Individual bacterial colonies can be identified by morphology, or the observation of colony colors and physical shapes observed under a microscope. Gram positive or negative cultures can be distinguished with staining. More recently, 16S rRNA gene sequences have widely been used to identify bacterial species and to construct a phenogram. Bacterial genomic DNA needs to be isolated in order to amplify specific 16S rRNA gene sequences using a standard bacterial DNA isolation protocol (Sambrook et al. 1989). For general bacterial endophyte classification, universal PCR primers F27 (5′-AGA GTT TAT CMT GGC TCA G-3′) and R1492 (5′-GRT ACC TTG TTA CGA CTT-3′) are used to amplify partial bacterial 16S rDNA sequences (Diallo et al. 2004). The ability of bacterial endophytes to fix atmospheric nitrogen can be tested by growing bacteria in nitrogen — free medium for several cycles of cultures or PCR can be used to amplify the nifH gene, which is a conserved region in the dinitrogenase reductase gene complex. Fatty acid analysis, carbon source utilization, and antibiotic resistance (hygromycin, chloramphenicol, gentamycin, kanamycin, ampicillin, streptomycin, tetracycline, and rifampin) could be done for further identification.