None of the parameters tested correlated with the grouping of the amoA communities
in the green cane soil, with the exception of the C:N ratio in one replicate. The clear distinction between the bacterial communities in the control soil and in the burnt cane soil was correlated with the high exchangeable Mg content and the low WFPS value in the former. Moreover, SYN-117 ic50 it was associated with low values of the sum of bases, cation exchange capacity, exchangeable Ca and the degree of saturation of the bases in the burnt cane soil (Figure 3). The nirK gene based DGGE profile (denitrifying bacteria) showed more complex patterns (8–15 bands) than that of the ammonia oxidizing bacteria. The triplicate profiles were similar between each other. Much like the total bacteria, the nirK based patterns (Figure 4) showed significant differences between treatments (MRPP < 0.03). However, there was great variation in community structure. Selleckchem mTOR inhibitor There was a distinction between green cane and control samples along the Y axis and a marked distinction between the burnt cane and the other samples along the X axis, that contained the major percentage of variance (74%). Figure 4 NMS ordination of the DGGE profiles of nirK gene fragments (denitrifier bacteria) amplified from the soil samples (0–10 cm) collected
from the treatments Control (C), Green cane (GC) and Burnt cane (BC). The fraction of total variance that accounts for each axis is indicated in parentheses. The angles and the length of radiating lines indicate the direction and strength of the relationship between the chemical and biological variables with the ordination scores. None of the soil parameters tested showed significant correlation with the alterations in the structure of the denitrifying community in the green cane soil. In the burnt cane soil, the factors involved in the process were the same as described above. The communities in the control soil were also strongly influenced by the high exchangeable Mg value
and the low WFPS (Figure 4). Ordination of the physicochemical data as primary matrices classified the treatments as three distinct Tanespimycin manufacturer groups (data not shown), which is 3-mercaptopyruvate sulfurtransferase the same basic grouping found with the bacterial community. In contrast, the two functional communities did not follow the same pattern as the bacterial communities, perhaps because these groups were subjected to more specific selective forces, such as caused by different levels of NH4 +-N and/or NO3 –N. The Mantel correlation data (not shown), that test the correlation and the significance between two matrices, provided evidence for the latter hypothesis, because the largest correlation value found was that of the ammonia oxidizing community with the denitrifier community (r = 0.70), while the correlation of these groups with soil properties was respectively at r = 0.45 and r = 0.63.