Separate Hydrolysis And Fermentation Research Articles

Interdependence between lignocellulosic biomasses, enzymatic hydrolysis and yeast cell factories in biorefineries.

SummaryBiorefineries have a pivotal role in the bioeconomy scenario for the transition from fossil‐based processes towards more sustainable ones relying on renewable resources. Lignocellulose is a prominent feedstock since its abundance and relatively low cost. Microorganisms are often protagonists of biorefineries, as they contribute both to the enzymatic degradation of lignocellulose complex polymers and to the fermentative conversion of the hydrolyzed biomasses into fine and bulk chemicals. Enzymes have therefore become crucial for the development of sustainable biorefineries, being able to provide nutrients to cells from lignocellulose. Enzymatic hydrolysis can be performed by a portfolio of natural enzymes that degrade lignocellulose, often combined into cocktails. As enzymes can be deployed in different operative settings, such as separate hydrolysis and fermentation (SHF) or simultaneous saccharification and fermentation (SSF), their characteristics need to be combined with microbial ones to maximize the process. We therefore reviewed how the optimization of lignocellulose enzymatic hydrolysis can ameliorate bioethanol production when Saccharomyces cerevisiae is used as cell factory. Expanding beyond biofuels, enzymatic cocktail optimization can also be pivotal to unlock the potential of non‐Saccharomyces yeasts, which, thanks to broader substrate utilization, inhibitor resistance and peculiar metabolism, can widen the array of feedstocks and products of biorefineries.

Enzymatic Hydrolysis and Fermentation of Banana Pseudostem Hydrolysate to Produce Bioethanol.

Banana pseudostem (BPS) is an agricultural waste with a high holocellulose content, which, upon hydrolysis, releases fermentable sugars that can be used for bioethanol production. Different pretreatment methods, namely, 3% (w/v) NaOH, 5% (v/v) H2SO4, and liquid hot water, applied on the BPS resulted in the availability of 52%, 48%, and 25% cellulose after treatment, respectively. Saccharification of the pretreated BPS with 10 FPU/g dry solids (29.3 mg protein/g d.s) crude enzyme from Trichoderma harzianum LMLBP07 13-5 at 50°C and a substrate loading of 10 to 15% released 3.8 to 21.8 g/L and from T. longibrachiatum LMLSAUL 14-1 released 5.4 to 43.5 g/L glucose to the biomass. Ethanol was produced through separate hydrolysis and fermentation (SHF) of alkaline pretreated BPS hydrolysate using Saccharomyces cerevisiae UL01 at 30°C and 100 rpm. Highest ethanol produced was 17.6 g/L. Banana pseudostem was shown as a potentially cheap substrate for bioethanol production.

Bioethanol Production from Cellulose-Rich Corncob Residue by the Thermotolerant Saccharomyces cerevisiae TC-5.

This study aimed to select thermotolerant yeast for bioethanol production from cellulose-rich corncob (CRC) residue. An effective yeast strain was identified as Saccharomyces cerevisiae TC-5. Bioethanol production from CRC residue via separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), and prehydrolysis-SSF (pre-SSF) using this strain were examined at 35–42 °C compared with the use of commercial S. cerevisiae. Temperatures up to 40 °C did not affect ethanol production by TC-5. The ethanol concentration obtained via the commercial S. cerevisiae decreased with increasing temperatures. The highest bioethanol concentrations obtained via SHF, SSF, and pre-SSF at 35–40 °C of strain TC-5 were not significantly different (20.13–21.64 g/L). The SSF process, with the highest ethanol productivity (0.291 g/L/h), was chosen to study the effect of solid loading at 40 °C. A CRC level of 12.5% (w/v) via fed-batch SSF resulted in the highest ethanol concentrations of 38.23 g/L. Thereafter, bioethanol production via fed-batch SSF with 12.5% (w/v) CRC was performed in 5-L bioreactor. The maximum ethanol concentration and ethanol productivity values were 31.96 g/L and 0.222 g/L/h, respectively. The thermotolerant S. cerevisiae TC-5 is promising yeast for bioethanol production under elevated temperatures via SSF and the use of second-generation substrates.

L-lactic acid production from multi-supply autohydrolyzed economically unexploited lignocellulosic biomass

The present paradigm of a new concept of biomass conversion system has been focused on the development of a multi-supply biorefinery concept towards a circular and sustainable bioeconomy.This work was focused on evaluating a mixture of six lignocellulosic biomass types, from forest ecosystems and biological resources from marginal land, in order to produce lactic acid (L-LA) by Lactobacillus rhamnosus within a multi-supply biorefinery scheme. The mixture of lignocellulosic biomass was submitted to autohydrolysis pretreatment under non-isothermal regime at 226 °C (corresponding to a severity of 4.15) yielding a glucan recovery of 93 % in the solid phase.Two different strategies were assayed for L-LA production, namely separated hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF). The glucose to LA yield obtained for both assays was 1 g/g, although the volumetric productivity of SSF (2.5 g/Lh) was higher than SHF (0.8 g/Lh). Therefore, the SSF process was optimized through a factorial design to evaluate the effect of the independent variables, solids load (SL) and enzyme-substrate ratio (ESR), on LA production. The maximum concentration of LA was obtained using the highest solids load (16 %) and with the highest ESR (54 FPU/g). Finally, L-LA was produced using in a bioreactor under the optimized conditions from experimental design, obtaining 61.74 g/L of LA at 44 h, with an optical purity of 98 % and a LA yield of 0.97 g/g. This study showed the potential of multi-supply unexploited lignocellulosic biomass as a raw material to LA fermentation.

Poly-γ-glutamic acid production by simultaneous saccharification and fermentation using corn straw and its fertilizer synergistic effect evaluation.

Agricultural wastes rich in lignocellulosic biomass have been used in the production of poly-γ-glutamic acid (γ-PGA) through separate hydrolysis and fermentation (SHF), but this process is complicated and generates a lot of wastes. In order to find a simpler and greener way to produce γ-PGA using agricultural wastes, this study attempted to establish simultaneous saccharification and fermentation (SSF) with citric acid-pretreated corn straw. The possibility of Bacillus amyloliquefaciens JX-6 using corn straw as substrate to synthesize γ-PGA was validated, and the results showed that increasing the proportion of glucose in the substrate could improve the γ-PGA yield. Based on these preliminary results, the corn straw was pretreated using citric acid. Then, the liquid fraction (xylan-rich) was used for cultivation of seed culture, and the solid fraction (glucan-rich) was used as the substrate for SSF. In a 10-L fermenter, the maximum cumulative γ-PGA concentration in batch and fed-batch SSF were 5.08 ± 0.78g/L and 10.78 ± 0.32g/L, respectively. Moreover, the product from SSF without γ-PGA extraction was used as a fertilizer synergist, increasing the yield of pepper by 13.46% (P < 0.05). Our study greatly simplified the production steps of γ-PGA, and each step achieved zero emission as far as possible. The SSF process for γ-PGA production provided a simple and green way for lignocellulose biorefinery and sustainable cultivation in agriculture.

Augmented ethanol production from alkali-assisted hydrothermal pretreated cassava peel waste

ABSTRACT Cassava peel is a by-product produced at large amounts in starch-based agro industries and could be a major feedstock for bioethanol in most of the Asian countries. In this work, we aimed to evaluate two fermentation strategies for bioethanol production from alkali-assisted hydrothermal pretreated cassava peel by thermotolerant Kluyveromyces marxianus MTCC 4139 strain. Initially, milled cassava peel was subjected to alkali-assisted hydrothermal pretreatment at different autoclaving temperatures (110°C − 130°C) and residence times (15 − 30 min) in the presence of different NaOH concentrations (0.25%−1.0% w/v NaOH). On subsequent enzymatic hydrolysis of pretreated cassava peel (1% NaOH at 120°C for 30 min) with different optimal enzyme loadings (α-amylase, glucoamylase and cellulase) showed maximum 670.58 ± 10.13 mg/g reducing sugar yield with 81.25% ± 3.20% saccharification efficiency. Furthermore, SHF (separate hydrolysis and fermentation) and SSF (simultaneous saccharification and fermentation) of cassava hydrolyzates were studied for improved ethanol yield and fermentation efficiencies. SSF of hydrothermal pretreated cassava hydrolyzate with K. marxianus strain showed higher ethanol yield (0.44 g/g) with 86.11% fermentation efficiency as compared to SHF process (0.41 g/g; 80.24% fermentation efficiency).

Comparison of Enzymatic and Acidic Fractionation of Corn Fiber for Glucose-rich Hydrolysate and Bioethanol Production by Candida boidinii

Corn fiber is a by-product of the corn wet milling process and a promising raw material to produce bioethanol in a bio-refinery process. In this study, enzymatic and acidic fractionations of corn fiber were compared with particular attention to produce glucose-rich hydrolyzates. The acidic fractionation contained two, sequential, sulphuric acid-catalyzed, hydrolysis steps based on our previous study. In the enzymatic fractionation process, corn fiber was pre-treated by soaking in aqueous ammonia (18.5 % (w/w) dry matter, 15 % (w/w) ammonia solution, 24 hours) and then hydrolyzed by using Hemicellulase (NS 22002) enzyme cocktail. The cellulose part of the solid residues obtained after the acidic and enzymatic fractionation processes was enzymatically hydrolyzed by using Cellic Ctec2 and Novozymes 188 (12.5 % (w/w) dry matter, 50 °C, 72 hours). Cellulose hydrolysis after the acidic and enzymatic fractionation resulted in a supernatant containing 64 g/L and 25 g/L glucose, respectively. Therefore, ethanol fermentation experiments were performed in Separated Hydrolysis and Fermentation (SHF) and Simultaneous Saccharification and Fermentation (SSF) configurations after the acidic fractionation of corn fiber. SHF configuration was found to be more advantageous regarding the achievable ethanol yield. Although the fermentation with Candida boidinii NCAIM Y.01308 was accomplished within longer time (43 hours) compared to Saccharomyces cerevisiae (5 hours), the achieved ethanol yields were similar (79%) during the SHF process. It was concluded that acidic fractionation is more efficient to produce glucose-rich hydrolyzate from corn fiber compared to enzymatic fractionation, and Candida boidinii is suitable for ethanol fermentation on the glucose-rich hydrolyzate.

Biochemical properties of cellulolytic and xylanolytic enzymes from Sporotrichum thermophile and their utility in bioethanol production using rice straw

Production of cellulolytic and xylanolytic enzymes by Sporotrichum thermophile was enhanced using response surface methodology in solid-state fermentation (SSF) using wheat straw and cotton oil cake. Cellulolytic and xylanolytic enzymes were partially purified by ammonium sulfate precipitation followed by ion exchange and gel filtration chromatographic techniques. Xylanase of S. thermophile is neutral xylanase displaying optimal activity at 60 °C with Km and Vmax values of 0.2 mg/mL and 238.05 µmole/min, respectively. All cellulases produced by the thermophilic mold showed optimal activity at pH 5.0 and 60 °C with Km values of 0.312 mg/mL, 0.113 mg/mL, and 0.285 mM for carboxymethyl cellulase (CMCase), filter paper cellulase (FPase), and β-glucosidase, respectively and while Vmax values were 181.81, 138.88, and 66.67 µmole/min, respectively. The presence of various metal ions (Ca2+ and Co2+), chemical reagent (glutaraldehyde), and surfactants (Tween 80 and Triton X-100) significantly improved the activities of all enzymes. All the enzymes showed high storage stability under low temperature (−20 and 4 °C) conditions. Cellulolytic and xylanolytic enzymes resulted in enhanced liberation of reducing sugars (356.34 mg/g) by hydrolyzing both cellulosic and hemicellulosic fractions of ammonia-pretreated rice straw as compared to other pretreatment methods used in the study. Fermentation of enzymatic hydrolysate resulted in the formation of 28.88 and 27.18 g/L of bioethanol in separate hydrolysis and fermentation (SHF) process by Saccharomyces cerevisiae and Pichia stipitis, respectively. Therefore, cellulolytic and xylanolytic enzymes of S. thermophile exhibited ideal properties of biocatalysts useful in the saccharification of cellulosic and hemicellulosic fractions of rice straw for the production of bioethanol.

Scaling-up and techno-economics of ethanol production from cassava starch via separate hydrolysis and fermentation

Nowadays bioethanol is being used extensively in fuel production because of its technical feasibility, economically competitive, and environmentally friendly. It is expected that biofuel will contribute to 30% of the global energy demand by 2050. Therefore, it is very important to investigate any cost-effective bioprocessing that can improve the overall production yield. The study aims to produce bioethanol from cassava starch by Kluyveromyces marxianus at a laboratory scale and a 5L fermentation rig. A separate hydrolysis and fermentation (SHF) process of cassava starch was introduced due to high sugar content in starch, using a thermoanaerobe able to reduce the cooling time after hydrolysis. A combination of 0.35% v/w amylase and 0.20% v/w amyloglucosidase used in the hydrolysis of cassava starch produced 19.18 g/L of sugar. A 15 g/L of K. marxianus showed to be the best yeast concentration which could produce the highest bioethanol, 42.85 g/L. When the laboratory scale was scaled up to 5 L fermentation, the result was comparable at 42.33 g/L. The same SHF parameters in laboratory scale had been proven to be effective in a larger scale fermentation based on similar results obtained. Simulation using SuperPro software indicated that 50.13% of starch can be converted into ethanol.

Ethanol Production from Alkaline-treated Rice Straw via Separate Hydrolysis and Fermentation (SHF) using K. marxianus UniMAP 1-1

The decreasing reserves of non-renewable energy especially fossil fuel has led to an urgent need to establish alternative fuels. Ethanol is one of the energies explored, which can be generated by fermentation method. The use of environmentally friendly material such as lignocellulosic biomass to develop a biofuel is significant. Ethanol production at high temperature was preferred as it will significantly reduce the cooling cost involved. Thus, the use of thermotolerant strain in the fermentation process was recommended. In this study, separate hydrolysis and fermentation (SHF) was employed to produce ethanol from 2% sodium hydroxide-treated rice straw using cellulase enzyme, and fermented by a thermotolerant K. marxianus UniMAP 1-1 strain. The fermentation process was done at two different temperatures, 37°C and 50°C, at pH 4.8. The ethanol yield from both 37°C and 50°C was 0.36 g/g and 0.38 g/g, respectively. K. marxianus UniMAP 1-1 showed a good production of ethanol at elevated temperature. This is the first study reporting ethanol production from rice straw using K. marxianus UniMAP 1-1. Thus, this study can improve our understanding of the development of thermotolerant yeast accountable to the SHF process for ethanol production.

Consolidated bioprocessing of lignocellulose for production of glucaric acid by an artificial microbial consortium

BackgroundThe biomanufacturing of d-glucaric acid has attracted increasing interest because it is one of the top value-added chemicals produced from biomass. Saccharomyces cerevisiae is regarded as an excellent host for d-glucaric acid production.ResultsThe opi1 gene was knocked out because of its negative regulation on myo-inositol synthesis, which is the limiting step of d-glucaric acid production by S. cerevisiae. We then constructed the biosynthesis pathway of d-glucaric acid in S. cerevisiae INVSc1 opi1Δ and obtained two engineered strains, LGA-1 and LGA-C, producing record-breaking titers of d-glucaric acid: 9.53 ± 0.46 g/L and 11.21 ± 0.63 g/L d-glucaric acid from 30 g/L glucose and 10.8 g/L myo-inositol in fed-batch fermentation mode, respectively. However, LGA-1 was preferable because of its genetic stability and its superior performance in practical applications. There have been no reports on d-glucaric acid production from lignocellulose. Therefore, the biorefinery processes, including separated hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF) and consolidated bioprocessing (CBP) were investigated and compared. CBP using an artificial microbial consortium composed of Trichoderma reesei (T. reesei) Rut-C30 and S. cerevisiae LGA-1 was found to have relatively high d-glucaric acid titers and yields after 7 d of fermentation, 0.54 ± 0.12 g/L d-glucaric acid from 15 g/L Avicel and 0.45 ± 0.06 g/L d-glucaric acid from 15 g/L steam-exploded corn stover (SECS), respectively. In an attempt to design the microbial consortium for more efficient CBP, the team consisting of T. reesei Rut-C30 and S. cerevisiae LGA-1 was found to be the best, with excellent work distribution and collaboration.ConclusionsTwo engineered S. cerevisiae strains, LGA-1 and LGA-C, with high titers of d-glucaric acid were obtained. This indicated that S. cerevisiae INVSc1 is an excellent host for d-glucaric acid production. Lignocellulose is a preferable substrate over myo-inositol. SHF, SSF, and CBP were studied, and CBP using an artificial microbial consortium of T. reesei Rut-C30 and S. cerevisiae LGA-1 was found to be promising because of its relatively high titer and yield. T. reesei Rut-C30 and S. cerevisiae LGA-1were proven to be the best teammates for CBP. Further work should be done to improve the efficiency of this microbial consortium for d-glucaric acid production from lignocellulose.

Surfactant-assisted green liquor dregs pretreatment to enhance the digestibility of paper mill sludge

This study optimizes a novel surfactant-assisted green liquor dregs (GLD) pretreatment of paper mill sludge (PMS), both of which are wastes from the kraft pulping industry, using a combined Response Surface Methodology (RSM) design. Optimized conditions give a maximal reducing sugar release of 16.38 g/L. A substantial reduction in heavy metals aluminum, chromium, cobalt, arsenic, lead, and copper after pretreatment illustrates the enhancement of substrate digestibility by reducing toxic elements. Separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) for hydrogen production are assessed. SSF produced a hydrogen yield of 3.72 mL/g, displaying a 36.26% increase from pretreated PMS compared to SHF. These findings provide insights into possible methods of reducing process duration, energy input, and costs incurred with waste disposal within the paper industry. Furthermore, improved hydrogen yield using an SSF process demonstrates the potential beneficiation of pulp and paper GLD and PMS wastes.

Cellulosic Bioethanol from Industrial Eucalyptus globulus Bark Residues Using Kraft Pulping as a Pretreatment

The pulp and paper industry faces an emerging challenge for valorising wastes and side-streams generated according to the biorefinery concept. Eucalyptus globulus bark, an abundant industrial residue in the Portuguese pulp and paper sector, has a high potential to be converted into biobased products instead of being burned. This work aimed to evaluate the ethanol production from E. globulus bark previously submitted to kraft pulping through separate hydrolysis and fermentation (SHF) configuration. Fed-batch enzymatic hydrolysis provided a concentrated hydrolysate with 161.6 g·L−1 of cellulosic sugars. S. cerevisiae and Ethanol Red® strains demonstrated a very good fermentation performance, despite a negligible xylose consumption. S. passalidarum, a yeast known for its capability to consume pentoses, was studied in a simultaneous co-culture with Ethanol Red®. However, bioethanol production was not improved. The best fermentation performance was achieved by Ethanol Red®, which provided a maximum ethanol concentration near 50 g·L−1 and fermentation efficiency of 80%. Concluding, kraft pulp from E. globulus bark showed a high potential to be converted into cellulosic bioethanol, being susceptible to implementing an integrated biorefinery on the pulp and paper industrial plants.

Transformation of lignocellulose from corn stove for bioethanol production

The use of fossil fuels, as well as the environmental issues associated with their burning, has pushed for the development of clean, renewable energy sources. Biofuels made from lignocellulosic biomass are considered a carbon-neutral and sustainable method. As the demand for non-petroleum fuels grows, more attention will be placed on developing a cost-competitive liquid transportation biofuel like ethanol. This study was conducted to produce bioethanol utilizing the SHF (separate hydrolysis and fermentation) technique from corn stove lignocellulose. Pretreatment with sodium hydroxide at various concentrations was also studied. The influence of enzymatic saccharification, fermentation time, and substrate concentration on sugar yield and, eventually, ethanol production was investigated. Fermentation was carried out by using the enzymatically saccharified hydrolysate and monoculture of Saccharomyces cerevisiae. The results reveal that pretreatment with 2% NaOH followed by 48 hours of hydrolysis produced the maximum bioethanol production (30.21 ±0.13 g/L). This study findings indicated that alkali-pretreated corn stove might be used as a feedstock for bioethanol production, reducing reliance on fossil fuels.

PEMBUATAN BIOETANOL DARI ROTI SISA DENGAN PROSES HIDROLISA ENZIMATIS DAN FERMENTASI

Bread waste contains 57% carbohydrate, that can be used as the raw material of bioethanol production. This research aims was to study the producing bioethanol process from bread waste, and to determine the effect of catalyst concentration of enzyme glucoamylase (Aspergillus Niger). The bioethanol production with bread waste consisted of three stages: hydrolysis (liquification and sacharification), fermentation and distillation. Saccharification performed for 6 hours at 30oC and pH 4.5 using a variable catalyst enzyme glucoamylase (Aspergillus Niger), with 6, 8, 10, and 12 ml/200 ml of media. The glucose level value in sacharification process is obtained of 12.85 gr/ml, 137.236 gr/ml, 154.82 gr/ml, and 198.0327 gr/ml. The optimum value of glucose level occurs in the glucoamylase (Aspergillus Niger) enzyme addition of 12 ml. In separated hydrolysis and fermentation (SHF) process, there is a separation of glucose formation from starch (hydrolysis) and glucose reduction into bioethanol (fermentation). The enzyme catalyst (Aspergillus Niger) with 6, 8, 10, and 12 ml/200 ml media, it is obtained the bioethanol reduction value respective conditions of 14.1261%, 18.4909%, 24.7592%, and 28.6993%. The optimum condition is obtained in the glucoamylase (Aspergillus Niger) enzyme addition of 12 ml.

Optimization of Inulin Hydrolysis by Penicillium lanosocoeruleum Inulinases and Efficient Conversion Into Polyhydroxyalkanoates.

Inulin, a polydisperse fructan found as a common storage polysaccharide in the roots of several plants, represents a renewable non-food biomass resource for the synthesis of bio-based products. Exploitation of inulin-containing feedstocks requires the integration of different processes, including inulinase production, saccharification of inulin, and microbial fermentation for the conversion of released sugars into added-value products. In this work paper, a new microbial source of inulinase, Penicillium lanosocoeruleum, was identified through the screening of a fungal library. Inulinase production using inulin as C-source was optimized, reaching up to 28 U mL–1 at the 4th day of growth. The fungal inulinase mixture (PlaI) was characterized for pH and temperature stability and activity profile, and its isoenzymes composition was investigated by proteomic strategies. Statistical optimization of inulin hydrolysis was performed using a central composite rotatable design (CCRD), by analyzing the effect of four factors. In the optimized conditions (T, 45.5°C; pH, 5.1; substrate concentration, 60 g L–1; enzyme loading, 50 U gsubstrate –1), up to 96% inulin is converted in fructose within 20 h. The integration of PlaI in a process for polyhydroxyalkanoate (PHA) production by Cupriavidus necator from inulin was tested in both separated hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF). A maximum of 3.2 g L–1 of PHB accumulation, corresponding to 82% polymer content, was achieved in the SSF. The proved efficiency in inulin hydrolysis and its effective integration into a SSF process pave the way to a profitable exploitation of the PlaI enzymatic mixture in inulin-based biorefineries.

THERMOCHEMICAL PRETREATMENT METHOD FOLLOWED BY ENZYME HYDROLYSIS OF TOBACCO STALKS FOR BIOETHANOL PRODUCTION

Energy use from fossil fuels increases, causing an energy crisis, increasing greenhouse gases, and other environmental issues. In this study, obtaining renewable energy sources from biomass to replace fossil fuels is vital for future energy supply. Ethanol production from lignocellulosic materials was gain more attention recently. It is an interesting process and an alternative way countries with agricultural waste can be recycled as energy. To convert such waste biomass source into energy in ethanol needed to adjust cellulose conversion to different suitability. Therefore, to obtain the fermentable sugars for bioethanol production, the pretreatment process involved a vital role. In this experimental study, 4% of calcium oxide (CaO) was applied. Moreover, a scanning electron microscope (SEM) distinguished the characteristics of untreated and pretreated samples. In this study, the separated hydrolysis and fermentation (SHF) method was used for bioethanol production. Total and reducing sugars yield confirmed that tobacco stalks are suitable feedstock for bioethanol production.

A Comparison of the Bioethanol Production from Suweg (Amorphophallus campanulatus) through Separate Hydrolysis and Fermentation as well as Simultaneous Saccharification and Fermentation Using Saccharomyces cerevisiae

Suweg has the potential to develop bioethanol because of the high starch content. This is a form of ethanol produced from living organisms. The processes used include separate hydrolysis and fermentation (SHF) as well as simultaneous saccharification and fermentation (SSF). Furthermore, the components utilised in this study include StargenTM 002 (1.5%, w/w) for hydrolysis, Saccharomyces cerevisiae for fermentation at a temperature, and PH of 30ºC and 4.5 respectively, with varying starch concentrations (150-250 gL−1). The results showed the highest ethanol yield of 89.57 and 99.52 gL−1 from SHF and SSF, respectively from a suweg concentration of 200 gL−1 treated for 54 h. Meanwhile, 250 gL−1 samples attained 62.22; 99.57; and 101.56 gL−1, respectively. Therefore, SSF method provided a more efficient process for producing bioethanol using the 250 gL−1 concentration, although the increase from 200 gL−1 to 250 gL−1 only produced a 1.96% higher yield.

Enzymatic Hydrolysate of Cinnamon Waste Material as Feedstock for the Microbial Production of Carotenoids

In the context of the global need to move towards circular economies, microbial cell factories can be employed thanks to their ability to use side-stream biomasses from the agro-industrial sector to obtain additional products. The valorization of residues allows for better and complete use of natural resources and, at the same time, for the avoidance of waste management to address our needs. In this work, we focused our attention on the microbial valorization of cinnamon waste material after polyphenol extraction (C-PEW) (Cinnamomum verum J.Presl), generally discarded without any additional processing. The sugars embedded in C-PEW were released by enzymatic hydrolysis, more compatible than acid hydrolysis with the subsequent microbial cultivation. We demonstrated that the yeast Rhodosporidium toruloides was able to grow and produce up to 2.00 (±0.23) mg/L of carotenoids in the resulting hydrolysate as a sole carbon and nitrogen source despite the presence of antimicrobial compounds typical of cinnamon. To further extend the potential of our finding, we tested other fungal cell factories for growth on the same media. Overall, these results are opening the possibility to develop separate hydrolysis and fermentation (SHF) bioprocesses based on C-PEW and microbial biotransformation to obtain high-value molecules.

Integrating enzymatic hydrolysis into subcritical water pretreatment optimization for bioethanol production from wheat straw

The conversion of lignocellulosic biomass to bioethanol is a potential approach to alleviate the energy crisis and environmental deterioration. To improve the conversion efficiency of bioethanol from wheat straw (WS), the optimization of subcritical water pretreatment and high solid hydrolysis were investigated in this study. Response surface methodology (RSM) accompanied with glucose concentration after enzymatic hydrolysis as a more reasonable response value was applied for the pretreatment optimization, and the optimum conditions were obtained as 220.51 °C of extraction temperature, 22.01 min of extraction time and 2.50% (w/v) of substrate loading. After pretreatment, the hemicellulose decreased by 18.37%, and the cellulose and lignin increased by 25.92% and 8.81%, respectively, which were consistent with the destroyed microstructure and raised crystallinity. The high efficiency of separate hydrolysis and fermentation (SHF) was verified by five commercial cellulases, and yields of hydrolysis and fermentation were 77.85–89.59% and 93.34–96.18%, respectively. Based on the high solid (15%) hydrolysis and fermentation, the ethanol concentration was significantly improved to 37.00 g/L. Interestingly, 64.47% of lignin was accumulated in the solid residue after enzymatic hydrolysis and it did not affect the efficiency of SHF, which further suggested that subcritical water mainly affected the structure of WS rather than the removal of lignin. Therefore, subcritical water pretreatment combined with high solid hydrolysis is a more effective solution for bioethanol conversion, which is also a promising strategy to utilize all components of lignocellulosic biomass.