Isolation of endophytic bacteria
Seventy-one isolates of endophytic bacteria were isolated from three parts of rice tissue (root, lower
stem and higher stem) using PDA and TSA medium. Rice tissue samples were collected from different
three types of rice farm; 1 year, 3 years organic rice farms, and conventional rice farm in Udon Thani,
Thailand. The serial dilutions of macerated rice samples were spreaded on TSA and PDA medium. The
colony forming units (CFU) were determined after appropriate inoculation at 30 qC. A majority of the
microorganisms were screened and isolated (26 strains) from root tissue of 3 years organic rice farm. As
shown in Table 1. Bacterial isolates were identified based on Gram’s staining and physiological tests.
3.2 Characterization of bacterial colony
Figure 1 showed the colony characteristics of some isolates on TSA medium. They were classified into
three group of colony morphology depending on color, form, elevation, and margin. The members of
group one were white circular, convex and entire; those in group two were pale orange, circular and
undulate; and those in group three were light yellow circular, undulate with creamy colonies.