Abstract
In order to analyze soil microbial biomass and community structure, we investigated the amounts and composition of phospholipid fatty acids extracted from four different types of upland soils. The contents of phospholipid fatty acid of aoil were higher in the order of Humic Andosol ≒ Light Colored Andosol > Gray Lowland soil > Red soil. In light colored Andosol and Gray Lowland soil, phospholipid fatty acid content in soil of the 20-30 cm depth layer was lower than in the 0-10 and 10-20 cm depth soil layers. The major fatty acids in four types of soil were 16 : 0, 18 : 0, 18 : 1 ω 7, 18 : 1 ω 9, 18 : 1 ω 5, 16 : 1 ω 7, 16 : 1 ω 5, 16 : 1 ω 9, i17 : 1 ω 8, p11-19 : 1, 20 : 1, 18 : 2 ω 6, 20 : 4, 17 : 0cyc, 19 : 0cyc, p10 17 : 0, i15 : 0, a15 : 0,i16 : 0, i17 : 0, a17 : 0, p10-19 : 0 and 2OH-24 : 0. The phospholipid fatty acid composition indicated that the origin of the soil phospholipids was bacterial membrane lipids. The proportion of the branched chain fatty acids in the 20-30 cm depth soil layer was lower than that in 0-10 and 10-20 cm depth soil layers, indicating that the ratio of Gram-positive bacteria to Gramnegative bactcria would be higher in the 20-30 cm layer than in the 0-10 cm and 10-20 cm layers. An anaiysis of variance tests showed a significant change in the proportion of 18 : 1 ω 7, 16 : 0, i15 : 0, p11-19 : 1, p10-19 : 0, 18 : 2 ω 6 (seasonal change) and p10-17 : 0, a15 : 0, 16 : 1 ω 7, 18 : 1 ω 9, 17 : 0cyc, 19 : 0cyc (soil types). In the principal components using a principal component analysis of the compositions of phospholipid fatty acid, the total cumulative variance was retained as 67.0%. The data to distinguish seasonal changes werer present in the first principal component and the data to distinguish each soil type existed in the second principal component. A cluster analysis classified the composition of phospholipid fatty acid as to groups of soils sampled in February 1997 and other soils.
