Bioethanol Yield Research Articles

Efficient Conversion of Oil Palm Trunk and Frond to Bioethanol and Biogas Using Two-Stage Steam Explosion Pretreatment

Bioethanol and biogas production from oil palm trunk (OPT) and oil palm frond (OPF) investigated within a biorefinery concept. Firstly, bioethanol production from OPT and OPF pretreated two-stage steam explosion by comparing with enzyme hydrolysis and without enzyme hydrolysis in the SSF process, which used S. cerevisiae in fermentation. The amount of bioethanol increased rapidly, which was stable when the fermentation process entered 96 hrs, resulting in the highest amount of bioethanol produced from OPF and OPT equal to 0.31 and 0.40 g ethanol/g glucose of bioethanol yield, which was about 24.96% and 25.99% higher than the non-enzymatic fermentation of OPF and OPT. The total stillage from OPT and OPF distillation produced a methane yield of 164.38 ml/CH4 g COD at 30 days of HRT and an organic loading rate (OLR) of 12.45 g COD/L-day. Biofuels in the biorefinery concept of OPF/OPT material at 1,000 kg produced bioethanol, biogas, and solid residue as 49 L at 95% bioethanol, 7,116 L at 63.05% of methane composition, and 13 kilograms of solid residue.

Development of an ultrasound-assisted pre-treatment strategy for the extraction of d-Limonene toward the production of bioethanol from citrus peel waste (CPW)

Citrus is one of the world’s most abundant fruits containing vitamins, pigments, and fragrances, making it vital for several industries. However, these fruits contain about 45–50% residues (peels), which often end up as waste and can be harmful to the environment if not properly treated. Bioethanol production from citrus peel waste offers a potential solution to this problem. Hence, this study explores the potential of using ultrasound-assisted pre-treatment method as a novel strategy to extract d-Limonene (essential oil in the residue), and further demonstrates bioethanol production. This was done by investigating ultrasonication’s optimal effect on pre-treatment of the citrus residue, followed by bioethanol production. The results show that, optimum values for d-Limonene extraction were obtained at a temperature of 14.6 °C and an ultrasound intensity of 25.81 W/cm2 with a validation yield of 134 ± 4.24 mg/100 g dry CPW. With optimal ultrasonic parameters, the study went further to demonstrate the effect of the essential oil on bioethanol production which is hindered by the oils present. Key findings show better bioethanol yield once the essential oil was extracted (treated) from the citrus waste as opposed to it not extracted (untreated), with a 66 and a 29% increase when comparing simultaneous saccharification and fermentation (SSF) and sequential hydrolysis and fermentation (SHF) respectively. Based on this result, ultrasound-assisted extraction as a pretreatment method was found suitable for bioethanol production from citrus residue and could be utilized as a biorefinery pre-treatment approach to scale bioethanol production.

Performance of combined hydrochemo-mechanical pretreatment of rice straw for bioethanol production

Pretreatment was an inevitable process in the biorefinery process of lignocellulosic biomass utilization. Generally, biomass was considered an essential carbon source that could be converted into several bio-based products such as biofuels and biochemicals. This study aimed to evaluate the performance of combined hydrochemo-mechanical pretreatment of rice straw for bioethanol production. Rice straw was pretreated with autoclave followed by ball-milling pretreatment. The hydrochemical pretreatment was performed in an autoclave with different concentrations of NaOH (1 and 10%) at 121 °C for two different durations (30, 60 min). The pretreated biomasses were then subjected to ball-milling pretreatment for size reduction and subsequently hydrolyzed via enzymatic and bioethanol fermentation. The obtained results indicated that the highest reducing sugars were 0.4513 kg reducing sugar/kg biomass obtained by 1% of NaOH at 121 °C, 30 min, which provided the highest energy efficiency and the lowest waste generation was 0.1423 kg reducing sugar/kWh and 0.2570 kg of waste/kg reducing sugar respectively. Moreover, the highest bioethanol yield was 0.0491 kg/kg biomass obtained from a similar condition. Additionally, the combined pretreatment suggested that it could be an alternative pretreatment for a lignocellulosic biorefinery in industrial applications.

Optimization of Some Fermentation Conditions for Bioethanol Production from Yam Peels (Dioscorea rotundata) Using Box-Behnken Design (BBD)

Aim: The aim of this research was to optimize the production of bioethanol from a select second generation feedstock (yam peels).
 Methodology: Bioethanol was produced from yam peels using Box Behnken Design (BBD). The independent variables selected for optimization of bioethanol yield were; fermentation temperature (˚C), fermentation time (hours) and yeast concentration (%w/v). A set of 17 experiments were considered by design expert software. All experiments were run in triplicates. Test for bioethanol was carried out using acidified potassium dichromate method and absorbance was taken using a spectrophotometer at 600nm.
 Results: From the experiments carried out above, the optimum conditions under which the highest bioethanol (yield%) was produced were a fermentation temperature of 30̊C, yeast concentration of 5.50%w/v and fermentation time of 96hours under which a bioethanol yield of 45.79% was produced.
 Conclusion: Yam peels may therefore have the potentials to serve as substrates for bioethanol production rather than using food crops such as sugarcane juice and cassava flesh which may lead to food shortages and crisis especially is developing countries such as Nigeria.

Potensi limbah kulit dan biji rambutan (Nephelium lappaceum L) sebagai bioetanol

In view of information on rambutan creation which is expanding, the misuse of rambutan strips and seeds is likewise expanding. Remembering that rambutan strips and seeds contain a few mixtures that can be utilized as elective unrefined components in the production of bioethanol. This study aims to determine the effect of variations in the addition of yeast on the yield and content of bioethanol, and also to determine the maximum mass of the addition of yeast to acquire the biggest yield and ethanol content. This research went through 5 stages, first stage is the readiness of the skin and seeds of rambutan, second stage is α-cellulose detachment, third step is hydrolysis with 1% HCl to create glucose which will be analyzed using Benedict's reagent and the Luff-Schoorl method. Qualitative analysis showed positive results and glucose levels obtained were 22.39% with a glucose yield of 1.50%. The fourth stage is glucose fermentation by using five days with variations in yeast weight of 5, 6 and 7 grams. The fifth step is to separate the resulting bioethanol by distillation and determine alcohol content using an alcohol refractometer. Yield bioethanol obtained by varying the weight of yeast 5, 6, and 7 grams respectively was 1.05%, 1.18%, and 1.67% with the levels of bioethanol obtained 1.95%, 2.15%, and 3.00%. The highest yield and content of bioethanol were obtained by adding 7 grams of yeast. The yield obtained on this bioethanol is 1.67% and the bioethanol content is 3.00%.
 Keywords: bioethanol, cellulose, fermentation, hydrolysis, rambutan peels.

Immobilization of Cellulase Enzymes on Single-Walled Carbon Nanotubes for Recycling of Enzymes and Better Yield of Bioethanol Using Computer Simulations.

The utilization of microbial cellulase enzymes for transforming plant biomass into biofuel or bioethanol, which can serve as a substitute for fossil fuel, is a subject of growing interest. Nonetheless, large-scale production of biofuel using cellulases is not economically feasible as the extraction of these enzymes from diverse microorganisms is an expensive process. To address this issue, immobilizing the enzyme to a substrate material, e.g., carbon nanotubes (CNTs), to recycle without a significant decline in its catalytic activity is a promising solution. Due to the hydrophobic nature of CNTs, we employed molecular docking and network analysis methodologies to identify potential CNT-binding sites on the outer surface of a wild-type cellulase enzyme, CelS. Classical molecular dynamics simulations of CNT-bound CelS through one of the selected binding sites resulted in negligible changes in the secondary structure of the enzyme and its catalytic domain, implying the least possible effect on the catalytic activity post-immobilization. Furthermore, our study reveals that while the unfolding near the CNT-binding region in CelS is more pronounced when the enzyme is interacting with a wider CNT, resulting in enhanced contact area and improved binding affinity, its impact on the overall CelS structure is relatively less significant when compared to thinner CNTs. Particularly, CNTs of diameter ∼12 Å can serve as a favorable option for substrate materials in cellulase immobilization. Our study also provides critical insights into the binding mechanisms between cellulase and CNTs, which could lead to the development of more efficient biocatalysts for biofuel production.

Fiber wastes of date palm for bioethanol production in Saudi Arabia

A huge rise in energy consumption has been observed in the past few decades because of population and economic growth. One of the renewable energy fuels that can be made from biomass is bioethanol. In Saudi Arabia, date palm provides tons of biomass waste each year, leading to serious problems. The current study aimed to use the date palm fibers (DPF) for bioethanol production via a saccharization step (by hydrochloric acid or by Trichoderma harzianum) for cellulose. This was followed by fermentation (by Saccharomyces cerevisiae). The maximum amount of total carbohydrates (95.55 ± 2.6 mg/dL) and reducing sugar (11.35 ± 0.35 mg/dL) were obtained on the 7th day using T. harzianum. The optimum period of bioethanol production was at day 6 (12.52 ± 1.3 g/L), while at day 5 it became (12.76 ± 0.75 g/L) when the DPF were fortified with yeast extract. The bioethanol maximum yield (12.03 ± 1.10 g/L) was obtained at 30 °C. Moreover, 2 mL of S. cerevisiae inoculum gave maximum yield of bioethanol. Gas chromatographic analysis showed that bioethanol in the fermented broth represented the major constituent with a peak area of 75.01%. The findings indicate that the fortified DPF with yeast extract gave a promising bioethanol yield.

Holistic lignocellulosic biorefinery approach for dual production of bioethanol and xylonic acid coupled with efficient dye removal

The complete valorization of lignocellulosic biomass (LCB) to valuable bio-products with one-step fractionation is still challenging. This study represents sustainable waste-free biorefinery routes for efficient fractionation of LCB, employing a novel pretreatment method using hydrotropic p–toluenesulfonic acid (TsOH) mixed with pentanol. The potential of LCB pretreatment using TsOH/pentanol reagent as lignin absorbent with co-production of bioethanol and xylonic acid was investigated. Biomass pretreatment at 120 °C for 40 min with 20% TsOH dosage was the optimal condition that significantly dissolved more than 88.2% of lignin and 95.1% of hemicellulose in the biphasic phase, while 95.6% of cellulose was retained in the solid phase. Further fermentation of cellulose-rich fraction using Saccharomyces cerevisiae resulted in 225 g kg−1 bioethanol yield. In addition, xylose-rich phase was converted into xylonic acid by Gluconobacter oxydans fermentation with a yield of 202 g kg−1. Importantly, the isolated lignin was altered by acid groups during sulphonation through TsOH/pentanol pretreatment, which makes lignin a potential adsorbent for cationic contaminants in wastewater. In particular, the isolated lignin achieved high adsorption capacity (300 mg/g) of methylene blue. The proposed biorefinery routes showed a high net positive energy of 3.65 MJ kg−1 dry biomass with an energy ratio of 1.70. Therefore, this study provides an innovative synergistic pretreatment using TsOH/pentanol as a promising fractionation process for efficient cascade valorization of LCB into valuable bio-products.

Bioethanol Production from Two Varieties (Saccharum Officinarum and Saccharum Barberi) Of Sugarcane Peels

Provision of an alternative clean source of fuel with less cost, will reduce fossil fuel demand. Pollution is the major environmental problem. Air pollution is among the three types of pollution where harmful substances such as CO2 and CO are introduced to the environment and cause harm to humans and animals. Fossil fuel combustion from automobiles and industries causes this type of pollution. There is need to replace another source of fuel with renewable feedstock such as the peels of Saccharum officinarum and Saccharum barberi which are lignocellulose materials to produce bioethanol that has a lower impact on air pollution and the Ozone layer which causes Green-House effect than fossil fuels. Dilute H2SO4 at different concentrations of 1M,2M,3M,4M and 5M were replicated into three different parts respectively as hydrolysing solution. Saccharomyces cerevisiae was used as fermentation enzymes. Different pH values of 5, 6 and 7 was used for fermentation periods of 5, 6 and 7 days, respectively. The Bioethanol was distilled by the use of fractional distillation. Hydrolysed samples of 3M for 6th day of both Saccharum officinarum and Saccharum barberi produced the best yields of bioethanol at the pH of 5 and 5M hydrolysed samples of both Saccharum officinarum and Saccharum barberi produced the least bioethanol for all pH values and fermentation days. The Bioethanol produced was blended with kerosene fuel to create EK10 and EK20 kerosene-bioethanol blends for use as a fuel source in a kerosene lamp. EK10 blend took 126 hours to burn in a rotary kerosene lamp, while EK20 blend took 167 hours to burn-off in the same kerosene lamp. Hydrolysed H2SO4 of 3M, pH 5 and fermentation period of 6 days for both Saccharum officinarum and Saccharum barberi shows the best sample to produce bioethanol. The bioethanol kerosene blend EK10 and E20 was concluded to show long period of burning with clean soot in a rotary kerosene lamp, therefore the bioethanol kerosene blends can be used as substitutes for kerosene fuel.

Performance of high solids enzymatic hydrolysis and bioethanol fermentation of food waste under the regulation of saponin

Bioethanol recovery from food waste through high solids enzymatic hydrolysis (HSEH) and high solids bioethanol fermentation (HSBF) alleviate the energy crisis. However, this cause decreased glucose and bioethanol yields due to the high solids content. In this study, saponin was introduced into food waste HSEH and HSBF systems to enhance the product yields. Under the regulation of saponin, the substrate released >90% of the theoretical reducing sugar. The glucose concentration increased by 137.41 g/L after 24 h of HSEH with 2.0% saponin. The bioethanol titer reached 73.2 g/L (1.0%-saponin). Untargeted metabolomics illustrating that saponin had higher antifungal properties at lower concentrations (0.5%-saponin) that caused a decrease in bioethanol yield. The addition of saponin concentrations of 1.0%∼3.0% promoted HSEH, HSBF, and the metabolism of Saccharomyces cerevisiae; thus, 1.0% was suggested for practical use. This study deepened the understanding of saponin in enhancing HSBF and provides theoretical support for further application.

Improvement of Large-Scale Production of Lignocellulosic Bioethanol through Synthetic Biology Approaches: A Comprehensive Review

This review article explores the use of synthetic biology approaches like gene editing and metabolic engineering to create genetically-modified organisms that can produce commercially-valuable products on large-scale, clean environmental pollutants, and serve as efficient biosensors. The Biobrick system includes a registry of available genetic information and a set of standard protocols for assembling and testing them, which finds various significant uses in synthetic biology, such as in the production of "Fourth generation” biofuel. Genetic engineering techniques may be applied to manipulate crops or microbes for more efficient biofuel production. Such synthetic biology techniques also include modification of lignin structure and content, use of bacterial enzymes abundantly expressed in plants, and manipulation of hemicellulose biosynthesis. However, challenges such as high temperature, efficient conversion of all substrate molecules for maximum product yield, efficient pentose fermentation, and tolerance to acetic acid and bioethanol concentration can all impact the yield of the product. This article explores innovative genetic modification approaches designed to decrease lignin levels and enhance crop digestibility in plants, with a specific focus on the model plant Arabidopsis thaliana and herbaceous plants such as Alfalfa. The aim is to manipulate the Monolignol pathway and modify the CSE gene, known for its ability to decrease lignin content. These modifications have been shown to significantly improve saccharification efficiency and increase the yield of lignocellulosic bioethanol. Besides, the role of xylulose-5-phosphate as an intermediate in the non-oxidative pentose phosphate pathway and the oxidative pentose phosphate pathway, and the use of heterologous xylose transporters and modified sugar transporters as potential solutions to improve the biofuel production efficiency is also discussed in this review article.

Optimization of Fermentation for Bioethanol Production from sour Citrus aurantifolia Fruit Juice using Natural Palmyrah Toddy Yeast


 Large scale consumption of fossil fuel to meet the increasing demand causes adverse effects on the environment due to the emission of harmful greenhouse gases. The production of bioethanol from diverse fruit juices that are underutilized because of poor taste quality could be one of the alternative fuels to overcome the issues. The objective of the study was to produce bioethanol from sour Citrus aurantifolia fruit juice using palmyrah toddy yeast and to optimize the conditions to increase the bioethanol yield. The sour Citrus fruit juice was inoculated with palmyrah toddy yeast (Saccharomyces cerevisiae - 2g/L) in the fermentation media (100ml, sour Citrus fruit juice: distilled water = 1:3) composed of 10 g/L yeast extract, 10 g/L KH2PO4, 2 g/L (NH4)2SO4, 2 g/L peptone and 0.5 g/L MgSO4·7H2O and allowed for fermentation for 24 hours at room temperature. The amount of ethanol produced from the Citrus juice was 0.8% (V/V) after 24 hours of fermentation. In order to optimize the fermentation process for Citrus aurantifolia, a variety of experimental parameters were studied, including the type of nitrogen source (ammonium sulphate, ammonium nitrate, ammonium chloride, and urea), inoculum size (0.4 to 1.0 g/100 mL), temperature (20 to 40 °C), rotation speed (50 to 250 rpm), concentration of raw fruit juice (5 to 100%), amount of urea (0.1 to 2.0 g/100 mL), carbon source (glucose, sucrose, maltose, and dextrose), amount of sucrose (1 to 20 g), pH of the medium (3.0 to 8.0), and incubation period (24 to 96 h). After conducting the experiments, it was found that using Citrus aurantifolia at 100% concentration resulted in significantly higher ethanol yields of 11.50%, which was 14.37 times higher than the non-optimized conditions. The highest yield was achieved when the fermentation was carried out at 35 °C for 24 h with an inoculum concentration of 0.5 g/100 mL, a rotation speed of 150 rpm, a pH of 4.0, 0.1 g/100 mL urea as the nitrogen source, and 10 g/100 mL sucrose as the carbon source. Large scale fermentation study using bioreactor should be done to determine whether this finding could be commercialized.
 Key words: Bioethanol, Fermentation, Palmyrah toddy yeast, Citrus fruit juice, Urea

Integrated Approach for Bioethanol and Paper Production using Populus deltoides Wood Biomass: An Experimental Study

Lignocellulosic materials contain two major sugar macromolecules, cellulose and hemicellulose, and polyphenolic lignin. During pulping, lignin and hemicellulose are broken down into smaller molecules such as organic acids, and removed in the black liquor, leaving cellulose fibers for papermaking. Lignocellulose consists of approximately 28–35% hemicelluloses, which are lost during the pulping process in black liquor and are an important source of sugars that can be used to produce bioethanol as a liquid fuel. The hemicellulosic sugars from the Populus deltoides (poplar) lignocellulosic biomass were partially extracted keeping in mind that it does not affect the properties of paper beyond acceptable limits, further converting these extracted sugars by fermentation to bioethanol, followed by pulping the residual biomass and papermaking and determining pulping and papermaking properties. With the increasing demand for lignocellulosic biomass by various industries, an integrated biorefinery approach for maximum utilization of its chemical components with minimum degradation is necessary in the future. The maximum bioethanol yield was found to be 3.58 g/L. On manufactured paper sheets, the mechanical properties tensile index and tear index of pre-extracted biomass were observed as 19.23 Nm/g and 3.5 mNm2/g and slightly lower against the control 21.34 Nm/g and 4.0 mNm2/g. The main objective of the present study is to recover reducing sugars before the pulping process for bioethanol production and to further utilize the remaining residue for papermaking without disturbing its fiber integrity.

Bioethanol production from sugarcane molasses with supplemented nutrients by industrial yeast

Sugarcane molasses, a sugar industry by-product, is being used as a convenient source of carbon for microorganisms to produce bioethanol. The industrial yield of bioethanol derived from Saccharomyces cerevisiae decreases with increasing temperature in the summer season and it is a common issue in the tropical region. It is inevitable to boost the production of bioethanol on an industrial scale to make it commercially profitable. This study has been conducted to analyze and compare the effect of three supplements on boosting alcohol products including thiamine (vitamin B1), pyridoxine (vitamin B6), and D-biotin (vitamin H). Collected molasses were diluted to 20 Brix to make them consumable by yeast, and thiamine, pyridoxine, and biotin were added as 1 mg/l, 1 mg/l, and 0.44 µg/l, respectively. Results depicted that the addition of vitamins impacted very positively on increasing alcohol production, yeast growth, and dry yeast weight where the residual glucose concentration was further decreased. Despite an extended lag phase resulting from higher vitamin doses, there was a significant improvement observed in both alcohol generation and yeast cell growth. This study presents the optimal dosing of supplements in the fermentation broth as a strategy to enhance bioethanol production.

Experimental investigation on effect of season on the production of bioethanol from wheat-stalk (WS) using simultaneous saccharification and fermentation (SSF) method

Global dependency on conventional fuel, its limited stock, and their adverse effects on the environment have driven researchers into alternative fuel. Wheat-stalk (WS), which is a residue of the harvested wheat crop, is considered a potential feedstock for bioethanol production as an alternative fuel due to its high cellulose and hemicellulose content and abundant availability. The objective of this work is to optimize the environment condition for fermentation in the different seasons to get the maximum bioethanol production yield from wheat-stalk straw (WSS) by using minimal laboratory resources. In this study, field collected WS was taken for physical treatment to get size less than 1 mm. Steam explosion pretreatment of WSS was performed to increase its accessible surface area and to reduce degree of polymerization. Next, to remove lignin, it was pretreated with alkali (1 M NaOH) with a solid-loading of 1:15 (w/v) at pH 10. After that, an acidic pretreatment was performed with 0.1 N diluted H2SO4 at pH 4.8 to increase anaerobic digestibility and for quicker hydrolysis. The pretreated WSS slurry was further enzymatically hydrolysed for 48 h to have monomeric sugar from cellulose and hemicellulose by adding cocktail of three enzymes amylase, cellulase, and hemicellulase with amount of 0.1% w/v of each. After that simultaneous saccharification and fermentation (SSF) were performed to convert monomeric sugar into bioethanol in the presence of microbial yeast media containing yeast (1% w/v), and peptone (2% w/v) under anaerobic conditions at pH 5.0. It has been found that the minimum time required during SSF for bioethanol production is different for different seasons. In addition, the fermentation period is shorter in monsoon as compared to spring and summer. As the fermentation period increases, the production of bioethanol yield increases up to a certain limit. The maximum bioethanol yields from the WSS were obtained as 0.183, 0.19, and 0.21 ml/g of dry WSS biomass in the spring, summer, and monsoon seasons for the fermentation period of 15, 9, and 11 days respectively. Consequently, it has been found that the enhancement in maximum bioethanol yield in the monsoon season is 8.42% and 12.57% as compared to the summer and spring seasons, respectively.

Bioethanol production from sorghum grain with Zymomonas mobilis: increasing the yield and quality of raw distillates.

The present study aimed to demonstrate the superiority of bioethanol yield and its quality from sorghum using the granular starch degrading enzyme Stargen™ 002 over simultaneous saccharification and fermentation, and separate hydrolysis and fermentation using Zymomonas mobilis CCM 3881 and Ethanol Red® yeast. Bacteria were found to produce ethanol at higher yield than the yeast in all fermentations. The highest ethanol yield was obtained with Z. mobilis during 48 h of simultaneous saccharification and fermentation (83.85% theoretical yield) and fermentation with Stargen™ 002 (81.27% theoretical yield). Pre-liquefaction in fermentation with Stargen™ 002 did not improve ethanol yields for both Z. mobilis and Saccharomyces cerevisiae. Chromatographic analysis showed twice less total volatile compounds in distillates obtained after bacterial (3.29-5.54 g L-1 ) than after yeast (7.84-9.75 g L-1 ) fermentations. Distillates obtained after bacterial fermentation were characterized by high level of aldehydes (up to 65% of total volatiles) and distillates obtained after yeast fermentation of higher alcohols (up to 95% of total volatiles). The process of fermentation using granular starch hydrolyzing enzyme cocktail Stargen™ 002 resulted in low amounts of all volatile compounds in distillates obtained after bacterial fermentation, but the highest amounts in distillates obtained after yeast fermentation. The present study emphasizes the great potential of bioethanol production from sorghum with Z. mobilis using granular starch hydrolyzing enzyme Stargen™ 002, which leads to reduced water and energy consumption, especially when energy sources are strongly related to global climate change. © 2023 Society of Chemical Industry.

Improved production of bioethanol from alkali-pretreated lignocellulosic feedstock using Saccharomyces cerevisiae under simultaneous saccharification and fermentation

The most plentiful bioresource on earth is lignocellulosic biomass. The breakdown of lignocellulosic biomass attains different fermentable sugars which are considered to be very significant for the manufacturing of biogas, bioethanol etc. The major composition of lignocellulosic biomass is cellulose, lignin and hemicelluloses which are strongly linked with each other by hydrogen and covalent linkages thus generating a tough and rigid structure. The recalcitrant structure of lignin resists to solubilization thus arresting the degradation of cellulose and hemicelluloses present in bioplymeric structure. This addresses a striking challenge for the production of biofuels. To cope up with these limitations, immense research has been carried out for the development of pretreatment strategies. The present study utilized the alkaline pretreatment approach to digest cellulose, hemicelluloses and lignin content in locally available different agroindustrial wastes. This study employed Simultaneous Saccharification and Fermentation (SSF) process for bioethanol production from selected lignocellulosic biomass. Prior to fermentation all collected biomass was treated with 1% NaOH and then fermentation was carried out using Saccharomyces cerevisiae. The SSF was conducted at 30°C for 4-5 days. Along with pretreated biomass, untreated biomass was also subjected to SSF in order to compare the yield of bioethanol. The results of present research elaborate that pretreatment with 1% NaOH significantly degraded the complex polymeric structure of biomass hence induced enhanced production of bioethanol as compared to untreated agrowaste. Among all lignocellulosic biomass, pretreated banana peels attained higher production of bioethanol 118g/L with fermentation efficiency 139.75% and sugar utilization 97.9% than untreated banana peels achieved maximum ethanol production 42.4g/L with fermentation efficiency 53% and sugar utilization 68%. These findings indicate that before fermentation, a suitable pretreatment protocol must be applied to lignocellulosic substrates in order to increase the yield of ethanol and to meet the commercial needs.

Effect of nickel oxide nanoparticles on bioethanol production by Pichia kudriavzveii IFM 53048 using banana peel waste substrate

ABSTRACT The use of nanomaterials in bioethanol production is promising and on the increase. In this report, the effect of nickel oxide nanoparticles (NiO NPs) on bioethanol production in the presence of a novel yeast strain, Pichia kudriavzveii IFM 53048 isolated from banana wastes was investigated. The hot percolation method was employed for the green synthesis of NiO NPs. The logistic and modified Gompertz kinetic models employed in this study showed a 0.99 coefficient of determination (R2) on cell growth, and substrate utilization on the initial rate data plot which indicate that these model were best suited for bioethanol production studies. As a result, 99.95% of the substrate was utilized to give 0.23 g/L/h−1 bioethanol productivity, and 51.28% fermentation efficiency, respectively. At 0.01 wt% of NiO NPs, maximum production was achieved with 0.27 g/g bioethanol yield. Meanwhile, 0.78 h−1 maximum specific growth rate (µmax) of the microorganism, 3.77 g/L bioethanol concentration (Pm), 0.49 g/L/h production rate (rp.m), and 2.43 h production lag time (tL) were obtained when 0.01 wt% of NiO NPs were used during the bioethanol production process. However, a decrease in bioethanol concentrations occurred at ≥0.02 wt% of NiO NPs. The incorporation of NiO NPs in the simultaneous saccharification and fermentation (SSF) process improved the production of bioethanol by 1.90 fold using banana peel wastes as substrate. These revealed NiO NPs could serve as a suitable biocatalyst in the green production of bioethanol from banana peel waste materials.

Co-production of ethanol and polyhydroxybutyrate from lignocellulosic biomass using an engineered Saccharomyces cerevisiae

The development of glucose/xylose co-fermenting Saccharomyces cerevisiae has improved bioethanol yield from lignocellulosic biomass, the most abundant and sustainable resource for net-zero production of fuels and chemicals. The co-production of value-added chemicals would further improve the economic feasibility of lignocellulosic bioethanol production. Here, we developed a glucose/xylose co-fermenting S. cerevisiae strain capable of co-producing polyhydroxybutyrate, a prominent biodegradable polymer, as an intracellularly accumulated co-product by introducing a polycistronic polyhydroxybutyrate biosynthetic pathway. The engineered strain accumulated polyhydroxybutyrate with a content of 64 mg/g DCW while maintaining extracellular production of ethanol with a high yield (0.43 g ethanol/g sugar). The co-production of ethanol and polyhydroxybutyrate was then evaluated using various types of biomass, including sugarcane bagasse, silver grass, and even cardboard boxes. This study demonstrates the feasibility of co-production of bioethanol and value-added chemicals to maximize the values derivable from lignocellulosic biomass.

Valorization potential of pine needle waste biomass: recent trends and future perspectives.

Pines play a significant role in forest biodiversity globally and generate huge forest litter. Dry pine needles due to low ignition temperature and high frictional force with the ground catch fire quickly. Annual forest fires in the northern states of India greatly impact the Indian economy besides causing huge loss to biodiversity, livelihood, and environment. Pine needles are also considered unfit for fodder consumption due to presence of tannins. Although the presence of softwood lignin in pine needles makes it difficult to degrade easily, the presence of holocellulose (68.5%) containing 45-51% cellulose makes this biomass a potential substrate to be used in pulp-making industries for low-grade paper sheets. The good fiber length of pine needles (1.3-1.4mm) with a diameter of 30-32μm, maybe considered important property for paper making. The use of pine needles in the pharmaceutical and food industries are due to the presence of secondary metabolites (α-pinene, β-pinene, caryophyllene etc.). The various other potential applications of pine needles are for producing bio-ethanol (yield, 3.98%; purity, 94%), biogas (yield, 23.1 L kg-1), smokeless briquettes (calorific value, 18.77MJkg-1), biochar (calorific value, 25.6MJkg-1), bio-composites (tensile strength, 21-60MPa), and bio-pesticides. This paper comprehensively reviews the current applications of pine needles along with its future prospective applications that can have the dual advantage of providing employment opportunities to the people along with environmental protection.