samples from 0 to 10 cm. Concentrat

samples from 0 to 10 cm. Concentrations of each PLFA were
calculated based on 19:0 internal standard concentrations. The
PLFAs i14:0, 15:0 i15:0, a15:0, i16:0, 16:1u7c, 17:0, a17:0, i17:0,
cy17:0, 18:1u7 and cy19:0 were chosen to represent the bacterial
biomass while the sum of i14:0, i15:0, a15:0, i16:0, a17:0 and i17:0
were used to express the Gram-positive bacteria. In this study, the
Gram-negative bacteria were identified by the PLFAs including:
16:1u7c, cy17:0, 18:1u7 and cy19:0