Investigation of simultaneous lutein and lipid extraction from wet microalgae using Nile Red as solvatochromic shift probe

Microalgae have been proposed as an alternative lutein source due to their high productivity, reliability, and versatility. In this study lutein and lipid extraction from wet Chlorella vulgaris UTEX 265 was investigated. The lutein production was monitored throughout the microalgal growth phase and several extraction parameters such as the sample size, drying method, and cell disruption method were investigated. The performance of solvents on lutein extraction was compared using Nile Red as a solvatochromic polarity probe. The simultaneous lutein and lipid extraction was also studied for different polarities using an ethanol-hexane binary solvent at the optimal solvent compositions suitable for lutein extraction. Among the solvents investigated, 3:1 (v/v) ethanol/hexane was recognized as the optimal solvent for lutein and lipid co-extraction, which contributed to a 13.03 mg g^?1 lutein and 101.8 mg g^?1 FAME yield. The saponifiable lipids content (86.9% w/w) was higher than conventional extraction methods. Based on our results, wet extraction approach exhibits good potential, while the bead-beater is the most suitable technique for cell disruption and lutein extraction.     

β-Carotene extraction from Dunaliella salina by supercritical CO2

This paper reports the results of supercritical carbon dioxide (scCO₂) extraction of β-carotene from Dunaliella salina as potential alternative to conventional organic solvent extraction. In pilot-scale scCO₂ experiments, the pressure, temperature, and co-solvent concentration were varied. The supercritical extraction at 500 bar, 70 °C, and 10 wt% ethanol as co-solvent yielded in the highly efficient pigment recovery of over 90%. Techno-economic assessment demonstrated higher energy consumption for the scCO₂ extraction that was compensated by lower solvent costs. Thus, comparable pigment production costs to the reference extraction with n-hexane were estimated for the scCO₂ process. Due to the green solvent properties of scCO₂ and ethanol, this approach is highly promising for extraction of algal biomass in industrial scale.

     

Phycoremediation of municipal wastewater by microalgae to produce biofuel

Municipal wastewater (WW), if not properly remediated, poses a threat to the environment and human health by carrying significant loads of nutrients and pathogens. These contaminants pollute rivers, lakes, and natural reservoirs where they cause eutrophication and pathogen-mediated diseases. However, the high nutrient content of WW makes it an ideal environment for remediation with microalgae that require high nutrient concentrations for growth and are not susceptible to toxins and pathogens. Given that an appropriate algal strain is used for remediation, the incurred biomass can be refined for the production of biofuel. Four microalgal species (Chlamydomonas reinhardtii, Chlorella sp., Parachlorella kessleri-I, and Nannochloropsis gaditana) were screened for efficient phycoremediation of municipal WW and potential use for biodiesel production. Among the four strains tested, P. kessleri-I showed the highest growth rate and biomass production in 100% WW. It efficiently removed all major nutrients with a removal rate of up to 98% for phosphate after 10 days of growth in 100% municipal WW collected from Delhi. The growth of P. kessleri-I in WW resulted in a 50% increase of biomass and a 115% increase of lipid yield in comparison to growth in control media. The Fatty acid methyl ester (FAME), and fuel properties of lipids isolated from cells grown in WW complied with international standards. The present study provides evidence that the green alga P. kessleri-I effectively remediates municipal WW and can be used to produce biodiesel.     

The microalga Parachlorella kessleri––A novel highly efficient lipid producer

The alga Parachlorella kessleri, strain CCALA 255, grown under optimal conditions, is characterized by storage of energy in the form of starch rather than lipids. If grown in the complete medium, the cultures grew rapidly, producing large amounts of biomass in a relatively short time. The cells, however, contained negligible lipid reserves (1–10% of DW). Treatments inducing hyperproduction of storage lipids in P. kessleri biomass were described. The cultures were grown in the absence or fivefold decreased concentration of either nitrogen or phosphorus or sulfur. Limitation by all elements using fivefold or 10‐fold diluted mineral medium was also tested. Limitation with any macroelement (nitrogen, sulfur, or phosphorus) led to an increase in the amount of lipids; nitrogen limitation was the most effective. Diluted nutrient media (5‐ or 10‐fold) were identified as the best method to stimulate lipid overproduction (60% of DW). The strategy for lipid overproduction consists of the fast growth of P. kessleri culture grown in the complete medium to produce sufficient biomass (DW more than 10 g/L) followed by the dilution of nutrient medium to stop growth and cell division by limitation of all elements, leading to induction of lipid production and accumulation up to 60% DW. Cultivation conditions necessary for maximizing lipid content in P. kessleri biomass generated in a scale‐up solar open thin‐layer photobioreactor were described. Biotechnol. Bioeng. 2013; 110: 97–107. © 2012 Wiley Periodicals, Inc.     

Trehalose phosphate synthase overexpression in Parachlorella kessleri improves growth and photosynthetic performance under high light conditions

Parachlorella kessleri is a promising oil-bearing marine alga which shows decreased growth under high light stress. Osmolytes are known to relieve stress by protecting the cell membrane, proteins, and enzymes. Enhanced production of osmolyte (trehalose) was thus used to relieve stress in P. kessleri by overexpression of trehalose phosphate synthase (TPS) gene. Transformed P. kessleri was grown under different light regimes to study the effect of trehalose overproduction on growth. Study of one of the TPS transformants showed increased trehalose as well as increased biomass and decreased pigments, reactive oxygen species, and lipid peroxidation of cell membrane. The improved photosynthetic performance of the transformant was also signified by pulse-amplitude-modulated fluorometric analysis. All of these factors reveal improved stress tolerance under high light conditions by increased trehalose accumulation due to TPS overexpression in P. kessleri.     

Saccharification of Parthenium hysterophorus biomass using cellulase from Streptomyces sp. NAA2

Parthenium hysterophorus biomass can be used as a non-conventional renewable feedstock for the production of bioethanol. Therefore, the present work was designed to hydrolyze P. hysterophorus biomass using cellulase enzyme produced from an actinomycete, i.e., Streptomyces sp. NAA2 using P. hysterophorus biomass as a substrate. The isolate NAA2 was identified by molecular characterization of 16SrDNA. The enzyme production by strain NAA2 was enhanced by optimization studies conducted under submerged fermentation conditions using P. hysterophorus as a substrate. The crude enzyme produced under optimized conditions was used to hydrolyze alkali-acid pretreated P. hysterophorus biomass. The highest CMCase production was achieved in 4–5 days when steam-pretreated P. hysterophorus biomass was used at 1% (w/v) concentration, using 2 discs (1 disc = 5 × 10⁷ spores/ml) of inoculum, an initial pH 6.5, temperature at 40 °C, an agitation speed of 120–150 rpm, and by supplementing fermentation medium with 1.5% (w/v) carboxymethyl cellulose (CMC) as additional carbon source. Under optimized conditions, the actinomycete strain NAA2 showed production of 0.967 ± 0.016 U/ml CMCase, 0.116 ± 0.08 FPU/ml FPase, and 0.22 ± 0.012 U/ml β-glucosidase enzymes. On utilizing the cellulase enzyme for biomass hydrolysis, maximum 18.2% saccharification yield (of cellulose 0.202 g/g) was achieved in 96 h when enzyme and substrate levels were 30 FPU/100 ml and 2% (w/v) respectively. Parthenium hysterophorus biomass can be hydrolyzed enzymatically yielding considerable amounts of total reducing sugars. It can, therefore, be used as a feedstock for the production of bioethanol. Also, it has the potential to act as a substrate for the production of cellulases. Furthermore, the improved cellulolytic potential of Streptomyces sp. NAA2 can be exploited in various industrial applications.

     

Application of high-voltage electrical discharges and high-pressure homogenization for recovery of intracellular compounds from microalgae Parachlorella kessleri

Treatments with high-voltage electrical discharges (HVED) and high-pressure homogenization (HPH) were studied and compared for the release of ionic components, carbohydrates, proteins, and pigments from microalgae Parachlorella kessleri (P. kessleri). Suspensions (1% w/w) of microalgae were treated by HVED (40 kV/cm, 1–8 ms) or by HPH (400–1200 bar, 1–10 passes). Particle-size distribution (PSD) and microscopic analyses were used to detect the disruption and damage of cells. HVED were very effective for the extraction of ionic cell components and carbohydrates (421 mg/L after 8 ms of the treatment). However, HVED were ineffective for pigments and protein extraction. The concentration of proteins extracted by HVED was just 750 mg/L and did not exceed 15% of the total quantity of proteins. HPH permitted an effective release overall of intracellular compounds from P. kessleri microalgae including a large quantity of proteins, whose release (at 1200 bar) was 4.9 times higher than that obtained by HVED. Consequently, HVED can be used at the first step of the overall extraction process for the selective recovery of low-molecular-weight components. HPH can be then used at the second step for the recovery of remaining cell compounds.

     

Optimization and economic evaluation of ultrasound extraction of lutein from Chlorella vulgaris

The main carotenoid in Chlorella vulgaris is lutein. The ultrasound alone or together with enzymatic pretreatment for the extraction of lutein from C. vulgaris was optimized using response surface methodology (RSM) to improve the extraction process. The optimal ultrasound extraction condition was: ultrasound frequency, 35 kHz; ultrasound intensity, 56.58 W/cm²; extraction temperature, 37.7°C; extraction time, 5 h; and ratio of solvent to solid, 31 mL/g, where the lutein recovery was 3.16 ± 0.03 mg/g wet C. vulgaris. The optimal enzymatic pretreatment was: reaction time, 2 h; enzyme concentration, 1.23% (v/w); pH, 4.5, and temperature 50°C. The optimal ultrasound extraction with enzymatic pretreatment was: ultrasound frequency, 35 kHz; ultrasound intensity, 56.58 W/cm²; extraction temperature, 37.7°C; extraction time, 162 min; and ratio of solvent to solid, 35.6 mL/g wet C. vulgaris, where the extraction yield of lutein was 3.36 ± 0.10 mg/g wet C. vulgaris. This was much higher than for ultrasound treatment alone. The surface areas of microalga cells treated by ultrasound with/without enzymatic pretreatment increased significantly, which might contribute to the increase in lutein yield. There were no significant differences in structure, color, and antioxidant activity of lutein between the ultrasound and conventional methods. The highest cost of the crude and lutein was obtained by the ultrasound with enzymatic pretreatment due to the complex process and liquid waste in the enzymatic pretreatment process, but the ultrasound treatment alone was the lowest. Therefore, ultrasound extraction is the most economical method for the extraction of microalgal lutein.     

Evaluation of green solvents: Oil extraction from oleaginous yeast Lipomyces starkeyi using cyclopentyl methyl ether (CPME)

Cyclopentyl methyl ether (CPME) was evaluated for extracting oil or triacylglycerol (TAG) from wet cells of the oleaginous yeast Lipomyces starkeyi. CPME is a greener alternative to chloroform as a potential solvent for oil recovery. A monophasic system of CPME and biphasic system of CPME:water (1:0.7) performed poorly having the lowest TAG extraction efficiency and TAG selectivity compared to other monophasic systems of hexane and chloroform and the biphasic Bligh and Dyer method (chloroform:methanol:water). Biphasic systems of CPME:water:alcohol (methanol/ethanol/1‐propanol) were tested and methanol achieved the best oil extraction efficiency compared to ethanol and 1‐propanol. Different biphasic systems of CPME:methanol:water were tested, the best TAG extraction efficiency and TAG selectivity achieved was 9.9 mg/mL and 64.6%, respectively, using a starting ratio of 1:1.7:0.6 and a final ratio of 1:1:0.8 (CPME:methanol:water). Similar results were achieved for the Bligh and Dyer method (TAG extraction efficiency of 10.2 mg/mL and TAG selectivity of 66.0%) indicating that the biphasic CPME system was comparable. The fatty acid profile remained constant across all the solvent systems tested indicating that choice of solvent was not specific for any certain fatty acid. This study was able to demonstrate that CPME could be used as an alternative solvent for the extraction of oil from the wet biomass of oleaginous yeast. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1096–1103, 2017     

Energy recovery from lipid extracted,transesterified and glycerol codigested microalgae biomass

The production of methane (CH₄) via the anaerobic digestion of microalgae biomass residues from the biodiesel production process has the potential to meet some of the energy requirements of the primary biomass to fuel conversion process. This paper investigates the practical CH₄ yields achievable from the anaerobic conversion of the microalgae residues (as well as codigestion with glycerol) after biodiesel production using both the conventional and in situ transesterification methods. Results demonstrate that the type of lipid extraction solvent utilized in the conventional transesterification process could inhibit subsequent CH₄ production. On the basis of actual CH₄ production, a recoverable energy of 8.7–10.5 MJ kg^?1 of dry microalgae biomass residue was obtained using the lipid extracted and transesterified microalgae samples. On codigesting the microalgae residues with glycerol, a 4–7% increase in CH₄ production was observed.     

Hierarchical dynamic regulation of Saccharomyces cerevisiae for enhanced lutein biosynthesis

Lutein, as a carotenoid with strong antioxidant capacity and an important component of macular pigment in the retina, has wide applications in pharmaceutical, food, feed, and cosmetics industries. Besides extraction from plant and algae, microbial fermentation using engineered cell factories to produce lutein has emerged as a promising route. However, intra-pathway competition between the lycopene cyclases and the conflict between cell growth and production are two major challenges. In our previous study, de novo synthesis of lutein had been achieved in Saccharomyces cerevisiae by dividing the pathway into two stages (δ-carotene formation and conversion) using temperature as the input signal to realize sequential cyclation of lycopene. However, lutein production was limited to microgram level, which is still too low to meet industrial demand. In this study, a dual-signal hierarchical dynamic regulation system was developed and applied to divide lutein biosynthesis into three stages in response to glucose concentration and culture temperature. By placing the genes involved in δ-carotene formation under the glucose-responsive ADH2 promoter and genes involved in the conversion of δ-carotene to lutein under temperature-responsive GAL promoters, the growth-production conflict and intra-pathway competition were simultaneously resolved. Meanwhile, the rate-limiting lycopene ε-cyclation and carotene hydroxylation reactions were improved by screening for lycopene ε-cyclase with higher activity and fine tuning of the P450 enzymes and their redox partners. Finally, a lutein titer of 19.92 mg/L (4.53 mg/g DCW) was obtained in shake-flask cultures using the engineered yeast strain YLutein-3S-6, which is the highest lutein titer ever reported in heterologous production systems.     

Improvement of hydrocarbon recovery by spouting solvent into culture of Botryococcus braunii

Botryococcus braunii, a green microalga, is known to produce plentiful liquid hydrocarbons as promising biodiesel resources. However, the hydrocarbon extraction methods that have so far achieved have several problems such as low efficiency and high cost. In our study, a solvent-spouted extraction process integrated with photo-bioculture was designed for simultaneous realization of hydrocarbon extraction and cell culture in two phases. The n-octane was selected as the best solvent among several solvents because its biocompatibility was highest for B. braunii. As a result, high level of biomass and hydrocarbon, 4.17 and 893.79 mg/L, respectively, was attained at 100 mL/min of solvent recycling rate through three times of processes for 66 days. Moreover, formation of cell clump was suppressed in solvent extraction, cells were regenerated after it, and thus cell viability was maintained even after repeated cycles of it. Finally, this solvent-spouted culture process required the smaller cost due to reuse of the less solvent and regenerated cells, compared with the other conventional methods. Accordingly, this technique would be applicable to exploit the continuous extraction of hydrocarbon from the algal biomass, especially for application on a large scale.     

Enhanced production of lutein in heterotrophic Chlorella protothecoides by oxidative stress

The fast growing unicellular green microalgae Chlorella protothecoides has attracted interest as a promising organism for commercial production of a high-value carotenoid, lutein, by heterotrophic fermentation. Effects of two oxidant-forming reactive oxygen species (ROS) on the biomass concentration, and yield and content of lutein in batch culture of heterotrophic Chlorella protothecoides were investigated in this study. The addition of 0.1 mmol/L H₂O₂ and 0.01 mmol/L NaClO plus 0.5 mmol/L Fe²⁺ to the culture led to the generation of ^·OH and enhanced the lutein content from 1.75 to 1.90 and 1.95 mg/g, respectively. The lutein content further increased to 1.98 mg/g when 0.01 mmol/L H₂O₂ and 0.5 mmol/L NaClO were added to generate ¹O₂. The maximum yield of lutein (28.5, 29.8 and 31.4 mg/L) and a high biomass concentration (15.0, 15.3 and 15.9 g/L) were also achieved through the above treatments. The results indicated that 1O2 could promote lutein formation and enhance lutein production in heterotrophic Chlorella protothecoides. Moreover, ¹O₂ produced from the reaction of H₂O₂ and NaClO was more effective in enhancing lutein production and reducing biomass loss than ^·OH from the reaction of H₂O₂ or NaClO plus Fe²⁺. Supported by the National Key Project of Sci & Tech Supporting Programs Funded by Ministry of Science & Technology of China (Grant No. 2006BAD27B03), Sci & Tech Project of Guangzhou (Grant No. 2005Z3-E0331) and Sci & Tech Project of Guangdong (Grant No. 20052050166)     

Heterotrophic production of lutein by selected Chlorella strains

Seven Chlorella strains representing three species obtained from culture collections and research laboratories were screened for their potential of heterotrophic production of lutein on two different media (Basal and Kuhl) containing glucose. While both media supported good growth and lutein formation of the seven strains in darkness, higher biomass concentrations and lutein content were achieved on Basal medium. Chlorella protothecoides CS-41 was chosen from the seven strains for further investigation due to its higher productivities of both biomass and lutein. The maximal biomass concentration and lutein content of C. protothecoides cultivated heterotrophically with 9 g L^-1 glucose in a 3.7-L fermentor were respectively 4.6 g dry cells L^-1 and 4.60 mg lutein g^-1 dry cells on Basal medium, and 4.0 g dry cells L^-1 and 4.36 mg lutein g^-1 dry cells on Kuhl medium. The heterotrophic cultivation process was scaled up successfully to 30 L using a fermentor, in which the Basal medium containing 36 g L^-1 glucose was used; the maximal biomass concentration of 16.4 g dry cells L^-1, specific growth rate of 0.92 d^-1,lutein content of 4.85 mg lutein g^-1 dry cells,growth yield of 0.47 g dry cells g^-1 glucose and lutein yield of 1.93 mg lutein g^-1 glucose were respectively achieved. This revised version was published online in August 2006 with corrections to the Cover Date.     

Integration of algae cultivation as biodiesel production feedstock with municipal wastewater treatment: strains screening and significance evaluation of environmental factors

The objectives of this study are to find the robust strains for the centrate cultivation system and to evaluate the effect of environmental factors including light intensity, light–dark cycle, and exogenous CO₂ concentration on biomass accumulation, wastewater nutrient removal and biodiesel production. The results showed that all 14 algae strains from the genus of Chlorella, Haematococcus, Scenedesmus, Chlamydomonas, and Chloroccum were able to grow on centrate. The highest net biomass accumulation (2.01 g/L) was observed with Chlorella kessleri followed by Chlorella protothecoides (1.31 g/L), and both of them were proved to be capable of mixotrophic growth when cultivated on centrate. Environmental factors had significant effect on algal biomass accumulation, wastewater nutrients removal and biodiesel production. Higher light intensity and exogenous CO₂ concentration with longer lighting period promote biomass accumulation, biodiesel production, as well as the removal of chemical oxygen demand and nitrogen, while, lower exogenous CO₂ concentration promotes phosphorus removal.     

A new approach to preparative enzymatic synthesis

A new approach to preparative organic synthesis in aqueous–organic systems is suggested. It is based on the idea that the enzymatic process is carried out in a biphasic system “water–water-immiscible organic solvent.” Thereby the enzyme is localized in the aqueous phase—this eliminates the traditional problem of stabilizing the enzyme against inactivation by a nonaqueous solvent. Hence, in contrast to the commonly used combinations “water–water-miscible organic solvent,” in the suggested system the content of water may be infinitely low. This allows one to dramatically shift the equilibrium of the reactions forming water as a reaction product (synthesis of esters and amides, polymerization of amino acids, sugars and nucleotides, dehydration reactions, etc.) toward the products. The fact that the system consists of two phases provides another very important source for an equilibrium shift, i.e., free energies of the transfer of a reagent from one phase to the other. Equations are derived describing the dependence of the equilibrium constant in a biphasic system on the ratio of the volumes of the aqueous and nonaqueous phases and the partition coefficients of the reagents between the phases. The approach has been experimentally verified with the synthesis of N-acetyl-L -tryptophan ethyl ester from the respective alcohol and acid. Porous glass was impregnated with aqueous buffer solution of chymotrypsin and suspended in chloroform containing N-acetyl-L -tryptophan and ethanol. In water (no organic phase) the yield of the ester is about 0.01%, whereas in this biphasic system it is practically 100%. The idea is applicable to a great number of preparative enzymatic reactions.     

Effect of Biomass Pre-Treatment and Solvent Extraction on β-Carotene and Lycopene Recovery from Blakeslea trispora Cells

Abstract

The production of carotenoids from Blakeslea trispora cells in a synthetic medium has been reported, with the main products being β-carotene, lycopene, and γ-carotene. The effect of biomass pretreatment and solvent extraction on their selective recovery is reported here. Eight solvents of class II and III of the International Conference of Harmonization: ethanol, methanol, acetone, 2-propanol, pentane, hexane, ethyl acetate, and ethyl ether, and HPLC analysis were used for the evaluation of their selectivities towards the three main carotenoids with regard to different biomass pre-treatment. The average C_max values (maximum concentration of caronoids in a specific solvent) were estimated to 16 mg/L with the five out of eight solvents investigated, whereas methanol, pentane, and hexane gave lower values of 10, 11, and 9 mg/L, respectively. The highest carotenoid yield was obtained in the case of wet biomass, where 44–56% is recovered with one solvent and three extractions and the rest is recovered only after subsequent treatment with acetone; thus, four extractions of 2.5 h are needed. Two extractions of 54 min are enough to recover carotenoids from dehydrated biomass, with the disadvantage of a high degree of degradation. Our results showed that, for maximum carotenoid recovery, ethyl ether, 2-propanol, and ethanol could be successfully used with biomass without prior treatment, whereas fractions enriched in β-carotene or lycopene can be obtained by extraction with the proper solvent, thus avoiding degradation due to time-consuming processes.     

Some studies on optimization of extraction process for protease production in SSF

A locally isolated filamentous fungus belonging to the group phycomycetes namely Rhizopus oryzae was identified to secrete alkaline protease. The production of this enzyme through solid state fermentation process has been attempted. From fermented biomass extraction of the enzyme was found to depend on the different parameters like nature of solvent, time of soaking, temperature etc. While optimizing the extraction process, it was found that 10% ethanol with 3% glycerol was the best solvent for protease extraction, when the soaking time was 2 hours and temperature 30v°C. It was further observed that double wash of fermented biomass yielded almost total enzyme in the leachate.     

An efficient method for the sequential production of lipid and carotenoids from the Chlorella Growth Factor-extracted biomass of <Emphasis Type="Italic">Chlorella vulgaris</Emphasis>

Efficient methodology for simultaneous extraction of multiple bioactive compounds from microalgae still remains a major challenge. The present study provides a method for the sequential production of three major products: Chlorella Growth Factor (CGF, a nucleotide-peptide complex enriched with vitamins, minerals, and carbohydrates), lipid, and carotenoids from Chlorella vulgaris biomass in an economically feasible manner. After protein-rich CGF was extracted, the spent biomass was found to contain 12% lipid and 3% carotenoids when extracted individually, compared to that of the un-utilized (fresh) biomass (lipid, 14%; carotenoids, 4%). When extracted simultaneously using conventional methods, the yield of lipid from “CGF and carotenoids-extracted biomass,” and carotenoids from “CGF and lipid-extracted biomass” were significantly reduced (50%). However, simultaneous extraction using different solvent mixtures such as hexane:methanol:water and pentane:methanol:water mixture-augmented lipid yield by 38.5% and carotenoids by 14%, and additionally retained chlorophyll and its derivatives. Column chromatographic approach yielded sequential production of lipid (18%), lutein (9%) with better yields as well as without chlorophyll interference. Different geometric isomers of lutein all-E-(trans)-(3R,3′R,6′R)-β,ε-carotene-3,3′diol, 9Z(cis)-(3R,3′R,6′R)-β,ε-carotene-3,3′diol, and 13Z(cis)-(3R,3′R,6′R)-β,ε-carotene-3,3′diol were purified by HPLC and elucidated by CD, UV, NMR, FT-IR, and Mass spectra. In conclusion, the study provides an efficient and economically viable methodology for sequential production of lipid and lutein along with its geometrical isomers without chlorophyll influence and yield loss from the protein-rich CGF-extracted spent biomass of marine microalga, Chlorella vulgaris.     

Evaluating new isolates of microalgae from Kazakhstan for biodiesel production

New microalgal strains that are native to South-East Kazakhstan were isolated and characterized with a view to identifying suitable candidates for biodiesel production. Six strains of chlorophyte algae (named K1–K6) were recovered from environmental samples as axenic cultures, and molecular analysis revealed that five (K1–K5) are strains of Parachlorella kessleri, whereas K6 is a strain of Chlorella vulgaris. A third isolate from Uzbekistan (termed UZ) was also identified as a separate strain of P. kessleri. All strains show high growth rates and an ability to utilize acetate as an exogenous source of fixed carbon. Furthermore, under conditions of nitrogen depletion, all three strains showed a significant accumulation of neutral lipids (triacylglycerides). P. kessleri K5 and C. vulgaris K6 therefore represent promising autochthon strains for large-scale cultivation and biodiesel production in Kazakhstan.