Untreated Corn Research Articles

Effects of ammonia fiber expansion (AFEX) treated corn stover on anaerobic microbes and corresponding digestion performance

Dynamic changes in microbial communities and digestion performance of AFEX treated corn stover co-digestion were compared to untreated corn stover co-digestion. Even though it took longer to stabilize the AFEX treated corn stover co-digestion system than it did for the untreated corn stover co-digestion, the results show that AFEX treated corn stover is a good feedstock to enhance the archaea community and improve biogas production. In the stabilized digestion system, the AFEX treated corn stover co-digestion increased abundance of archaea community (11.8%) by approximately three times compared to the untreated corn stover co-digestion (4.3%), The corresponding biogas production (213 L/kg VS loading) of the AFEX treated corn stover co-digestion was 22% higher than that (175 L/kg VS loading) of the untreated corn stover co-digestion. AFEX treatment could enable more extensive use of lignocellulosic biomass for anaerobic digestion to generate biogas and thereby provide another route for lignocellulosic biofuel production.

Removal of Methyl Orange from Aqueous Solutions by Adsorption Using Corn Leaves as Adsorbent Material

A comparative study was done on the adsorption of methyl orange dye (MO) using non-activated and activated corn leaves with hydrochloric acid as an adsorbent material. Scanning electron microscopy (SEM) and Fourier Transform Infrared spectroscopy (FTIR) were utilized to specify the properties of adsorbent material. The effect of several variables (pH, initial dye concentration, temperature, amount of adsorbent and contact time) on the removal efficiency was studied and the results indicated that the adsorption efficiency increases with the increase in the concentration of dye, adsorbent dosage and contact time, while inversely proportional to the increase in pH and temperature for both the treated and untreated corn leaves. The equilibrium data is best fitted to Freundlich isotherm for untreated adsorbent, while Langmuir isotherm show best agreement with the data when the treated adsorbent is used. The rate of adsorption was found to follow the pseudo first order kinetic model (PFO) when non-activated adsorbent is used, while the pseudo second order model (PSO) is fitted to the adsorption data using activated adsorbent.

The effect of combined pretreatments on the pyrolysis of corn stalk

Untreated corn stalk (CS), deionized water washed CS (WCS), aqueous phase bio-oil washed CS (LCS), and 5% acetic acid washed CS (CCS) were torrefied at 230, 260, and 290 °C. The influences of washing, torrefaction, and combined washing-torrefaction pretreatments on corn stalk pyrolysis were investigated. The combined pretreatments, especially aqueous phase bio-oil washing-torrefaction improved fuel properties of pretreated samples largely by increasing their volatile and hydrogen contents. Absorption peaks of O–H and CO groups in combined pretreatment samples increased when torrefaction temperature increased. In addition, CO, H2, and CH4 contents of pyrolysis gas increased, while CO2 decreased after combined pretreatments. The bio-oil yields from WCS290, LCS290, and CCS290 increased by 134.04%, 127.66%, and 129.79% respectively, compared with that from CS290. Similarly, their relative sugar contents (rich in levoglucosan) increased to 36.63%, 45.89%, and 52.34%, respectively. Aqueous phase oil washing-torrefaction is a promising pretreatment and acetic acid plays the most important role.

Two-stage thermophilic anaerobic co-digestion of corn stover and cattle manure to enhance biomethane production

Two-stage thermophilic anaerobic co-digestion of cattle manure and corn stover was conducted to increase biomethane production. The first stage pre-digestion of corn stover was studied based on the following treatment variables: corn stover to liquid fraction of digestate (CS:LFD) ratio (1:7, 1:10, 1:13, 1:14), digestion temperature (55 °C, 60 °C) and digestion time (3, 7, 14 days). The reduction in lignin, cellulose and hemicellulose (LCH) was between 3.97% and 11.98%, which increased the biodegradability of corn stover. Corn stover pre-digested with a CS:LFD ratio of 1:10 at 55 °C for a period of 3 and 7 days was subjected to anaerobic co-digestion with cattle manure. The highest biomethane yield was observed on day 21 with a value of 357.41 mL/g volatile solids (VS) for untreated corn stover, 446.84 mL/g VS for corn stover pre-digested for 3 days and 518.58 mL/g VS for corn stover pre-digested for 7 days with LFD. The VS conversion efficiency for co-digestion of cattle manure with untreated corn stover, corn stover pre-digested for 3 days and 7 days was 42.8%, 43.3% and 51.8%, respectively, on day 21, which was higher than that (34.0%) of cattle manure only.

Effect of physicochemical pretreatments plus enzymatic hydrolysis on the composition and morphologic structure of corn straw

In order to decrease corn straw crystallinity for improving reducing sugar yield, physicochemical pretreatments plus enzymatic hydrolysis were investigated. The results showed that hemicellulose and lignin degradation rates in corn straw treated with physical method (ultrasound wave (group 12), extrusion + ultrasound wave (group 14), extrusion + ultrasound wave + microwave (group 15)) combined with chemical compounds (lime + sodium hydroxide + hydrogen peroxide) were significantly higher than the untreated corn straw (P < 0.05). After the above three physicochemical pretreatments were fulfilled and followed by enzymatic hydrolysis, the cellulose, hemicelluloses, lignin degradation rates and reducing sugar yield were respectively increased by 51.38%, 82.44%, 64.63% and 378.86% in group 12, 69.61%, 86.05%, 62.88% and 421.77% in group14, 61.59%, 74.51%, 56.19% and 425.98% in group 15, compared with the untreated corn straw (P < 0.05). The scanning electron microscope showed that straw structure treated with extrusion + ultrasonic + chemical pretreatment was more seriously damaged than that with single physical or chemical pretreatment. The different sequences of physicochemical treatments had different effects on corn straw degradation. It could be concluded that the optimal physicochemical pretreatments plus enzymatic hydrolysis were effective for corn straw degradation and reducing sugar yield.

Lipid Production by Yeast Trichosporon oleaginosus on the Enzymatic Hydrolysate of Alkaline Pretreated Corn Cobs for Biodiesel Production

Biodiesel is still mainly produced from different vegetable (e.g., rapeseed, palm, soybean, sunflower, and used cooking oils) oils and animal fats, and therefore it has a negative impact on food and feed prices. For biodiesel production as an alternative feedstock, lipids from oleaginous microorganisms could be used. One of the oleaginous microorganisms is yeast Trichosporon oleaginosus that has the capacity to grow and accumulate lipids on different lignocellulosic hydrolysates. In this study, corn cobs were pretreated by alkali at loading from 0.08 to 1.6 g/g dry weight of untreated (raw) corn cobs (g NaOH/gDW_UCC) at 121 °C for 30 min. In a further step, alkaline pretreated corn cobs were subjected to the enzymatic hydrolysis by using commercial multienzymes mixtures. The optimal alkali loading (0.16 g/gDW_UCC) was related to the highest glucose and xylose yields which were observed during enzymatic hydrolysis of substrate. In this study, T. oleaginosus was applied for lipid production on the enzymatic...

Hydrolysis of untreated lignocellulosic feedstock is independent of S-lignin composition in newly classified anaerobic fungal isolate, Piromyces sp. UH3-1

BackgroundPlant biomass is an abundant but underused feedstock for bioenergy production due to its complex and variable composition, which resists breakdown into fermentable sugars. These feedstocks, however, are routinely degraded by many uncommercialized microbes such as anaerobic gut fungi. These gut fungi express a broad range of carbohydrate active enzymes and are native to the digestive tracts of ruminants and hindgut fermenters. In this study, we examine gut fungal performance on these substrates as a function of composition, and the ability of this isolate to degrade inhibitory high syringyl lignin-containing forestry residues.ResultsWe isolated a novel fungal specimen from a donkey in Independence, Indiana, United States. Phylogenetic analysis of the Internal Transcribed Spacer 1 sequence classified the isolate as a member of the genus Piromyces within the phylum Neocallimastigomycota (Piromyces sp. UH3-1, strain UH3-1). The isolate penetrates the substrate with an extensive rhizomycelial network and secretes many cellulose-binding enzymes, which are active on various components of lignocellulose. These activities enable the fungus to hydrolyze at least 58% of the glucan and 28% of the available xylan in untreated corn stover within 168 h and support growth on crude agricultural residues, food waste, and energy crops. Importantly, UH3-1 hydrolyzes high syringyl lignin-containing poplar that is inhibitory to many fungi with efficiencies equal to that of low syringyl lignin-containing poplar with no reduction in fungal growth. This behavior is correlated with slight remodeling of the fungal secretome whose composition adapts with substrate to express an enzyme cocktail optimized to degrade the available biomass.ConclusionsPiromyces sp. UH3-1, a newly isolated anaerobic gut fungus, grows on diverse untreated substrates through production of a broad range of carbohydrate active enzymes that are robust to variations in substrate composition. Additionally, UH3-1 and potentially other anaerobic fungi are resistant to inhibitory lignin composition possibly due to changes in enzyme secretion with substrate. Thus, anaerobic fungi are an attractive platform for the production of enzymes that efficiently use mixed feedstocks of variable composition for second generation biofuels. More importantly, our work suggests that the study of anaerobic fungi may reveal naturally evolved strategies to circumvent common hydrolytic inhibitors that hinder biomass usage.

EFFECT OF BIOLOGICAL TREATMENTS OF GREEN CORN STOVER AND STALKS ON DIGESTIBILITY COEFFICIENTS, RUMEN FERMENTATION AND SOME BLOOD PARAMETERS IN SHEEP

This study aimed to investigate the effect of a mixture of (ZAD) and (Lacto bacillus plantarum) on chemical composition of green corn stover and corn stalks and the effect of these treatments in a metabolism trial on digestibility coefficients , rumen fermentation and some blood parameters. One ton of either green corn stover or corn stalks was chopped into (2-3 cm) and its mixed with 0. 5 cubic metre of water or one cubic metre of water, respectively. They were then mixed with 3%w/w molasses and 1.5%w/w urea and incubated for six weeks. The experiment included six treatments, three of them were on green corn stover and the rest were on corn stalks. The treatments on green corn stover were as follows: (T1) Untreated green corn stover (control). (T2) corn stover + lactobacillus palantarum + ZAD (2litres of ZAD + 1 liter of lactobacillus palantarum / 1ton). (T3) corn stover + ZAD ( 2 liters of ZAD/ 1 ton). The treatments on corn stalks were as follows: (T4) Untreated corn stalks (control). (T5) corn stalks + lactobacillus palantarum+ ZAD (2litres of ZAD +1 liter of lactobacillus palantarum /1ton) (T6) corn stalks + ZAD (2 liters of ZAD/ 1 ton). Eighteen Ossimi male lambs were divided to six group rations for 15 days in metabolism trials. Results indicated that biological treatment on T2 and T3 treatments on green stover and T5 and T6 on dry corn stalks decreased CF and NDF, ADF, ADL contents and increased CP content compared to the control. Feeding lambs on treated green corn stover or treated dry corn stalks significantly (P<0.05) improved all of nutrients digestibility compared with those fed on control. The nutritive values as TDN, DCP and N balance for lambs fed treated green stover or treated dry corn stalks showed significant(P<0.05) higher than those fed untreated and it had the same trend of nutrient digestibility . Adding lactobacillus palantarum + ZAD improved digestion coefficients of nutrients and TDN values compared with control. Results of blood parameter indicated that T2 of green corn stover and T5 of corn stalks had a significant (P<0.05) effect on (Tp, Alb, Glb, A/G) compared to the control and T3 of corn stover and T6 of corn stalks. All values of plasma ALT and AST for all treatments were in normal rang where all treatments had no effect on ALT. However, T2 of green corn stover and T5 of corn stalks had a significant (P<0.05) effect on AST compared to the control and T3 of corn stover and T6 of corn stalks. All values of plasma creatinine and urea for biological treatments appeared to significant(P<0.05) higher values. However, these values were in normal range. Results of rumen parameters indicated that all treatments had no effect on pH and NH3-N. On the other hand T2 of green corn stover and T5 of corn stalks significantly (P<0.05) increased TVF'S. Generally, Adding enzyme with or without lactobacillus to green corn stover or dry corn stalks tended to improved nutrient components , digestibility coefficients, feeding values and nitrogen balance with no adverse effect of animal health .

Microbial lipid production from enzymatic hydrolysate of corn stover pretreated by combining with biological pretreatment and alkalic salt soaking

The conversion of lignocellulose for biofuel production requires an effective pretreatment to disrupt the recalcitrant plant cell walls and to make the cellulose accessible to cellulases. In this study, sequential biological pretreatment (BP) with Galactomyces sp. CCZU11-1 under the mild condition and alkalic salt pretreatment (AP) with Na2CO3 by autoclaving was used to pretreat untreated corn stover (CS) for enhancing its enzymatic saccharification. After the optimization, the optimum pretreatment conditions were obtained. The crystallinity, porosity, and morphology of the pretreated solid residue of CS were correlated with the enhancement of enzymatic saccharification. After 72 h, the yields of glucose from the hydrolysis of 50 g/L BP-AP-CS with a cocktail of Galactomyces sp. CCZU11-1 cellulases in the absence and presence of Na2CO3 (0.82 wt%) could be obtained at 47.2% and 46.1% respectively. Using BP-AP-CS-hydrolysates containing 25.6 g/L glucose as carbon source, microbial lipids effectively produced by Rhodococcus pyridinivorans CCZU-B16 in the presence of Na2CO3 (0.82 wt%). Four fatty acids including palmitic acid (C16:0; 23.5%), palmitoleic acid (C16:1; 19.0%), stearic acid (C18:0; 16.2%), and oleic acid (C18:1; 24.8%) were distributed in total fatty acids. In conclusion, this combination pretreatment strategy has potential application for the production of microbial lipids from biomass in future.

Consecutive Recovery of Non-Structural Sugars and Xylooligomers from Corn Stover using Hot Water and Acidified Calcium Chloride

Corn stover, which has a high non-structural sugar content, was treated by two-stage fractionation using water and acidified CaCl2 for the consecutive recovery of non-structural sugars and xylooligomers. In this process, water treatment under mild conditions (60 °C to 140 °C) was used for the recovery of non-structural sugars in the first stage, followed by the recovery of xylooligomers using acidified CaCl2 in the second stage under severe conditions (160 °C to 180 °C). For the recovery of non-structural sugars, a water treatment at 80 °C was observed to be effective, recovering 95.6% of the non-structural sugars. With a non-structural sugar-free solid, the reaction conditions for the second stage of treatment using acidified CaCl2 were statistically optimized. The highest recovery yield of xylooligomers (72.5%) was obtained under optimum conditions (172.9 °C, 22.2 min, 4.7% CaCl2). With the two-stage fractionation process, the glucan digestibility of treated solid was enhanced from 34.0% for untreated corn stover to 91.0% for the treated solid (with 15 FPU/g-glucan).

Technical note: A comparison of alkali treatment methods to improve neutral detergent fiber digestibility of corn stover

The objective of this study was to compare neutral detergent fiber (NDF) digestibility of corn stover that had been treated by 2 alkali treatment methods. Two experiments were conducted to test a sodium hydroxide (NaOH) treatment method that uses an ethanol/water co-solvent (NaOH/ethanol-H2O, United States Patent No. 20140220228) and a calcium hydroxide (CaOH) treatment method, which uses water as a solvent (CaOH/H2O). An in situ trial was conducted to compare NDF digestion kinetics between NaOH/ethanol-H2O-treated stover, CaOH/H2O-treated stover, untreated corn stover, and soy hulls. The digestion rate of potentially digestible NDF (kd) of NaOH/ethanol-H2O-treated corn stover (5.36%/h) was higher than CaOH/H2O-treated stover (2.27%/h), or untreated corn stover (1.76%/h) and similar to the kd of soy hulls (4.93%/h). The indigestible NDF (iNDF) fraction of untreated corn stover (35.1% of NDF) was reduced by CaOH/H2O treatment (27.3% of NDF) and by NaOH/ethanol-H2O treatment (2.8% of NDF). The iNDF fraction in soy hulls (3.6% of NDF) was similar to iNDF of NaOH/ethanol-H2O-treated stover. An in vivo digestibility trial was also conducted to compare fiber digestibility of diets supplemented with untreated corn stover, NaOH/ethanol-H2O-treated corn stover, or soy hulls. Total-tract apparent dry matter (DM) and NDF digestibility were measured with 8 lactating Holstein cows in a replicated 4 × 4 Latin square with four 21-d periods. Apparent DM digestibility (DMD) was improved when supplemental soy hulls were added to the base diet (60.0% DMD) compared with the base diet with no supplemental fiber (57.7% DMD). Apparent DM digestibility was reduced when diets were supplemented with untreated stover (52.4%). Dry matter digestibility of NaOH/ethanol-H2O-treated stover was similar (54.8% DMD) to all other treatments. Digestibility of NDF was lowest when cows were fed the diet with supplemented untreated stover (35.5% of NDF), and improved when soy hulls (40.6% of NDF) or NaOH/ethanol-H2O-treated stover (43.8% of NDF) were added to the diets. The NaOH/ethanol-H2O treatment process improves the DM and NDF digestibility of corn stover to values similar to those of soy hulls.

Inoculation of corn silage with Lactobacillus plantarum and Bacillus subtilis associated with amylolytic enzyme supply at feeding. 2. Growth performance and carcass and meat traits of lambs

The objective of this research was to investigate the effects of inoculation of corn silage and dietary supplementation of amylolytic enzymes, and their interaction, on lamb growth performance and carcass and meat traits. Whole-crop corn forage was treated either with water (untreated) or with Lactobacillus plantarum MA 18/5U at 1 × 105 cfu/g fresh forage combined with Bacillus subtilis AT553098 at 1 × 105 cfu/g fresh forage (inoculated) and ensiled for 170 d. Forty non-castrated Texel × Dorper male lambs were arranged in a randomized block design (n = 10) and then assigned to one of four diets, as follows: 1) untreated corn silage with no amylolytic enzyme supply (NI-NA); 2) untreated corn silage with amylolytic enzyme supply (NI-WA); 3) inoculated corn silage with no amylolytic enzyme supply (WI-NA); and 4) inoculated corn silage with amylolytic enzyme supply (WI-WA). α-Amylase (602 dextrinizing units/kg of dry matter (DM)) was supplied to the lambs at total mixed ration delivery. Inoculation of corn silage increased (P = 0.003) both digestible energy (DE) and metabolizable energy (ME) intake by 1.4 and 1.2 MJ/kg DM, respectively, and also resulted in higher average daily gain (ADG; P = 0.023) of lambs (233 vs. 212 g/d in lambs fed NI diet). In contrast, dietary supplementation with amylolytic enzymes had no effect on the DM intake (P = 0.90) or ADG (P = 0.15) of lambs. Moreover, inoculation, enzyme supplementation, and their interaction had no significant effects on carcass traits (P ≥ 0.06), commercial cut yield (P ≥ 0.26), chemical composition of meat (P ≥ 0.13), and meat tenderness and color (P ≥ 0.11). In terms of the fatty acid composition of longissimus muscle, inoculation of corn silage increased concentrations of saturated fatty acids (SFA; P = 0.035) from 46.2% to 47.6%, and reduced concentrations of unsaturated fatty acids (UFA; P = 0.035) from 53.8% to 52.5%, compared to the NI diet. Inoculation also reduced the UFA:SFA ratio (P = 0.031) from 1.17 to 1.11, a small but significant difference. Dietary supplementation with amylolytic enzymes did not alter (P ≥ 0.09) SFA, UFA, and polyunsaturated fatty acid concentrations, or their ratios. In conclusion, our results indicated that the silage inoculant examined in the present study is recommended for use in improving lamb production at the farm scale, whereas inclusion of amylolytic enzymes is not required under our experimental conditions.

Inoculation of corn silage with Lactobacillus plantarum and Bacillus subtilis associated with amylolytic enzyme supply at feeding. 1. Feed intake, apparent digestibility, and microbial protein synthesis in wethers

The current study aimed to investigate the effects of corn silage inoculation and dietary supplementation with amylolytic enzymes, and their interactions, on feed intake, apparent digestibility, and microbial protein synthesis in wethers. Whole-crop corn forage was ensiled either with water (untreated) or with Lactobacillus plantarum MA 18/5U at 1 × 105 cfu/g fresh forage combined with Bacillus subtilis AT553098 at 1 × 105 cfu/g fresh forage (inoculated). Eight ruminally cannulated Dorper × Santa Inês crossbred wethers were used in a double 4 × 4 Latin square design. Wethers were assigned to one of four diets, as follows: 1) untreated corn silage with no amylolytic enzyme supply (US-NE); 2) untreated corn silage with amylolytic enzyme supply (US-WE); 3) inoculated corn silage with no amylolytic enzyme supply (IS-NE); and 4) inoculated corn silage with amylolytic enzyme supply (IS-WE). α-Amylase (602 dextrinizing units/kg of dry matter (DM)) was supplied to the wethers at total mixed ration delivery. Dietary supplementation with amylolytic enzyme increased (P = 0.045) DM and starch (P = 0.014) intake in wethers fed the US diet (+245 and +136 g/d, respectively), but not in those fed the IS diet. Inoculation of corn silage (P = 0.026) improved organic matter (OM), crude protein (CP), neutral detergent fiber (aNDFom), and gross energy (GE) digestibility by 5.3%, 11.5%, 25.8%, and 7.1%, respectively. Likewise, enzyme supply increased (P = 0.042) the apparent digestibility of DM, OM, CP, aNDFom, and GE by 5.1%, 4.7%, 9.4%, 20.7%, and 6.2%, respectively. Enzyme supply increased the molar proportion of propionic acid (P = 0.002; 24.1 vs. 19.6 mM / 100 mM) in wethers fed the US diet, but not in those fed the IS diet. Enzyme supply decreased microbial N synthesis (P = 0.025; 6.33 vs. 8.05 g/d) when the wethers were fed the IS diet, but not the US diet. In conclusion, despite the improved OM digestibility, dietary supplementation with amylolytic enzyme yielded inconsistent results with respect to feed intake and microbial protein synthesis in wethers fed diets differing in the use of silage inoculant.

An efficient strategy for enhancing enzymatic saccharification with delignified fungus Myrothecium verrucaria and solid acid

In this work, corn stover was studied as a lignocellulosic material with the potential of serving as a feedstock in the field of bioenergetics. To improve the enzymatic digestibility of carbohydrates in the lignocellulosic biomass, corn stover was pretreated using Myrothecium verrucaria to deplete the lignin, combined with a solid acid pretreatment method to deplete the hemicellulose. The effects of lignin degradation conditions and solid acid concentration on cellulose conversion were investigated. The two-stage pretreatment with M. verrucaria and solid acid under optimal conditions gave 81.54% cellulose conversion yield, 214.22% higher than that of untreated corn stover. Significant lignin and hemicellulose removal rates were observed with the two-stage pretreatment. Scanning electron microscope (SEM), X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses showed major structural changes in the pretreated corn stover. This study provided an efficient strategy to enhance the enzymatic saccharification of cellulose in corn stover.

Effective Saccharification of Corn Stover Using Low-Liquid Aqueous Ammonia Pretreatment and Enzymatic Hydrolysis.

Low-liquid aqueous ammonia (LLAA) pretreatment using aqueous ammonia was investigated to enhance enzymatic saccharification of corn stover. In this method, ground corn stover was simply contacted with aqueous ammonia mist (ammoniation step), followed by pretreatment at elevated temperature (90–150 °C) for an extended period (24–120 h) at different solid/liquid (S/L) ratios (0.29, 0.47 or 0.67), termed a pretreatment step. After that, excess (unreacted) ammonia was removed by evaporation, and the pretreated material was immediately saccharified by an enzyme without a washing step. The effects of key reaction parameters on both glucan digestibility and XMG digestibility were evaluated by analysis of variance (ANOVA). Under the best pretreatment conditions [S/L = 0.47, 0.16 (g NH3)/(g biomass), 90 °C, 24 h], LLAA pretreatment enhanced enzymatic digestibility from 23.1% for glucan and 11.3% for XMG (xylan + galactan + mannan) of untreated corn stover to 91.8% for glucan and 72.6% for XMG in pretreated solid.

Evaluation of Screened Lignin-degrading Fungi for the Biological Pretreatment of Corn Stover

The biological pretreatment of lignocellulosic biomass is a low-cost and eco-friendly method for facilitating enzymatic hydrolysis. In this study, strains with lignin depletion capability were screened using a high-throughput screening method. Sixty-three strains were screened out and Myrothecium verrucaria secreted three lignin-degrading enzymes simultaneously during the bio-pretreatment process. The activity levels of laccase, lignin peroxidase and manganese peroxidase were 6.61, 0.78 and 1.31 U g−1 dry biomass. The content of lignin in corn stover decreased by 42.30% after bio-pretreatment, and the conversion rate increased by 123.84% during the subsequent saccharification process in comparison with the untreated corn stover. Furthermore, the effects of bio-pretreatment on the structure of corn stover were presented using a scanning electron microscope (SEM), Brunauer-Emmet-Teller (BET), X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). The results showed that M.V. is a promising lignin-degrading fungus. This research demonstrated an efficient pretreatment approach for enhancing the enzymatic saccharification of corn stover.

Enhancing Biogas Production from Lime Soaked Corn Cob Residue

This study assessed the impact of lime (Ca(OH) 2 ) soaking pretreatment on biomass digestibility and potential of biogas production compare to untreated corn cob. Corn cob was soaked for different time of incubation, 7, 15, and 30 days. Scanning electron micrograph perceived destruction in the morphology of treated corn cob. The highest cumulative biogas of 360.5, 305.4, 218.6 NmL/gVS was obtained from 30, 15, 7 days pretreated corn cob respectively, which was 2-times higher than the cumulative biogas produced from the untreated corn cob 115.1 NmL/gVS. The best result for the methane yield (136.8 NmL/gVS) was obtained for 30 days soaking. The present study suggested that soaking with Ca(OH) 2 for longer time is effective for increasing digestibility of agriculture waste biomass and improving biogas production.

Bioflocculants\u2019 production in a biomass-degrading bacterium using untreated corn stover as carbon source and use of bioflocculants for microalgae harvest

BackgroundBioflocculation has been developed as a cost-effective and environment-friendly method to harvest multiple microalgae. However, the high production cost of bioflocculants makes it difficult to scale up. In the current study, low-cost bioflocculants were produced from untreated corn stover by a biomass-degrading bacterium Pseudomonas sp. GO2.ResultsPseudomonas sp. GO2 showed excellent production ability of bioflocculants through directly hydrolyzing various biomasses. The untreated corn stover was selected as carbon source for bioflocculants’ production due to its highest flocculating efficiency compared to that when using other biomasses as carbon source. The effects of fermentation parameters on bioflocculants’ production were optimized via response surface methodology. According to the optimal model, an ideal flocculating efficiency of 99.8% was obtained with the fermentation time of 130.46 h, initial pH of 7.46, and biomass content of 0.64%. The relative importance of carboxymethyl cellulase and xylanase accounted for 51.8% in the process of bioflocculants’ production by boosted regression tree analysis, further indicating that the bioflocculants were mainly from the hydrolysates of biomass. Biochemical analysis showed that it contained 59.0% polysaccharides with uronic acid (34.2%), 32.1% protein, and 6.1% nucleic acid in the bioflocculants, which had an average molecular weight as 1.33 × 106 Da. In addition, the bioflocculants showed the highest flocculating efficiency at a concentration of 12.5 mg L−1 and were stable over broad ranges of pH and temperature. The highest flocculating efficiencies obtained for Chlorella zofingiensis and Neochloris oleoabundans were 77.9 and 88.9%, respectively.ConclusionsThe results indicated that Pseudomonas sp. GO2 can directly utilize various untreated lignocellulolytic biomasses to produce low-cost bioflocculants, which showed the high efficiency to harvest two green microalgae in a low GO2 fermentation broth/algal culture ratio.

Sublethal Effects of vATPase-A and Snf7 dsRNAs on Biology of Southern Corn Rootworm, Diabrotica undecimpunctata howardi Barber.

RNA interference is a powerful tool against corn rootworm. Adults and neonates of southern corn rootworm, Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae), were exposed to the LC50 of vATPase-A and Snf7 double-stranded RNAs (dsRNAs), and the effects on female fecundity, egg viability, male fitness as measured by sperm viability and mating capacity, larval recovery along with dry weight, and instar determination 10 d after exposure to dsRNA, were determined. Significant reductions were observed for a number of parameters in dsRNA-exposed rootworms relative to control treatments. Female fecundity and larval recovery were significantly reduced after exposure to both dsRNAs. In addition, larval dry weight and recovery of 2nd and 3rd instars along with dry weight for 3rd instars were significantly reduced after neonate exposure to vATPase-A dsRNA. Neither dsRNA affected male capacity to mate or sperm viability after exposure to the respective LC50s. After 10 d of feeding on untreated corn roots, neonates that survived exposure for 2 d to the vATPase-A dsRNA LC50 exhibited lower dry weight than the control. There was significant gene knockdown in adult males and females after exposure for 5 d to LC50 of vATPase-A and Snf7 dsRNAs. The parameters are discussed in terms of fitness and possible outcomes after deployment of corn hybrids expressing dsRNAs.

Effect of physicochemical pretreatments and enzymatic hydrolysis on corn straw degradation and reducing sugar yield

Straw lignocelluloses were converted to reducing sugar for possible use for bioenergy production via physicochemical pretreatments and enzymatic hydrolysis. The experiment was divided into 2 steps. The first step focused on breaking the crystal structure and removing lignin in corn straw. The lignin, hemicellulose, and cellulose degradation rates observed were 92.2%, 73.7%, and 4.6%, respectively, after corn straw was treated with sodium hydroxide (3% w/w) plus high-pressure steam (autoclave), 74.8%, 72.5%, and 4.3% after corn straw was treated with sodium hydroxide (8%, w/w) plus wet steam explosion, compared with native corn straw (P &lt; 0.05). The second step was enzymatic hydrolysis for the pretreated straw. The enzymatic hydrolysis could yield 576 mg/g reducing sugar and significantly degrade cellulose and hemicellulose contents by 93.3% and 94.4% for the corn straw pretreated with sodium hydroxide plus high-pressure steam. For the corn straw pretreated with sodium hydroxide plus wet steam explosion, the enzymatic hydrolysis could yield 508 mg/g reducing sugar, and degrade cellulose and hemicellulose contents by 83.5% and 84.2%, respectively, compared with the untreated corn straw (P&lt;0.05). Scanning electron microscopy showed that the physicochemical pretreatments plus enzymatic hydrolysis degraded corn straw to many small molecules. Thus, physicochemical pretreatments plus enzymatic hydrolysis converted lignocellulose to reducing sugar effectively.