Kelimpahan Bakteri Proteolitik pada Rizosfer Mangrove dan Sedimen Bagek Kembar: Sumber Potensial untuk Aplikasi Bioteknologi

Abstract

Ekosistem mangrove merupakan habitat kaya bahan organik dan kondisi lingkungan khas yang mendukung pertumbuhan mikroorganisme fungsional, termasuk bakteri proteolitik. Bakteri ini berperan dalam dekomposisi protein dan berpotensi untuk aplikasi di bidang pangan, pertanian, dan kesehatan. Penelitian ini bertujuan menganalisis kelimpahan bakteri proteolitik pada rhizosfer dan sedimen di ekosistem mangrove Bagek Kembar, Kecamatan Sekotong, Lombok Barat. Sampel diambil secara purposive sampling dari area sekitar perakaran mangrove dan sedimen. Isolasi dilakukan dengan metode spread plate menggunakan media Skim Milk Agar (SMA) setelah sampel tanah dihomogenkan, diencerkan secara berseri hingga 10⁻⁴, lalu diinokulasikan ke media dan diinkubasi pada suhu 30°C selama 48–72 jam; koloni proteolitik ditandai dengan terbentuknya zona bening akibat hidrolisis kasein dan selanjutnya dimurnikan melalui subkultur. Kelimpahan bakteri proteolitik dihitung menggunakan metode cawan hitung dengan hasil dinyatakan dalam Colony Forming Units (CFU/g) sesuai rumus CFU g⁻¹ = jumlah koloni × 1/faktor pengenceran, untuk kemudian dianalisis perbedaan kelimpahan antar lokasi pengambilan sampe. Hasil penelitian menunjukkan bahwa rizosfer mangrove di daerah Bagek Kembar memiliki kelimpahan bakteri proteolitik yang lebih tinggi dibandingkan sedimen, dengan nilai masing-masing 3,2 × 10⁵ CFU/g dan 1 × 10⁵ CFU/g. Perbedaan ini mencerminkan pengaruh eksudat akar, struktur akar, dan kondisi mikrohabitat yang lebih mendukung pada rhizosfer. Faktor lingkungan seperti pH, kelembaban, dan salinitas juga memengaruhi kelimpahan dan aktivitas mikroba. Rhizosfer menunjukkan pH dan kelembaban yang lebih sesuai bagi pertumbuhan bakteri dibandingkan sedimen.

Mangrove ecosystems are habitats rich in organic matter and unique environmental conditions that support the growth of functional microorganisms, including proteolytic bacteria. These bacteria play a role in protein decomposition and have potential applications in food, agriculture, and health. This study aims to analyze the abundance of proteolytic bacteria in the rhizosphere and sediments of the Bagek Kembar mangrove ecosystem, Sekotong District, West Lombok. Samples were taken using purposive sampling from areas around mangrove roots and sediments. Isolation was performed using the spread plate method with Skim Milk Agar (SMA) media after the soil samples were homogenized, serially diluted to 10⁻⁴, then inoculated into the media and incubated at 30°C for 48–72 hours; proteolytic colonies were identified by the formation of clear zones due to casein hydrolysis and were further purified through subculture. The abundance of proteolytic bacteria was calculated using the counting plate method with results expressed in Colony Forming Units (CFU/g) according to the formula CFU g⁻¹ = number of colonies × 1/dilution factor, to then analyse the differences in abundance between sampling locations. The results showed that the rhizosphere of mangroves in the Bagek Kembar area had a higher abundance of proteolytic bacteria than sediment, with values of 3.2 × 10⁵ CFU/g and 1 × 10⁵ CFU/g, respectively. These differences reflect the influence of root exudates, root structure, and more favourable microhabitat conditions in the rhizosphere. Environmental factors such as pH, moisture, and salinity also affect microbial abundance and activity. The rhizosphere exhibits pH and moisture levels that are more suitable for bacterial growth than sediment.