Pietikäinen Janna, Pettersson Marie, Bååth Erland
Department of Microbial Ecology, Ecology Building, Lund University, Helgonavagen 5, SE-223 62 Lund, Sweden.
FEMS Microbiol Ecol. 2005 Mar 1;52(1):49-58. doi: 10.1016/j.femsec.2004.10.002. Epub 2004 Nov 18.
Temperature is an important factor regulating microbial activity and shaping the soil microbial community. Little is known, however, on how temperature affects the most important groups of the soil microorganisms, the bacteria and the fungi, in situ. We have therefore measured the instantaneous total activity (respiration rate), bacterial activity (growth rate as thymidine incorporation rate) and fungal activity (growth rate as acetate-in-ergosterol incorporation rate) in soil at different temperatures (0-45 degrees C). Two soils were compared: one was an agricultural soil low in organic matter and with high pH, and the other was a forest humus soil with high organic matter content and low pH. Fungal and bacterial growth rates had optimum temperatures around 25-30 degrees C, while at higher temperatures lower values were found. This decrease was more drastic for fungi than for bacteria, resulting in an increase in the ratio of bacterial to fungal growth rate at higher temperatures. A tendency towards the opposite effect was observed at low temperatures, indicating that fungi were more adapted to low-temperature conditions than bacteria. The temperature dependence of all three activities was well modelled by the square root (Ratkowsky) model below the optimum temperature for fungal and bacterial growth. The respiration rate increased over almost the whole temperature range, showing the highest value at around 45 degrees C. Thus, at temperatures above 30 degrees C there was an uncoupling between the instantaneous respiration rate and bacterial and fungal activity. At these high temperatures, the respiration rate closely followed the Arrhenius temperature relationship.
温度是调节微生物活动和塑造土壤微生物群落的重要因素。然而，关于温度如何原位影响土壤中最重要的微生物类群——细菌和真菌，我们却知之甚少。因此，我们测定了不同温度（0 - 45摄氏度）下土壤中的瞬时总活性（呼吸速率）、细菌活性（以胸苷掺入率表示的生长速率）和真菌活性（以麦角固醇中乙酸掺入率表示的生长速率）。我们比较了两种土壤：一种是低有机质、高pH值的农业土壤，另一种是高有机质含量、低pH值的森林腐殖土。真菌和细菌的生长速率在25 - 30摄氏度左右有最佳温度，而在较高温度下数值较低。真菌的这种下降比细菌更为剧烈，导致在较高温度下细菌与真菌生长速率的比值增加。在低温下观察到相反的趋势，表明真菌比细菌更适应低温条件。在低于真菌和细菌生长的最佳温度下，所有三种活性的温度依赖性都能很好地用平方根（Ratkowsky）模型来模拟。呼吸速率在几乎整个温度范围内都有所增加，在约45摄氏度时达到最高值。因此，在30摄氏度以上的温度下，瞬时呼吸速率与细菌和真菌活性之间出现了解偶联。在这些高温下，呼吸速率紧密遵循阿伦尼乌斯温度关系。
