ISOLASI DAN KARAKTERISASI BAKTERI PENAMBAT NITROGEN INDIGENOUS POTENSIAL SEBAGAI PUPUK HAYATI DALAM REMEDIASI LAHAN BEKAS TAMBANG BATU KAPUR

Abstract

Post-mining sites typically exhibit suboptimal physical and chemical properties for plant growth. Indigenous soil bacteria represent a viable approach for facilitating the remediation of post-mining lands through their utilization as biofertilizers. Notably, nitrogen-fixing bacteria stand out among these microorganisms due to their capacity to enhance soil nitrogen content. This study aims to isolate and characterize nitrogen-fixing bacteria from post-mining limestone quarry in the Cirebon, West Java. The bacterial isolation targeted 13 soil samples from former limestone mining sites, resulted in 6 isolates of free-living nitrogen-fixing bacteria and 2 isolates of symbiotic nitrogen-fixing bacteria. All isolates exhibited the ability to produce Indole-3-acetic acid (IAA) when supplemented with 1 mM L-tryptophan. Subsequent to morphological characterization, two isolates, namely 7B21Y and 5A22, were selected for further physiological testing. Nitrogenase activity for isolates 7B21Y and 5A22 was quantified utilizing the Acetylene Reduction Assay, yielding values of 7.09 ppm and 5.59 ppm, respectively. Isolate 7B21Y underwent additional physiological identification using the API kit, revealing a 99.9% similarity with Rhizobium radiobacter.