A biorefinery approach to microbial oil production from glycerol by Rhodotorula glutinis

The use of biodiesel-derived glycerol as a carbon source for microbial oil production is a biorefinery engineering strategy that aims to reduce the glycerol surplus and make the microbial oil process more cost-effective. In this work, glycerol was used as the sole carbon source for the cultivation of the oleaginous yeast Rhodotorula glutinis along with only yeast extract as a nutrient supply and without pH control. Shake-flask cultivations showed that the specific growth rate and glycerol consumption of Rhodotorula glutinis were higher at lower glycerol concentrations (≤40 g L⁻¹), while higher C/N atom ratios enhanced oil content. The present study extends the knowledge on the influence of the aeration rate and oxygen supply in cellular growth rate and microbial oil production, providing a wiser use of glycerol as an attempt to further reduce process costs. Cultivations at different air flow rates were performed in a 2 L bioreactor and showed that a low aeration rate of 0.5 L min⁻¹ gave the best glycerol and nitrogen uptake rates, resulting in the highest growth (5.3 g L⁻¹) and oil mass fraction (33% of the dry cell weight). A further 68% increase in cellular growth (16.8 g L⁻¹) and a 34% oil mass fraction of the dry cell weight was achieved after applying a feeding strategy targeting combined growth and oil production.     

High selectivity of erythritol production from glycerol by Yarrowia lipolytica

The effect of different vitamins and nitrogen sources on the yield, productivity and selectivity of erythritol production from glycerol in batch and fed-batch cultures by Yarrowia lipolytica Wratislavia K1 strain was examined in the study.Thiamine was a vitamin necessary for efficient erythritol production and the yeast extract (YE) turned out to be its best source. The YE was additionally a very good source of nitrogen in this process. Erythritol production may be efficient in the media containing only yeast extract and crude glycerol. The application of a high substrate concentration (325 kg m⁻³) in the fed-batch system with pulsed addition of glycerol resulted in erythritol production of 201.2 kg m⁻³ after 168 h of cultivation. The mass fraction of by-products, such as other polyols and organic acids, did not exceed 10%. The study showed that by-products formation could be significantly reduced by the addition of a nitrogen source after glycerol depletion from the media. Wratislavia K1 strain does not utilize erythritol in the presence of other carbon sources and this feature was used in order to increase product selectivity up to 99.7% and protein content in yeast biomass up to 28.7%. The factors determining the use of biomass as animal feed, i.e. protein concentration and presence of metal ions, were discussed as well.     

Effect of chitosan on reactor performance and population of specific methanogens in a modified CSTR treating raw POME

In this study, chitosan was periodically added to a CSTR treating raw POME in order to retain more working microorganisms at high OLRs. The data indicated that the CSTR with chitosan addition can be operated with reactor stability at an OLR of 26.5 kg m⁻³ d⁻¹ which is approximately 7.5 kg m⁻³ d⁻¹ higher than that for the control CSTR without chitosan addition. In the control CSTR, the biogas production did not increase with increased OLR, and the overall process was limited by slow methanogenic rates. For the CSTR with chitosan addition, the biogas production was 9.39 m³ m⁻³ d⁻¹ with a methane volume fraction of 68% at an OLR of 26.5 kg m⁻³ d⁻¹. Corresponding to this increase in methane production, it was found that Methanosarcinales numbers were significantly higher (P < 0.05) in the CSTR with chitosan addition than in the control CSTR.     

Analytical evaluation of different carbon sources and growth stimulators on the biomass and lipid production of Chlorella vulgaris – Implications for biofuels

The key challenges in lipid production from marine microalgae include the selection of appropriate strain, optimization of the culture conditions and enhancement of biolipid yield. This study is aimed at evaluating the optimal harvest time and effect of chlorella growth factor (CGF) extract, carbon sources and phytohormones on the biomass and lipid production in Chlorella vulgaris. CGF, extracted using hot water from Chlorella has been reported to possess various medicinal properties. However, in the present study, for the first time in C. vulgaris, CGF was found as a best growth stimulator by enhancing the biomass level (1.208 kg m⁻³) significantly on day 5. Gibberellin and citrate augmented the biomass by 0.935 kg m⁻³ and 1.025 kg m⁻³. Combination of CGF and phytohormones were more effective than CGF and carbon sources. Analysis of fatty acid methyl esters indicated that the ratio of saturated to unsaturated fatty acids is higher in cytokinin, abscisic acid and CGF, and are also rich in short chain carbon atoms, ideal criteria for biodiesel. Nitrogen starvation favoured synthesis of more unsaturated fatty acids than saturated. This study shows that CGF enhances the biomass and lipid significantly and thus can be used for large scale biomass production.     

Residue of dates from the food industry as a new cheap feedstock for ethanol production

Syrup resulting from date by-products constitutes a favorable medium for yeast development, owing to its sugar composition; it was hence tested for ethanol production. Three yeasts, Saccharomyces cerevisiae, Zygosaccharomyces rouxii and Candida pelliculosa, were selected for ethanol production on dates syrup. In batch fermentation, the ethanol concentration depended on the initial sugar concentration and the yeast strain. For an initial sugar concentration of 174.0 ± 0.2 kg m⁻³, maximum ethanol concentration was 63.0 ± 0.1 kg m⁻³ during S. cerevisiae growth, namely higher than the amounts achieved during Z. rouxii and C. pelliculosa growth, 33.0 ± 2.0 kg m⁻³ and 41.0 ± 0.3 kg m⁻³ respectively. Contrarily, only Z. rouxii was able to grow on 358.0 ± 1.0 kg m⁻³ initial sugar amount, resulting in 55.0 ± 1.0 kg m⁻³ ethanol produced.     

Development of a membrane bioreactor for enzymatic hydrolysis of cellulose

Cellulose hydrolysis is an important step in the production of bioethanol from lignocellulose. Using enzymes, as a biocatalyst, is expected to have a lower utility cost compared to the conventional acidic hydrolysis because it is carried out at milder conditions and does not require subsequent treatment step. The major obstacle to the practical realization of the potentials of enzymatic hydrolysis is the high cost of the enzymes and the slow reaction rate due to the inhibition of the enzyme by the products. In this work, a membrane bioreactor was simulated to tackle these two obstacles and enhance the reaction rate. It was found that for a 5000 kg h⁻¹ lignocellulosic feed, to achieve 50% hydrolysis conversion, a 125 m³ membrane bioreactor containing 923 kg m⁻³ cellulase need to be used. The amount of the enzyme that escapes from the system and needs replacement was estimated at 92 kg h⁻¹. The membrane reactor model was further tested using the competitive product inhibition model for the hydrolysis of totally amorphous Carboxymethylcellulose (CMC). It was shown that the reactor volume required to achieve a conversion of 50% was significantly less than that required for the lignocelluloses, even at a lower membrane mass transfer coefficient.     

Isochrysis sp. IOAC724S,a newly isolated,lipid-enriched,marine microalga for lipid production,and optimized cultivation conditions

An oleaginous, unicellular, marine microalga termed IOAC724S was isolated from the South China Sea. Morphology and genetic analyses indicated it belongs to the genus Isochrysis. Gas chromatography (GC) results showed that more than 10 types of fatty acids existed in Isochrysis sp. IOAC724S and that 90% of them were suitable for lipid production. The culture conditions suitable for cell growth were progressively optimized through photosynthetic and respiratory analyses. The optimal culture conditions were: photon flux 200–500 μmol m⁻² s⁻¹, temperature 35 °C during daytime and 24 °C at night, pH value between 7 and 8, NaNO₃ 160 g m⁻³ and NaH₂PO₄·2H₂O 80 g m⁻³ for starting culture. When microalgal cultures were exposed to these optimal conditions, the specific growth rate reached to 0.26 d⁻¹ on average and 1.0 d⁻¹ in MAX. Lipid production was optimized through nutrient starvation processes, including nitrate or phosphate deprivation and simultaneous nitrate and phosphate deprivation. The highest lipid mass fraction of dry cell weight (about 55.6%) was obtained after the stationary phase algal culture was transferred into phosphate-free medium for 3 days. GC data demonstrated that the enhancement of lipid accumulation in algal cells maintained under nutrient starvation came mainly from an increase of C16:0 and C18:1 fatty acids; however, the lipids with a chain length appropriate for fuel use (C14 to C18) were unchanged at 90% mass fraction of the dry cell weight. Based on these good characteristics, Isochrysis sp. IOAC724S appeared to be a strong candidate for lipid production.     

Bioconversion of crude glycerol from waste cooking oils into hydrogen by sub-tropical mixed and pure cultures

This study compared the biohydrogen generation by sub-tropical mixed and pure cultures from the crude glycerol from the biodiesel production using waste cooking oils (WCO). The crude glycerol was pretreated by pH adjustment. The mixed culture was obtained from a subtropical granular sludge of the UASB (Upflow Anaerobic Sludge Blanket) reactor used in the treatment of vinasse from sugarcane of ethanol and sugar industry. It was heat treated in order to inactivate hydrogen-consuming bacteria, which was identified by Illumina MiSeq Sequencing with a relative abundance of 97.96% Firmicutes Philum, 91.81% Clostridia Class and 91.81% Clostridiales Order. The pure culture was isolated from a sub-tropical granular sludge from UASB reactor of treating brewery wastewater and identified as Enterobacter sp. (KP893397). Two assays were carried in anaerobic batch reactors in order to verify the hydrogen production from crude glycerol bioconversion with: (I) mixed culture and (II) pure culture. The experiments were conducted at 37 °C, initial pH of 5.5 for assay I and 7.0 for assay II, with 20 g COD L⁻¹ of crude glycerol. The crude glycerol consumption was 56.2% and 88.0% for the assay I and II, respectively. The hydrogen yields were 0.80 moL H₂ mol⁻¹ glycerol for the assay I and 0.13 moL H₂ mol⁻¹ glycerol for the assay II. Enterobacter sp. preferred the reductive metabolic route, generating 1460.0 mg L⁻¹ of 1,3-propanediol, and it showed to be more sensitive in the presence of methanol from crude glycerol than mixed culture that preferred the oxidative metabolic route with biohydrogen generation. The mixed culture was more able to generate H₂ than pure culture from the crude glycerol coming from the biodiesel production using WCO.     

Catalytic conversion of Helianthus tuberosus L. to sugars, 5-hydroxymethylfurfural and levulinic acid using hydrothermal reaction

In this study, the efficient conversion of Helianthus tuberosus L. (Jerusalem artichoke) to sugar, 5-hydroxymethylfurfural (5-HMF), and levulinic acid (LA) were investigated using a Brønsted acid-catalyzed hydrothermal reaction. From this approach, the optimal amounts and reaction conditions for total reducing sugar (TRS), 5-HMF, and LA were as follows: 444 g kg⁻¹ of TRS yield (150.4 °C, 14.6 kg m⁻³ sulfuric acid, and 9.8 min), 193 g kg⁻¹ of 5-HMF yield (166.0 °C, 4.6 kg m⁻³, 30.8 min), and 323 g kg⁻¹ of LA yield (185 °C, 30.8 kg m⁻³, 33.7 min). In terms of combined severity, the TRS and 5-HMF concentrations decreased linearly with increasing combined severity, whereas, the LA concentration was increased at a high combined severity factor. The H. tuberosus L. may be useful as a significant feedstock for the production of platform chemicals such as 5-HMF and LA.     

Grinding energy and physical properties of chopped and hammer-milled barley,wheat, oat,and canola straws

In the present study, specific energy for grinding and physical properties of wheat, canola, oat and barley straw grinds were investigated. The initial moisture content of the straw was about 0.13–0.15 (fraction total mass basis). Particle size reduction experiments were conducted in two stages: (1) a chopper without a screen, and (2) a hammer mill using three screen sizes (19.05, 25.4, and 31.75 mm). The lowest grinding energy (1.96 and 2.91 kWh t⁻¹) was recorded for canola straw using a chopper and hammer mill with 19.05-mm screen size, whereas the highest (3.15 and 8.05 kWh t⁻¹) was recorded for barley and oat straws. The physical properties (geometric mean particle diameter, bulk, tapped and particle density, and porosity) of the chopped and hammer-milled wheat, barley, canola, and oat straw grinds measured were in the range of 0.98–4.22 mm, 36–80 kg m⁻³, 49–119 kg m⁻³, 600–1220 kg m⁻³, and 0.9–0.96, respectively. The average mean particle diameter was highest for the chopped wheat straw (4.22-mm) and lowest for the canola grind (0.98-mm). The canola grinds produced using the hammer mill (19.05-mm screen size) had the highest bulk and tapped density of about 80 and 119 kg m⁻³; whereas, the wheat and oat grinds had the lowest of about 58 and 88–90 kg m⁻³. The results indicate that the bulk and tapped densities are inversely proportional to the particle size of the grinds. The flow properties of the grinds calculated are better for chopped straws compared to hammer milled using smaller screen size (19.05 mm).     

Optimization of ethanol production from high dry matter liquefied dry sweet sorghum stalks

The ability of sweet sorghum to be utilized as feedstock for ethanol production at high initial dry material concentration was investigated. Sweet sorghum, after being dried, was liquefacted employing commercial cellulase solution Celluclast^® 1.5L, in order submerged fermentation to be permitted under high-solids concentrations. The presence of a separate enzymatic liquefaction step at 350 kg m⁻³ initial DM enhanced both ethanol production and productivity by 29.76% and 250%, respectively. Response surface methodology, based on the central composite design was applied to explore the combined effect of liquefaction duration and enzyme loading in order liquefaction conditions to be optimized. When the optimum conditions were tested using an enzyme load of 8.32 FPU g⁻¹ of dry material for 8.6 h at 50 °C, high productivity (3.0 kg m⁻³ h⁻¹) and final ethanol production (62.5 kg m⁻³) were achieved.     

Lipid accumulation in the new oleaginous yeast Debaryomyces etchellsii correlates with ascosporogenesis

The growth characteristics, lipid accumulation and composition during the life cycle of a newly isolated strain of Debaryomyces etchellsii were studied under nitrogen limiting conditions. This yeast, grown in batch flask or bioreactor cultures, reproduced asexually by buds when nitrogen was available in the growth medium, or sexually by ascospores after nitrogen exhaustion, producing more than 7 g L⁻¹ biomass. During ascosporogenesis, an important increase in the cellular lipid content in dry cell mass occurred, i.e. from a mass fraction of 11.9% in the vegetative phase to 22.4%, in the ascosporogenic phase. During transition of D. etchellsii from batch to continuous cultures using dilution rates 0.026 and 0.019 h⁻¹, a shift from sexual to asexual reproduction was observed. At 0.019 h⁻¹, few pseudomycelia were also formed. The yeast synthesized lipids containing long chain fatty acids (mainly C16 and C18). Budded cells at steady-states contained only 8.6–9.3 % of lipids mass fraction per dry cell mass that were composed of oleic and linoleic acids and, to a lesser extent, of palmitic and palmitoleic acids. Neutral lipids were the major fraction represented 61.8–66.1%, of total lipids followed by phospholipids, which was the only fraction in which linoleic acid predominated over oleic acid.     

Soil carbon accrual in particle-size fractions under Miscanthus x. giganteus cultivation

The energy crop Miscanthus x. giganteus is a deep rooting perennial rhizomatous C4 grass with great biomass production, even under temperate German climate conditions. Accordingly we hypothesized that this crop may accumulate great amounts of carbon in soil, particularly in deeper soil layers. We sampled several former C3-derived arable fields that had been cropped with Miscanthus for 0–19 years. We were able to trace the origin and turnover of soil organic C (SOC) on the basis of natural ¹³C/¹²C abundance measurements. The analysis was performed on bulk soil samples and on particle-size fractions that are known to comprise SOC of different availability for decay. Miscanthus-derived C accumulated at a rate of 1800 kg ha⁻¹ y⁻¹ down to a soil depth of 100 cm. Only about 50% of this C accrual occurred in the surface soil (0–10 cm). The C accumulation differed among size fractions. Miscanthus-derived C in the coarse-POM fraction increased rapidly during the first years of Miscanthus cultivation until a steady state was reached after approximately seven years. The stocks of Miscanthus-derived C associated with the clay fraction increased at a rate of 230 kg ha⁻¹ y⁻¹ in 0–5 cm, 45 kg ha⁻¹ y⁻¹ in 20–30 cm and 38 kg ha⁻¹ y⁻¹ in 50–75 cm. The C accumulation rate decreased with increasing soil depth. In particular, Miscanthus-derived C associated with the clay fraction led to increasing SOC stocks, even below the former Ap; that is, below a depth that would respond sensitively to a future land use change.     

Improving anaerobic digestion of pig manure by adding in the same reactor a stabilizing agent formulated with low-grade magnesium oxide

Struvite precipitation and pig manure anaerobic digestion were coupled in the same reactor in order to mitigate the inhibitory effect of free ammonia and avoid precipitator costs. The stabilizing agent used to facilitate struvite precipitation was formulated with low-grade magnesium oxide by-product; an approach that would notably reduce struvite processing costs. The interaction between pig manure and stabilizing agent was analyzed in batch experiments, on a wide range of stabilizing agent additions from 5 to 100 kg m⁻³. The monitoring of the pH and ammonia removal during 24 h showed the high capacity of the stabilizing agent to remove ammonia; removal efficiencies above 80% were obtained from 40 kg m⁻³. However, a long-term anaerobic digester operation was required to assess the feasibility of the process and to ensure that the stabilizing agent does not introduce any harmful compound for the anaerobic biomass. In this vein, the addition of 5 and 30 kg m⁻³ of the stabilizing agent in a pig manure continuous digester resulted in a 25% (0.17 m³ kg⁻¹) and a 40% (0.19 m³ kg⁻¹) increase in methane production per mass of volatile solid, respectively, when compared with the reference digester (0.13 m³ kg⁻¹). Moreover, the stability of the process during four hydraulic retention times guarantees that the stabilizing agent did not exert a negative effect on the consortium of microorganisms. Finally, scanning electron microscopy and X-ray diffraction analysis confirmed the presence of struvite as well as two precipitation mechanisms, struvite precipitation on the stabilizing agent surface and in the bulk solution.     

Harvest frequency effects on white clover forage biomass,quality, and theoretical ethanol yield

Understanding the growth of white clover (Trifolium repens L.) under varying management regimes and weather conditions will aid producers in making sound decisions on the utilization of this crop. The objectives of this study were to determine the effect of harvest frequencies on white clover forage biomass potential, theoretical ethanol yield, crude protein (CP) concentration, and in vitro digestible organic matter (IVDOM). Frequency of forage removal (treatment), year, and treatment × year interactions significantly affected forage quantity and quality. This 4-year study indicated that forage dry matter (DM) yield, theoretical ethanol yield, CP concentration, and IVDOM with four harvests (15 May, 1 and 15 June, and 1 July) or two harvests (15 May, and 15 June) were consistently better than the other one, two, or three harvest systems. Four harvests yielded on average 2380 ± 80 kg ha⁻¹ (a theoretical ethanol yield of 570 ± 20 L ha⁻¹) with 540 kg ha⁻¹ of CP and 1780 kg ha⁻¹ of digestible DM. Forage removed with two harvests (15 May and 15 June) yielded on average 2200 ± 80 kg ha⁻¹ (a theoretical ethanol yield of 530 ± 20 L ha⁻¹) with 490 kg ha⁻¹ of CP and 1640 kg ha⁻¹ of digestible DM. A two harvest system would reduce harvest costs over that of a four harvest system and would allow for two haying or grazing rotations (each with 28–30 day rest) before a decline of white clover DM production in mid-summer.     

Influences of carbon sources on the biomass,production and compositions of exopolysaccharides from Paecilomyces hepiali HN1

The parasitic fungus, Paecilomyces hepiali, is used to produce Cordyceps materials as succedaneum of natural Cordyceps sinensis in China. The purpose of this research was to investigate the effects of glucose, mannose, sucrose, lactose as solo carbon source and sucrose + lactose or mannose + sucrose as synthetic carbon source on the growth of mycelium and production, chemical composition, molecular weight distribution and monosaccharide composition of exopolysaccharides from P. hepiali HN1 (PHEPS). The maximum mycelium biomass of 12.16 kg m⁻³ and PHEPS yield of 4.57 kg m⁻³ were achieved from the culture with sucrose (50 kg m⁻³) as carbon source. The resulting PHEPS was characterized by analyses of chemical composition, size-exclusion chromatography and high performance liquid chromatography with 1-phenyl-3-methyl-5-pyrazolone pre-column derivatization. It was found that the chemical compositions and monosaccharide ratios in PHEPS were significantly affected by the carbon sources used. Glucose or mannose as carbon source enhanced the biosynthesis of PHEPS with higher-molecular weight (>1000 kD), but solo carbon source of lactose or synthetic carbon source of mannose + lactose did not increase the ratio of galactose in PHEPS. The metabolism kinetics of carbon sources demonstrated the correlation between PHEPS synthesis and the utilization of carbon sources. These findings will be useful for further works on the production, structure and function of PHEPS.     

Microbial lipid production by the oleaginous yeast Cryptococcus curvatus O3 grown in fed-batch culture

This study investigates the capability of the oleaginous yeast Cryptococcus curvatus O3 to synthesize microbial lipids using glucose as its sole carbon source. Both glucose concentration and varying nitrogen sources have a significant effect on cell growth and microbial lipid accumulation in batch and fed-batch cultures. When cultivated in a shaking flask at 30 °C with glucose as sole carbon source, the cellular biomass and lipid content reached 51.8 kg m⁻³ and 651 g kg⁻¹, respectively. The fed-batch culture in a 30 × 10⁻³ m³ stirred-tank fermentor run for 185 h produced a cellular biomass, lipid content, and lipid productivity rate of up to 104.1 kg m⁻³, 827 g kg⁻¹, and 0.47 kg m⁻³ h⁻¹, respectively. These data indicate that C. curvatus O3 can be used as an ideal oleaginous yeast for microbial lipid production. Gas chromatography analysis of the synthesized microbial lipids revealed that the major constituents are long-chain fatty acids, such as palmitic acid, stearic acid, oleic acid, and linoleic acid. The results suggest that the microbial lipids produced by C. curvatus O3 can be used to produce biodiesel.     

Effects of delayed winter harvest on biomass yield and quality of napiergrass and energycane

Napiergrass (Cenchrus purpureus (Schumach.) Morrone) and energycane (Saccharum hyb.) are perennial grasses that are well-suited for biomass production in the southeastern USA. The purpose of this study was to determine the effects of delayed winter harvest on biomass yield and quality of these grasses. The study was conducted on two adjacent sites near Midville, GA. Each site used a split-plot design with four replications, with species as the main plot, and harvest times (December, January, or February) as sub-plots. Dry matter (DM) yields were measured by mechanical harvesting, and a sample of biomass was taken from each harvest for determination of ethanol production by simultaneous saccharification and fermentation (SSF). Biomass moisture, N, P, K, and ash mass fractions were also measured. Energycane DM yields were stable from December (46.8 Mg ha⁻¹) to January (42.9 Mg ha⁻¹), but then declined (36.8 Mg ha⁻¹), while napiergrass yields declined sharply from December (47.0 Mg ha⁻¹) to January (35.0 Mg ha⁻¹). Napiergrass moisture mass fraction was reduced by an average of 18% in February harvests compared to December. Mass fractions of N, K, and ash tended to decrease with later harvesting, but sometimes increased due to changes in biomass composition. Delaying harvest of napiergrass from December to January reduced N removal by an average of 144 kg ha⁻¹, while delaying harvest of energycane to February reduced N removal by an average of 54 kg ha⁻¹. In SSF, later-harvested energycane produced less ethanol per unit of DM while napiergrass was less affected by harvest date.     

Bioreactor for glycerol conversion into H2 by bacterium Enterobacter aerogenes

Glycerol was used as a substrate for H₂ production by bacterium Enterobacter aerogenes in the test tubes and bioreactor. A BioFlo/CelliGen 115 bioreactor (10 L working volume) was utilized to conduct the experiments for conversion of glycerol into H₂ by E. aerogenes cells. The highest H₂ production rate was observed under 2% glycerol in the culture medium. The glycerol uptake efficiency by bacteria in the bioreactor was found to be 65% during the 6 day period, matching glycerol uptake efficiency observed in the test tubes experiment (65%).Hydrogen production from glycerol (2% glycerol, v/v) by E. aerogenes in the bioreactor and test tubes was measured over the 6 days, showing the maximal H₂ rate at 650 mL g⁻¹ dry weight h⁻¹. The yield of H₂ production from glycerol at 0.89 mol/mol in the bioreactor was high, corresponding to the theoretical yield of 1 mol of H₂ per 1 mol of glycerol.     

Switchgrass (Panicum virgatum L.) nutrients use efficiency and uptake characteristics,and biomass yield for solid biofuel production under Mediterranean conditions

Switchgrass produces high amounts of biomass that can be used for solid biofuel production. In this study, the dry biomass yield vs. N–P–K nutrient uptake relations as well as the N-mineralization and the N-fertilization recovery fraction for switchgrass (cv. Alamo) were determined under field conditions for three N-fertilization (0, 80 and 160 kg ha⁻¹) and for two irrigation (0 and 250 mm) levels, in two soils in central Greece with rather different moisture status over the period 2009–2012. It was found that dry biomass yield on the aquic soil may reach 27–30 t ha⁻¹ using supplemental irrigation, and remain at high levels (19–24 t ha⁻¹) without irrigation. In the xeric soil, however, lower biomass yields of 14–15 t ha⁻¹ may be produced with supplemental irrigation. The average N-concentration varies between 0.23% in stems and 1.10% in leaves, showing the very low needs in N. P-content varies between 0.16% in leaves and 0.03% in stems, whereas K-content fluctuates between 0.67% and 0.78%. Linear biomass yield-nutrient uptake relationships were found with high R², pointing to nutrient use efficiencies of 240 and 160 kg kg⁻¹, for N and K respectively. The base N-uptake ranged 70–84 kg ha⁻¹ in the aquic to 60 kg ha⁻¹ or less in the xeric soil. N-recovery fraction was about 30% in the aquic soil and lower in the xeric. Therefore, switchgrass is very promising for biomass production and its introduction in land use systems (especially in aquic soils of similar environments) should be seriously taken into consideration.