Separate Hydrolysis And Fermentation Research Articles

Optimization of enzymatic hydrolysis of cellulose extracted from bamboo culm for bioethanol production by Saccharomyces cerevisiae modified via CRISPR/Cas9

In the context of biorefinery, researchers have been looking for lignocellulosic biomasses and ideal treatments to produce economically viable biofuels. In this scenario, the bamboo culm appears as a plant matrix of great potential, given the high cellulose content of low crystallinity. Thus, the objective and differential of this work was to determine the best conditions for enzymatic hydrolysis of cellulose extracted from bamboo culm and to evaluate its potential application in the production of bioethanol through Separate Hydrolysis and Fermentation (SHF) and Saccharification and Simultaneous Fermentation (SSF) by Saccharomyces cerevisiae modified via CRISPR/Cas9. The average cellulose extraction yield was 41.87 % with an extraction efficiency of 86.76 %. In general, as the hydrolysis time increased, an increase in glucose production was observed in almost all assays, with higher hydrolysis efficiency values at 72 h. The results ranged from 2.09 to 19.8 g/L of glucose obtained with efficiency values of 10.47 to 99 %. The best conditions were found in test 5 (temperature of 36 °C and pH 5.0, with only 10 FPU/g of substrate Cellic Ctec2 Novozymes ® cocktail). It is observed that for all hydrolysis times the independent variables pH and temperature were significant under the hydrolysis efficiency, showing a negative effect, indicating that higher values of the same promote lower values of the response variable. For bioethanol production, a maximum concentration of 7.84 g/L was observed for the SSH process after 4 h of fermentation, while for the SSF process it was 12.6 g/L after 24 h of fermentation, indicating the large potential of the simultaneous process together with the application of bamboo culm biomass for high production of biofuel.

A Short Review of Second-Generation Isobutanol Production by SHF and SSF

As isobutanol exhibits higher energy density and lower hygroscopicity than ethanol, it is considered a better candidate biofuel. The sustainable supply of inedible biomass and lack of competition with the food supply have stimulated significant worldwide interest in the production of isobutanol from this resource. Both separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) have been applied to isobutanol production to effectively utilize inedible biomass as a feedstock. However, both processes have various challenges, including low isobutanol yield and high production costs. This review summarizes the potential of isobutanol as a biofuel, methods for conferring isobutanol productivity, recent experimental studies, and developments in both SHF and SSF with the isobutanol-producing strains. Challenges to increasing the isobutanol yield and various suggestions for improvements to enable commercial production are also discussed.

Statistical optimization for comparative hydrolysis and fermentation for hemicellulosic ethanolgenesis

The concept of ‘Energy from waste’ is one of the most focused areas of work to find a solution for controlling trash and combat energy crises. In Pakistan and other agricultural countries, because of their substantial use during the summer, watermelon peels as fruit waste are usually thrown out as a trash. This study supported the management of huge quantities of waste to value-added products at a commercial scale. The current study aims to select and subject xylanolytic and ethanologenic Bacillus cereus XG2 for water melon peels valorization appropriately with comparison of three hydrolysis techniques. The study will be helpful for selection of economical and environmentally beneficial valorization strategies. For ethanalogenesis, separate hydrolysis and fermentation (SHF) protocols with Saccharomyces cerevisiae K7 and Metchnikowia cibodasensis Y34 were used. For hydrolysis, three different saccharification approaches, viz. dilute sulfuric acid, enzymatic hydrolysis (using Bacillus cereus XG2 xylanases), and combined acidic and enzymatic hydrolysis, were adopted. Two statistical models, Placket-Burman (hydrolysis) and Central composite design (ethanologenesis) were used. In untreated watermelon waste (WW), reducing sugar, total lipids, total carbohydrates, and protein contents were calculated as 16.70±0.05 g/L, 3.20±0.02 g/L, 28.7±0.04 g/L, and 3.70±0.03 g/L, respectively. Similarly, the lignin (15.51±0.22%), hemicellulose (17.20±2.30%). and cellulose (52.26±0.33%) contents were also analyzed. Based on the significance of the Plackett–Burman model for enzymatic saccharification, the released reducing sugars as well as total sugars were 21.62±0.01 g/L and 43.30±1.55 g/L, respectively, and enzymatic hydrolyzate was adopted for further fermentation experiments. By CCD model, the highest ethanol yield calculated for yeast Metchnikowia cibodasensis Y34 was 0.4±0.04 g/g of fermentable sugars at 32.5oC with 50% enzymatic hydrolysate of WW by incubating for 8 days. It was suggested that SHF could be a beneficial approach to increase the conversion of hemicellulose to fermentable sugars to produce bioethanol on a large scale.

Bioethanol from Arthrospira platensis biomass using a combined pretreatment

With the aim to reduce the reliance on gasoline by supporting efficient bioethanol production to meet the biofuel goal of 46 % in the transportation sector by 2050, the present study proposes a combined pretreatment of microwave-assisted acid hydrolysis for bioethanol production, which was applied to commercially-produced microalgal biomass of Arthrospira platensis. The Separated Hydrolysis and Fermentation (SHF) method was applied to prevent sugar loss and produce a higher bioethanol yield. After examining the effect of acid concentrations (0, 0.1, 0.2, and 0.3 M) and hydrolysis duration (30, 60, 90, 120, and 180 min) on the fermentable sugars, it was discovered that both operation parameters had a major impact on the synthesis of monosaccharides. With a 0.3 M H2SO4 concentration and a 90-minute hydrolysis time at 100 °C, the maximum concentration of fermentable sugars of 11.60 g/L was obtained. Regarding the fermentable sugar yield, the suggested combined pretreatment (78.4 %) outperforms the literature-reported single pretreatment of acid hydrolysis (55 %), under comparable operating settings. After 96 h of anaerobic fermentation with Saccharomyces cerevisiae, the hydrolysate of the fermentable sugars produced 0.06 g ethanol/g biomass, corresponding to 0.35 g ethanol/g total carbohydrates in Arthrospira platensis.

Bio-2,3-butanediol production from banana waste: Preliminary techno-economic evaluation of processing strategies

This study evaluates different fermentation strategies to produce 2,3-butanediol (2,3-BD) from banana industry waste, such as whole bananas (fruit + peels) and banana peels, selecting the most favorable from a technical and economic point of view. Both residues have enough free sugars (17.8 %–35.8 %), glucan (11.0 %–14.2 %) and hemicellulose (2.8 %–6.3 %), to be promising substrates for 2,3-BD fermentation. Saccharification was studied by comparing enzymatic hydrolysis, hydrothermal pretreatment, and hydrothermal pretreatment followed by enzymatic hydrolysis. Different fermentation scenarios were also compared regarding the 2,3-BD yield and productivity: Separate Hydrolysis and Fermentation (SHF), Simultaneous Saccharification and Fermentation (SSF), and direct fermentation without prior saccharification using Paenibacillus polymyxa DSM-365 as the fermenting microorganism. The results showed that the pretreatment step was not necessary to improve the release of fermentable sugars. Enzymatic hydrolysis was the most effective alternative for maximizing sugar recovery, reaching sugar concentrations of 18.1 g/L (recovery: 92.5 %) for banana peels and 33.3 g/L (recovery: ∼100 %) for whole bananas. The SSF strategy led to higher 2,3-BD concentrations of 15.0 g/L and 26.6 g/L for banana peels and whole bananas, respectively. The preliminary economic analysis indicated that SSF and direct fermentation could be the more cost-effective process alternatives for banana peels and whole bananas, respectively. Thus, it was demonstrated that banana waste is an interesting resource for the production of 2,3-BD. The bioprocess can be competitive when using a low-cost raw material and reducing the number of process steps compared to traditional technologies.

Enzymatic hydrolysis of organosolv-pretreated corncob and succinic acid production by Actinobacillus succinogenes

In this study, the conversion of organosolv-treated corncob into monosaccharides through enzymatic saccharification was investigated, with the resulting monosaccharides being utilized as a carbon source to produce succinic acid. The synergy between the cellulase and xylanase provided 76% cellulose and 64% xylan digestibility at 50 °C and pH 5.2. In separate hydrolysis and fermentation (SHF), Actinobacillus succinogenes produced 12.7 g/L of succinic acid from the hydrolysate with 0.12 g/g yield based on the pretreated corncob. Simultaneous saccharification and fermentation (SSF) demonstrated better performance with 16 g/L succinic acid titer and 0.24 g/g yield, though SHF provided a higher production rate. The condition in the SSF (37 °C and pH near neutral) was suboptimal for the enzymes, thus the succinic acid production was limited by the saccharification step. These findings emphasize the potential of organosolv-treated corncob to serve as an enzymatic hydrolysis substrate without neutralization and detoxification, supplying glucose and xylose for succinic acid production by A. succinogenes.

CONVERSION OF PINEAPPLE PEEL GLUCOSE INTO BIOETHANOL USING SIMULTANEOUS SACCHARIFICATION AND FERMENTATION (SSF) METHOD AND SEPARATE HYDROLYSIS AND FERMENTATION (SHF) METHOD

This study aims to determine the bioethanol yield and characteristics from pineapple peel with two methods such as Simultaneous Saccharification and Fermentation (SSF) and Separate Hydrolysis and Fermentation (SHF). The percent yield of bioethanol produced from the fermentation of pineapple peel (Ananas comosus) with the Simultaneous Saccharification and Fermentation method was 63.50%, while the yield of bioethanol from the Separate Hydrolysis and Fermentation method was 58.75%. The physical characteristics of bioethanol pineapple peel waste using Simultaneous Saccharification and Fermentation method has a density of 0.8237 w/v whilst with Separate Hydrolysis and Fermentation is 0.8858 w/v. Furthermore, viscosity of bioethanol using Simultaneous Saccharification and Fermentation is 1.05 Cp whereas using Separate Hydrolysis and Fermentation is 1.02 Cp. Pineapple peel bioethanol method of Simultaneous Saccharification and Fermentation has concentration of 13% while Separate Hydrolysis and Fermentation method has concentration of 7.92%. FTIR spectra from SHF bioethanol missing the peak correlated with CH, CH3, and CO. These missing peaks is due to the high percentage of water. Furthermore, bioethanol from SSF method showed peaks corresponding to CH, CH3, and CO functional groups. It can be concluded that SSF method give bioethanol with optimum result.

Utilization of pretreated oil palm empty fruit bunches and their hydrolysate for ethanol production by Indonesian ethanologenic yeast

Abstract. Anita SH, Oktaviani M, Hermiati E. 2023. Utilization of pretreated oil palm empty fruit bunches and their hydrolysate for ethanol production by Indonesian ethanologenic yeast. Biodiversitas 24: 5243-5252. Oil Palm Empty Fruit Bunches (OPEFB) represent a polysaccharide-rich raw material with promising potential for ethanol production. This study aimed to investigate the ethanologenic yeasts, specifically Saccharomyces cerevisiae InaCC Y93 and Kluyveromyces marxianus InaCC Y119, affect bioethanol production in three different systems: Separate Hydrolysis and Fermentation (SHF), Simultaneous Saccharification and Fermentation (SSF), and Prehydrolysis-Simultaneous Saccharification and Fermentation (PSSF). This work is distinguished by the use of indigenous Indonesian yeast strains, including a thermotolerant strain. In the pretreatment process, 1.13% oxalic acid was added to OPEFB and subjected to microwave treatment at 190°C for 3.01 min. Subsequently, cellulase enzymes (40 FPU/g) and a 10% (w/v) yeast inoculum were introduced into 5.27 g dry weight of pretreated OPEFB pulp. The OPEFB acid hydrolysate was also subjected to fermentation. Ethanol content was monitored at 24 h intervals for 72 h. The PSSF system employs K. marxianus InaCC Y119 at 48 h exhibited the highest ethanol concentration, yielding 0.290 g/g, equivalent to approximately 51.20% of the theoretical yield. Additionally, K. marxianus InaCC Y119 demonstrated its capability to ferment the OPEFB acid hydrolysate into ethanol. These findings underscore the considerable potential of K. marxianus for applications in fermenting both hexose and pentose sugars to produce ethanol within higher-temperature systems.

Fed-batch SSF with pre-saccharification as a strategy to reduce enzyme dosage in cellulosic ethanol production

The pulp and paper industry is a strategic sector to be converted into a forest-based biorefinery, taking advantage of know-how, existing infrastructures and well-established logistic operations to deal with a daily high volume of forest residues. Bioethanol production from Eucalyptus globulus bark previously pretreated by kraft pulping was assessed following two configurations at the bioreactor scale: separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF). This last configuration was optimized by using a pre-saccharification and a fed-batch feeding (FB PS-SSF), allowing for a reduction in the enzyme dosage from 25 to 10 FPU gCH−1, which is very advantageous from an economic point of view. For 10 FPU gCH−1 enzyme dosage and 20 % (w/v) total solids loading, an ethanol concentration of around 70.6 g L−1 was accomplished, corresponding to overall conversion efficiency and productivity of about 78 % and 1.35 g L−1 h−1, respectively. Increasing solids loading from 20 to 26 % (w/v), using the same enzyme dosage, resulted in the highest ethanol concentration (84.6 g L−1) despite the too-long assay and the decline in productivity. Overall, FB PS-SSF improved bioethanol concentration and allowed decreased enzymatic usage over SHF, maintaining high ethanol concentration.

Exploration of separate hydrolysis and fermentation and simultaneous saccharification and co-fermentation for acetone, butanol, and ethanol production from combined diluted acid with laccase pretreated Puerariae Slag in Clostridium beijerinckii ART44

In this study, an efficient pretreatment technology was developed for the bioconversion of puerariae slag (PS) into biobutanol. To accelerate the enzymatic saccharification of PS, the method of dilute acid combined with laccase pretreatment (DALP) was performed. With this effort, the highest concentration of reducing sugar was 48.96 ± 1.69 g/L after enzymatic hydrolysis of the whole slurry pretreatment under the optimal condition. Subsequently, the highest butanol productivity (0.15 g/L/h) was obtained by the simultaneous saccharification and co-fermentation (SSCF), which was 114.29% higher than that of the separate hydrolysis and fermentation (SHF). Furthermore, the microstructural changes of PS after different pretreatment were initially investigated by FT-IR, and we found that the DALP method resulted in more severe damage during the pretreatment process, which could improve the efficiency of enzymatic saccharification. This study suggests that the DALP is an attainable and efficient pretreatment method for production of butanol in the SSCF process.

Enhanced lactic acid production by Lactobacillus rhamnosus ATCC 7469 through simultaneous saccharification and fermentation from household food waste

AbstractA large amount of household food waste (HFW) is generated yearly and may negatively impact the environment and human health. The recovery of value‐added chemicals lactic acid (LA) from HFW through anaerobic treatment is a promising approach. However, it remains a challenge to increase the LA yield. In this paper, the LA production from HFW was enhanced by Lactobacillus rhamnosus ATCC 7469 through simultaneous saccharification and fermentation (SSF). The results showed that the mixed commercial enzymes of plant enzymes (E1), animal proteases (E2), and glucoamylase (E3) were more conducive to LA production than those used separately. Compared to the separate hydrolysis and fermentation (SHF), the LA production increased by 14% in the SSF, and the glucose concentration showed different change rules. Additionally, an average LA concentration of 47.7 g L–1 was obtained by repeated batch fermentation through SSF. However, the maximum LA concentration decreased with the fermentation ongoing. The trend of decreasing LA production could be improved by repeated batch fermentation with supplementary inoculation.

Simultaneous saccharification and fermentation for biobutanol production from corn starch via ABE fermentation

The preparation of bio-butanol from corn starch requires saccharification and fermentation processes. In view of the fact that the pH value at the later stage of fermentation is applicable to the enzymatic hydrolysis of glucoamylase, the effects of simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) were compared in this paper. 11.2 g/L butanol and 21.5 g/L total solvent could be obtained by the SSF process, while the yield was 9.74 g/L butanol and 17.2 g/L total solvent in the SHF process. The SSF process required a shorter overall process time (120 h) than the SHF process (144 h) and resulted in a large increase of 38.9% in butanol productivity (2.25 g/Ld for SSF compared to 1.62 g/Ld for SHF). These results show that the application of SSF can reduce the fermentation overall time, simplify the fermentation process, and reduce equipment investment and operating costs.

Ethanol production from Agave salmiana leaves by semi and simultaneous saccharification and fermentation at high temperature using Kluyveromycesmarxianus

Second-generation ethanol production by separate hydrolysis and fermentation (SHF) currently remains economically unviable, and thus more profitable alternatives are being sought. In the present study, the lignocellulosic biomass (LB) of Agave salmiana leaves was evaluated in the production of bioethanol through the processes of SHF, semi-simultaneous saccharification and fermentation (SSSF), and simultaneous saccharification and fermentation (SSF). The leaves of A. salmiana were subjected to acid pretreatment (1% H2SO4) and then to saccharification at temperatures of 40 and 50 °C. The processes of SHF, SSSF, and SSF were evaluated at 40 °C using the yeast Kluyveromyces marxianus OFF1. The results show that saccharification at 50 °C released up to 103.12 ± 1.07 g/L of reducing sugars, while at a temperature of 40 °C, the value was 78.41 ± 0.80 g/L, and thus the enzyme retained 76% of its activity at the latter temperature. In the fermentation processes, sugar consumption was up to 89% and ethanol yield up to 94%. The maximum ethanol production was recorded with the process of SSF, with concentrations of 51.5 g/L, which were significant and at least 13% higher compared to the other processes. The results show that the thermotolerance of K. marxianus OFF1 allows fermentation at 40 °C and a more efficient SSF process for transforming the sugars from this agro-industrial waste into ethanol.

Biotechnology process for microbial lipid synthesis from enzymatic hydrolysate of pre-treated sugarcane bagasse for potential bio-oil production

Sugarcane bagasse is a lignocellulosic biomass waste produced from sugar and alcohol production. The aim of this study was to produce cellular lipids from sugarcane bagasse with a biotechnology process using microbial enzymes and lipid-accumulating yeast. Sugarcane bagasse, pre-treated with a steam explosion method, was subjected to enzymatic hydrolysis by a separate hydrolysis and fermentation (SHF) system, using crude enzymes from a new strain of Trichoderma SG2 (T. SG2) with or without supplementation with a commercial enzyme (Cellic CTec2). The mixture of both enzymes produced substantial amounts of sugar from pretreated sugarcane bagasse. In a multistage SHF process, in the second stage (21 + 21 h), a total of 26.92 g L−1 of sugar was converted. In another stage-wise process (21 + 21+21 h) of hydrolysis of residual biomass, 26.23 g L−1 of sugar was recorded; thus maximizing the production of fermentable sugars from bagasse. The cultivation of Rhodotorula sp. R1 in sugarcane bagasse enzymatic hydrolysate (BH) for lipid production was evaluated. The enrichment of the hydrolysate with d-glucose, Y-yeast extract, and P-peptone (BH + P20D20/N0.93) and (BH + Y10D20/N0.2) produced 7.69% and 10.50% of lipids, respectively. Similar to vegetable oils and other yeasts, the lipids accumulated by Rhodotorula R1 contain mainly elaidic acid, palmitic acid, stearic acid, linoleic acid, and a lower percentage of other fatty acids, indicating a suitable composition for biodiesel production.

From Waste Biomass to Cellulosic Ethanol by Separate Hydrolysis and Fermentation (SHF) with Trichoderma viride

Advanced biofuels can reduce fossil fuel use and the number of harmful compounds released during combustion, by reducing the use of fossil fuels. Lignocellulosic materials, especially waste biomass, are suitable substrates for the production of advanced biofuels. Among the most expensive steps in the production of ethanol is enzyme-based hydrolysis. Using microorganisms can reduce these costs. This study investigated the effectiveness of hydrolyzing three waste lignocellulosic biomass materials (barley straw, oak shavings, spent grains) into ethanol, after biological pretreatment with Trichoderma viride fungi. The number of fermentable sugars obtained from each substrate was subjected to preliminary study, and the correlation between the temperature and fungal activity in the decomposition of lignocellulosic materials was determined. Ethanol was produced by the separate hydrolysis and fermentation (SHF) method. It was found that not all lignocellulosic biomass is suitable to decomposition and hydrolysis in the presence of T. viride. Regardless of the process temperature, the average enzymatic activity of fungi (activity index) ranged from 1.25 to 1.31. 94 mL of distillate, with a 65% (v/v) ethanol concentration produced by the hydrolysis and fermentation of the sugars released from the barley straw.

Subcritical Water as Pretreatment Technique for Bioethanol Production from Brewer's Spent Grain within a Biorefinery Concept.

Bioeconomy and environmental issues envisage industrial by-products such as Brewer's spent grain (BSG) as renewable resources for their recycling and reuse within a biorefinery concept. This study aimed to investigate the production of bioethanol from subcritical water (subW) pretreated BSG, following the conversion of the BSG biopolymers cellulose and hemicelluloses. The subW pretreatment was performed in a batch reactor at 174 °C, during 60 min and 5% (w/v) of dry BSG charge. The behavior of BSG biopolymers under subW pretreatment was monitored by evaluating the chemical composition of the liquid and solid streams and the chemical and structural changes caused in the solid residues by scanning electron microscope (SEM), CHNS elemental analysis and water retention value (WRV). The production of bioethanol from subW-pretreated BSG was assessed by separate hydrolysis and fermentation (SHF) and also by simultaneous saccharification and fermentation (SSF) by using the enzymatic cocktail Celluclast 1.5 L (40 FPU/gsolids) and the yeast Ethanol Red®. The higher bioethanol productivity (1.073 g∙L-1∙h-1) and concentration (32.18 g/L) were achieved by SSF with higher solids' loading (25%) and following a fed-batch strategy. These results suggest that subcritical water pretreatment is a promising technology for the valorization of BSG as a feedstock for second-generation bioethanol production.

Direct consolidated bioprocessing for d-glucaric acid production from lignocellulose under subcritical water pretreatment

d-glucaric acid production from lignocellulose is a valuable research field, but meets the same challenge as other biorefinery processes that prevents it from commercialization, high production costs. The very path to tackle this is to increase the titer, rate and yield (TRY) of d-glucaric acid production and simplify the process, on which this study focused. Herein we used a novel, clean and environmentally friendly pretreatment, subcritical water pretreatment (SCWP), based on which we compared consolidated bioprocessing (CBP) by the microbial consortium composed of Trichoderma reesei C10 and Saccharomyces cerevisiae LGA-1C3S2 with separated hydrolysis and fermentation (SHF). CBP was found to be advantageous over SHF because of its comparable yield, much more simplified bioprocess and bigger space for cost reduction. Then CBP was upgraded to direct consolidated bioprocessing (dCBP) by adapting the microbial consortium in the raw liquors of SCWP containing inhibitors and toxic chemicals. As a result, more integrated biorefinery processes from corn stover (CS), wheat straw (WS), rice straw (RS) and switchgrass (SG) to d-glucaric acid under SCWP were developed and scaled up from shake flasks to 10 L fermenters, stirred and airlift. The TRYs of d-glucaric acid were improved significantly. The airlift fermenter was preferable for the dCBPs, producing the highest concentrations of d-glucaric acid, which were 10.03 g/L from subcritical water pretreated CS (SWCPCS), 9.53 g/L from SWCPWS, 8.87 g/L from SWCPRS and 10.66 g/L from SWCPSG respectively. Subsequently, the dCBPs were coupled with the downstream separation to establish a closed-circuit circulation and 30 rounds was run successfully. The highly integrated process from lignocellulose to d-glucaric acid with the smallest number of single unit operations was obtained and reported for the first time, providing an important design for biorefinery. This work is of great significance for biomanufacturing d-glucaric acid and other bio-based chemicals.

Bioethanol production process with SHF method from EFBs pulp and its microcrystalline

Bioethanol is an alternative energy to reduce fossil fuels dependency as well as for industrial utilization. This study aims to investigate the effectiveness of bioethanol production from oil palm empty fruit bunch (OPEFB) in the pulp compare to its microcrystalline OPEFB by applying Separate Hydrolysis and Fermentation (SHF) method. The process was carried out by pretreatment using alkaline for both materials and then subjective to the bleaching process by applying H2O2 10% for microcrystalline OPEFB. Subsequently both pulp and its microcrystalline were subjected to enzymatic hydrolysis by cellulase 30 FPU/g to break lignocellulose chains into simple sugars. The final stage was fermentation process to convert glucose into ethanol by using Saccharomyces cerevisiae. Analysis of sugar, cellulose, and lignin content was performed by using the NREL method, and for ethanol content using a densitometer. This study revealed that the sugar conversion after hydrolysis by enzymes was 79.77% for microcrystalline and 66.76% for pulp. Meanwhile, the ethanol content in the microcrystalline was higher than the ethanol in the pulp that was 4.87% in the medium of 0.1% NPK and 0.3% urea.

Ultrasonic‑assisted molten salt hydrates pretreated Eucheuma cottonii residues as a greener precursor for third-generation l-lactic acid production

This study aims to establish an efficient pretreatment method that facilitates the conversion of sugars from macroalgae wastes, Eucheuma cottonii residues (ECRs) during hydrolysis and subsequently enhances l-lactic acid (L-LA) production. Hence, ultrasonic-assisted molten salt hydrates (UMSHs) pretreatment was proposed to enhance the accessibility of ECRs to hydrolyze into glucose through dilute acid hydrolysis (DAH). The obtained hydrolysates were employed as the substrate in producing L-LA by separate hydrolysis and fermentation (SHF). The maximum glucose yield (97.75 %) was achieved using UMSHs pretreated ECRs with 40 wt% ZnCl2 at 80 °C for 2 h and followed with DAH. The optimum glucose to L-LA yield obtained for SHF was 90.08 % using 5 % (w/w) inoculum cell densities of B. coagulans ATCC 7050 with yeast extract (YE). A comparable performance (89.65 %) was obtained using a nutrient combination (lipid-extracted Chlorella vulgaris residues (CVRs), vitamin B3, and vitamin B5) as a partial alternative for YE.

Separate hydrolysis and fermentation (SHF) of pretreated sugar beet pulp (SBP) into ethanol

Separate hydrolysis and fermentation (SHF) of pretreated sugar beet pulp (SBP) into ethanol