Biomass Cultivation Research Articles

IN VITRO SCREENING OF CELL WALL DEGRADING ENZYME PRODUCTIVITY FROM FUNGAL CULTURE FILTRATES ON DEPROTEINISED PLANT FLUID BY CUP PLATE ASSAY

The present study purpose is to evaluate the potentiality of the Deproteinised juice made from selected plants to induce the enzyme productivity by growing the fungi on it. It is because, in earlier findings, the DPJ was found potential in enhancing fungi and the plant growth when used as the medium. The internal factors are responsible in DPJ which induces plants and fungi growth. During the process of Green Crop Fractionation (GCF), the deproteinised (DPJ) obtained from tissues of cabbage, beet, lucerne (Alfalfa), carrot and Anathum (Dill) forages left after leaf protein extraction employed as a medium for the cultivation of mycelial biomass of Penicillium and Aspergillus fungi. The mycelial growth in vitro was compared with the glucose nitrate medium. The culture filtrates were used to screen different secreted hydrolytic or cell wall degrading enzymes.. The agar ‘cup‐plate’ diffusion technique has been applied to the quantitative determination of enzyme activity, principally to amylase, cellulase and protease. With all enzymes so far examined, the relationship between diameter of zone over a wide range secreted quantitatively was examined. All fungi grew well on DPJ in comparison to their growth on glucose nitrate (GN) medium. Comparatively with GN medium, lucerne DPJ was found having more mycelial cellular proliferation. When the fungi grown on different concentrations of substrates, enriched with carboxymethyl cellulose, casein and starch in deproteinised leaf extracts and GN medium, it was found that there was the enhancement in the mycelial dry weight grown on DPJ as compared with glucose nitrate medium. Penicillium showed more yield of enzyme activities especially of cellulases and amylases as compared to protease by cup plate method. There was enhancement of mycelial biomass when the concentrations of substrates increased from 1% to 2%, while there was no change in the activity of all enzymes by increasing the concentrations of substrates. Activities of the enzymes in vitro can be indicative of the pattern of organogenesis in callus cultures in further studies by fungal culture filtrates cultured on deproteinised fluid medium.

Soil application of microalgae for nitrogen recovery: A life-cycle approach

The application of algal biomass in the soil represents an alternative of efficient use of fertilizers. In the present study, the environmental impacts generated by the application of 1 kg of nitrogen from the algal biomass (biofertilizer) were analyzed through life cycle analysis. Nitrogen was recovered from a meat processing industry effluent in a high-rate algal pond. Impacts related to the entire biofertilizer chain were mainly impacting on climate changes (115 kgCO2eq). Other categories (particle formation, terrestrial acidification, freshwater eutrophication and freshwater ecotoxicity) were not very representative. Biomass cultivation was the most critical step regarding energy and time consumption. On the other hand, the use of effluent as the culture medium for microalgae growth reduced impact categories, such as freshwater eutrophication. Results showed that microalgae cultivation and harvesting steps need to be technologically developed, especially when compared to a conventional fertilizer already established in the market. In order to make microalgae biofertilizer environmental advantageous, alternatives should be beforehand: i) the use of photovoltaic energy instead of hydropower energy; ii) the use of a nitrogen richer effluent; iii) and the consideration of an environmental compensation for the treatment of effluent can be accounted for, disregarding the biomass production stage.

Biomethane from Short Rotation Forestry and Microalgal Open Ponds: System Modeling and Life Cycle Assessment

Gasification of Short Rotation Forestry (SRF) poplar wood chips and anaerobic digestion of the microalga Chlorella vulgaris have been analyzed as alternative supply chains for the production of biomethane. Life Cycle Assessment (LCA) was performed from the biomass cultivation to the upgrading stages. Process simulation of gasification and upgrading was carried out, environmental impacts of the entire supply chains have been estimated and discussed. The highest CO2 removal has been reached by absorption on monoethanolamine. Electricity requirements heavily affect the SRF chain, while productions of carbon dioxide and fertilizers are the main sources of impact of the microalgae cultivation. The recycle of non-absorbed fertilizers, as well as integration of microalgae digestion in wastewater plants, are recommended. Capture and re-injection of the CO2 lost during the upgrading stages would result, simultaneously, in an 8.53% reduction of the atmospheric emission, and in a minor demand to promote algal growth.

Arthrospira maxima OF15 biomass cultivation at laboratory and pilot scale from sugarcane vinasse for potential biological new peptides production

An environmental friendly process was developed to produce Arthrospira maxima's biomass from sugarcane vinasse, which was generated in a bioethanol production chain, at laboratory and pilot scale. Peptides fractions were than obtained from enzymatically hydrolyzed biomass. High microalgae biomass productivities were reached (0.150 g L−1 day−1) coupled with a significant reduction of BOD and COD (89.2 and 81%, respectively). Three peptide fractions were obtained from microalgae biomass through single or sequential enzymatic hydrolysis. Antioxidant, antimicrobial, anti-inflammatory, and/or anti-collagenase activities of biopetides’ fractions were observed. The PHS showed multi-biological activities. The three peptides fractions could be potential candidates for different applications in pharmaceutical, cosmetic and food industry.

Scaling-up sustainable Chlorella vulgaris microalgal biomass cultivation from laboratory to pilot-plant photobioreactor, towards biofuel

<p>Unicellular microalgal culture represents a new opportunity for producing significant biofuel quantities in the future along with other specialty products, due to several major advantages microalgae species present when compared to conventional crops, including much faster growth rates, cultivation in a variety of environments and photobioreactor systems, and almost 100% recycling of nutrients. In the current research, the scaling-up of the cultivation of Chlorella vulgaris microalgae to a 4 m3 pilot-plant photobioreactor is examined, compared to the performance of a 25 L automated laboratory bioreactor. Beyond the size and configuration, the main differences of the two bioreactors are the mode of operation, the illumination nature and depth, the temperature, and pH. Specifically, temperature and illumination are naturally varying from day to day and season to season into the pilot-plant photobioreactor that is set inside a greenhouse. The specific growth factor appears to be higher for microalgal cultivation in the laboratory bioreactor. It is also found that the growth kinetics is severely slowed down during the winter months. This is primarily due to the low temperatures and the poor illumination observed during winter.</p>

Genomic characterization reveals significant divergence within Chlorella sorokiniana (Chlorellales, Trebouxiophyceae)

Selection of highly productive algal strains is crucial for establishing economically viable biomass and bioproduct cultivation systems. Characterization of algal genomes, including understanding strain-specific differences in genome content and architecture is a critical step in this process. Using genomic analyses, we demonstrate significant differences between three strains of Chlorella sorokiniana (strain 1228, UTEX 1230, and DOE1412). We found that unique, strain-specific genes comprise a substantial proportion of each genome, and genomic regions with >80% local nucleotide identity constitute <15% of each genome among the strains, indicating substantial strain specific evolution. Furthermore, cataloging of meiosis and other sex-related genes in C. sorokiniana strains suggests strategic breeding could be utilized to improve biomass and bioproduct yields if a sexual cycle can be characterized. Finally, preliminary investigation of epigenetic machinery suggests the presence of potentially unique transcriptional regulation in each strain. Our data demonstrate that these three C. sorokiniana strains represent significantly different genomic content. Based on these findings, we propose individualized assessment of each strain for potential performance in cultivation systems.

Importance of considering environmental sustainability in dietary guidelines

Importance of considering environmental sustainability in dietary guidelines

Multi-factor kinetic modelling of microalgal biomass cultivation for optimised lipid production

This paper presents a new quadruple-factor kinetic model of microalgal cultivation considering carbon and nitrogen concentration, light intensity and temperature, developed in conjunction with laboratory-scale experiments using the well-studied chlorophyte microalgal species Chlamydomonas reinhardtii. Multi-parameter quantification was exploited to assess the predictive capabilities of the model. The validated model was utilized in an optimization study to determine the optimal light intensity and temperature for achieving maximum lipid productivity while using optimal acetate and nitrogen concentrations (2.1906 g L−1 acetate and 0.0742 g L−1 nitrogen) computed in a recent publication. It was found that the optimal lipid productivity increased by 50.9% compared to the base case, and by 13.6% compared to the previously computed optimal case. Optimization results were successfully validated experimentally. Such comprehensive modelling approaches can be exploited for robust design, scale-up and optimization of microalgal oil production, reducing operating costs and bringing this important technology closer to industrialization.

Optimization of the 9α-hydroxylation of steroid substrates using an original culture of Rhodococcus erythropolis

To obtain inoculation material (cultivation stage 1), the biomass of Rhodococcus erythropolis VKPM AC-1740 was transferred from agar slants into 750 ml conic flasks containing 100 ml of vegetation media of the following composition (g/l): medium 1 – yeast extract, 10.0; glucose, 10.0; soybean flour, 10.0; КН2РО4, 2.0; Na2НРО4, 4.0 (рН 6.8–7.4); medium 2 – corn extract, 15.0; glucose, 10.0; КН2РО4, 2.0; Na2НРО4, 4.0 (рН 6.8–7.4). The culture was grown on a rotary shaker (220 rpm) for 68–72 h at 28–29 °С. To obtain a working biomass (cultivation stage 2), the inoculum obtained at the stage 1 was transferred into flasks containing the same media (the volume of seed material was 20% of the medium volume) and grown under the same conditions for 23–25 h. During a study of the effect of the inducer concentration on the rate of 9α-OH-AD formation, different concentrations (0.25, 0.50, and 1 g/l) of the AD solution in dimethylformamide (DMF) were added to the vegetation medium after 6 h of incubation. To perform AD transformation at a load of 5 g/l, 10 ml of Rh. erythropolis cells at the age of 23–25 h were transferred into 750 mL flasks with baffles containing 40 mL of vegetation medium supplemented with the steroid. AD was added in the form of microcrystals or suspension with a surfactant or DMF. The process was carried out at 28–29 ºC and with constant mixing (220 rpm). During AD transformation at a load of 10–30 g/l, the steroid was preliminarily precipitated from DMF solution. The resulting paste was mixed with a surfactant and transformation medium. The obtained homogeneous suspension was poured in equal amounts into the flasks with baffles, and then a concentrated cell mass was added (25 vol.%). To obtain a cell concentrate, cells were centrifuged for 1 h at 1500 rpm at the age of 23–25 h. The resulting biomass was homogenized, supplemented with a fresh medium to the required volume, and added into transformation flasks. The amount of a biomass required for AD transformation at a load of 10 g/l was 3.13 g/l (dry weight); in the case of a 30 g/l load, the biomass was added by two equal portions, and its total amount was 6.2 g/l (dry weight). The amount of 9α-OH-AD in a culture broth was evaluated by a thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Steroids were extracted by ethylacetate. To perform TLC, Sorbifil plates (Russia) and benzol: acetone mix (3 : 1) were used. HPLC was performed on a Gilson chromatographer (United States) equipped with a Silasorb C-18 column (10 μm, 4.0 × 250 mm); the flow rate was 0.8 ml/min. The mobile phase was МеОН : Н2О mix (70 : 30). The absorbance was measured at 260 nm. Replacement of corn extract, which has an unstable composition, by yeast extract and soybean flour and the use of glucose as an optimal carbon source for a Rh. erythropolis culture have provided a high-yield production of 9α-hydroxy-4-ene-3,17-dione with increased AD loads. Use of such techniques as the inoculum induction and application of surfactants have provided a positive effect on the AD transformation with a load exceeding 10 g/l. During 9α-hydroxylation of AD with a load of 30 g/l, a target product with the yield of 83% has been obtained.

Integrating life cycle assessment and energy system modelling: Methodology and application to the world energy scenarios

Today’s energy systems are dominated by finite fossil fuels and related environmental and human health impacts. To strive for the Sustainable Development Goal (SDG) related to energy, their transformation must be initiated. Insights on the sustainability of energy system transformation pathways can be gained by combining partial equilibrium energy system modelling and life cycle assessment (LCA) due to their complementary characteristics. The present study aims at demonstrating an approach on how LCA indicators can be quantified for the integration in partial equilibrium energy system models without double-counting of impacts of the energy system and how such analyses can be used to estimate environmental and human health impacts of energy system transformation pathways. The results for the World Energy Scenarios show that the environmental and human health “hotspots” are coal (mining, heat and power generation, ash disposal), oil (freight and passenger transport, industrial motors) and biomass (cultivation, heat generation, ash disposal) technologies. The regional results are found to be more informative than the global results, also because many environmental and human health indicators reflect regional impacts. The transformation pathway with a focus on climate change mitigation policies has co-benefits regarding environmental and human health impacts and thus contributes to several SDGs, while it encounters challenges related to water and land use.

Influence of nitrogen source on photochemistry and antenna size of the photosystems in marine green macroalgae, Ulva lactuca

Ulva lactuca is regarded as a prospective energy crop for biorefinery owing to its affluent biochemical composition and high growth rate. In fast-growing macroalgae, biomass development strictly depends on external nitrogen pools. Additionally, nitrogen uptake rates and photosynthetic pigment content vary with type of nitrogen source and light conditions. However, the combined influence of nitrogen source and light intensity on photosynthesis is not widely studied. In present study, pale green phenotype of U. lactuca was obtained under high light (HL) condition when inorganic nitrogen (nitrate) in the media was substituted with organic nitrogen (urea). Further, pale green phenotype survived the saturating light intensities in contrast to the normal pigmented control which bleached in HL. Detailed analysis of biochemical composition and photosynthesis was performed to understand functional antenna size and photoprotection in pale green phenotype. Under HL, urea-grown cultures exhibited increased growth rate, carbohydrate and lipid content while substantial reduction in protein, chlorophyll content and PSII antenna size was observed. Further, in vivo slow and polyphasic chlorophyll a (Chl a) fluorescence studies revealed reduction in excitation pressure on PSII along with low non-photochemical quenching thus, transmitting most of the absorbed energy into photochemistry. The results obtained could be correlated to previous report on cultivation of U. lactuca through saturating summer intensities (1000 µmole photons m-2 s-1) in urea based: poultry litter extract (PLE). Having proved critical role of urea in conforming photoprotection, the application PLE was authenticated for futuristic, sustainable and year-round biomass cultivation.

Eco-Investments - Life Cycle Assessment of Different Scenarios of Biomass Combustion

Abstract The article presents the results of life cycle assessment of different scenarios of biomass use to produce energy in a selected company. The study is made on the case of Lesaffre Polska S.A. and its facility in Wolczyn which is one of the most modern biomass plants in Central Europe. The company is one of the leaders of using the environmental criteria in its strategic decision-making. Its goal is to avoid any waste and to form its own circular business system. One of its recent investments is a biomass fired steam boiler that uses agricultural and woody biomass to produce energy. Previously, biomass was sold to power plant and co-fired with coal. The scope of the paper is to assess the actual change in the environmental impact of biomass use in the Wolczyn facility. For that purpose, the life cycle assessment is used with the ReCiPe endpoint indicator. The assessment is based on the comparison of two scenarios: one assuming the biomass combustion in a new boiler, and the second one, assuming co-firing biomass with coal. The results of the study show that the investment is making a significant difference as far as the overall environmental impact is. Through avoiding the co-firing related emissions the company makes a big step ahead towards the decrease of their environmental impacts. The analysis shows that the significant impact in the co-firing scenario is posed in such categories as fossil depletion, climate change with impacts on human health and on ecosystems, particulate matter formation and agricultural land occupation. In the biomass combustion scenario, the above categories are complemented with metal depletion, natural land transformation, urban land occupation and human toxicity categories but with 4 times decrease of the overall impact. The study also shows that the change of the combustion system makes the most significant difference, while all the other factors, like biomass cultivation and processing, biomass transport have much lesser impact.

Impacts of biomass production at civil airports on grassland bird conservation and aviation strike risk.

Growing concerns about climate change, foreign oil dependency, and environmental quality have fostered interest in perennial native grasses (e.g., switchgrass [Panicum virgatum]) for bioenergy production while also maintaining biodiversity and ecosystem function. However, biomass cultivation in marginal landscapes such as airport grasslands may have detrimental effects on aviation safety as well as conservation efforts for grassland birds. In 2011-2013, we investigated effects of vegetation composition and harvest frequency on seasonal species richness and habitat use of grassland birds and modeled relative abundance, aviation risk, and conservation value of birds associated with biomass crops. Avian relative abundance was greater in switchgrass monoculture plots during the winter months, whereas Native Warm-Season Grass (NWSG) mixed species plantings were favored by species during the breeding season. Conversely, treatment differences in aviation risk and conservation value were not biologically significant. Only 2.6% of observations included avian species of high hazard to aircraft, providing support for semi-natural grasslands as a feasible landcover option at civil airports. Additionally, varied harvest frequencies across a mosaic of switchgrass monocultures and NWSG plots allows for biomass production with multiple vegetation structure options for grassland birds to increase seasonal avian biodiversity and habitat use.

A comparison of photoautotrophic, heterotrophic, and mixotrophic growth for biomass production by the green alga Scenedesmus sp. (Chlorophyceae)

:Substantial research has been devoted to testing the potential for algal-derived biofuels. However, because of the high cost and low biomass productivity of algal mass culture, this is not yet a commercial reality. Most research has focused on optimizing photoautotrophic cultivation of algal biomass. Other modes of growing algae such as heterotrophy and mixotrophy need to be investigated. Our objective was to compare the biomass productivity and the macromolecular pools of Scenedesmus sp. grown under photoautotrophic and heterotrophic conditions, and to expose the heterotrophic cultures to light after their growth slowed or ceased. We found that heterotrophy led to larger cells, faster growth rates, and denser cultures than photoautotrophically grown cultures. Exposing heterotrophically growing cells to light caused an immediate significant boost to growth rates and biomass production. As a result, biomass obtained through this process (mixotrophy) was double that of heterotrophically grown cultures, and three times greater than with photosynthetically grown cultures. Higher cellular carbohydrates and proteins were observed in mixotrophic cultures than in photoautotrophic ones. Despite these cellular changes, overall biomass and lipid productivity can be ranked as follows: mixotrophy > heterotrophy > photoautotrophy. This study provides promising leads for the use of molasses in algal biomass cultivation.

Exergy efficiency of solar energy conversion to biomass of green macroalgae Ulva (Chlorophyta) in the photobioreactor

Offshore production of macroalgae biomass, which was recently given the name seagriculture, is one of the important but least explored alternative energy resources. Unlike microalgae, macroalgae cultivation can be done offshore and therefore brings real news to the biofuel – food land agriculture conflict. A wide variety of small-scale laboratory experiments are done lately in order to deepen the knowledge and develop expertise in macroalgae cultivation and its downstream processing. For energy applications, it is common to evaluate the performance of an energy source or system in exergy efficiency terms. Another important parameter that is evaluated to determine the system's environmental impact is it’s volumetric and areal footprint. The current work examines two exergy efficiency indexes, the Exergy Efficiency (EE), which takes into account all exergy inputs, and the Exergy Return On Investment (ExROI), that includes only fossil fuel exergy inputs, both on a green macroalgae Ulva grown in the macroalgae photobioreactor system (MPBR) incorporated into a building. Cultivation of macroalgae in the building embedded MPBR achieved maximal values of 0.012 and 0.22 for EE and ExROI, compared to a range of 0.05–8.34 and 0.013–0.327 found in published papers of microalgae systems. In addition, a modelled optimization of the initial biomass density leads to maximal values of about 0.035 for EE and 0.433 for ExROI, while further improvement may be achieved by optimization of nutrient addition and mixing methodology. This work demonstrates a tool to measure the performance of laboratory scale macroalgae biomass cultivation systems, followed by preliminary efficiency and environmental impact values, important for future upscaling.

Life cycle assessment of UV-Curable bio-based wood flooring coatings

Abstract An important recent trend in the paints and coatings industry has been the use of bio-based alternatives to fossil-based building blocks in many applications. This trend is being driven in part by cleaner production and sustainability goals. As bio-based ingredients have been widely shown to present environmental trade-offs along their life cycle, new formulations should ideally be assessed for environmental preference before entering into full-scale production. In this paper, a bio-renewable content (BRC) formulation for wood flooring coating is analyzed using a life cycle assessment (LCA) framework and quantitatively compared to a conventional petrochemical formulation of similar performance across a range of impact categories. This BRC formulation has 50% bio-based ingredients and zero-to-low VOC emissions and was developed by PPG Industries, Inc. The scope of the analysis is cradle-to-gate and includes biomass cultivation and crude oil extraction and refining for renewable and non-renewable chemical inputs, formulation, transport, and application of 1 m2 of each coating, followed by UV-curing. Comparative results show more than 30% reduction in six out of ten impact categories, using the USEPA TRACI 2.1 impact assessment method, with smog formation, acidification, eutrophication and respiratory effects showing increases in environmental impacts, largely due to burdens from bio-based components. Bisphenol A–epichlorohydrin resin and corn-derived itaconic acid are the most impactful chemicals in the composition of conventional and bio-renewable wood flooring coatings, respectively. Energy use from UV-curing does not appreciably contribute to impacts. The contribution of various building blocks to environmental impacts of both coatings are presented in detail, potentially guiding further formulation research and development. Modifying the BRC formulation to use corn stover instead of corn grain for synthesis of sugar-derived chemicals would improve the environmental profile of the BRC formulation, leading to reductions in all impact categories. The results underscore that meeting targets for bio-based content can have multiple secondary benefits to the environment and human health, but these depend on the particular biofeedstock and conversion processes as well as on the petrochemical components that are being replaced.

A Two-Stage System for the Large-Scale Cultivation of Biomass: a Design and Operation Analysis Based on a Simple Steady-State Model Tuned on Laboratory Measurements

The optimal design and operation at large scale of a continuous fermentation process including a biological reactor/photobioreactor and a gravity settler with partial recycle and purge of the biomass are addressed. The proposed method is developed with reference to microalgae (Scenedesmus obliquus) cultivation, but it can be applied to any fermentation process as well as to activated sludge wastewater treatment. A procedure is developed to predict the effect of process variables, mainly the recycle ratio (R), the solid retention time (θ c ), the reactor residence time (θ), and the ratio between feed and purge flow rates (F I /F W ). It includes a simple steady-state model of the two units coupled in the process and the experimental measurement of basic kinetic data, in both the bioreactor and the settler, for the tuning of model parameters. The bioreactor is assumed as perfectly mixed, and a rigorous gravity-flux approach is used for the settler. The process model is solved in terms of dimensionless variables, and plots are given to allow sensitivity analyses and optimization of operating conditions. A discussion about washout is presented, and a simple method is outlined for the calculation of the minimum values of residence time (θ min ) and recycle ratio (R min ) and of the maximum allowed recycle ratio (R max,operating ) and biomass purge rate (F Wmax ). In particular, it is shown that the system is sensitive to the concentration of biomass lost from the top of the settler (C X S ). The proposed method can be useful for the design and analysis of large-scale processes of this type.

Biochar production from microalgae cultivation through pyrolysis as a sustainable carbon sequestration and biorefinery approach

Microalgae cultivation and biomass to biochar conversion is a potential approach for global carbon sequestration in microalgal biorefinery. Excessive atmospheric carbon dioxide (CO2) is utilized in microalgal biomass cultivation for biochar production. In the current study, microalgal biomass productivity was determined using different CO2 concentrations for biochar production, and the physicochemical properties of microalgal biochar were characterized to determine its potential applications for carbon sequestration and biorefinery. The indigenous microalga Chlorella vulgaris FSP-E was cultivated in photobioreactors under controlled environment with different CO2 gas concentrations as the sole carbon source. Microalgal biomass pyrolysis was performed thereafter in a fixed-bed reactor to produce biochar and other coproducts. C. vulgaris FSP-E showed a maximum biomass productivity of 0.87 g L−1 day−1. A biochar yield of 26.9% was obtained from pyrolysis under an optimum temperature of 500 °C at a heating rate of 10 °C min−1. C. vulgaris FSP-E biochar showed an alkaline pH value of 8.1 with H/C and O/C atomic ratios beneficial for carbon sequestration and soil application. The potential use of microalgal biochar as an alternative coal was also demonstrated by the increased heating value of 23.42 MJ kg−1. C. vulgaris FSP-E biochar exhibited a surface morphology, thereby suggesting its applicability as a bio-adsorbent. The cultivation of microalgae C. vulgaris FSP-E and the production of its respective biochar is a potential approach as clean technology for carbon sequestration and microalgal biorefinery toward a sustainable environment.

Cultivation of microalgal biomass using swine manure for biohydrogen production: Impact of dilution ratio and pretreatment

This study assessed the impact of swine manure (SM) dilution ratio on the microalgal biomass cultivation and further tested for biohydrogen production efficiency from the mixed microalgal biomass. At first, various solid/liquid (S/L) ratio of the SM ranged from 2.5 to 10 g/L was prepared as a nutrient medium for the algal biomass cultivation without addition of the external nutrient sources over a period of 18 d. The peak biomass concentration of 2.57 ± 0.03 g/L was obtained under the initial S/L loading rates of 5 g/L. Further, the cultivated biomass was subjected to two-step (ultrasonication + enzymatic) pretreatment and evaluated for biohydrogen production potential. Results showed that the variable amount of hydrogen production was observed with different S/L ratio of the SM. The peak hydrogen yield of 116 ± 6 mL/g TSadded was observed at the 5 g/L grown SM mixed algal biomass.

Simple and efficient method for extraction of C-Phycocyanin from dry biomass of Arthospira platensis

Conventional methods for primary extraction can extract only 50–60% of the total C-phycocyanin (C-PC) present in a given biomass because of the resistance offered by the cell membrane for its disruption. Current practice for extraction of C-PC is from wet biomass of Arthospira platensis, which is highly perishable. Drying of biomass increases the shelf life and helps the small scale industries as the need for considerable space and expertise for cultivation of biomass is avoided. However, dry biomass was reported to be unsuitable for C-PC extraction due to its higher resistance to cell disruption. So, the main objective of the current study is to develop a method for primary extraction of C-PC from dry biomass of A. platensis. Practically such reports are scarce. Conventional methods such as homogenization, maceration, freezing and thawing were attempted besides ultrasonication. A presoaking step (0–150 min) of biomass introduced prior to extraction has significantly increased the efficiency of all the extraction methods. Standardization of process parameters such as solid-liquid ratio (1:6, 1:8 and 1:10) and processing time was carried out besides amplitude (10–70%) and time (0–3.0 min) of ultrasonication. When ultrasonication was employed in combination with the conventional primary extraction methods, significant synergy was observed. Ultrasonication in combination with ‘Freezing and thawing’ resulted in 30% increase (maximum) in extraction efficiency over ‘freezing and thawing’ alone. Among all the methods employed, ‘ultrasonication + freezing and thawing’ resulted in the highest extraction efficiency of 92% followed by ‘ultrasonication + maceration’ (83.45%). Studies on extraction kinetics and energy requirement are also carried out. In any given primary extraction method, colour measurements showed a qualitative correlation of the extraction efficiency of C-PC with the extent of discoloration of spent biomass. These synergistic methods can be applied for extraction of biomolecules from other microalgae.