Endophytic Bacterial Population in Philippine Sugarcane Cultivars and Isolation of Nitrogen-fixing Strains.

The number of endophytic bacteria in the stem of sugarcane cultivars collected from different sites in the Philippines ranged from 104 to 109 cells ml-1 juice. Bacterial population was correlated with the sugar content (% Brix) of the juice and varied depending on the cultivar and sampling site. Twenty-eight isolates had a positive reaction in the acetylene reduction assay (ARA). Presumptive tests indicated that 15 isolates were putative strains of Acetobacter diazotrophicus, 5 isolates showed similar characteristics to those of Herbaspirillum seropedicae, and 8 isolates consisted of Herbaspirillum rubribalbicans-like strains. This study confirmed the existence of N2-fixing endophytic bacteria in sugarcane cultivars in the Philippines.