Isolation and partial characterization of endophytic diazotrophs associated with Japanese sugarcane cultivar

Endophytic bacteria were isolated from the juice of a 6 month-old sugarcane cv. NiF-8, which was collected from Miyako, Okinawa and planted in a field lysimeter in Tsukuba, Ibaraki, Japan. The most probable number of N-2-fixing endophytes was 4.5X10(5) cells per gram of fresh weight sample and 21 isolates have a positive reaction for ARA in an N-free semi-solid medium with 10% crystallized sugarcane sugar and 0.5% sugarcane juice. Analyses of some of the biochemical properties of the N-2-fixing isolates indicated that 13 isolates were putative strains of Acetobacter diazotrophicus, 4 isolates showed similar characteristics to those of Herbaspirillum seropedicae, and 4 isolates consisted of Herbaspirillum rubribalbicans-like strains. This study confirmed the existence of N-2-fixing endophytic bacteria in the Japanese sugarcane cv. NiF-8.