to isolate an elevated CO2-tolerant microalgal consortium (CMAC) and then characterize growth-influencing environmental factors, CO2 sequestration capacity and the potential applications of CMAC for elevated CO2 sequestration. The CMAC was isolated from a wastewater treatment plant under a selection condition consisting of 50% CO2 in air (v/v). The CMAC species were identified as Chlorella sp., Scenedesmus sp., Sphaerocystis sp. and Spirulina sp. Multiple variables including 20% CO2, culture medium pH of 8–9, and an illumination intensity of 50–80μmolm−2s−1 were found to be optimal for high density growth of CMAC for uptake of elevated CO2, although the CMAC were demonstrated to grow well in up to 50% CO2. The CMAC showed high CO2 sequestration (53–100%; 150–291mgg−1) with strong growth performance in wastewater. The lipid content of CMAC was high (350±0.31mgg−1), which gave a high biodiesel yielding capacity (420±0.43mgg−1). CMAC was also found to have high nutrient removal abilities (PO4-P, up to 59% and NH4-N, up to 39%). These characteristics all indicate that the isolated CMAC could be used as an efficient tool for biofuel generation from wastewater as well as bioremediation of pollutants. Thus by coupling the identified CO2 sequestration potential of the CMAC with the wastewater tolerance characteristics, there is novel potential to integrate wastewater treatment with CO2 sequestration and biomass utilization in order to mitigate the problems of increased GHG in response to global warming.

Organic carbon, influent microbial diversity and temperature strongly influence algal diversity and biomass in raceway ponds treating raw municipal wastewater

Algae based wastewater treatment coupled to biofuel production has financial benefits and practical difficulties. This study evaluated the factors influencing diversity and growth of indigenous algal consortium cultivated on untreated municipal wastewater in a high rate algal pond (HRAP) for a period of 1year using multivariate statistics. Diversity analyses revealed the presence of Chlorophyta, Cyanophyta and Bacillariophyta. Dominant microalgal genera by biovolume in various seasons were Scenedesmus sp., Microcystis sp., and Chlorella sp. Scenedesmus sp., persisted throughout the year but none of three strains co-dominated with the other. The most significant factors affecting genus dominance were temperature, inflow cyanophyta and organic carbon concentration. Cyanophyta concentration affected microalgal biomass and diversity, whereas temperature impacted biomass. Preferred diversity of microalgae is not sustained in wastewater systems but is obligatory for biofuel production. This study serves as a guideline to sustain desired microalgal consortium in wastewater treatment plants for biofuel production.

Microalgal process for treatment of high conductivity concentrates from inland desalination

Desalination concentrate contains high levels of dissolved ions such as alkalinity, sulfate, and synthetic chemicals. Microalgal species that have ability to grow in the presence of these ions can be used to treat concentrates. A natural indigenous microalgal consortium originally grown in the concentrate of an evaporation pond was selected, cultured, and seeded in the growth medium for treatment of concentrates. Fed-batch experiments were performed with five different conductivities of concentrates in five reactors, with duplicates. Supernatants or leachates from anaerobic digested sludges were supplied as nutrients. Energy was supplied by sunlight during regularly scheduled office hours. Artificial light was supplied as energy during the weekend and all holiday hours. Environmental air was supplied as carbon during the office hours, weekend, and holidays. Water quality from treated concentrate in reactor R1 at 20 d of treatment was sufficiently pure to be given to sheep. Overall mass conductivity reductions from concentrate and supernatant or leachate were 54.7, 53.4, 45.8, 37.3, and 40.4% at 110 d for reactors R1–R5, respectively. These reductions depend on the initial conductivity of concentrate. Mass reduction percentage is inversely proportional to initial mass conductivity, with a variation of the coefficients “a” and “b” as a second-order of polynomial function of the treatment time.

Culturing of Autoflocculating Microalgal Consortium in Continuous Raceway Pond Reactor

The goal of this study was to develop a self-settling microalgal consortium in raceway pond reactor (RPR). Experiments were carried out with cultures that developed without additional seeding, but naturally promoted by process conditions in a raceway pond reactor. The changes in microalgal communities and total biomass under nitrogen and phosphorous limitations were studied in both batch and continuous systems. At the steady state batch had the population of 46% Euglena sp., 16% Closterium sp., 14% Chlorella sp., 14% Scenedesmus sp. and 10% Ankistrodesmus sp. with a maximum biomass of 900 mg/L. In order to get self-settling microalgal consortium, the operation was changed to continuous continuous mode with the aid of a specially designed settler for daily harvest and recycling of the biomass. Grazing fauna could be controlled by managing reduced liquid and solid retention time. At steady-state condition, an autofloculating and self-settling consortium was developed which had mainly Fragilaria sp., Scenedesmus sp., and filamentous Ulothrix sp. The maximum biomass concentration obtained was 140 mg/L. The presence of neutral lipid droplets in the consortium was identified by staining with Nile Red. Development of the lipid rich consortium could be a suitable method for producing biofuel.

Enhanced Carbon Dioxide Fixation and Bio‐oil Production of a Microalgal Consortium

In this study, a microalgal consortium was cultivated with different CO2 supplements: ambient air (0.03% CO2), 10 and 30% (v/v) CO2. It was found that the growth rate of the cultures supplemented with 30% CO2 was the highest among the others. The biomass and lipid productivity for the microalgal consortium with 30% CO2 were 21.1 and 4.8 mg L−1 day−1 (27.6% of dry weight, dw). The ability of CO2 fixation under 30% CO2 supplementation was found to be 0.0271 g CO2 L−1 day−1, which is higher than in the ambient air supplementation. Then, the microalgal consortium was cultivated with exhaust gas (19% CO2) from a power generator supplied by biogas from chicken manure. It was found that the growth of the microalgae supplemented with exhaust gas was higher than in the ambient air. The biomass and lipid productivity for the microalgal consortium with exhaust gas were 25.82 and 5.2 mg L−1 day−1 (16.96% of dw) and the most dominant algal species observed were Acutodesmus (Scenedesmus) sp., A. dimorphus (Turpin) Tsarenko and Scenedesmus obliquus (Turpin) Kützing, respectively. Moreover, it could be revealed that the ability of CO2 fixation under supplementations with exhaust gas increased 1.3‐fold compared with ambient air. Therefore, the microalgal consortium has high potential for both CO2 reduction and bio‐oil production, simultaneously.

Microalgae triacylglycerols content by FT-IR spectroscopy

The present study aims to develop a methodology via Fourier transform infrared (FT-IR) spectroscopy for the semiquantitative determination of triacylglycerols (TAGs) in microalgal consortia, consistent with the use of the technique as process control. FT-IR spectroscopy has proved to be a powerful analytical tool for the identification of macromolecular pools (e.g., proteins, lipids, and carbohydrates) and in monitoring biochemical changes (including lipids) in response to nutrient stress or environmental modifications. In the Oocystis-based consortium under examination, the synthesis of neutral lipid in the form of TAGs can be induced, applying stress condition, and these lipids are suitable as biodiesel precursors. In the exponential growing phase, the consortium shows a low TAGs content, in the order of 5 %w, that can be increased till around 22 %w on ash free dry matter, after nitrogen starvation.

Carbon conversion efficiency and population dynamics of a marine algae–bacteria consortium growing on simplified synthetic digestate: First step in a bioprocess coupling algal production and anaerobic digestion

Association of microalgae culture and anaerobic digestion seems a promising technology for sustainable algal biomass and biogas production. The use of digestates for sustaining the growth of microalgae reduces the costs and the environmental impacts associated with the substantial algal nutrient requirements. A natural marine algae–bacteria consortium was selected by growing on a medium containing macro nutrients (ammonia, phosphate and acetate) specific of a digestate, and was submitted to a factorial experimental design with different levels of temperature, light and pH. The microalgal consortium reached a maximum C conversion efficiency (i.e. ratio between carbon content produced and carbon supplied through light photosynthetic C conversion and acetate) of 3.6%. The presence of bacteria increased this maximum C conversion efficiency up to 6.3%. The associated bacterial community was considered beneficial to the total biomass production by recycling the carbon lost during photosynthesis and assimilating organic by-products from anaerobic digestion.

Modelling growth of, and removal of Zn and Hg by a wild microalgal consortium

Microorganisms isolated from sites contaminated with heavy metals usually possess a higher removal capacity than strains from regular cultures. Heavy metal-containing soil samples from an industrial dumpsite in Northern Portugal were accordingly collected; following enrichment under metal stress, a consortium of wild microalgae was obtained. Their ability to grow in the presence of, and their capacity to recover heavy metals was comprehensively studied; the datasets thus generated were fitted to by a combined model of biomass growth and metal uptake, derived from first principles. After exposure to 15 and 25 mg/L Zn(2+) for 6 days, the microalgal consortium reached similar, or higher cell density than the control; however, under 50 and 65 mg/L Zn(2+), 71% to 84% inhibition was observed. Growth in the presence of Hg(2+) was significantly inhibited, even at a concentration as low as 25 μg/L, and 90% inhibition was observed above 100 μg/L. The maximum amount of Zn(2+) removed was 21.3 mg/L, upon exposure to 25 mg/L for 6 day, whereas the maximum removal of Hg(2+) was 335 μg/L, upon 6 day in the presence of 350 μg/L. The aforementioned mechanistic model was built upon Monod assumptions (including heavy metal inhibition), coupled with Leudeking-Piret relationships between the rates of biomass growth and metal removal. The overall fits were good under all experimental conditions tested, thus conveying a useful tool for rational optimisation of microalga-mediated bioremediation.

Lipid composition in microalgal community under laboratory and outdoor conditions

Microalgae are the most sought after sources for biofuel production due to their capacity to utilize carbon and synthesize it into high density liquid. Current energy crisis have put microalgae under scanner for economical production of biodiesel. Modifications like physiological stress and genetic variation is done to increase the lipid yield of the microalgae. A study was conducted using a microalgal consortium for a period of 15 days to evaluate the feasibility of algal biomass from laboratory as well as outdoor culture conditions. Native algal strains were isolated from a tropical freshwater lake. Preliminary growth studies indicated the relationship between the nitrates and phosphates to the community structure through the days. The lipid profile done using Gas chromatography – Mass spectrometry, revealed the profile of the algal community. Resource competition led to isolation of algae, aided in the lipid profile of a single alga. However, further studies on the application of the mixed population are required to make this consortium approach economically viable for producing algae biofuels.

Lipid composition in microalgal community under laboratory and outdoor conditions

Microalgae are the most sought after sources for biofuel production due to their capacity to utilize carbon and synthesize it into high density liquid. Current energy crisis have put microalgae under scanner for economical production of biodiesel. Modifications like physiological stress and genetic variation is done to increase the lipid yield of the microalgae. A study was conducted using a microalgal consortium for a period of 15 days to evaluate the feasibility of algal biomass from laboratory as well as outdoor culture conditions. Native algal strains were isolated from a tropical freshwater lake. Preliminary growth studies indicated the relationship between the nitrates and phosphates to the community structure through the days. The lipid profile done using Gas chromatography – Mass spectrometry, revealed the profile of the algal community. Resource competition led to isolation of algae, aided in the lipid profile of a single alga. However, further studies on the application of the mixed population are required to make this consortium approach economically viable for producing algae biofuels.