Fermentation Of Straw Research Articles

Enhancement in functional stability of microbial endoglanases produced using paddy straw via treatment with manganese oxide based porous nanocomposite synthesized from mixed fruit waste

Microbial cellulases are the enzymes used in numerous industrial biotechnological applications. Efficiency of celluloytic cocktails plays a key role in the conversion of biomass into biofuels, but limited production, high cost and low efficiency are the main obstacles to sustainable biorefining. The current work aims to establish a feasible approach for boosting the production of fungal endoglucanse (EG) and its functional stability utilizing nanocomposite materials based on manganese oxide. Herein, aqueous extract from mixed fruit waste was used to synthesize the nanocomposite sample, which was subsequently subjected to several characterization techniques for analysis. Following the solid-state fermentation of paddy straw, and by employing 75 mg nanocomposite, 192 IU/gds EG was produced under the optimal conditions, while 19 IU/gds FP and 98 IU/gds BGL production were recorded. The crude EG enzyme treated with nanocomposite also shows complete stability at pH 5.0 for 3.5 h while retaining thermal activity at 70 °C for 4 h.

Bioprocessing of Two Crop Residues for Animal Feeding into a High-Yield Lovastatin Feed Supplement.

Simple SummaryLovastatin is a fungal secondary metabolite that can mitigate rumen methane production. This work aimed at evaluating the lovastatin production by solid-state fermentation from selected crop residues and A. terreus strains, considering the post-fermented residues as feed supplements for ruminants. Fermented oat straw by A. terreus CDBB H-194 exhibited the highest lovastatin yield (23.8 mg/g DM fed). GC–MS analysis identified only a couple of compounds from the residues fermented by CDBB H-194 (1,3-dipalmitin trimethylsilyl ether in the fermented oat straw) and stearic acid hydrazide in the fermented wheat bran) that could negatively affect ruminal bacteria and fungi.This work aimed to evaluate the lovastatin (Lv) production by solid-state fermentation (SSF) from selected crop residues, considering the post-fermented residues as feed supplements for ruminants. The SSF was performed with two substrates (wheat bran and oat straw) and two A. terreus strains (CDBB H-194 and CDBB H-1976). The Lv yield, proximate analysis, and organic compounds by GC–MS in the post-fermented residues were assessed. The combination of the CDBB H-194 strain with oat straw at 16 d of incubation time showed the highest Lv yield (23.8 mg/g DM fed) and the corresponding degradation efficiency of hemicellulose + cellulose was low to moderate (24.1%). The other three treatments showed final Lv concentrations in decreasing order of 9.1, 6.8, and 5.67 mg/g DM fed for the oat straw + CDBB H-1976, wheat bran + CDBB H-194, and wheat bran + CDBB H-1976, respectively. An analysis of variance of the 22 factorial experiment of Lv showed a strong significant interaction between the strain and substrate factors. The kinetic of Lv production adequately fitted a zero-order model in the four treatments. GC–MS analysis identified only a couple of compounds from the residues fermented by A. terreus CDBB H-194 (1,3-dipalmitin trimethylsilyl ether in the fermented oat straw and stearic acid hydrazide in the fermented wheat bran) that could negatively affect ruminal bacteria and fungi. Solid-state fermentation of oat straw with CDBB H-194 deserves further investigation due to its high yield of Lv; low dietary proportions of this post-fermented oat straw could be used as an Lv-carrier supplement for rumen methane mitigation.

Adsorptive removal of Cu(II) from aqueous solution by fermented sweet sorghum residues as a novel biosorbent

Sweet sorghum straw is a kind of natural wood cellulose with high porosity and high specific surface, which is theoretically conducive to the physical adsorption of heavy metal ions. In this paper, we reported a new biosorbent, the fermented sweet sorghum residues (FSSR), which is a byproduct of bioethanol production by fermentation of sweet sorghum straw, for the removal of Cu(II) from aqueous solution. The properties of the adsorption of Cu(II) on SSR and FSSR were studied and compared. The adsorption process of Cu(II) by SSR and FSSR conformed to the Elovich kinetic model. The isothermal adsorption process conformed to the Freundlich and the Tempkin models. The adsorption capacity of FSSR for Cu(II) was increased with the increase of pH. The adsorption mechanism of Cu(II) by FSSR was mainly attributed to ion exchange. SSR and FSSR were characterized by SEM-EDS, FTIR and XRD. The surface of FSSR had microporous structure, the content of –OH and other active functional groups increased. The fermentation has a certain destructive effect on the crystal structure of cellulose with the increase of amorphous structure. Therefore, fermentation process could be regarded as an effective means of microbial modification, to destroy the structure of the straw and result in the porous structure, which improved the adsorption capacity of SSR for heavy metals. FSSR could be used as a potential biosorbent for heavy metal removal from aqueous solution. Ethanol fermentation might be an effective method to improve performance of biosorbent for Cu adsorption.

Optimization and biochemical characterization of a thermotolerant processive cellulase, PtCel1, of Parageobacillus thermoglucosidasius NBCB1.

Vermicomposting involves enrichment of microorganisms that are able to resist higher temperatures and perform simultaneous degradation of lignocellulose, and therefore, such microbial communities are a potential source of cellulolytic enzymes. This study aimed to optimize the production of a processive cellulase by Parageobacillus thermoglucosidasius NBCB1 isolated from vermicompost, under submerged fermentation of rice straw and to characterize the purified enzyme for industrial suitability. Cellulase production in basal medium (7.27 IU/mg) was enhanced to 61 IU/mg by One Factor At a Time approach, which was further improved to 78.46 IU/mg by genetic algorithm based artificial neural networking. The cellulase PtCel1 purified from bacterial culture showed a molecular weight of≈33 kD, had activity on both crystalline (305 IU/mg) and amorphous (184 IU/mg) cellulose as substrates. It had pH and temperature optima of 5.5°C and 60°C, respectively, and retained 100% activity upon preincubation at 60°C for 1 h indicating thermostability. PtCel1 was tolerant to sodium dodecyl sulfate, glucose and mannose; and the various metal chlorides, such as sodium, magnesium, calcium and zinc, acted as inducers giving 77.54%, 45.15%, 61.10%, and 169.14% augmentation of activity, respectively. Its efficiency on cellulosic substrates and robustness against aforementioned chemical and thermal environment makes it suitable for industrial applications.

Biochemical Process and Microbial Evolution in the Conversion of Corn Straw Combined with Coal to Biogas.

The combined anaerobic fermentation of coal and straw can increase the production of biogas. To explore the mechanism of adding corn straw to increase methane production, coal with different metamorphic degrees and corn straw were collected for biogas production simulation experiments under different substrate ratios. The changes in liquid products, the structure of lignocellulose in corn straw, and microbial evolution were monitored. The results showed that the combined fermentation of bituminous coal A with corn straw and bituminous coal C with corn straw at a mass ratio of 2:1 each ((AC-2) and (CC-2)) and that of bituminous coal B and corn straw at a mass ratio of 3:1 (BC-3) had the best gas production, and methane yields reached 17.28, 12.51, and 14.88 mL/g, respectively. The fermentation liquid had organic matter with more types and higher contents during the early and peak stages of gas production, and fewer types of organic matter were detected in the terminal stage. The degradation of lignocelluloses in the corn straw of AC-2 was higher. With the increase in fermentation time, the carbohydrates in the fermentation system increased and the degradation rate of cellulose decreased gradually. The abundance of genes related to nitrate reduction gradually increased, while that of sulfate reduction was on the contrary. Bacteria in the cofermentation system mainly metabolized carbohydrates. During cofermentation with high metamorphic coal, corn straw would be preferentially degraded. The structure of the archaea community changed from Methanosarcina and Methanothrix to Methanobacterium.

Effects of corn straw treated with CaO on rumen degradation characteristics and fermentation parameters and their correlation with microbial diversity in rumen

The objectives of this study were to investigate the degradation characteristics and fermentation parameters of corn straw treated with different concentrations of calcium oxide (CaO) and degradation characteristics and fermentation parameters of samples in relation to microorganisms diversity in the rumen. Corn straw with 60 % moisture were treated with four concentrations of CaO (0 %, 3 %, 5 %, and 7 % of dry straw weight) respectively: i) The nylon bag technology method was used in estimating the rumen effective degradability, and each treatment was performed eight times. Then, the degradability of dry matter (DM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were determined by taking nylon bags from rumen at 0 h, 4 h, 8 h, 12 h, 24 h, 48 h and 72 h, respectively. ii) The fermentation parameters of corn straw were measured by rumen simulation technology in vitro. The mixture was measured at different times (6 h, 12 h, 24 h and 72 h) for the determination of ammonia nitrogen (NH3–N), volatile fatty acids (VFAs) indexes and rumen microbes. iii) The free online platform of Majorbio Cloud Platform was used in evaluating microbe diversity, abundance, and taxonomic composition in the rumen. Species difference analysis was designed, each treatment had three replicates, and 48 samples in total were used. iv) The correlations among effective degradability, fermentation indexes, and rumen microorganisms of corn straw treated by CaO were analyzed by means of an online platform. The results showed that i) the effective rumen degradability of corn straw treated with CaO significant differed among treatments (P < 0.01). The degradability of DM, NDF, and ADF in 7 % and 5 % treatments were higher than that in other treatments (P < 0.01). Soluble and rapidly degraded components in corn straw had significant higher in 5 % and 7 % treatments than in the 0 % and 3 % treatments. ii）The concentrations of acetate, propionate, butyrate, and total VFA at 6 h in vitro had significant differences (P < 0.01) or obvious upward tendency with increasing concentration of CaO. iii) Alpha index analysis revealed that rumen microorganisms diversity and abundance obviously decreased from 0 % to 7 % treatment in 6 h fermentation. Rikenellaceae_RC9_gut_group at the genus level decreased in the top 15 species in terms of average abundance (P < 0.01), but the most abundant genus Prevotella_1 had an upward tendency in 6 h incubation (P = 0.066). iv) Correlation analysis demonstrated that Prevotella_1 and Prevotellaceae_UCG-003 had positive correlations with acetate, propionate, total VFA, and DM, NDF, and ADF degradability (P < 0.01). Overall, corn straw treated with CaO at 5 % and 7 % can improve rumen effective degradability and promote the fermentation of corn straw, especially promoting Prevotella_1 enrichment in the straw in a short time. In terms of cost saving, 5 % CaO treatment is the best choice.

Effect of biochar on methane production and structural characteristics in the anaerobic digestion (AD) of rape straw

This study investigated the mesophilic and thermophilic anaerobic fermentation of rape straw with biochar addition. The effects of biochar on the biogas yield, degradation of lignocellulose, bacterial community, and crystallinity were explored. The results showed that the biogas yield and methane content increased as the biochar concentration was increased. The biochar concentration of 5.0% resulted in a high biogas yield in mesophilic and thermophilic anaerobic digestion at 142.2 mL/g and 193.5 mL/g, respectively, which were 40.5% and 21.0% improvements compared with the control. The corresponding methane contents were 59.4% and 57.0%, respectively. For the lignocellulose degradation, the cellulose content in the mesophilic AD decreased from 54.0% in the pretreated rape straw to between 18.7% and 25.0%. The microbial community results showed that as the biochar concentration was increased, the relative abundance of Firmicutes initially increased before it decreased. Among the microbial community results, the relative abundances of Firmicutes and Bacteroides in the biogas residue of the mesophilic anaerobic digestion were the highest in the biogas residue with the 5.0% biochar concentration sample in the mesophilic AD, at 27.06% and 39.20%, respectively. This result revealed the mechanism of biochar to improve the biogas production of rape straw in anaerobic fermentation.

Effects of ethanol addition on caproic acid production and rumen microorganism community structure from straw fermentation

In order to enhance caproic acid concentration from wheat straw fermentation and elucidate the microbial community inside the system. This study investigated ethanol addition with different mode for wheat straw co-cultured with rumen fluid. The results showed that segmentation addition of ethanol resulted in a higher caproic acid of 1473 mg/L. The structural characteristics of the microorganism community were further analyzed to reveal the functional of microorganisms in the acid fermentation from straw. Among them, Prevotella had a strong hemicellulose degradation capacity; Corynebacterium, Ureibacillus, and Clostridium_sensu_stricto_12, were correlated with the increasing trend of caproic acid. Control the proper ethanol concentration and optimum fermentation conditions would avoid the biotoxicity for the microorganisms and enhance the product yield.

A Combination of Novel Microecological Agents and Molasses Role in Digestibility and Fermentation of Rice Straw by Facilitating the Ruminal Microbial Colonization.

In this study, we evaluated the effect of microecological agents (MA) combined with molasses (M) on the biodegradation of rice straw in the rumen. Rice straw was pretreated in laboratory polyethylene 25 × 35 cm sterile bags with no additive control (Con), MA, and MA + M for 7, 15, 30, and 45 days, and then the efficacy of MA + M pretreatment was evaluated both in vitro and in vivo. The scanning electron microscopy, X-ray diffraction analysis, and Fourier-transform infrared spectroscopy results showed that the MA or MA + M pretreatment altered the physical and chemical structure of rice straw. Meanwhile, the ruminal microbial attachment on the surface of rice straw was significantly increased after MA+M pretreatment. Furthermore, MA + M not only promoted rice straw fermentation in vitro but also improved digestibility by specifically inducing rumen colonization of Prevotellaceae_UCG-001, Butyrivibrio, and Succinimonas. Altogether, we concluded that microecological agents and molasses could be the best choices as a biological pretreatment for rice straw to enhance its nutritive value as a ruminant's feed.

Digestibility and Nutritional Value of Fermented Straw Supplemented with Green Concentrate as Feed Ingredients for Holstein Friesian Dairy Cattle

The purpose of this study was to determine the effect of fermented straw supplementation with green concentrate on nutrient content and nutrient digestibility. Green concentrate used as treatment was white lead tree leaf flour ( Leucaena leucocephala ), Gamal leaf meal ( Gliricidia sepium ), and Indigofera leaf meal. Proximate analysis was carried out on fermented rice straw, 70% fermented rice straw + 30% lamtoro (FRS + white lead tree), 70% fermented rice straw + 30% Gamal (FRS + Gamal ) and 70% fermented rice straw + 30% Indigofera (FRS + Indigofera ). The livestock used for the nutrient digestibility test was 12 Friesian Holstein dairy cows. A randomized block design was used to test nutrient digestibility. The results showed that supplementation of green concentrate in fermented rice straw was able to increase crude protein, crude fat, and BETN and decrease crude fiber. Crude protein digestibility did not differ in the three types of green concentrates. Crude fat digestibility of FRS + white lead tree and FRS + Indigofera was higher than FRS + Gamal . The digestibility of BETN FRS + Gamal was higher than the digestibility of FRS + white lead tree and FRS + Indigofera . This study concludes that the three types of green concentrate can be used for the supplementation of fermented rice straw as dairy cattle feed.

Solid-state hydrolysis and fermentation of rice straw and manure for bioethanol production

Solid-state hydrolysis and fermentation of rice straw and manure for bioethanol production

Efficacy of sodium bentonite (SB) to ameliorate adverse effects of aflatoxin on In Vitro rumen fermentation of wheat straw

The present experiment was conducted to study the effect of sodium bentonite (SB) in ameliorating the adverseeffects of aflatoxin on in vitro rumen fermentation of wheat straw. Five treatment groups, viz. T1: control (wheatstraw); T2: T1 + 300 ppb aflatoxin B1 (AFB1); T3: T2 + 0.33% SB; T4: T2 + 0.5% SB and T5: T2 + 1.0% SB wereprepared and incubated in vitro. Truly degradable dry matter (TDDM), truly degradable organic matter (TDOM),gas production (GP), microbial biomass production (MBP) and partitioning factor (PF) values in T1 were higherthan those of other treatment groups (T2 to T5). TDDM, TDOM, GP, MBP and PF values in T2 were lower thanthose of other treatment groups. The values of these parameters improved with increasing concentration of SB.Total volatile fatty acids (TVFA), acetate (A), propionate (P) and butyrate (B) values in T1 were higher than thoseof other treatment groups (T2 to T5). TVFA and A value between T2 and T3 were statistically similar. TVFA, A, Pand B values improved with increasing level of SB, however, these values were lower than that of control even athighest inclusion level of SB. A:P ratio among various treatments did not vary significantly. It was concluded thataflatoxin contamination of feed at 300 ppb level significantly affected the in vitro rumen fermentation in terms ofreduced truly degradable dry matter, truly degradable organic matter, gas production, microbial biomass production, partitioning factor and total volatile fatty acids concentration. Incorporation of sodium bentonite up to 1.0% level to the aflatoxin-contaminated wheat straw, partially ameliorated the adverse effects of aflatoxin on in vitro rumen fermentation parameters.

Research on Soft Sensing Method of Straw Ethanol Fermentation Process Based on BSVR

Straw fermented fuel ethanol is a complex process with multivariable, large lag, and strong nonlinearity. It is difficult to directly measure the key parameters such as ethanol concentration and cell concentration online. Aiming at the problem, a soft sensing model of straw fermented ethanol based on improved support vector regression (SVR) is proposed. Based on the analysis of the process of ethanol production from straw fermentation, the Bayesian method is used to optimize the support vector regression (BSVR). And the concepts of generation a priori and generation likelihood are introduced to optimize the data prediction model. The comparative experiment of model training and testing is carried out. The simulation results show that the proposed BSVR method is better than SVR. It can improve the generalization ability of data and the anti-interference of the model, and its prediction accuracy and stability are higher.

Study on biogas production from corn straw pretreated by compound microorganisms

The pretreated corn straw is pretreated by Fomes fomentarius, Trichoderma adaptatum and the compound microbial agent of Fomes fomentarius and Trichoderma adaptatum under the same conditions. Then biogas was produced by anaerobic fermentation of pretreated straw. According to the experimental results, it has been found that the straw pretreatment with complex microorganisms can not only promote the process of straw anaerobic fermentation biogas production, but also improve the gas production and gas production efficiency, among which the compound microbial agent pretreatment shows the best effect. Compared with the untreated straw, the degradation of lignin and cellulose in straw pretreated with compound microbial agent is much higher, and the lignin content is decreased from 16.6% to 6.8%, and the cellulose content is decreased from 32.3% to 19.8%. Besides, the gas production of compound microbial agent pretreatment has increased by 14.86%, the gas production time is 6 d earlier, the gas production peak is 17 d earlier, the volume gas production rate reaches 2.008 mL/(mL⋅d), and the gas production rate of raw materials reaches 526.66 mL/g. The straw pretreatment with only Fomes fomentarius also has a good effect. However, the effect of straw pretreatment by Trichoderma adaptatum is poor, which has indicated that straw pretreatment by lignin-degrading strain plays an important role in improving the anaerobic fermentation efficiency of straw.

Effect of Ammoniated and/or Basidiomycete White-Rot Fungi Treatment on Rice Straw Proximate Composition, Cell Wall Component, and In Vitro Rumen Fermentation Characteristics

Various pretreatments are employed to increase the utilization of rice straw as a ruminant feed ingredient to minimize its negative environmental impact. However, an efficient alternative is still needed. The purpose of this study was to evaluate the ability of ammonia and/or white-rot fungi (Pleurotus ostreatus) to degrade lignin, increase the nutritional value, and enhance the rumen fermentability of rice straw. Rice straw was treated with ammonia and/or basidiomycete white-rot fungi (P. ostreatus) with untreated straw as control under solid-state fermentation employing a completely randomized design. The crude protein increased from 2.05% in the control to 3.47% in ammoniated rice straw, 5.24% in basidiomycete white-rot fungi (P. ostreatus), and 6.58% in ammoniated-basidiomycete white-rot fungi-treated (P. ostreatus) rice straw. The ammoniated-basidiomycete white-rot fungi-treated (P. ostreatus) rice straw had the least lignin content (3.76%). Ammoniated-basidiomycete white-rot fungi-treated (P. ostreatus) rice straw had improved in vitro dry matter digestibility (65.52%), total volatile fatty acid (76.56 mM), and total gas production (56.78 mL/g) compared to ammoniated rice straw (56.16%, 67.71 mM, 44.30 mL/g) or basidiomycete white-rot fungi-treated (P. ostreatus) rice straw (61.12%, 75.36 mM, 49.31 mL/g), respectively. The ammoniated-basidiomycete white-rot fungi (P. ostreatus) treatment improved rice straw’s nutritional value, in vitro dry matter digestibility, volatile fatty acids, and gas production.

Pretreatment of straw using filamentous fungi improves the remediation effect of straw biochar on bivalent cadmium contaminated soil.

Carbonized products of waste agricultural straws used for soil remediation can reduce impact of heavy metals on soil ecology and crop growth. Here, we demonstrated straw fermentation residues to be suitable for preparation of soil remediation agents by pyrolysis. Lignocellulose degradability of filamentous fungi during fermentation was found to significantly enhance properties of biochar for cadmium (Cd (II))-contaminated paddy soil remediation. Obtained biochars were indicated to have rich oxygen-containing groups, thus showing enhanced removal ability of Cd (II). Adsorption capacity of biochar (BaWS) prepared from wheat straw, which has been fermented by Trichoderma asperellum T-1, reached 105.9 mg g-1, 372.8% higher than that from natural wheat straw (BWS). Fermentation of straws by Trichoderma reesei QM6a can also improve the adsorption performance of biochar, but the effect is much weaker. The content of bioavailable Cd (II) in paddy soil reduced 83.7% within 15 days after addition of 1% BaWS. Significantly, adding 1% BaWS had better effect on increasing soil pH and removing available Cd (II) , than adding 3% BWS. These results suggest that the used dosage of microbial pretreated straw biochar for the remediation of Cd (II)-contaminated paddy soil was only 1/3 of that of conventional biochar. The enhanced property of biochar was attributed to deconstruction of straws by filamentous fungi before being pyrolyzed. Thus, fermented straws were indicated more suitable for the preparation of biochar used as effective soil remediation agents.

Enhanced straw fermentation process based on microbial electrolysis cell coupled anaerobic digestion

The low quality and yield of methane severely hinder the industrial application of straw biogas fermentation, and no effective solution has been found so far. In this study, a novel method was developed when a microbial electrolysis cell (MEC) was coupled with normal anaerobic fermentation to enhance methane yield and purity. The fermentation process achieved a methane purity of more than 85%, which is considerably higher than that of previously published reports. With microbial stimulation and an electric current, the degradation of fibers has been greatly enhanced. The MEC system substantially improved the yield and purity of biogas, bringing a new path to the synthesis of methane by carbon dioxide and hydrogen ions in solution under electron irradiation. Electrochemical index analysis showed extra methane synthesis, due to the external circuit electron transfer. The results of the gas chromatography and solid degradation rate showed that the carbon source of extra methane was CO 2 produced during normal fermentation and additional volatile solid degradation. These results show that the MEC considerably enhanced the quality and yield of methane in the straw fermentation process, providing insights into normal anaerobic fermentation.

Solid state fermentation of rice straw using Penicillium citrinum for chitosan production and application as nanobiosorbent

Chitosan production by Penicillium citrinum using rice straw was investigated by varying the moisture content (50–80%) and particle size of rice straw, and their optimum levels were found to be 70% and 4–5 mm, respectively. A lab scale tray fermenter was later employed to carry out the solid-state fermentation which yielded a maximum chitosan production of 9 g/kg of rice straw. Nanobiosorbents based on the fungal chitosan produced in this study was further prepared and evaluated for heavy metal removal. Magnetic iron (Fe3O4) nanoparticles coated with chitosan and carboxymethyl chitosan (CMC) were used as the nano-biosorbents to remove Cr(VI) and Pb(II) from corresponding aqueous solutions. Maximum removal of Cr (VI) and Pb (II) were 42.43 and 178.2 mg/g with CMCNPs. Heavy metal removal kinetics by the nanobiosorbents followed the pseudo-second order kinetics. Furthermore, the nanobiosorbents were found suitable for reuse for up to three cycles of sorption-desorption.

Experimental Study on Pyrolysis of Rice Straw Catalyzed by CaO/Al2O3-Phosphate Mixture

CaO and phosphates showed synergistic effects in the regulation of pyrolysis products in the pyrolysis of when they were directly mixed with camphor wood. The alkyl phenol yield increased during the pyrolysis process of corn straw fermentation residue directly mixed with KH2PO4 supported by γ-Al2O3. Rice stalks from agricultural crops are often disposed as waste. However, the potassium phosphate impregnated raw straw pyrolysis with CaO and Al2O3 has not been reported. This paper studied the synergistic effects of CaO or Al2O3 and three potassium phosphates (i.e., KH2PO4, K2HPO4·3H2O, and K3PO4·3H2O) in the rice straw pyrolysis through pyrolysis–gas chromatography-mass spectrometer (Py-GC/MS) experiments. The results showed that CaO/Al2O3 and potassium phosphates showed synergistic effects in the regulation of the types or contents of phenols, ketones, aldehydes, etc. and increased the contents of phenols, aldehydes, acids, and levoglucosan (LG) from most samples and increased those of ketones compared with those catalyzed by potassium phosphates alone. They were suitable for the production of ketone-rich and acid-low bio-oil, which is an important precursor for the preparation of power or jet fuel. The highest contents of ketones (HCK) reached 56.65% and 56.02% in the pyrolysis of K3PO4·3H2O impregnated rice straw with CaO or Al2O3, respectively. The lowest contents of acids and acetic acid (LCA) were nearly or equal to 0, respectively. HCK and LCA were respectively significantly higher and lower than the values reported in the literatures for biomass catalytic pyrolysis using CaO/Al2O3 and potassium phosphates alone or in combination. Dehydration reactions, etc. were further promoted under the co-catalysis of the two catalysts, and some phenols could be converted to benzene products, etc. For 50% K3PO4·3H2O impregnated sample, the yields of furans reduced sharply after CaO addition. For most impregnated samples except 50% K2HPO4·3H2O and 30% and 50% K3PO4·3H2O samples, the contents of total furans and furfural increased after Al2O3 addition.

Effect of ligninolytic axenic and coculture white-rot fungi on rice straw chemical composition and in vitro fermentation characteristics

The study sought to investigate the potentials of axenic cultures of Pleurotus ostreatus, Phanerochaete chrysosporium and their coculture (P. chrysosporium and P. ostreatus) to break down lignin and to enhance the rumen fermentability of rice straw. Rice straw was fermented by two lignin-degrading fungi, namely, P. ostreatus, P. chrysosporium and its coculture (P. ostreatus and P. chrysosporium) with uninoculated straw as control under solid-state fermentation employing a completely randomized research design. The coculture exhibited a mutual intermingling plus inhibition interaction. The fungi treatment increased the crude protein from (5.1%) in the control to (6.5%, 6.6%, and 6.7%) in the P. ostreatus, P. chrysosporium and coculture respectively. The coculture treated straw had a lower lignin content (5.3%) compared to the P. chrysosporium (6.2%) with the P. ostreatus recording the least (3.3%) lignin fraction. Treatment of rice straw with coculture improved the in vitro dry matter digestibility (68.1%), total volatile fatty acids (35.3 mM), and total gas (57.4 ml/200 mg) compared to P. chrysosporium (45.1%, 32.2 mM, 44.4 ml/200 mg) but was second to P. ostreatus (75.3%, 38.3 mM, 65.6 ml/200 mg). Instead of an anticipated synergistic effect from the coculture, a competitive antagonistic effect was rather observed at the end of the study, a condition that can be attributed to the coculture behavior.