Two methods for isolation of endophytic and edaphic Bacillus spp. from sugarcane fields

Abstract

Bacillus has been widely studied and used for the control of pests and diseases. The adapted protocol proposed by POLANCZYK (2004) proved to be more efficient than the one by the World Health Organization (WHO, 1985) to isolate edaphic strains of Bacillus. However, it has not been assessed for isolation of endophytic strains, which are much less abundant in the nature and more difficult to be isolated. This study aimed to compare two methodological procedures for isolation of Bacillus, established by the WHO (1985) and by POLANCZYK (2004), regarding their efficiency for isolation of endophytics and edaphics Bacillus strains from inside the root tissue of sugarcane, as well as from the associated soil sample, collected from 11 locations; and to compare the density of bacteria in both environments. Endophytic and edaphic strains of Bacillus were isolated by both procedures. However, the isolation protocol performed by POLANCZYK (2004) made more efficient by having a greater number of colony forming units (CFU) per gram of soil and root indicating that this procedure is more useful, especially for isolation of endophytic strains of Bacillus, which are much less abundant in the nature than edaphic strains, being therefore more difficult to be isolated. Using the Polanczyk protocol (2004), Bacillus strains were recovered from all roots (endophytic) and soil (edaphic) samples of all the 11 fields, suggesting that the plant root may be another important source for isolation of Bacillus besides the soil. Higher densities of Bacillus were isolated from the edaphic environment compared with the endophytic environment, with significant differences when isolated by Polanczyk method (2004).