在煤的厌氧发酵系统中加入秸秆能够显著提高煤制生物甲烷产气量，但联合发酵伴随的底物与菌群代谢的变化规律却鲜有研究。开展不同煤阶煤与玉米秸秆联合发酵生物产气试验，基于16S rRNA测试探讨菌群代谢特征，采用SEM测试分析煤与玉米秸秆的微生物附着特征，XPS测试煤的表面元素赋存形态变化特征。结果表明，瘦煤、弱黏煤和焦煤与玉米秸秆最佳质量比为2:1、2:1、3:1，相应的甲烷产量分别为17.28、12.51和14.88 mL/g，不同煤阶煤与秸秆联合发酵的促进效果依次为瘦煤>焦煤>弱黏煤。菌群鉴定揭示了混合发酵体系中球螺菌属(Sphaerochaeta)和噬蛋白菌属(Proteiniphilum)为优势细菌属，分别占35.95%和24.36%，而优势古菌属为甲烷八叠球菌属(Methanosarcina)、甲烷杆菌属(Methanobacterium)和甲烷丝菌属(Methanoculleus)，分别占比达到49.71%、31.83%和9.87%。瘦煤与焦煤和弱黏煤相比，联合发酵液中代谢糖类物质的细菌属及古菌属和基因功能占据优势，而这与甲烷产气规律趋于一致。不同混合底物发酵时，随着煤阶的升高，煤表面的菌群附着量逐渐减少，而玉米秸秆表面始终附着大量菌群，表明玉米秸秆始终具有降解优势。联合发酵后焦煤和弱黏煤表面C元素相对含量相比于瘦煤减少更加明显，而含氧有机碳（C—O、C=O和O—C=O）的总相对含量明显升高，表明联合发酵能够促进菌群生长代谢，使得更多有机碳转化为生物甲烷，研究结果查明了不同煤阶煤与玉米秸秆联合发酵在微观层面上的作用效果，对于揭示煤与玉米秸秆联合发酵内在机制具有参考意义。

Adding corn straw to the anaerobic fermentation system of coal can significantly increase the gas production of coal-to-biomethane. However, the changes in substrate and microbial metabolism accompanying this combined fermentation are rarely studied. The Scanning Electron Microscope (SEM) test was utilized to analyze the microbial adhesion characteristics of coal and corn straw, while the X-ray Photoelectron Spectroscopy (XPS) test examined the changes in surface elements of coal. The results indicated that the optimal ratios of lean coal, weakly caking coal, and coking coal to corn straw were 2∶1, 2∶1, and 3∶1, respectively, and the corresponding methane yields were 17.28 mL/g, 12.51 mL/g, and 14.88 mL/g. The promotional effect of co-fermentation of different rank coal and straw was observed in the order of lean coal > coking coal > weakly caking coal. Microbial identification revealed that Sphaerochaeta and Proteiniphilum were the dominant bacterial genera in the mixed fermentation system, comprising 35.95% and 24.36% of the population, respectively. Additionally, Methanosarcina, Methanobacterium, and Methanoculleus emerged as the dominant archaea, constituting 49.71%, 31.83%, and 9.87%, respectively. In comparison with coking coal and weakly caking coal, the bacterial and archaeal genera, along with their associated gene functions responsible for carbohydrate metabolism in the combined fermentation broth of lean coal, coking coal, and weakly caking coal, were found to be dominant. This observation aligns with the principles governing methane production. Notably, in mixed substrate fermentation, as coal rank increased, bacterial presence on the coal surface gradually declined, while a substantial bacterial population consistently adhered to the surface of corn straw, indicating the latter's sustained advantage in degradation. After co-fermentation, the relative content of C element on the surface of coking coal and weakly caking coal decreased more significantly than that of lean coal, while the total relative content of oxygen-containing organic carbon ( C—O, C=O and O—C=O ) increased significantly, indicating that co-fermentation can promote the growth and metabolism of bacteria, so that more organic carbon can be converted into biological methane. The research results identified the effect of co-fermentation of different rank coal and corn straw at the micro level, which has reference significance for revealing the internal mechanism of co-fermentation of coal and corn straw.