Assessment of triacylglycerol content in Chlorella vulgaris cultivated in a two-stage process

Chlorella vulgaris cultivation in two-stage process was applied to increase the lipid productivity without compromising the biomass productivity. At the first stage, microalgae was cultivated under nutrient sufficient conditions to obtain a maximized cell density; at the second stage, nitrate conditions are changed to trigger the accumulation of TAG. During first stage, the maximum biomass productivity (32 mg L⁻¹ d⁻¹) was observed after 13 days under nutrient sufficient conditions with 1.21 g L⁻¹ NaNO₃ and 0.00449 g L⁻¹ K₂HPO₄. Maximum lipid content (25.4% DW), lipid productivity (7.5 mg L⁻¹ d⁻¹) and TAG content (41.3% in total lipids) were favored by the nitrogen starvation conditions for more 4 days, at the second stage. Oil extracted at the second stage contained lower percentage of PUFAs being more suitable for the biodiesel production when compared with the oil extracted at the first stage. This two-stage phototrophic process is promising to provide a more efficient way for on a large-scale production of algal biomass and biodiesel production.     

Effect of carbon supply mode on biomass and lipid in CSMCRI's Chlorella variabilis (ATCC 12198)

CSIR-CSMCRI's Chlorella variabilis (ATCC 12198) was evaluated through autotrophic, mixotrophic and heterotrophic growth for lipid production. Autotrophic growth was assessed by providing sodium bicarbonate/sodium carbonate/CO₂ (air in a medium). Higher lipid productivity (115.94 mg L⁻¹ d⁻¹) with higher biomass productivity (724.98 mg L⁻¹ d⁻¹) of this strain was attained through bicarbonate and CO₂ sequestration in a photobioreactor. Ability to regulate the pH in favorable bicarbonate/carbonate ratio showed its potential in alkaline effluent based carbon sequestration system for biofuel generation. The simultaneous study was also conducted to understand the effect of elevated CO₂ (0.4, 1 and 1.2 g L⁻¹) in air on the culture to assess adaptation, growth and lipid in the closed chamber conditions. It was observed that CO₂ sequestration by the microalgae from the CO₂ enriched environment was optimum at 1 g L⁻¹ C. variabilis adapted to comparatively higher CO₂ (1 g L⁻¹) but grew better in low CO₂ (0.4 g L⁻¹). It was also observed that the growth, lipid content and fatty acid composition was significantly affected by CO₂ supply strategies. The effect of intermittently added sodium bicarbonate at different pH on microalgal lipid content and composition of fatty acids was observed which could affect the quality of biodiesel. The effect on fatty acid composition was observed in response to carbon supply mode during the microalgal growth at different pH dictating the properties of biodiesel.     

Prospecting the biofuel potential of new microalgae isolates

The continued search and urgent need for renewable fuel sources have necessitated the exploration of microalgae to identify relevant species for making biofuels. The aim of the study was bioprospecting and screening native microalgae strains from freshwater habitats of the Almaty region, Kazakhstan, to assess the potential for producing biofuel. The studied strains demonstrated simultaneous biomass productivity, lipid productivity, suitable fatty acid composition, and biodiesel properties. The sequence analysis of the ribosomal DNA internal transcribed spacer partial region and ribulose-bisphosphate carboxylase gene (rbcL) led to the identification of five microalgae: Monoraphidium griffithii ZBD-01, Nephrochlamys subsolitaria ZBD-02, Ankistrodesmus falcatus ZBD-03, Parachlorella kessleri ZBD-04, and Desmodesmus pannonicus ZBD-05. P. kessleri had the highest biomass production (1.42 ± 0.08 g L⁻¹ day⁻¹), lipid productivity (29 ± 1.2 g L⁻¹day⁻¹), and C₁₆–C₁₈ fatty acid contents (90%), followed by A. falcatus and M. griffithi. Gas chromatography/mass spectrometry analysis indicated that the dominant fatty acids in these strains were palmitic, stearic, and oleic acids. The calculated biodiesel properties of P. kessleri and A. falcatus based on fatty acid methyl esters (FAME) profiles showed relatively good fuel properties (cetane numbers - 48 and 50; iodine and saponification values - 83.4 and 103.6 g I₂/100 g oil, 260.8 and 199.5 mg KOH g⁻¹), which correlate well with. Our results suggest that P. kessleri and A. falcatus are promising strains for biodiesel production due to their high lipid productivity, fatty acid profile with relatively high content of oleic acid, and suitable biodiesel properties. The isolated native species of microalgae from natural freshwater bodies of the Almaty region present opportunities for further exploitation for the sustainable production of biomass and biodiesel.     

Lignocellulosic ethanol production employing immobilized Saccharomyces cerevisiae in packed bed reactor

Most of ethanol production processes are limited by lower ethanol production rate and recyclability problem of ethanologenic organism. In the present study, immobilized co-fermenting Saccharomyces cerevisiae GSE1618 was employed for ethanol fermentation using rice straw enzymatic hydrolysate in a packed bed reactor (PBR). The immobilization of S. cerevisiae was performed by entrapment in Ca-alginate for optimization of ethanol production by varying alginic acid concentration, bead size, glucose concentration, temperature and hardening time. Remarkably, extra hardened beads (EHB) immobilized with S. cerevisiae could be used up to repeated 40 fermentation batches. In continuous PBR, maximum 81.82 g L⁻¹ ethanol was obtained with 29.95 g L⁻¹ h⁻¹ productivity with initial glucose concentration of 180 g L⁻¹ in feed at dilution rate of 0.37 h⁻¹. However, maximum ethanol concentration of 40.33 g L⁻¹ (99% yield) with 24.61 g L⁻¹ h⁻¹ productivity was attained at 0.61 h⁻¹ dilution rate in fermentation of un-detoxified rice straw enzymatic hydrolysate (REH). At commercial scale, EHB has great potential for continuous ethanol production with high productivity using lignocellulosic hydrolysate in PBR.     

Biomass and lipid productivities of marine microalgae isolated from the Persian Gulf and the Qeshm Island

In this work, the screening of 147 microalgal strains from the Persian Gulf and the Qeshm Island (Iran) were done in order to choose the best ones, in terms of growth (biomass) rate and lipid content for biodiesel production. A methodology, combining experiments in lab-scale and pilot plant (open pond) used to produce and evaluate biomass and lipid productivity is presented for the systematic investigation of the potential of different microalgae species. The culture conditions, including photo flux (180 ??E m⁻² s⁻¹), photoperiod (12 h light/dark), temperature (25 °C), pH (≈8), air (carbon dioxide) and growth medium, were kept constant for all experiments. Microalgae were screened in two stages using optical density (for evaluation of biomass concentration) and Nile red and gas chromatography (for determination of lipid content and fatty acid fractions). In general, maximum specific growth rate and the maximum biomass productivity were obtained after 8-12-day culture. Nannochloropsis sp. and Neochloris sp. were selected from the marine microalgal culture collection, due to their high biomass (50 and 21.7 g L⁻¹, respectively) and oil content (52% and 46%, respectively). If the purpose is to produce biodiesel only from one species, Nannochloropsis sp. presented the most adequate fatty acid profile, namely linolenic and other polyunsaturated fatty acids. However, the microalgae Chlorella sp. can also be used if associated with other microalgal oils. In addition, selected strains could be potent candidates for commercial production in the open pond culture.     

Effectiveness of dilute oxalic acid pretreatment of Miscanthus × giganteus biomass for ethanol production

In the present study the effect of temperature, reaction time and dilute oxalic acid (OA) concentration during steam-pretreatment of Miscanthus × gigantueus has been evaluated using the combined severity factor (CS). At the highest CS glucan and lignin content in the water insoluble fraction (WIF) increased, while xylan content decreased. While glucose recovery in the water soluble fraction (WSF) was found at low concentration when mild CS were used (≤5.0 g L⁻¹ at CS ≤ 2.17), xylose and arabinose concentrations were higher at low-mild CS (1.58–2.17) with a concentration peak at CS 2.03 (39.9 and 3.2 g L⁻¹ for xylose and arabinose, respectively). The decrease in pentoses coincided with inhibitory formation in the WSF, namely acetic acid, furfural, HMF and phenolic compounds. Glucan conversion rose from 46.1% at CS 1.54 to 91.2% at CS 2.76. Likewise, maximum ethanol concentration was achieved at CS 2.76, corresponding to 20.2 g L⁻¹ and a volumetric ethanol productivity of 0.28 g L⁻¹ h⁻¹. Negative correlations have been found between xylan vs. glucan conversion and xylan vs. ethanol production, suggesting that decreasing the xylan content in WIF increases both saccharification rate and ethanol concentration (R² 0.91 and R² 0.93, respectively). On the other hand, a positive correlation was found between ethanol production and glucan conversion (R² 0.93). Fermentation of WSF by Scheffersomyces (Pichia) stipitis CBS 6054 at CS 1.54 produced 12.1 g L⁻¹ of ethanol after 96 h incubation with a volumetric ethanol productivity of 0.13 g L⁻¹ h⁻¹.     

Isolation and identification by 18S rDNA sequence of high lipid potential microalgal species for fuel production in Hainan Dao

To exploit indigenous microalgal species with the potential for biodiesel production, 101 algal cultures were isolated from partial waters in Hainan province. Eight cultures were selected based on their high biomass, high lipid content and ease of cultivation, then identified based on morphology and 18S rDNA sequence analysis. These isolates were identified as Tetranephris brasiliensis DL12, Ankistrodesmus gracilis DL25, Ankistrodesmus sp. CJ02, Desmodesmus subspicatus WC01, A. gracilis CJ09, Chlorella vulgaris CJ15, Desmodesmus sp. WC08, Chlorella sorokiniana XS04, respectively. Desmodesmus sp. WC08 reached the highest biomass concentration (2.32 g L⁻¹) with the lipid content of 31.30%. Higher lipid content of 47.90% and 47.39% were gained by A. gracilis CJ09 and C. vulgaris CJ15, respectively. However, C. vulgaris CJ15 and Desmodesmus sp. WC08 had higher lipid productivity (117.37 mg L⁻¹ d⁻¹and 115.73 mg L⁻¹ d⁻¹, respectively) in terms of comprehensive consideration. The fatty acid compositions of these microalgal species were mainly palmitic, palmitoleic, stearic, oleic with GC–MS (gas chromatography–mass spectrometer) analysis. A. gracilis CJ09, T. brasiliensis DL12, A. gracilis DL25 and Desmodesmus sp. WC08 had the higher oleic acid content (over 50% of the total fatty acids) than the others. The results suggest that marine microalgae strain Desmodesmus sp. WC08 can be the most appropriate candidate for producing oil for biodiesel, based on its higher biomass productivity, lipid productivity and fatty acid profile.     

Productivity and biochemical composition of Phaeodactylum tricornutum (Bacillariophyceae) cultures grown outdoors in tubular photobioreactors and open ponds

In this study we compared the biomass productivity and the chemical composition of the diatom Phaeodactylum tricornutum grown outdoors at different biomass concentrations, in open ponds and photobioreactors (PBRs). Optimal biomass concentration of 0.6 g L⁻¹ and 1.0 g L⁻¹ was found in open ponds and in PBRs, respectively. During summer the mean net areal biomass yield was 11.7 g m⁻² day⁻¹ and 13.1 g m⁻² day⁻¹ in open ponds and in PBRs, respectively. Night biomass loss was comparable (17.4% and 21.4% of the daylight productivity, in open ponds, and PBRs, respectively). Lipid content ranged between 25% and 27.5% of dry weight, and increased up to 34.7% of biomass grown in dense cultures (>0.6 g L⁻¹ in ponds; >1.0 g L⁻¹ in PBRs). In the evening they ranged between 21% and 31%, while a reduced amount was found in the morning – between 14.5% and 24%. An induction of the diadino–diatoxanthin cycle was observed in the cultures when they were grown at lower biomass concentrations, particularly in cultures grown in photobioreactors, indicating down-regulation of the photosynthetic apparatus due to high irradiance, which was confirmed by a sizeable reduction in the F_v/F_m ratio in the middle of day. It was found that the productivity of cultures was higher in photobioreactors compared to that in open ponds most likely as a result of a better light–dark regime experienced by the cells in short light-path tubular PBRs, which may have allowed a more efficient use of light.     

Application of sweet sorghum for biodiesel production by heterotrophic microalga Chlorella protothecoides

Microalga Chlorella protothecoides can grow heterotrophically with glucose as the carbon source and accumulate high proportion of lipids. The microalgal lipids are suitable for biodiesel production. To further increase lipid yield and reduce biodiesel cost, sweet sorghum juice was investigated as an alternative carbon source to glucose in the present study. When the initial reducing sugar concentration was 10 g L⁻¹ in the culture medium, the dry cell yield and lipid content were 5.1 g L⁻¹ and 52.5% using enzymatic hydrolyzates of sweet sorghum juice as the carbon source after 120 h-culture in flasks. The lipid yield was 35.7% higher than that using glucose. When 3.0 g L⁻¹ yeast extract was added to the medium, the dry cell yield and lipid productivity was increased to 1.2 g L⁻¹ day⁻¹ and 586.8 mg L⁻¹ day⁻¹. Biodiesel produced from the lipid of C. protothecoides through acid catalyzed transesterification was analyzed by GC–MS, and the three most abundant components were oleic acid methyl ester, cetane acid methyl ester and linoleic acid methyl ester. The results indicate that sweet sorghum juice could effectively enhance algal lipid production, and its application may reduce the cost of algae-based biodiesel.     

Ethanol production from halophyte Juncus maritimus using freezing and thawing biomass pretreatment

Juncus maritimus contains (41.5 ± 0.3)% cellulose and (31.34 ± 0.2)% hemicellulose on dry solid (DS) basis and has the potential to serve as a low cost feedstock for ethanol production. Dilute acid or freezing/thawing pretreatments and enzymatic saccharification were evaluated for conversion of halophyte plant from J. maritimus cellulose and hemicelluloses to monomeric sugars. The maximum concentration of released glucose from J. maritimus (53.78 ± 3.24) g L⁻¹) by Freezing/thawing pretreatment and enzymatic saccharification (55 °C, pH 5.0 and 48 h) using CellicCTec2 from Novozymes and (49.14 ± 5.24) g L⁻¹ obtained by dilute acid pretreatment. The maximum yield of ethanol from acid pretreated enzyme saccharified J. maritimus hydrolyzate by Saccharomyces cerevisiae strain was (84.28 ± 5.11)% of the theoretical yield with a productivity of (0.88 ± 0.16)g L⁻¹ h⁻¹. It was (90.87 ± 1.94)% of the theoretical yield with a productivity of (1.04 ± 0.10) g L⁻¹h⁻¹ for freezing/thawing pretreated plant and enzymatic hydrolysis by CellicCTec2.     

ABE fermentation from enzymatic hydrolysate of NaOH-pretreated corncobs

Acetone butanol ethanol (ABE) was produced from enzymatic-hydrolyzed corncobs by Clostridium saccharobutylicum DSM 13864. Pretreatment of corncobs was carried out with 0.5 mol L⁻¹ NaOH followed by enzymatic hydrolysis. The yield of total reducing sugars was 917 g kg⁻¹ pretreated (de-lignified) and washed corncobs. The hydrolysate was used without sediments removal for ABE fermentation. A solvent production of 19.44 g L⁻¹ with 12.27 g L⁻¹ butanol was obtained from 55.22 g L⁻¹ sugars, resulting in an ABE yield of 350 g kg⁻¹ and a production rate of 0.54 g L⁻¹ h⁻¹. A control experiment using 55.3 g L⁻¹ mixed sugars resulted in an ABE production of 16.81 g L⁻¹ with 10.26 g L⁻¹ butanol, corresponding to an ABE yield of 300 g kg⁻¹ and a production rate of 0.47 g L⁻¹ h⁻¹, indicating that the enzymatic hydrolysates may contain stimulating compounds that can improve the ABE fermentation.     

Production of ethanol from raw juice and thick juice of sugar beet by continuous ethanol fermentation with flocculating yeast strain KF-7

Sugar beet juice can serve as feedstock for ethanol product due to its high content of fermentable sugars and high energy output/input ratio. Batch ethanol fermentation of raw juice and thick juice proved that addition of mineral nutrients could not improve ethanol concentration, but could accelerate the fermentation rate. Fermentation of thick juice with an initial pH of 9.1 did not affect the fermentation process. The continuous ethanol fermentation of raw juice was performed at 35 °C with a dilution rate of 0.3 h⁻¹, resulting in ethanol concentration, ethanol yield and productivity of 70.7 g L⁻¹, 89.8% and 21.2 g L⁻¹ h⁻¹, respectively. A two-stage reactor was used in the continuous ethanol fermentation of thick juice by feeding fresh yeast cells into the second reactor. This process was stable at a total process dilution rate of 0.11 h⁻¹ with an overall sugar concentration of 190 g L⁻¹ in the influent. The ethanol concentration was kept at approximately 80 g L⁻¹, corresponding to ethanol yield of 82.5% and productivity of 8.8 g L⁻¹ h⁻¹.     

Performances comparison between three technologies for continuous ethanol production from molasses

Molasses are a potential feedstock for ethanol production. The successful application of anaerobic fermentation for ethanol production from molasses is critically dependent to the development and the use of high rate bioreactors. In this study the fermentation of sugar cane molasses by Saccharomyces cerevisiae for the ethanol production in a continuously stirred tank reactor (CSTR), an immobilised cell reactor (ICR) and a membrane reactor (MBR) was investigated. Ethanol production and reactor productivities were compared under different dilution rates (D). When using the CSTR, a decent ethanol productivity (Qp) of 6.8 g L⁻¹ h⁻¹ was obtained at a dilution rate of 0.5 h⁻¹. The Qp was improved by 48% and the residual sugar concentration was reduced by using the ICR. Intensifying the production of ethanol was investigated in the MBR to achieve a maximum ethanol concentration and a Qp of 46.5 g L⁻¹ and 19.2 g L⁻¹ h⁻¹, respectively. The achieved results in the MBR worked with high substrate concentration are promising for the scale up operation.     

Hydrogen production by Escherichia coli during anaerobic utilization of mixture of lactose and glycerol: Enhanced rate and yield,prolonged production

Escherichia coli wild type has the ability to utilize lactose or the mixture of lactose and glycerol producing bio-hydrogen (H₂) at different pH values. At pH 7.5 in hyaB (lacking large subunit of hydrogenase (Hyd)-1) and hybC (lacking large subunit of Hyd-2) single mutants fermenting lactose (1 g L⁻¹) H₂ yield was ∼7- and 5-fold more, respectively, compared to the wild type. During the fermentation of lactose (1 g L⁻¹) and glycerol (10 g L⁻¹) mixture H₂ yield in wild type increased ∼3-fold, compared to fermenting lactose only. H₂ generation in wild type was monitored in batch cultures during 168 h of growth when utilizing the mixture of lactose and glycerol in all combinations of different concentration. In hyaB but not in hybC mutant H₂ evolution was detected till 240 h in the mixture of 5 g L⁻¹ lactose and 10 g L⁻¹ glycerol. The highest H₂ production rate of 21.94 mL L⁻¹ h⁻¹ was detected in hyaB mutant at pH 7.5 when 1 g L⁻¹ lactose was applied. The results showed optimized H₂ production using different mutants, lactose and its mixture with glycerol. They can be applied for renewable energy, especially bio-H₂ production.     

Efficient ethanol production from inulin by two-stage aerate strategy

A major concern for ethanol production from inulin-containing materials, is the higher unconverted sugar, which increases the cost of ethanol production and wastewater treatment. Some key factors, such as inulinase, biomass or aeration rates, were studied to solve the problems in the process of ethanol fermentation from inulin. It was showed that more inulinase and increasing inoculum size can shorten the fermentation time, but could not reduce residual sugars. Two-stage aerate strategy was developed to utilize the remained sugars: keep the aeration at 5 h⁻¹ at the first 12 h, and drop it to 1.2 h⁻¹. Under this condition, contradiction between fermentation time and high ethanol yield was solved (60 h and 0.43 g g⁻¹), and the final residual sugar concentration decreased to about 10 g L⁻¹ with 98 g L⁻¹ ethanol. The ethanol productivity was up to 1.63 g L⁻¹ h⁻¹, which is the highest productivity of ethanol fermentations from inulin-containing materials.     

Improvement of biohydrogen production from brewery wastewater: Evaluation of inocula,support and reactor

This work explores the production of biohydrogen from brewery wastewater using as inoculum a culture produced by natural fermentation of synthetic wastewater and Klebsiella pneumoniae isolated from the environment. Klebsiella pneumoniae showed good performance as inoculum, as evaluated using assays of between 9 and 16 cycles, with durations of 12 and 24 h, carbohydrate concentrations from 2.79 to 7.22 g L⁻¹, and applied volumetric organic loads from 2.6 to 12.6 g carbohydrate L⁻¹ day⁻¹. The best results were achieved with applied volumetric organic loads of 12.6 g carbohydrate L⁻¹ day⁻¹ and cycle length of 12 h, resulting in mean volumetric productivity of 0.88 L H₂ L⁻¹ day⁻¹, maximum molar flow of 10.80 mmol H₂ h⁻¹, and mean yield of 0.70 mol H₂ mol⁻¹ glucose consumed. The biogas H₂ content was between 18 and 42%, while the mean organic compounds removal and carbohydrate conversion efficiencies were 23 and 81%, respectively. The inoculum produced by natural fermentation was not viable.     

Statistical optimization of physical process variables for bio-plastic (PHB) production by Alcaligenes sp.

In the present study, efforts have been made to optimize the three physical process variables viz; pH, temperature and agitation speed for enhanced polyhydroxybutyrate (PHB) production in batch cultivation by Alcaligenes sp. which serves as precursor for bio-plastic (PHB) production. Strain selection was done by viable staining method using nile blue A dye. Agro-industrial by products; cane molasses and urea were used as carbon and nitrogen source for PHB production. Optimization of physical process variables was done by central composite rotatable design (CCRD) using design expert (DX 8.0.6) software. Shake flask cultivation performed under optimum physical condition viz; 34.5 °C temperature, 6.54 pH and agitation speed of 3.13 Hz, gave PHB mass fraction yield of 76.80% on dry molasses substrate and showed 98.0% resemblance with the predicted percentage yield of 77.78%. Batch cultivation further performed in 7.5 L lab scale bioreactor (working volume: 5.6 L) under optimized condition gave maximum cell biomass of 11 ± 0.5 g L⁻¹ with a PHB content of 8.8 ± 0.4 g L⁻¹ after 48.0 h of fermentation. Scale up study on bioreactor gave maximum PHB yield (Y_P/x) and productivity of 0.78 and 0.19 g L⁻¹ h, which are higher than previous reports under similar condition. Characterization of PHB was done by FTIR.     

Characterization and identification of lipid-producing microalgae species isolated from a freshwater lake

Microalgal lipids are the oils of the future for sustainable biodiesel production. One of the most important decisions in obtaining oil from microalgae is the choice of species. A total of 45 algal cultures were isolated from a freshwater lake at Wonju, South Korea. Five microalgal isolates were selected based on their morphology and ease of cultivation under our test conditions. These cultures were identified as strains of Scenedesmus obliquus YSL02, Chlamydomonas pitschmannii YSL03, Chlorella vulgaris YSL04, S. obliquus YSL05, and Chlamydomonas mexicana YSL07 based on microscopic examination and LSU rDNA (D1-D2) sequence analysis. S. obliquus YSL02 reached a higher biomass concentration (1.84 ± 0.30 g L⁻¹) with a lower lipid content (29% w/w), than did Chla. pitschmannii YSL03 (maximum biomass concentration of 1.04 ± 0.09 with a 51% lipid content). Our results suggest that Chla. pitschmannii YSL03 is appropriate for producing biodiesel based on its high lipid content and oleic acid proportion.     

Application of experimental design methodology for optimization of biofuel production from microalgae

Optimization of biofuel productivity, in terms of lipid content, polysaccharide content, and calorific value, from microalgae was performed by varying four variables (temperature, light intensity, nitrogen content, and CO₂ addition) using a 2⁴ full factorial design. A statistical analysis showing the influence of each variable and their interactions was conducted. The selected variables all influence biofuel productivity, but their importance varies according to the sequence: CO₂ addition > temperature > nitrogen content > light intensity. Interactive effects of temperature with light intensity and nitrogen with CO₂ addition for lipid and polysaccharide productivities were identified, respectively. For calorific value, interactive effects of CO₂ addition with light intensity and nitrogen content were observed. The highest biofuel productivity was obtained at the following conditions: temperature (>25 °C), light intensity (>60 μmol photons m⁻² s⁻¹), nitrogen content (<50 mg L⁻¹), and CO₂ addition (>18 mL L⁻¹ d⁻¹). 10 days was found to be the most favorable cultivation time for lipid production under the investigated conditions.     

Sweet sorghum as a whole-crop feedstock for ethanol production

The potential of sweet sorghum as an alternative crop for ethanol production was investigated in this study. Initially, the enzymatic hydrolysis of sorghum grains was optimized, and the hydrolysate produced under optimal conditions was used for ethanol production with an industrial strain of Saccharomyces cerevisiae, resulting in an ethanol concentration of 87 g L⁻¹. From the sugary fraction (sweet sorghum juice), 72 g L⁻¹ ethanol was produced. The sweet sorghum bagasse was submitted to acid pretreatment for hemicellulose removal and hydrolysis, and a flocculant strain of Scheffersomyces stipitis was used to evaluate the fermentability of the hemicellulosic hydrolysate. This process yielded an ethanol concentration of 30 g L⁻¹ at 23 h of fermentation. After acid pretreatment, the remaining solid underwent an alkaline extraction for lignin removal. This partially delignified material, known as partially delignified lignin (PDC), was enriched with nutrients in a solid/liquid ratio of 1 g/3.33 mL and subjected to simultaneous saccharification and fermentation (SSF) process, resulting in an ethanol concentration of 85 g L⁻¹ at 21 h of fermentation. Thus, from the conversion of starchy, sugary and lignocellulosic fractions approximately 160 L ethanol.ton⁻¹ sweet sorghum was obtained. This amount corresponds to 13,600 L ethanol.ha⁻¹.