Different Influences of Exudate Components on Microbial and Enzymatic Activities in a Subalpine Spruce Plantation
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摘要:
目的 揭示根系分泌物不同组分对土壤微生物及其胞外酶活性的影响差异。 方法 在受控良好的根际生态模拟装置中,通过模拟根系每天向采自西南亚高山云杉人工林(约70年)的土壤中分别添加葡萄糖、草酸和甘氨酸溶液,并培养25天(共添加了70.65 mg 碳)。 结果 葡萄糖添加显著增加了几乎所有微生物类群(除了革兰氏阴性细菌)的活性,草酸添加也显著增加了绝大多数微生物群落的活性(如革兰氏阳性细菌、革兰氏阴性细菌和总微生物群落),但葡萄糖添加对微生物群落活性的增加效应较草酸明显,而甘氨酸添加则呈现出抑制微生物活性的趋势。同时,葡萄糖添加和草酸添加分别显著增加了β-1,4-葡萄糖苷酶和过氧化物酶的活性,并且也有增加酸性磷酸酶和多酚氧化酶酶活性的趋势,而甘氨酸添加对多数胞外酶活性的影响不显著。 结论 根系分泌物不同组分(葡萄糖、草酸和甘氨酸)对土壤微生物活性、群落组成和胞外酶产生了差异化的影响,造成这些差异的原因可能与根系分泌物不同组分所含的化学官能团(甲基和羧基)以及能量属性有关。因此,在未来构建根际生物地球化学循环模型时,应当充分考虑根系分泌物组分之间的差异效应。 Abstract:Objective The aim is to reveal the differential effects of exudate components on the activities of soil microorganisms and their extracellular enzymes. Method In well-controlled rhizosphere systems, glucose, oxalic acid and glycine solutions were separately added to soils collected from a southwest subalpine spruce plantation (approximately 70 years old) via artificial roots, and incubated for 25 days (a total of 70.65 mg C was added). Result Glucose addition significantly increased the activities of almost all microbial communities (except the gram-negative bacteria). Oxalic acid addition also significantly increased the activities of most of the microbial communities (e.g., gram-positive bacteria and gram-negative bacteria and total microbial communities). However, the increments of activities of the microbial communities from glucose addition was higher than that observed from oxalic acid addition. In contrast, glycine addition tended to exert an inhibiting effect on microbial activities. In addition, glucose and oxalic acid additions significantly increased the activities of β-1,4-glucosidase and peroxidase (acid phosphatase and polyphenol oxidase activities showed an increasing trend), respectively, while the addition of glycine had little effect on the activities of extracellular enzymes. Conclusion The three exudate components (glucose, oxalic acid and glycine) exert different influences on soil microbial activity, community composition and extracellular enzymes. This discrepancy may be due to the differences in chemical functional groups and energy properties of the exudate components. Therefore, the component-specialized microbial and enzymatic properties induced by individual exudate components on rhizosphere processes under future study of biogeochemical cycling should be taken into account. -
图 2 根系分泌物不同组分添加对土壤微生物群落活性(A)原生动物磷脂脂肪酸,B)真菌磷脂脂肪酸,C)革兰氏阳性细菌磷脂脂肪酸,D)革兰氏阴性细菌磷脂脂肪酸,E)放线菌磷脂脂肪酸,F)总磷脂脂肪酸)的影响。不同小写字母表示各根系分泌物处理间在P < 0.05水平上差异显著。
Figure 2. Microbial community activities induced by exudate components (A) Protozoal PLFAs, B) Fungal PLFAs, C) Gram (−) bacterial PLFAs, D) Gram ( + ) bacterial PLFAs, E) Actinomycetic PLFAs, F) Total PLFAs. Different lowercase letters in the same column indicate significant differences among exudate components at P < 0.05. All the results are the means (SE) of three replicates (n = 3).
图 4 根系分泌物不同组分对土壤中胞外酶(A)β-1,4-葡萄糖苷酶,B)酸性磷酸酶,C)过氧化物酶,D)多酚氧化酶)的影响。不同小写字母表示各根系分泌物处理间在P < 0.05水平上差异显著。
Figure 4. Extracellular enzyme activities induced by exudate components (A) β-1,4-glucosidase, B) Acid phosphatase, C) Peroxidase, D) Polyphenol oxidase). Different lowercase letters in the same column indicate significant differences among exudates at P < 0.05. All the results are the means (± SE) of three replicates (n = 3).
表 1 云杉人工林的土壤特性
Table 1. Selected soil properties in the spruce plantation
土壤性质
Soil Property云杉人工林
Spruce plantation土壤容重 (g cm−3) 1.23 ± 0.05 pH值 6.35 ± 0.10 土壤电导率 (us cm−1) 89.00 ± 3.59 微生物量碳 (mg kg−1) 226.7 ± 31 微生物量氮 (mg kg−1) 81.2 ± 14.4 总碳 (g kg−1) 28.59 ± 1.52 总氮 (g kg−1) 1.67 ± 0.16 注:所有结果均为3次重复(n = 3)的平均值( SE)。 -
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