Electronic Theses and Dissertation

Penelitian bakteri tanah pada kawasan geotermal di Indonesia masih sangat terbatas.
Kawasan Geotermal Jaboi, Kota Sabang, memiliki kondisi lingkungan ekstrem berupa
variasi suhu permukaan tanah yang berpotensi memengaruhi kelimpahan dan karakteristik
bakteri tanah. Penelitian ini bertujuan untuk menghitung jumlah koloni bakteri tanah dan
menganalisis hubungan antara suhu tanah terhadap jumlah koloni bakteri serta
mengkarakterisasi morfologi makroskopis dan mikroskopis isolat bakteri. Pengambilan
sampel dilakukan menggunakan metode purposive sampling pada 15 titik sampel. Isolasi
bakteri tanah dilakukan menggunakan media Nutrien Agar dengan metode spread plate
dan dihitung dengan metode Total Plate Count (TPC), sedangkan karakterisasi isolat
dilakukan melalui pengamatan morfologi koloni dan pewarnaan Gram. Bakteri tanah di
kawasan geotermal Jaboi mampu tumbuh pada rentang suhu 27–44°C dengan jumlah
koloni yang berfluktuasi. Jumlah koloni tertinggi pada hasil perhitungan Total Plate Count
(TPC) terdapat pada suhu 27°C titik 1 yaitu 2,53 × 10⁹ CFU/g sedangkan jumlah koloni
terendah pada suhu 34°C titik 13 yaitu 6,05 × 10
CFU/g. Sebanyak 34 isolat berhasil
diperoleh dengan morfologi koloni yang beragam, didominasi bentuk koloni bundar yaitu
sebanyak 14 isolat sedangkan bentuk sel yang paling banyak ditemukan adalah basil
dengan dominasi bakteri Gram positif 27 isolat. Penelitian ini memberikan informasi dasar
mengenai kelimpahan dan karakteristik bakteri tanah di Kawasan Geotermal Jaboi.

Research on soil bacteria in geothermal areas in Indonesia is still very limited. The Jaboi Geothermal Area, Sabang City, has extreme environmental conditions in the form of variations in soil surface temperature that have the potential to affect the abundance and characteristics of soil bacteria. This study aims to calculate the number of soil bacterial colonies and analyze the relationship between soil temperature and the number of bacterial colonies as well as characterize the macroscopic and microscopic morphology of bacterial isolates. Sampling was carried out using a purposive sampling method at 15 sample points. Isolation of soil bacteria was carried out using Nutrient Agar media with the spread plate method and counted using the Total Plate Count (TPC) method, while characterization of isolates was carried out through observation of colony morphology and Gram staining. Soil bacteria in the Jaboi geothermal area can grow in the temperature range of 27–44°C with fluctuating colony numbers. The highest number of colonies in the Total Plate Count (TPC) calculation results were at 27°C point 1, namely 2.53 × 10⁹ CFU/g, while the lowest number of colonies was at 34°C point 13, namely 6.05 × 105 CFU/g. A total of 34 isolates were successfully obtained with diverse colony morphologies, dominated by round colonies (14 isolates), while the most common cell shape found was bacilli, with a predominance of Gram-positive bacteria (27 isolates). This study provides basic information on the abundance and characteristics of soil bacteria in the Jaboi Geothermal Area.