Mannonic Acid and Bio-Ethanol Production from Konjac Using a Two-Step Bioprocess with Candida Shehatae and Gluconobacter Oxydans

Amorphophallus konjac is rich in glucomannan,which can be hydrolyzed into glucose and mannose,thereby acting as an economic raw material for the acquisition of glucose and mannose.The total sugar yield was 91.2%when konjac powder was treated with 0.75%hydrochloric acid at 121℃for 1 h.Thus,dilute acid hydrolysates of konjac powder were used as a carbon source for obtaining value-added products.Here we showed that the microbial production of ethanol and mannonic acid was obtained by employing Candida shehatae(C.shehatae)and Gluconobacter oxydans(G.oxydans).Through a step-by-step bioprocess,glucose is the first selectively converted to ethanol by C.shehatae,which enables G.oxydans-mediated biocatalysis of mannose to mannonic acid.Finally,approximately 100 g ethanol and 340 g mannonic acid were produced starting from 1 kg refined konjac powder.The results demonstrated the feasibility of this bioconversion method for producing mannonic acid starting from crude hydrolysates of konjac powder.

Incorporation ofκ-carrageenan improves the practical features of agar/konjac glucomannan/κ-carrageenan ternary system

Three materials(agar,konjac glucomannan(KGM)andκ-carrageenan)were used to prepare ternary systems,i.e.,sol-gels and their dried composites conditioned at varied relative humidity(RH)(33%,54%and 75%).Combined methods,e.g.,scanning electron microscopy,small-angle X-ray scattering,infrared spectroscopy(IR)and X-ray diffraction(XRD),were used to disclose howκ-carrageenan addition tailors the features of agar/KGM/κ-carrageenan ternary system.As affirmed by IR and XRD,the ternary systems withκ-carrageenan below 25%(agar/KGM/carrageenan,50:25:25,m/m)displayed proper component interactions,which increased the sol-gel transition temperature and the hardness of obtained gels.For instance,the ternary composites could show hardness about 3 to 4 times higher than that for binary counterpart.These gels were dehydrated to acquire ternary composites.Compared to agar/KGM composite,the ternary composites showed fewer crystallites and nanoscale orders,and newly-formed nanoscale structures from chain assembly.Such multi-scale structures,for composites withκ-carrageenan below 25%,showed weaker changes with RH,as revealed by especially morphologic and crystalline features.Consequently,the ternary composites with lessκ-carrageenan(below 25%)exhibited stabilized elongation at break and hydrophilicity at different RHs.This hints to us that agar/KGM/κ-carrageenan composite systems can display series applications with improved features,e.g.,increased sol-gel transition point.

ANTICARC1NOGENIC EFFECT OF REFINED AMORPHO-PHALLUS KONJAC ON MNNG-INDUCED LUNG CANCER IN LACA MICE

Five hundreds and fifty LACA mice were used in 3 batches for studying the anticarcinogenic effect of Konjaku powder on MNNG-induced lung cancers. These mice (within each batch) were randomly allocated to four groups, namely, positive control (MNNG), Amorphophallus konjac (A.K.), complex (MNNG+A.K.), and blank control (C) group. In MNNG group, MNNG (250 μg) was injected intravenously once five days for seven times in each mouse, the total dosage of MNNG being 1.75 mk. In A.K. group, according to w/w, 8% A.K. was well mixed into 92% common diet for long-term breeding. In complex group, MNNG was given as that in MNNG group and the mice were reared as those in A.K. group. The mice in MNNG group and in C group were all reared by common diet. The results showed different degrees of anticarcinogenic and preventive effect of refined A.K. on MNNG-induced lung cancers in LACA mice. A.K. not only exerted effect on the number of induced cancer and precancer, causing a drop of the cancerous rate from 70.87% to 19.38% and the mean number of cancer and precancer in each animal, but also postponed the incubation period. The proportional distribution of the kinds of tumor denoted a decrease in malignancy (adenoma with malignant change) , absence of adenocarcinoma, relative Increase in benign adenoma, and prolonged survival time of animals. The results of experiments in 3 batches also exhibited good duplication.

Influence of Dodecyl Trimethylammonium Chloride on the Structure and Properties of Konjac Glucanmannan

This study presents the interaction between konjac glucanmannan（KGM） and cationic surfactant dodecyl trimethylammonium chloride（DTAC） to provide theoretical guidance and prediction for the experimental design and application of this composite system. Dissipative particle dynamics（DPD） method was used to simulate the interaction between KGM and the cationic surfactant. Influences of concentration, temperature and shear process on the structure and properties of aggregates were mainly examined. The results revealed that the density peak increased with the increase of concentration of KGM. With increasing the temperature, density peak moved to the right and increased, and then decreased when the temperature rose to a certain value. The density peak moved to the right at the low shear rate while decreased at the high one. During simulation, the high viscosity related to the low diffusion rate, which made it difficult to form a large continuous phase.

Effect of carboxymethyl konjac glucomannan coating on curcumin-loaded multilayered emulsion:stability evaluation

The stability against various environmental stresses of the curcumin-loaded secondary and tertiary emulsions that was emulsified by whey protein isolate(WPI)and coated by chitosan(CHI),carboxymethyl konjac glucomannan(CMKGM),or their combination through layer-by-layer assembly was investigated.Generally,the multilayered emulsions were destabilized in high Na Cl concentrations or medium p H that could interrupt the electrostatic interaction between the three polyelectrolytes or deprotonate CHI,indicating that electrostatic interaction played an important role in the stability of emulsions.Compared with the primary emulsion that was solely stabilized by WPI,extra coating with CHI and CMKGM generally increased the stability of the emulsion against repeated freezing-thawing,improved the retention of curcumin against heating,UV irradiation,and long-term storage,and the effects were more remarkable in the tertiary emulsion with CMKGM locating in the outmost layer.Since CMKGM has shown the colon-targeted delivery potency,the multilayered emulsions assembled by layer-by-layer deposition,especially the tertiary emulsion,could be used as an effective carrier for the targeted delivery of curcumin.

Research Progress in Biological Control of Soft Rot of Amorphophallus konjac

In this paper,the main control methods of soft rot of Amorphophallus konjac are reviewed,with a focus on the current research status of using plant growth promoting rhizobacteria for biological control of soft rot of A.konjac,and future research directions are looked forward to.

Screening of Antagonistic Actinomyces against Soft Rot of Amorphophallus konjac and Its Antibacterial Activity

[Objective] Antagonistic actinomyces of Amorphophallus konjac soft rot were isolated from the soil,the antibacterial activity of the fermentation was detected,and its active components were separated.[Method] The antagonistic actinomycetes were screened using plate confrontation culture method.The SJK18 antagonistic strain with strong activity was conducted single-factor tests using different carbon sources,nitrogen sources,temperatures and pH value as the culture condition,and the antibacterial activities of fermentation liquid was determined,respectively.The fermentation liquid of antagonistic strain was extracted with alcohol and acetic ester,and their antibacterial activities were determined.[Result] A total of 112 strains of actinomycetes were obtained,and 11 strains had antibacterial activity.The antibacterial activity of SJK18 strain was the strongest in the single-factor test,when the corn powder was adopted as the carbon sources,KNO3 was the nitrogen source,the temperature was 30 ℃ and the pH was 6.0,the appropriate pH value for the activity was 5.5-10.0.The diameters of inhibition zone of alcohol extract and raffinate of ethyl acetate were 17.0 and 20.0 mm,respectively,while the extraction of ethyl acetate had no antibacterial activity.[Conclusion] A strain of actinomyces with strong antibacterial activity against soft rot of A.konjac was obtained.

Rapid DNA Extraction Method from Amorphophallas.konjac and ISSR-PCR Amplification

[Objective]The research aimed to study the total DNA extraction methods of Amorphophallas.konjac.[Method]To investigate the optimum DNA extraction method,CTAB,SDS and new modified methods for isolating genomic DNA from Amorphophallas.konjac leaf were studied and the isolated DNAs were examined by ultraviolet absorption test,agarose gel electrophoresis and ISSR-PCR test for comparative analysis.[Result]The results showed that the new modified method was suitable for DNA isolation from Amorphophallas.konjac plants with high purity and yield;quality of DNA could meet ISSR-PCR requirement even extracted once by the new modified method.[Conclusion]The study provided basis for extracting high quality DNA sample,and offered the molecular genetics reference for exploring the genetic diversity of Amorphophallas.konjac.

Effects of Nitrogen, Phosphate and Potassium Fertilizers on Soft Rot of Konjac Based on Grey Correlation Analysis

[Objective] The effects of different application amounts of nitrogen, phos-phate and potassium fertilizers on soft rot of konjac were investigated in this study. [Method] The grey correlation analysis was adopted to evaluate the correlation be-tween the application amount of nitrogen, phosphate and potassium fertilizers and the occurrence of soft rot of konjac. [Result] The excessive application of nitrogen fertilizer would induce the occurrence of soft rot of konjac, but the application of potassium fertilizer had a good control effect on soft rot. [Conclusion] The applica-tion amount of nitrogen fertilizer should be control ed reasonably in the planting of konjac, but the application amount of phosphate and potassium fertilizer could be in-creased to some extent, reducing the occurrence of soft rot of konjac.

Studies on Hydrogen Bonding Network Structures of Konjac Glucomannan

In this paper, the hydrogen bonding network models of konjac glucomannan （KGM） are predicted in the approach of molecular dynamics （MD）. These models have been proved by experiments whose results are consistent with those from simulation. The results show that the hydrogen bonding network structures of KGM are stable and the key linking points of hydrogen bonding network are at the O（6） and O（2） positions on KGM ring. Moreover, acety has significant influence on hydrogen bonding network and hydrogen bonding network structures are more stable after deacetylation.

Synthesis and Characterization of Phosphated Konjac Glucomannan Hydrogels

Konjac glucomannan （KGM） was crosslinked with sodium tripolyphosphate （STPP） to synthesize hydrogels. The crosslinking reaction was confirmed by FT-IR. The results of degradation test show that the hydrogels retain the enzymatic degradation character of KGM and can be degraded for 74.45% in 5 days by cellulase E0240.

Study on Gel Formation Mechanism of Konjac Glucomannan

The transformation of molecular conformation after gelatinization of konjac glucomannan is characterized by means of GC, GPC, FT-IR, DSC, XRD and TEM. The results showed that the molecule of KGM had no branch, the monose composition and connecting type of the molecular chain had no change, the transformation of molecule weight was little, and its drying powder sample formed an evidently new crystalline region. The hollow double helix structure of KGM in hydrosol changed from stretch chain into intercross and entwisted after gelatinization. The gelatin formation mechanism of konjac glucomannan is thereby expounded.

Study on Molecular Chain Morphology of Konjac Glucomannan

The long-range structure of konjac glucomannan(KGM)is studied by using laser light scatter(LLS), gel permeation chromatography(GPC)and method of viscosidity. The weight-average molecular weight(Mw), root-mean-square ratio of gyration[(S2)1/2], second viral coefficient(A2)and multi-dispersion coefficient(Mw/Mn)are 1.04×106, 105. 0±0. 9 nm,(-1. 59±0.28)×10-3 mol ml g-2 and 1.015±0.003, respectively. Mark-Houwink equation is established as [η] = 5. 96×10-2Mw0.73 and the molecular chain parameters are as follows: ML=982. 82 nm-1, Lp = 27. 93 nm, d = 0. 74 nm, h = 0. 26 nm, L = l 054.11 nm. Further more molecular chain morphology of KGM is studied by using atom force microscope(AFM)and transmission electronic microscope(TEM), and the result shows that the KGM molecular is an extending semi-flexible linear chain without branch. Therefore, the image of molecular chain morphology confirms the deduction drawn by Mark-Houwink equation and molecular chain parameters.

Dynamics Study of the Influence of Temperature on Konjac Glucomannan Saline Solution’s Viscosity

Molecular dynamics （MD） method is adopted to simulate the conformation variations of konjac glucomannan （KGM） saline solution at different temperatures, and structurally analyze the trends and reasons of viscosity change in KGM saline solution with temperature. The experimental results have been analyzed to find out that the sum of formative hydrogen bonds decreases with the rise of temperature and the amount of intramolecular hydrogen bonds suddenly increases at 323 K. Besides, in terms of molecular orbital data obtained from simulation, we can know that hydrogen bonding energy also decreases with the rise of temperature. Therefore, we can predict the viscosity of KGM saline solution decreases gradually when rising the temperature.

Studies on Single Chain Structure of Konjac Glucomannan

The simulation is carried out by employing the method of molecular dynamics with the single chain of konjac glucomannan （KGM） in vacuum as the structural model to discuss the factors that affect the single chain structure, the dynamic structure of the chain and the acting forces that maintain the chain structure. The results show that the shape and stability of the chain are affected by the degree of polymerization. As for the KGM with high degree of polymerization, its chain presents random coiling state and its stability declines. Both before and after deacetylation in the process of dynamic motion, the chain of KGM presents random coiling state with periodic variation of extension and coil and demonstrates favorable flexibility, indicating acetyl is not the main factor that affects the shape of chain, whereas dihedral angle and static actions are respectively the key bonding and nonbonding acting forces that influence the single chain conformations in vacuum.

Analysis of Influential Factors of Konjac Glucomannan(KGM) Molecular Structure on Its Activity

Biological activity of konjac glucomannan is closely related to its structure,in particular to its high-level structure.Researches on the activity mechanism of konjac glucomannan are significant for revealing the mysteries of participation in life activity.In this paper,analysis of the effects of konjac glucomannan configuration and various factors on its structure and activity was conducted,mechanism of biological activity of konjac glucomannan was explored,and the hot research topic of konjac glucomannan was given.

Formation Sites and Microscopic Conformation Study on the Konjac Glucomannan Molecular Helices

In this work, the formation sites, helical parameters and hydrogen bond positions of Konjac glucomannan molecular helices were investigated using molecular dynamic simulation method. To our interest, the KGM chain is mainly composed by local left and right helix struetttres. The formation sites of KGM chain might locate at the chain-segments containing acetyl groups, and the left helix is the favorable conformation of KGM. Temperature-dependent molecule conformation study indicates that the right helix is dominant when the temperature is lower than 343 K, above which, however, the left helix is dominating （right helix disappears）. In addition, intramolecular hydrogen bonds in the left helix can be found at the -OH groups on C（2）, C（4） and C（6） of mannose residues; comparably, the intramolecular hydrogen bonds in the right helix can be mainly observed at the -OH groups on C（4） and C（6） of the mannose residues and C（3） of the glucose residues. In conclusion, molecular dynamic simulation is an efficient method for the microscopic conformation study of glucomannan molecular helices.

Hydrogen Bond Networks' QSAR and Topologica Analysis of Konjac Glucomannan Chains

Based on the knot theory and researching of network structures of glucomannan molecules, the polysaccharides were analyzed. The link prediction analysis is to further reveal the interactions between polysaccharides, to elaborate QSAR of polysaccharides, and to analyze the network conformation relationships among polysaccharides. We made a classification for glucomannan molecules based on the related domestic and international theories, and investigated their network structures and application prospects. The knot theory and the link predictions not only simplify the glucomannan microscopic descriptions but also play a guiding role in predicting and regulating the structures.

Studies on the Molecular Chain Conformation Stability of Aminated Konjac Glucomannan

Konjac glucomannan （KGM） was aminated by 2-chloroethyl-amine （CEA） as reagent so as to study the influence of concentration of CEA （based on the amount of KGM）, concentration of NaOH, reaction time and temperature on the extent of amination. And the molecular simulation technology was adopted to analyze the conformation stability of aminate （AKGM）. The results indicate that when the amount of CEA is higher, the extent of amination is higher. The optimum concentration of NaOH, reaction time and temperature are 10% NaOH, 70 ℃ and 45 rain, respectively. IR shows KGM is successfully aminated. The conformation of AKGM is in a random clew-like shape.

Effect of Plasma Treatment on the Structures and Properties of Konjac Glucomannan Film

To understand the effect of plasma treatment on the Konjac glucomannan film, the nitrogen plasma was injected into the film by ion beam injection machine in this study. The structures and properties of Konjac glucomannan film after plasma treatment were analyzed by Infrared spectroscopy, Raman spectrum, X-ray, ect. The result showed that nitrogen groups appeared in the KGM molecular chain and part of this chain fractured, and the number of hydrogen bonds increased after the treatment of plasma. The form of KGM molecule remained amorphous non-crystalline state, but the crystalline region was increased and became more ordered. The mechanical property of tensile strength and breaking elongation was improved, while the WVP was decreased. The nitrogen groups were grafted on the KGM molecular chain after plasma treatment, which led to the improvement of the properties of KGM film.