Changes in the soil properties due to cultivation causes rapid changes in the microbial communities and activities in the soil. Most of this soil microbial population are sensitive to the changes in soil, therefore, some microbiological parameter such as microbial biodiversity can be used as an indicator for soil quality. By applying 16S rDNA and denaturing gradient gel electrophoresis (DGGE), we investigated the bacterial composition in an area planted with oil palm in mineral soil in Belaga, Sarawak. Overall Shannon-Weaver biodiversity index showed that soil bacterial biodiversity in the oil palm planted area increased slightly after clean clearing. When palms reached the age of 2.5 years, the biodiversity index increased from early planting compared to the biodiversity in the strip areas. Prevalence of minor phylum showed that with the increase of oil palm age, there was an increase in the variations of new phylum groups contributing to the diverse population of soil bacteria in the oil palm area.

Perubahan tanah akibat daripada aktiviti pertanian mengakibatkan berlakunya perubahan populasi dan aktiviti mikrob di dalam tanah. Kebanyakan mikrob tanah ini adalah sensitif kepada perubahan dalam tanah. Oleh itu, parameter seperti indek biodiversiti mikrob boleh digunakan sebagai satu penunjuk untuk mengukur kualiti tanah. Primer 16S rDNA dan kaedah ’denaturing gradient gel electrophoresis‘ (DGGE), telah digunakan bagi mengkaji komposisi bakteria di kawasan penanaman sawit dan kawasan strip biodiversiti pada tanah mineral di Belaga, Sarawak. Secara keseluruhan indek biodiversiti Shannon-Weaver menunjukkan bahawa biodiversiti bakteria di kawasan sawit meningkat sedikit selepas pembersihan kawasan tanpa kaedah pembakaran. Apabila sawit mencapai umur 2.5 tahun, indek biodiversiti meningkat berbanding penanaman awal sawit dan kawasan strip biodiversiti. Kehadiran filum minoriti menunjukkan dengan peningkatan umur sawit, variasi kumpulan filum baru juga meningkat dan seterusnya ia menyumbang kepada peningkatan kepelbagaian populasi bakteria tanah kawasan penanaman sawit berbanding strip biodiversiti.