Cell Disruption Methods Research Articles

Microalgal cell disruption: Effect on the bioactivity and rheology of wheat bread

The aim of this study is to investigate the potential of the addition of a microalgal biomass to improve nutritional quality of bread. Microalgae contain a substantial amount of nutrients that are naturally encapsulated within cells, namely proteins, polysaccharides, polyunsaturated fatty acids and pigments (chlorophylls and carotenoids), which are capable of resisting harsh conditions during food processing. However, the cell wall integrity may significantly limit nutrient availability, and microalgal cell disruption is potentially required as a pretreatment.A suspension of a fresh Chlorella vulgaris biomass (0.88 g/L) was disrupted in a high-pressure homogenizer at 340 MPa using 1 and 4 passages. The impact of the cell disruption method was evaluated in terms of the reduction in the number of intact cells and average colony diameter of the remaining cells using flow cytometry and microscopy.Since cell disruption promotes the release of intracellular products, it can impart structural modifications to doughs and breads. Therefore, doughs and breads were prepared with the fresh C. vulgaris biomass (1.0 g of Cv/100 g of flour+Cv), the disrupted biomass, or a commercial powder. Doughs were characterized in terms of texture and oscillatory rheology. The texture and colour of breads were also evaluated. Cell wall disruption affected the colour and texture of the breads, resulting in breads with a higher firmness. Furthermore, bioactivity was evaluated, and the reducing power of the bread extracts obtained using the ferric ion reducing antioxidant power assay showed that cell disruption positively modulated the antioxidant capacity.

Identification of microalgae biorefinery scenarios and development of mass and energy balance flowsheets

The notion of bioeconomy is at the basis of recent European strategies aiming at conciliating economic growth and sustainability. Consequently, extensive research has been conducted on biobased solutions such as microalgae products. Numerous initiatives to commercialize microalgae have been launched but few of them were successful. Algae biofuel is the most obvious illustration with its promises as energy supply but faces many challenges to become economically competitive. Consequently, it was recently proposed to develop microalgae biorefineries for an optimal biomass valorisation, to dilute the overall costs within a wide range of products. Herein, the energy demand for different microalgae biorefinery scenarios is investigated and critical steps identified. Each scenario is modelled using information from literature and process engineering principles. The production of lipids, proteins, methane, fertilizers and dried biomass are considered. Once defined, the scenarios are modelled and their energy inputs are discussed. We also investigate the impact of using a biobased solvent for lipid extraction instead of a conventional one. On top of that, each scenario is assessed for two cells disruption methods. In both cases, the study starts with dewatering the growth medium of the microalgae Chlorella vulgaris (240 kg DW h−1) and ends with the recovery of the products. The results vary from 20.07 to 66.53 MJ kg−1 input DW and highlight the importance of the cell disruption method in the total energy demand. While lipid extraction presents adverse impacts on proteins extraction due to solvent recovery, proteins extraction has beneficial effects on further methane production step. Our study concludes with the comparison of microalgae biomass with soy, for proteins and lipids production, and demonstrates quantitatively that microalgae-based technologies are still inefficient compared to present alternatives. This work provides quantitative numbers for further evaluation of microalgae projects considering the current stage of the technology.

Effective Release of Intracellular Enzymes by Permeating the Cell Membrane with Hydrophobic Deep Eutectic Solvents.

An efficient and green method is crucial for the recovery of intracellular biological products. The major drawbacks of the conventional cell disruption method are nonselectivity and enzyme denaturation. The permeability of hydrophobic deep eutectic solvents (DESs) to the cell membrane was studied, for the first time, and then hydrophobic DESs were innovatively applied to release intracellular enzymes from recombinant Escherichia coli. After optimization, a DES suspension of l-menthol/oleic acid (0.5 %, v/v) showed the highest release yield of intracellular enzyme. Compared with that released by sonication, a release yield of phospholipase D (PLD) of up to 114.58 % was achieved, and the specific activity was increased by 1.96 times. The microstructure of the cell membrane under different treatments was observed by using an electron microscope to understand the permeation of DESs to the cell membrane. The feasibility and applicability of the proposed release method in industrial applications were also demonstrated. The effective and green release method of intracellular enzymes developed herein has bright prospects for industrial application to replace traditional cell disruption methods. A preliminary study on the permeability of hydrophobic DESs to the cell membrane showed that there would be a potential application prospect of hydrophobic DESs not only in releasing intracellular contents, but also in seeking new green penetrating agents.

Effect of cell disruption methods on the extraction of bioactive metabolites from microalgal biomass

Microalgae synthesize a variety of potentially high-value compounds. Due to their robust cell wall, cell disruption is necessary to improve extraction of these compounds. While cell disruption methods have been optimized for lipid and protein extraction, there are limited studies for other bioactive compounds. The present study investigated the effect of freeze-drying combined with sonication or ball-milling on the extraction of antioxidant and plant biostimulating compounds from Chlorella sp., Chlorella vulgaris and Scenedesmus acutus. Both cell disruption methods resulted in higher extract yields from the biomass compared to freeze-dried biomass using 50% methanol as a solvent. Antioxidant activity of Chlorella extracts was generally higher than freeze-dried extracts based on the diphenylpicrylhydrazyl (DPPH) and β-carotene linoleic acid assays. However, the effectiveness of each treatment varied between microalgae strains. Sonication resulted in the highest antioxidant activity in Chlorella sp. extracts. Ball-milling gave the best results for C. vulgaris extracts in the DPPH assay. Both cell disruption methods decreased antioxidant activity in S. acutus extracts. Plant biostimulating activity was tested using the mung bean rooting assay. Damaging the membrane by freeze-drying was sufficient to release the active compounds using water extracts. In contrast, both cell disruption methods negatively affected the biological activity of the extracts. These results indicate that bioactive compounds in microalgae are sensitive to post-harvest processes and their biological activity can be negatively affected by cell disruption methods. Care must be taken to not only optimize yield but to also preserve the biological activity of the target compounds.

Protein Extraction from Spirulina Platensis

The extraction of protein from green spirulina microalgae platensis was carried out by centrifugation, ultra sound assisted extraction and combination of centrifugation and ultrasound assisted extraction spirulina platensis was carried out using ultrasound-assisted extraction and statistical optimization method is used to obtain the optimum conditions. A Box–Behnken design method was used to optimize the process conditions affecting protein extraction. This conditions investigated on microalgae cell disruption method by the combination of both ultrasonication and centrifuge. Different buffer solutions were used and the time of the ultrasonication was also varied. The protein extraction quantity was evaluated. The obtained results confirm that mixed buffer III showed the high concentration of protein but low quality. The study on the effect of ultrasonication period, the concentration of protein increased and remains constant also when duration of sonication is elongated and this result was observed during continuous ultrasonication in similar manner. The protein concentration is one of the important aspect, the protein quality must be satisfied. The results confirms the optimum condition of protein extraction from green microalgae requires the combination of the use of buffer solution and a proper duration of ultrasonication to maximize the protein quantity.

Correlations between quality parameters of some types of unpasteurized beer and consumers safety

Most microalgae cells are very resistant to mechanical and chemical stresses. Because target products are mainly located inside the cells, disruption of the cell wall is an essential step in downstream processing to recover the microalgae ingredients. This study is focused on the development of a mild cell disruption method based on explosive CO2 decompression to allow the recovery of multiple sensitive products.The principle behind cell rupture via explosive decompression is the uptake of a gas under elevated pressure into the microalgae cells, where after a sudden depressurization gas expansion causes rupture of the cells. Conventional explosive decompression uses stirred tank reactors wherein, because of inefficient mixing, the gas/liquid interfacial area is minimal, resulting in long contact times, inefficient gas uptake and inefficient cell rupture. To increase the mixing yield and the formation of a gas-liquid micro-emulsion, a new continuous apparatus and a method were developed to process microalgae biomass by CO2 based explosive decompression. The final design consisted of 2 pumps, a tubing system, a sparger, a hydrodynamic agitation zone and a heated relief valve. Experimental comparison of the conventional batch and the new continuous devices showed that process time was reduced 3.2–9.6 fold, the biomass and biochemical release efficiency increased more than 2 fold, and CO2 consumption reduced 2–4 fold. The method can be considered as mild, since it can operate at room temperature without addition of chemicals. Moreover, the calculated shear rate on the algae cells is only 0.33% of the shear rate recorded during bead milling, while depending on the process parameters releasing a similar amount of biomass components from the cells into the supernatant. The article describes the development of the explosive decompression systems supported by computational fluid dynamics simulations and experimental data on algae cell disruption, complemented with a first techno-economic assessment.

Quantifying cell disruption as an integral part of natural product extraction

Cell disruption is a basic yet often overlooked step in the extraction of valuable substances from plants. A simple and easily applicable method is presented to assess cell membrane stability as an integral part of phytoextraction by measuring electric conductivity (EC) and calculating the Index of Injury (Id). In this paper, a wide range of industrially applicable methods is evaluated including mechanical disruption, heat, a combination of both, extreme pH-values, application of microwaves, ultrasound and pulsed electric field (PEF). Moreover, the approach via Id is compared to an alternative method using HPLC analysis of a marker substance to show the method’s limitations as well as to provide further applications of this basic system. For the feedstock used, heavy mechanical processing such as grinding, temperatures above 50°C as well as acidic condition below pH 2.5 were equally potent methods for complete cell disruption. Alternatively, moderate mechanical treatment like chopping or cutting could be combined with temperatures above 40°C for maximal cell damage. Although PEF application showed merely moderate effects applied alone, it may be combined with mechanical pre-treatment in order to achieve high cell disruption at low temperatures, making it ideal for the extraction of thermolabile compounds.

Nature-inspired virus-assisted algal cell disruption for cost-effective biofuel production

Algal biofuel has been advocated as a sustainable and environmentally friendly renewable energy source. However, intensive chemical usage, high energy consumption, and high operation and maintenance costs associated with current cell disruption methods have been identified as main challenges to cost-effective production of algal biofuel. Viral infection of algae is a natural process that can lyse algal cells under ambient conditions without using chemicals or energy-intensive equipment. This study, for the first time, provides a comprehensive and in-depth evaluation of the feasibility of using viruses to assist algal lipid extraction. Detailed mechanistic studies were conducted to evaluate the impact on mechanical strength of algal cell walls, lipid yield, and lipid distribution when Chlorella sp. were infected by Paramecium bursaria Chlorella virus 1 (PBCV-1). Viral disruption with multiplicity of infection of 10−8 was able to disrupt concentrated algal biomass completely in six days. Our results indicated that viral disruption significantly reduced the mechanical strength of algal cells. Lipid yield with viral disruption increased more than three times compared to no disruption controls and was similar to that of ultrasonic disruption. Moreover, lipid composition analysis showed that the quality of extracted lipids was not affected by viral infection. The results showed that viral infection is a highly cost-effective technique to promote lipid extraction without extensive energy input and chemicals required by existing disruption methods. The results of this study provided new insights in the development of nature-inspired lipid extraction methods for cost-efficient biofuel production.

Genomic Features for Desiccation Tolerance and Sugar Biosynthesis in the Extremophile Gloeocapsopsis sp. UTEX B3054.

For tolerating extreme desiccation, cyanobacteria are known to produce both compatible solutes at intracellular level and a copious amount of exopolysaccharides as a protective coat. However, these molecules make cyanobacterial cells refractory to a broad spectrum of cell disruption methods, hindering genome sequencing, and molecular studies. In fact, few genomes are already available from cyanobacteria from extremely desiccated environments such as deserts. In this work, we report the 5.4 Mbp draft genome (with 100% of completeness in 105 contigs) of Gloeocapsopsis sp. UTEX B3054 (subsection I; Order Chroococcales), a cultivable sugar-rich and hardly breakable hypolithic cyanobacterium from the Atacama Desert. Our in silico analyses focused on genomic features related to sugar-biosynthesis and adaptation to dryness. Among other findings, screening of Gloeocapsopsis genome revealed a unique genetic potential related to the biosynthesis and regulation of compatible solutes and polysaccharides. For instance, our findings showed for the first time a novel genomic arrangement exclusive of Chroococcaceae cyanobacteria associated with the recycling of trehalose, a compatible solute involved in desiccation tolerance. Additionally, we performed a comparative genome survey and analyses to entirely predict the highly diverse pool of glycosyltransferases enzymes, key players in polysaccharide biosynthesis and the formation of a protective coat to dryness. We expect that this work will set the fundamental genomic framework for further research on microbial tolerance to desiccation and to a wide range of other extreme environmental conditions. The study of microorganisms like Gloeocapsopsis sp. UTEX B3054 will contribute to expand our limited understanding regarding water optimization and molecular mechanisms allowing extremophiles to thrive in xeric environments such as the Atacama Desert.

Impact of DNA extraction methods on the observed microbial communities from the intestinal flora of the penaeid shrimp Litopenaeus vannamei.

Two DNA extraction methods, the Zirmil-beating cell disruption method (ZBC) and the QIAamp fast DNA stool mini kit (QIA), were used to extract DNA from the intestinal flora of the penaeid shrimp Litopenaeus vannamei, and their microbial communities were analyzed using 16S rDNA high-throughput sequencing. Results were obtained in terms of the number of reads, alpha diversity indexes, beta diversity indexes and taxonomic composition. The alpha diversity indexes of the community, according to the ZBC method, were higher than those according to the QIA method. Furthermore, results from the three samples using the ZBC method were less consistent than those where the QIA method was used. Further, using the latter method led to substantive clustering. It is suggested that the QIA method is more stable and repeatable than the ZBC method. Although the two extraction methods shared the major abundant microflora based on 16S rDNA high-throughput sequencing, bias associated with diversity analysis indexes and certain species was observed.

Evaluation, comparison of different solvent extraction, cell disruption methods and hydrothermal liquefaction of Oedogonium macroalgae for biofuel production

Cell disruption and lipid extraction methods for macroalgae are not well reported. Therefore, we compared various lipid extraction methods and extraction efficiency of various solvents to improve lipid yields from Oedogonium fresh water macroalgae. Lipid extraction was done by 2 methods viz., modified Bligh and Dyer method and soxhlet extraction using either single solvents or mixtures. In soxhlet extraction method five solvents were used (1) Hexane commonly used solvent for lipid extractions, (2) chloroform: methanol (2:1), (3) Chloroform: hexane (1:1), (4) Chloroform: hexane (1:2), (5) Dichloromethane + methanol (2:1). To improve lipid extraction yields, various cell disruption methods were also compared during the present study. Impurities of chlorophyll and protein were also detected in the extracted lipids. Hydrothermal liquefaction of algal biomass with TiO2 was also conducted at 300 °C. HTL was more effective by which 23.3 wt% of bio-crude oil was obtained.

Efficient nanowire-assisted electroporation and cellular inclusion release of microalgal cells achieved by a low voltage

A mild and low-energy cell disruption method with high efficiency has growing application potential in both the extraction of high-value microalgal products and the inactivation of microalgal cells. Conventional technologies available have disadvantages including high energy consumption, the use of chemicals and so on. Here, this study developed an efficient microalgal cell disruption method using the copper oxide nanowire (CuONW)-modified three-dimensional (3D) copper foam electrodes with a low applied voltage. Electrodes with nanowires synthesized at 400 °C, the optimal preparation temperature, achieved efficient microalgal cell electroporation. Microalgal cells were completely inactivated and disrupted at the voltage of 2 V with the hydraulic retention time (HRT) of 10 s. Scanning electron microscopy (SEM) images showed obvious electroporation damage on the cell surface upon electroporation-treatment (2 V, 30 s). The amount of released cellular inclusion increased significantly with prolonged HRT and the energy consumption of this technology was only 0.014 kWh/kg via the treatment of 2 V and 10 s. This study provided a novel, energy-efficient and chemical-free technique for both microalgal products extraction and cell inactivation.

Chlorella vulgaris cell disruption using copper sulfate

This study evaluated the feasibility of using copper sulfate as an agent for Chlorella vulgaris cell disruption. About 70% of the cells in a C. vulgaris suspension at ∼0.2 g/L concentration were disrupted at a copper sulfate dose of 500 mg/L as Cu and 72-hour contact time. Scanning electron microscope morphology of C. vulgaris cells confirmed that the cells were ruptured after treatment with copper sulfate. The effect of rupturing increased the lipid extraction yield. For a 10% C. vulgaris paste dosed with copper sulfate at 200 mg as Cu/g of dry algae and 24-hour contact time, the lipid extraction yield increased by 30% with respect to control samples. The specific energy requirement and CO2 emissions per kg of dry algae were estimated as 2.82 MJ and 0.26 kg CO2-eq., respectively. The existing algal cell disruption methods have estimated energy requirements of 10 to 300 times and CO2 emissions of 20 to 600 times greater than those of copper sulfate. Despite these advantages, the adaption of copper sulfate as an algal cell disruption method may be limited by the 24-hour contact time needed to achieve a significant increase in lipid extraction yield. Therefore, it is recommended that future research efforts be focused on addressing this challenge.

Disruption of microalgae with a novel continuous explosive decompression device

Most microalgae cells are very resistant to mechanical and chemical stresses. Because target products are mainly located inside the cells, disruption of the cell wall is an essential step in downstream processing to recover the microalgae ingredients. This study is focused on the development of a mild cell disruption method based on explosive CO2 decompression to allow the recovery of multiple sensitive products.The principle behind cell rupture via explosive decompression is the uptake of a gas under elevated pressure into the microalgae cells, where after a sudden depressurization gas expansion causes rupture of the cells. Conventional explosive decompression uses stirred tank reactors wherein, because of inefficient mixing, the gas/liquid interfacial area is minimal, resulting in long contact times, inefficient gas uptake and inefficient cell rupture. To increase the mixing yield and the formation of a gas-liquid micro-emulsion, a new continuous apparatus and a method were developed to process microalgae biomass by CO2 based explosive decompression. The final design consisted of 2 pumps, a tubing system, a sparger, a hydrodynamic agitation zone and a heated relief valve. Experimental comparison of the conventional batch and the new continuous devices showed that process time was reduced 3.2–9.6 fold, the biomass and biochemical release efficiency increased more than 2 fold, and CO2 consumption reduced 2–4 fold. The method can be considered as mild, since it can operate at room temperature without addition of chemicals. Moreover, the calculated shear rate on the algae cells is only 0.33% of the shear rate recorded during bead milling, while depending on the process parameters releasing a similar amount of biomass components from the cells into the supernatant. The article describes the development of the explosive decompression systems supported by computational fluid dynamics simulations and experimental data on algae cell disruption, complemented with a first techno-economic assessment.

Yeast extract production using spent yeast from beer manufacture: influence of industrially applicable disruption methods on selected substance groups with biotechnological relevance

Spent brewer’s yeast is an excellent source of a variety of bioactive substances. In this study, for the first time, the focus was solely on investigating the influence of three industrially applicable cell disruption methods (cell mill, sonotrode, and autolysis) on selected substance groups relevant for physiology and process technology. A consistent spent yeast (Saccharomyces cerevisiae TUM 68) produced in a standardized industrial pilot top-fermenting process was used as a raw material. Using mechanical methods, i.e., cell mill and sonotrode, the protein content (as not hydrolyzed in free amino acids), the trehalose and the total fat content in the yeast extract were increased compared with those produced in the autolytic method. The analyzed B vitamin levels were also higher, the biologically active 5-CH3-H4folate in particular had the greatest proportion in the folate vitamer distribution of the mechanically produced yeast extracts. An increased level of non-fragmented genomic and mitochondrial DNA could also be found in the yeast extract produced via the mechanical methods. The antioxidative and reduction potential was decreased by the degradation of polyphenols and glutathione in the yeast extract following autolysis. The mineral, RNA, glycogen, glucose, fructose and ash contents did not differ significantly. Therefore, the cell mill and sonotrode offered a good alternative method to conventional autolytic procedures, especially to transfer physiologically relevant substance groups in higher concentrations to the yeast extract.

Optimization of cell culture and cell disruption processes to enhance the production of thermophilic cellulase FnCel5A in E.coli using response surface methodology

FnCel5A from Fervidobacterium nodosum is one of the most thermostable endoglucanases that have phenomenal characteristics, such as high activity, pH stability, and multi-specificity towards various substrates. However, large-scale thermophilic enzyme production is still a challenge. Herein, we focus on an optimization approach based on response surface methodology to improve the production of this enzyme. First, a Box-Behnken design was used to examine physiochemical parameters such as induction temperatures, isopropylβ-D-1-thiogalactopyranoside concentrations and induction times on the heterogeneous expression of FnCel5A gene in E. coli. The best culture was collected after adding 0.56 mM IPTG and incubating it for 29.5 h at 24°C. The highest enzymatic activity observed was 3.31 IU/mL. Second, an economical "thermolysis" cell lysis method for the liberation of the enzymes was also optimized using Box-Behnken design. The optimal levels of the variables were temperature 77°C, pH 7.71, and incubation time of 20 min, which gave about 74.3% higher activity than the well-established bead-milling cell disruption method. The maximum productivity of FnCel5A achieved (5772 IU/L) illustrated that its production increased significantly after combining both optimal models. This strategy can be scaled-up readily for overproduction of FnCel5A from recombinant E.coli to facilitate its usage in biomass energy production.

Development of a method to extract protozoan DNA from black soil

ObjectivesMicroorganisms in environmental samples are identified by sequential screening, isolation, and culture steps, followed by the verification of physiological characteristics and morphological classification. Isolation and purification of Amoebae from soil samples is extremely complex, laborious, and time-consuming and require considerable expertise for morphological evaluation. PCR testing of soil DNA seems to be an effective means for protozoa habitat screening. In this study, we added Acanthamoeba sp. (MK strain) to soil and developed a method of extracting protozoan DNA from the soil. MethodsSoil allophane is a known DNA adsorbing substance that inhibits the PCR reaction. After comparing the soil properties and allophane contents of 7 soil samples, we attempted to combine multiple cell disruption and DNA purification methods to design an optimal soil DNA extraction method that can be used for downstream PCR analysis. ResultsWe compared five different crushing/refining methods. Amplification of the gene was confirmed by Acanthamoeba specific PCR in protocol V where the concentration of Acanthamoeba in soil (1.0 × 102/g) was the detection limit of PCR. ConclusionThe soil DNA extraction method following protocol V allows DNA amplification of protozoa, including Amoeba, which is difficult to cultivate, thus simplifying the investigation of protozoa habitats and genetic analyses.

A simple method for cell disruption by immobilization of lysozyme on the extrudate-shaped Na-Y zeolite: Recirculating packed bed disruption process

Carrier-based immobilization has been developed to improve the functional properties of enzymes and promote the employment of enzymatic lysis in downstream processing without the necessity to separate the lysis enzyme after processing. In this study, lysozyme was immobilized on an extrudate-shaped Na-Y zeolite and was used for the disruption of Micrococcus lysodeikticus in a recirculating packed bed reactor. The factors influencing immobilization process, namely, liquid velocity and initial concentration of lysozyme solution, were studied aiming to improve the amount of immobilized lysozyme. Additionally, the key process parameters of cell disruption operation using lysozyme-zeolite complex in recirculating packed bed reactor, including the volume of M. lysodeikticus suspension, liquid velocity and operating temperature, were further investigated for their effects on the efficiency of cell disruption. Under the optimal conditions (50 ml of 2.0 mg/ml cell suspension, liquid velocity of 500 cm/h, and operating temperature of 25 °C), the system successfully achieved cell disruption yield of 93% and released protein content of approximately 400 μg/ml. Besides, the system demonstrated its reusability by acquiring released protein content of 250 μg/ml after 12 successive cycles of operation.

The Effect of High-Intensity Ultraviolet Light to Elicit Microalgal Cell Lysis and Enhance Lipid Extraction.

Currently, the energy required to produce biofuel from algae is 1.38 times the energy available from the fuel. Current methods do not deliver scalable, commercially viable cell wall disruption, which creates a bottleneck on downstream processing. This is primarily due to the methods depositing energy within the water as opposed to within the algae. This study investigates ultraviolet B (UVB) as a disruption method for the green algae Chlamydomonas reinhardtii, Dunaliella salina and Micractinium inermum to enhance solvent lipid extraction. After 232 seconds of UVB exposure at 1.5 W/cm2, cultures of C. reinhardtii (culture density 0.7 mg/mL) showed 90% disruption, measured using cell counting, correlating to an energy consumption of 5.6 MJ/L algae. Small-scale laboratory tests on C. reinhardtii showed bead beating achieving 45.3 mg/L fatty acid methyl esters (FAME) and UV irradiation achieving 79.9 mg/L (lipids solvent extracted and converted to FAME for measurement). The alga M. inermum required a larger dosage of UVB due to its thicker cell wall, achieving a FAME yield of 226 mg/L, compared with 208 mg/L for bead beating. This indicates that UV disruption had a higher efficiency when used for solvent lipid extraction. This study serves as a proof of concept for UV irradiation as a method for algal cell disruption.

Application of pulse electric field pretreatment for enhancing lipid extraction from Chlorella pyrenoidosa grown in wastewater

Abstract Lipid extraction is a key step of biodiesel production from microalgae, however, the application of traditional extraction methods was limited due to the difficulties of cell disruption as well as solvent toxicity. In this work, pretreatment method using pulsed electric field (PEF), was primarily applied to lipid extraction process from microalgae Chlorella pyrenoidosa grown in wastewater. After the pretreatment with PEF, the yields of fatty acid methyl esters from C.pyrenoidosa was 12.0% higher than traditional pretreatment with ultrasonic. The results indicated that PEF was an effective method for cell disruption. Fluorescence staining and scanning electron microscopy showed that the integrity of the cell membrane of microalgae was damaged under pulsed electric field, which enhanced the penetration of solvents and lipid extraction.