本文采用饲料类芽孢杆菌(Paenibacillus pabuli, P)、深红紫链霉菌(Streptomyces violaceorubidus, S)和黄绿木霉(Trichoderma aureoviride, T), 组合构建了3种单菌剂(P、S和T)、3种两菌种复合菌剂(PT、PS和ST)及1种3菌种复合菌剂(PST), 并将之添加到红壤中, 监测各菌剂添加后土壤总磷脂脂肪酸(PLFAs)量、特征微生物 PLFAs 百分含量、土壤呼吸速率及总代谢熵的变化, 旨在探明外源腐解微生物的物种组合对土壤微生物群落结构和代谢活性的影响, 进而为优化有机物分解菌剂种群配置提供参考.结果显示, 添加单菌剂的 P、S和T处理及添加两菌种复合菌剂的PT和PS处理, 土壤微生物生物量显著增加, 增幅17.2%~121.6%(P＜0.05).添加外源腐解微生物后, 各处理的土壤微生物群落的细菌百分含量基本稳定在 79.6%~83.1%, 真菌百分含量显著增加8.8%~50.6%; 而放线菌百分含量除P和ST处理外, 其他处理显著降低9.4%~69.8%.PLFAs数据的主成分分析表明, 各外源菌剂处理与CK处理间的群落结构变异由小到大依次为: 接种单菌剂的P、S和T处理, 接种两菌种复合菌剂的PT、PS和ST处理, 接种3菌种复合菌剂的PST处理.添加单菌剂的P、T处理以及添加两菌种复合菌剂的ST处理, 在短期内影响了土壤微生物的对数生长, 使土壤呼吸速率的峰值分别提高48.7%、53.7%和78.7%; 且外源腐解微生物组合的物种数量越多, 土壤微生物进入潜伏期所需的时间越长.从外源腐解微生物对土壤肥力的长期影响来看, 两菌种复合菌剂ST的添加使土壤微生物代谢活性提高28.9%,因此该处理的土壤碳矿化量增加11.1%; 添加单菌剂的S处理使土壤微生物代谢活性显著降低32.4%, 因此该处理的土壤碳矿化量仅降低 7.3%; 而添加两菌种复合菌剂的 PS 处理和 3 菌种复合菌剂的 PST 处理, 在保持代谢活性不变的情况下, 其土壤碳矿化量也降低5.8%~8.7%, 其原因有待进一步研究.综上所述, 外源腐解微生物的添加会改变土壤微生物的群落结构及其生长轨迹, 且随外源腐解微生物组合的物种数量增多这一干扰程度越大, 而土壤微生物代谢活性与外源腐解微生物组合的物种数量无显著相关性.%An incubation experiment was conducted to study the effects of species combination of exogenous decomposing micro-organisms on soil microbial community structure and metabolic activity. The objective of the study was to lay the basis for the optimization of population configuration of decomposing microbial agents. In the study, three microbe species — Paenibacillus pabuli (P), Streptomyces violaceorubidus (S) and Trichoderma aureoviride (T)—were selected. For the experiments, in addition to single P, S and T microbe strains, the microbes were merged to produce two species (PT, PS and ST) and three species (PST) combinations of decomposing microorganisms (forming a total of 7 microbial agents). These microbial agents were then added to red soil sampled from Jiangxi Province in South China. Moreover, a control treatment of red soil added with sterile peat was set to the experimental design. During the incubation period, temporal changes in soil respiration rate and microbial biomass carbon were monitored. Additionally, the changes in total PLFAs content and in the proportion of characteristic microbial population in different treatments after 30 days of incubation were determined. The PLFAs percentages of microbial communities showed the total microbial biomass and composition of soil microbial communities. The results showed that, except for ST and PST, most treatments showed that total microbial biomass increased from 17.2% to 121.6% (P ＜ 0.05). Compared with the control, the proportion of fungus in all the treatments increased by 8.8%-50.6% (P ＜ 0.05). However, the proportion of bacteria in PLFAs remained basically unchanged, increasing from 79.6% to 83.1%. For most of the treatments, except for P and ST, the proportion of actinomyces decreased from 9.4% to 69.8%. Principal component analysis (PCA) of PLFAs data indicated that soil microbial community structure was influenced by different decomposing micro-organisms agents. The change in microbial community structure varied with treatment type, among which single P, S and T microbe strains were smallest and their trio-combination (PST) biggest, compared with the control. The results of soil respiration rate showed the growth of micro-organisms. Treatments of single P and T microbe strains and binary combination of micro-organisms S and T (ST) affected logarithmic growth of soil microbes in the short-term, increasing peak soil respiration rate by 48.7% (P), 53.7% (T) and 78.7% (ST), respectively. Additionally, with increasing number of species of decomposing micro-organisms, it took more time for soil microbes to enter latent phase. From long-term impact of exogenous decomposing micro-organisms on soil fertility, these micro-organisms changed soil microbial metabolic activity, which led to a change in the amount of soil carbon mineralization. The addition of ST combination of microorganisms increased soil microbial metabolic quotient by 28.9%, consequently, the amount of soil carbon mineralization increased by 11.1%. The addition of single S microbe strain decreased soil microbial metabolic quotient by 32.4%, while the amount of soil carbon mineralization only decreased by 7.3%. However, under PS and PST combinations, microbial metabolic activity remained unchanged, while the amount of soil carbon mineralization decreased by 5.8% and 8.7%, separately. There was the need for further study on these treatment combinations. In conclusion, the addition of exogenous decomposing micro-organisms changed soil microbial community structure and growth trajectory. Furthermore, with increasing number of species of decomposing micro-organisms, change in microbial community structure increased. Finally, the study failed to account for any relationship between soil microbial metabolic activity and the number of species of decomposing micro-organisms.
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