Isolation and identification of nitrogen-fixing bacteria in the corn rhizosphere (Zea mays l.) originating from Jeneponto Regency, South Sulawesi

Abstract

Abstract This study aims to determine the type of isolates and the characteristics of nitrogen-fixing bacteria in the rhizosphere of corn (Zea mays L.) from Jeneponto regency, South Sulawesi. This research is an explorative study consisting of nitrogen-fixing bacteria isolation and identification using nitrogen free bromohymol blue (Nfb) medium, and an ammonium excretion test on nitrogen-fixing bacteria using spectrophotometry methods. Bacteria identification methods include Gram staining, and physiological and biochemical characterization which consist of temperature resistance at 5°C, 25°C, and 40°C, pH resistance at 4, 6, and 8 and salt tolerance at 1%, 6% and 10 %. The study has found 20 bacterial isolates that can be characterized as round, mucoid, non-mucoid, white, clear, Gram-negative and bacilli. Physiological characteristics (biochemical tests) have shown growing pellicles and discoloration in the liquid Nfb medium. The ammonium excretion test showed there are 5 isolates excreting fairly high ammonium levels, namely BKr1, BKr2, BKr3, TKN2 and BBTg1, with concentrations of 42.3, 39.1, 41.5, 41.0 and 39.4 μत, respectively.