Study on the green extraction of corncob xylan by deep eutectic solvent

Corn as one of the world's major food crops,its by-product corn cob is also rich in resources.However,the unreasonable utilization of corn cob often causes the environmental pollution,waste of resources and other problems.As one of the most abundant polymers in nature,xylan is widely used in food,medicine,materials and other fields.Corn cob is rich in xylan,which is an ideal raw material for extracting xylan.However,the intractable lignin is covalently linked to xylan,which increases the difficulty of xylan extraction.It has been reported that the deep eutectic solvent(DES)could preferentially dissolve lignin in biomass,thereby dissolving the xylan.Then,the xylan in the extract was separated by ethanol precipitation method.The xylan precipitate was obtained after centrifugation,while the supernatant was retained.The components of the supernatant after ethanol precipitation were separated by the rotary evaporator.The ethanol,water and DES were collected for the subsequent extraction of corn cob xylan.In this study,a novel way was provided for the green production of corn cob xylan.The DES was used to extract xylan from corn cob which was used as the raw material.The effects of solid-liquid ratio,reaction time,reaction temperature and water content of DES on the extraction rate of corn cob xylan were investigated by the single factor test.Furthermore,the orthogonal test was designed to optimize the xylan extraction process.The structure of corn cob xylan was analyzed and verified.The results showed that the optimum extraction conditions of corn cob xylan were as follows:the ratio of corn cob to DES was 1:15(g:mL),the extraction time was 3 h,the extraction temperature was 60℃,and the water content of DES was 70%.Under these conditions,the extraction rate of xylan was 16.46%.The extracted corn cob xylan was distinctive triple helix of polysaccharide,which was similar to the structure of commercially available xylan.Xylan was effectively and workably extracted from corn cob by the DES method.This study provided a new approach for high value conversion of corn cob and the clean production of xylan.

Insights into the mechanism of Sub3 inhibiting Fusarium moniliforme infection in maize

Fusarium moniliforme(F.moniliforme) and its secondary metabolite fumonisin pose a severe threat to food safety,and searching for effective antimicrobial agents is a focus of current research.In this study,the secondary structure of Sub3 was analyzed by circular dichroism,meanwhile,the inhibition rate of Sub3 against spores,mycelia of F.moniliforme and infected maize was studied.To explore the possible inhibition mechanisms,morphological and structural changes of spores treated with Sub3 at0,1/2 MIC(minimum inhibitory concentration) and MIC were observed by scanning electron microscopy and transmission electron microscopy;the cell wall integrity,membrane integrity,reactive oxygen species,mitochondrial membrane potential,ATP synthase activity,redox reactions,and the nuclear damage of F.moniliforme were also investigated.The results showed that Sub3 was mostly in the state of random in deionized water,while mainly showed the β-sheet structure in the hydrophobic environment of 50% Trifluoroethanol(TFE) solution,indicating that Sub3 might generate partial structure deformation when acting on the cell membrane;and its MIC on F.moniliforme spores was 0.2 g/L.Under the 1/2 MIC and MIC,the inhibition rates of Sub3 against F.moniliforme infected maize were 34.3% and75.6%,respectively.The results of inhibition mechanisms revealed that the defective pathogenicity of F.moniliforme caused by Sub3 was attributed to damages on both the cell wall and the cell membrane,which might upset balance of intracellular redox system and mitochondrial energy metabolism and trigger nucleus damage,ultimately leading to cell death.Meanwhile,Sub3 could diminished ATP synthase enzyme activity in a dose-dependent manner.The results provided direct evidence for inhibition of F.moniliforme infection of maize by Sub3,and useful knowledge applicable for food preservation.

Anti-fungal properties of Puroindoline A against Aspergillus glaucus

Aspergillus glaucus can grow in low moisture grain,and is one of the main fungi responsible for agricultural product losses.Puroindoline A(PINA)is a tryptophan-rich alkaline adiponectin that can effectively inhibit numerous plant bacteria and fungi.However,the mechanism of PINA against A.glaucus remains unclear.Herein,we found that recombinant PINA(rPINA)could inhibit A.glaucus mycelia growth on salt Czapek dox agar(SCDA)medium and spore germination on Czapek dox(CD)medium.Scanning electron microscopy revealed that incomplete morphological characteristics of both A.glaucus spores and mycelia occurred following rPINA treatment.Laser scanning confocal microscopy(LSCM)showed that rPINA could enter the interior of spores.Flow cytometry and propidium iodide(PI)staining illustrated membranes of spores were severely damaged,especially after treatment with 0.9 mg/mL rPINA for 12 h,and spores with intact membranes were reduced by 30.7%.Additionally,rPINA reduced the mitochondrial membrane potential(MMP)by 5,5′,6,6′-tetrachlorr-1,1′,3,3′-tetraethyl-imidacarbocyanine iodide(JC-1)staining,and caused DNA damage by 4′,6-diamidino-2-phenylindole(DAPI)staining.These results indicated that rPINA may damage cell membranes and DNA structure and reduceMMP,thereby inhibiting the growth of A.glaucus.The antifungal mechanism has been demonstrated in this study,and results show that rPINA has application potential in preventing postharvest loss in the agricultural industry.

Effects of hexanal fumigation on fungal spoilage and grain quality of stored wheat

The prevention of fungal spoilage is an essential consideration in wheat storage.Recent studies have revealed that volatile organic compounds(VOCs),possibly with natural fungicidal properties,could be produced from stored wheat grains.In this study,the antifungal effect of hexanal,a main component of VOCs from stored wheat,against spoilage fungi on agar plate and in high-moisture wheat grains were investigated via the gas fumigation method.And the impact of hexanal fumigation on grain quality was evaluated through analysis of the malondialdehyde content,fatty acid values,germination percentages and vigor of 16%and 18%moisture wheat grains fumigated with 1.66,2.49,and 3.31 mmol/L hexanal vapor.The results of in vitro antifungal experiments on agar plates revealed that the minimum inhibitory concentration and minimum fungicidal(fatal)concentration of hexanal against the five fungi were 4–14 folds and 4–7 folds lower than those of propionic acid,respectively.The fungal spoilage of high-moisture wheat grains inoculated with pure fungal spores and with naturally occurring fungi could be completely inhibited by 1.66 mmol/L hexanal vapor.During 5-week storage of high-moisture wheat grains fumigated with 1.66,2.49,and 3.31 mmol/L hexanal vapor,the malondialdehyde content in high-moisture wheat grains did not change significantly in all samples,and fatty acid values were slightly higher in 18%moisture wheat than in 16%moisture wheat.The germination percentages and vigor of wheat samples decreased with increased hexanal vapor concentrations and moisture content.These results indicated that hexanal fumigation could be used as an alternative chemical control method to prevent the fungal spoilage of postharvest wheat.

Survey of Intracellular Protein Extraction Methods from Pichia pastoris

The broken efficiency of cell wall and the release amount of Pichia pastoris intracellular protein under different cell breaking conditions were investigated in this paper. The results showed that broken efficiency using hot alkali combined with high-pressure homogenizing method was higher than that of enzyme hydrolysis, hot alkali treatment and high-pressure homogenation, respectively. Suspended medium had little effect on the broken efficiency of yeast cell, but had significant effect on the protein release yield. The results indicated that optimal condition for intracellular proteins extraction was 30% (wet weight, w/v) of yeast cells suspend in 50 mM phosphate buffer (pH 10.0), water bathed at 60?C for 2 hours, homogenized twice at 100 MPa pressure. The broken efficiency of Pichia pastoris cell could reach 87.6% and the protein yield was 35.48 g per 100 g cells.

Consolidated bioprocess of corn stover to polysaccharide using Chaetomium globosum CGMCC 6882

Polysaccharide produced from medicinal endophytic fungus not only has applications in foods,but also exhibits multiple biological activities.In this work,an endophytic fungus Chaetomium globosum CGMCC 6882 could use corn stover to produce a polysaccharide(GCP-SC)by consolidated bioprocess and the titer of GCP-SC reached 3.2 g/L.The transcriptional levels of genes related to cellulose degradation(cbh,cdh,glu and egl)in C.globosum CGMCC 6882 were 4.38,3.85,3.13,and 2.17 folds compared to the control group when corn stover was used as the sole carbon source.Moreover,GCP-SC showed a time-and dose-dependent manner of inhibitory effect on A549 cells and the inhibitory rate reached 93.3%.This work provides meaningful data on agricultural residues utilization and facilitation of future relative resource conversion studies.