[目的]稻草还田是黑土地保护的必然要求,但稻草富含木质素,单独腐解较难,能否借助美拉德(Maillard)反应底物对腐殖质形成的激发效应来加速稻草的腐解?[方法]本研究采用室内培养法,以稻草为供试对象,加入适量MnO2 粉末,分别添加葡萄糖(Glucose,Glu)、邻苯二酚(Catechol,Cat)和甘氨酸(Glycine,Gly)的单一、两两组合(Glu-Cat、Glu-Gly和Cat-Gly)溶液及其混合液(Ms),以添加等体积无菌水为对照,接种EM微生物菌剂,在28℃恒温条件下培养90 d,在0、30、60和90 d分别取样进行腐殖质组成分析.[结果]①无论是否添加美拉德反应底物,稻草经腐解后水溶性物质碳含量(CWSS)均有所上升,相比之下,3种美拉德反应底物混合液的添加更有利于CWSS的提升,其次为Gly;添加美拉德反应底物更有利于胡敏素(Hu)的分解.②添加不同美拉德反应底物溶液及其混合液的影响下,稻草腐解产物可提取腐殖酸碳含量(CHE)的变化趋势不一.Glu-Cat处理对CHE含量的提升作用最大,其次为Glu,而Gly和Glu-Gly处理则不利于可提取腐殖酸(HE)的形成;(3)稻草腐解过程胡敏酸(HA)分子结构先简单而后渐趋复杂,重新缩合的HA分子结构更加简单,Cat-Gly处理更有利于HA的分解,使其分子结构简单化,除此之外的其他处理,与CK相比,均可有效抑制HA分子的简单化,其中,添加葡萄糖的效果最佳,更有利于HA分子结构的稳定性,且可提升CHA/CFA,使腐殖质品质得以改善,而Cat不利于腐殖质品质提升、却更易促进Hu的分解.[结论]添加美拉德反应底物更有利于稻草腐解产物CWSS的提升以及Hu的分解,添加葡萄糖更有利于提升稻草腐解产物HA分子结构的稳定性,进而改善其腐殖质品质.

To clarify the contribution of the bridging effect from three metal cations (K+, Mn2+, and Fe3+) on the humification of lignin-rich Tilia wood shavings and further enrich the theory of lignin humification, an indoor incubation method with constant temperature and humidity was adopted. K+, Mn2+, and Fe3+ served as additives, with CK as the control for studying the differential influence of metal cations with different valences on the humus composition of dark-brown soil mixed with Tilia wood shavings. The change in the C contents of water-soluble substance (CWSS), humic-extracted acid (CHE) and humin (CHu), ∆logK value of HE, atomic ratio and FTIR spectra of humic acid (HA), and the ratio of C content of humic acid to fulvic acid (CHA/CFA) of dark-brown soil mixed with Tilia wood shavings were analyzed after 0, 30, 80, and 150 days of incubation, and the following conclusions were reached: (1) The addition of metal cations, regardless of their valence, could effectively improve the microbial utilization and consumption of WSS, and the effect was as follows: Fe3+ > Mn2+ > K+. The addition of three metal cations could effectively inhibit mineralization and reduce the loss of TOC, and the effect could be seen as follows: Fe3+ > Mn2+ > K+. (2) Although the CHE content first decreased and then increased with incubation, the addition of Fe3+ and Mn2+ ions increased the CHE content, showing that Fe3+ > Mn2+, and K+ ions had no significant effect. Throughout the incubation, the structure of HE molecules changed first via a complex process and then through a simple process. Comparing the change before and after the incubation, the overall structure of HE molecules tended to be simpler with the CK control, and HE became more complicated with the addition of Fe3+ and Mn2+; however, the addition of K+ had little effect on the structure of HE molecules. (3) At the end of the incubation, the addition of Fe3+, Mn2+, and K+ ions strengthened the molecular condensation of HA and its aromatization degree, while the CK control without any added metal cations caused HA molecules to decompose and obtain a greater aliphatic degree. In addition, the number of O-containing functional groups and N-containing compounds in HA molecules increased to varying degrees regardless of which metal cation was added. The decomposition of Tilia wood chips led to a partial entry of the decomposition products into the HA component, which was then reconsumed by continuous mineralization. After incubation, the polysaccharides in HA molecules were consumed only with the addition of Mn2+ ions. Fe3+ and Mn2+ ions had greater advantages in increasing the CHA/CFA ratio and improving the humus quality than K+ ions. (4) The addition of metal cations could effectively inhibit the mineralization and decomposition of the Hu component, among which Fe3+ ions had the most significant effect, followed by Mn2+ ions. Compared to monovalent cations (K+), polyvalent cations (Fe3+ and Mn2+) had the advantage of a bridging effect, and their addition promoted the microbial utilization of WSS, effectively reduced the loss of TOC, increased the CHE content, complicated its molecular structure, improved the humus quality, and inhibited the decomposition of Hu. Regardless of which metal cation was added, the degree of molecular polycondensation and aromatization of HA was enhanced, and the number of O-functional groups and N-containing compounds in HA molecules increased.

[目的]研究不同价态金属阳离子对天然富含木质素的椴木屑在腐解期间腐殖质组成的影响,明确各金属阳离子对椴木屑腐殖化进程的贡献,为以木质素为主要成分的农业固体废弃物的资源化利用提供参考。[方法]采用室内恒温培养法,以富含木质素的椴木屑为供试材料,在培养体系中分别添加0.5 mol/L K + 、Mn 2+ 和Fe 3+ ,以不添加任何金属阳离子为对照（CK）,于28℃恒温好氧培养90 d,分别在培养0,45和90 d时取样,分析椴木屑腐解期间总有机碳（TOC）、水溶性物质碳含量(C WSS )、可提取腐殖酸碳含量(C HE )、胡敏酸（HA）碱溶液色调系数（Δlg K）、胡富比(胡敏酸与富里酸碳含量之比,C HA /C FA )和胡敏素碳含量(C Hu )的变化。[结果]（1）随着培养时间的延长,不同处理的TOC含量均表现为先升高后下降的变化规律;培养结束（90 d）时与CK相比,Mn 2+ 和Fe 3+ 处理的TOC含量均显著下降,其中Mn 2+ 处理的TOC含量下降幅度较大。（2）随着培养时间的延长,各处理C WSS 先降低后升高,最终表现为K+和Fe 3+ 能够促进WSS的积累,而Mn 2+ 更易促进WSS的消耗。（3）与其他处理相比,添加Fe 3+ 不仅减缓了CHE的下降,而且在整个培养期间使C HE 维持在最高水平。（4）与培养0 d相比,培养结束时,Fe 3+ 和K + 处理的HA碱溶液Δlg K均下降,而Mn 2+ 处理的HA碱溶液Δlg K则增加;Fe 3+ 和Mn 2+ 处理的C HA /C FA 分别降低了13.1%和6.7%,K+处理的C HA /C FA 无显著变化;Fe 3+ 、Mn 2+ 、K + 和CK处理的C Hu 分别下降了37.9%,14.6%,11.2%和21.5%,其中Fe 3+ 更有利于促进Hu的矿化分解。[结论]相比于K + 和Mn 2+ ,Fe 3+ 可有效促进椴木屑的分解并释放WSS,在促进Hu矿化的同时还能减缓HE的下降。

In view of the high content of lignin in Auricularia auricula chaff and the difficulty of independent decomposition,the Maillard reaction substrates were added to improve its decomposing effect,which could provide a technical reference for its scientific composting.The indoor culture method was adopted to explore the contribution of each Maillard reaction substrate in the humification of Auricularia auricula chaff.In the process,Auricularia auricula chaff served as the basic material,three Maillard reaction substrates such as catechol,glucose and glycine were added,with no reaction substrate added as a control,combined with the changes in the humus composition of Auricularia auricula chaff during the culture process.The result showed that:（1）with the culture,the total organic carbon（TOC）of Auricularia auricula chaff from all the treatments showed a gradual decrease trend,among which the addition of glucose was more conducive to the loss of TOC,and the addition of Maillard reaction substrates made the mineralization within 45 d of culture more obvious.All the treatments were beneficial to the increase of water-soluble carbon content（CWSS）of Auricularia auricula chaff,in which the catechol had the largest increase for CWSS,followed by glucose;（2）All the treatments were helpful to the accumulation of humic-extracted acid extracted from Auricularia auricula chaff,and had more advantages over the cultivation of Maillard reaction substrates in promoting the structural complexity of humic acid;（3）Addition of Maillard reaction substrate could promote the conversion of fulvic acid to humic acid in the Auricularia auricula chaff,among which the glycine had the most obvious effect.In addition,the glycine could also promote the decomposition of the inert humus component humin effectively.In summary,the glycine was more advantageous for the high-efficiency decomposition of Auricularia auricula chaff,mineralized the inert humus component and was also conducive to the improvement of humus quality.

The Maillard reaction is a type of nonenzymatic browning process and is an important pathway for the formation of humic-like substances (HLSs). Glucose is one of the three crucial precursors for the Maillard reaction, and a change in glucose concentration can inevitably affect the humification pathway, thereby regulating the composition and quality of HLSs. To verify the scientific hypothesis, the method of liquid shake-flask culture was adopted. Both catechol and glycine with fixed concentrations were added to a phosphate buffer including δ-MnO2, and only the concentration of glucose was adjusted in the sterile culture system. The obtained supernatant fluid and dark-brown residue were collected dynamically through the centrifugation method. The E4/E6 ratio and total organic C (TOC) of the supernatant fluid, the humus composition, and FTIR spectra for the dark-brown residue, and the elemental composition of humic-like acid (HLA) extracted from the dark-brown residue were analyzed to reveal the effect of varying glucose concentrations on the abiotic humification pathways for the Maillard reaction and the characteristics of relevant products under abiotic processes. The results reveal that (1) the exogenous addition of glucose at different concentrations simplifies the molecular structure in the supernatant fluid, and the TOC content is decreased to varying degrees, among which the addition of 0.24 mol/L glucose leads to the formation of simpler organic molecules in the supernatant compared to that for the other treatments, and the addition of 0.03 mol/L glucose shows the largest decrease in TOC content; (2) Under the coexistence of glycine and catechol, CHLA treated with the addition of glucose at different concentrations shows an upward trend in the course of the culture, which is significantly higher than that obtained for the CK control. The addition of 0.12 mol/L glucose results in the largest increase in CHLA. During the culture period, the structure of HLA molecules from each treatment first become complex and then gradually become simpler. Finally, the molecular structure of HLA treated with different concentrations of glucose becomes more complex, but the structure of HLA molecules from the CK control tends to be simplified. The addition of glucose can improve the condensation degree of HLA molecules, among which the addition of 0.12 mol/L glucose shows the most significant effect. With increasing exogenous glucose concentration, the number of N-containing compounds in the HLA molecules further decreases, while the number of O-containing functional groups increases. (3) The greater the concentration of glucose added, the higher the proportion of aromatic C structures in the dark-brown residue. During this process, the Mn-O bond lattice vibration of the δ-MnO2 layered structure is greatly enhanced. The organic molecules in the dark-brown residue and δ-MnO2 are bound to each other through intermolecular hydrogen bonding. The CHLA/CFLA ratio for each treatment increases to varying degrees after the culture period, indicating that the addition of glucose is more conducive to the improvement of humus quality than the CK control, among which the addition of 0.12 mol/L glucose shows the best effect.

The Maillard reaction is a type of nonenzymic browning process, and it is also an abiotic humification process of sugars, amino acids and phenols catalyzed by δ-MnO2. It is considered to be one of the possible pathways for the formation of humic-like substances (HLS). The change in the ratio of the Maillard precursors inevitably affects the chemical characteristics of HLS, among which the effect of amino acids concentration on the humification pathway and HLS formation has not yet been reported. In view of this, the glucose, glycine and catechol were chosen as tested objects for the present study, and the method of liquid shake-flask culture was adopted. Both catechol and glucose with fixed concentrations were added into a phosphate buffer solution (pH 8.0) containing δ-MnO2, and only the glycine concentration was adjusted in the sterile culture system. The supernatant solution and dark-brown residue were collected dynamically within 360 h through the centrifugation method. The E4/E6 ratio and total organic C (TOC) of the supernatant solution, the C content of the humic-like acid (CHLA), CHLA/CFLA (C content of fulvic-like acid) ratio and FTIR spectra of the dark-brown residue and the E4/E6 ratio and atomic ratio of humic-like acid (HLA) extracted from the dark-brown residue were systematically analyzed to reveal the effect of different glycine concentrations on the abiotic humification pathways and the characteristics of related products from the Maillard reaction under abiotic processes. The results showed that (1) Under the influence of the addition of different glycine concentrations, the structure of organic molecules in the supernatant after culture tended to be simplified, and the addition of three lower concentrations (0, 0.03 and 0.06 mol/L) of glycine made the E4/E6 ratios increase by 100.4%, 57.7% and 33.0%, respectively, and obtained a simpler structure of organic molecules in the supernatant than that of 0.12 and 0.24 mol/L glycine, which made the E4/E6 ratios increase by 5.6% and 18.0%, merely. After culture, the TOC content in the supernatant solution of each treatment decreased to varying degrees, and the addition of Maillard precursors effectively inhibited the loss of TOC in the supernatant solution, especially the addition of glycine at a concentration of 0.06 mol/L, which only reduced the TOC content by 0.1%. (2) The greater the concentration of glycine added, the higher proportion of aromatic C structure existed in the dark-brown residue. O-containing functional groups from the dark-brown residue and δ-MnO2 were bound to each other through hydrogen bonding, and (3) During the culture process, the CHLA treated with the addition of Maillard precursors was significantly higher than that of the CK control. Compared with the result at 0 h, the addition of higher concentrations of glycine (0.12 and 0.24 mol/L) were more conducive to the formation of HLA, making the CHLA increase by 666.2% and 422.7%, which were much more than these results for 256.6%, 282.2% and 360.0% from three concentrations of glycine (0, 0.03 and 0.06 mol/L) at the end of culture. After culture, the structure of HLA molecules treated by the addition of Maillard precursors became more complex, and the overall performance showed that the higher the concentration of added glycine, the more complex the HLA molecules became. Under the coexistence of glucose and catechol, the addition of glycine could promote abiotic condensation and improve the condensation degree of HLA molecules, among which the addition of 0.12 mol/L glycine had the most significant effect. Compared with the CK control, the addition of Maillard precursors could achieve a higher increase in the CHLA/CFLA ratio, which was more beneficial to the improvement of humus quality.