Bacterial Diversity in Peat Soils of Forest Ecosystems and Oil Palm Plantation

Abstract: Bacteria play a crucial role in regulating biogeochemical cycles in peatlands. Most of the studies on soil bacteria focus mainly on the peat surface and bacteria that exist in the deeper peat layers are still poorly known in tropical areas. This study was conducted to examine bacterial abundances along the peat depths in peat forest ecosystems (peat swamp forest (PSF) and logged-over secondary forest (LOF)) and an oil palm plantation (7.5 years after planting (7.5 YAP OPP)) at intervals of 0–30 cm, 30–40 cm, 40–50 cm, and 50–60 cm. Isolation of bacteria from peat samples was carried out on several selective and non-selective media. Bacteria identification was conducted by amplifying the 16S rRNA gene. The result showed that the same dominant bacterial taxa were found with different abundances in all study sites which were Proteobacteria, Firmicutes, and Actinobacteria. Vertical stratification of Proteobacteria and Firmicutes was observed along the depths, might due to the fluctuations of water table in the peatland mainly in 7.5 YAP OPP. Richness was highest at 0–30 cm in LOF and 7.5 YAP OPP, while PSF at 30–40 cm. This study suggests that deeper peat depth supports the bacterial growth and environmental conditions related to water table level influenced the bacterial abundances.