Population Dynamics and Diversity of Endophytic Bacteria Associated with Soybean (Glycine max (L) Merril)

Aim: Endophytic bacterial population and their diversity in soybean were investigated.
Study Design: Endophytic population was assessed during different growth stages of soybean (CV JS 335) viz., vegetative and reproductive stages.
Place and Duration of Study: Microbiology Research Laboratory, Department of Microbiology, R. A. Mahavidyalaya, Washim (MS), India, during the cultivation period of June-December 2010.
Methodology: Healthy plants of soybean were screened from the different locations of Washim district (M. S., India). Samples represent each growth stage viz., vegetative (V1-V5) and reproductive (R1-R8) were collected. Population densities were expressed as log10 colony forming units (CFU) g-1 fresh weight. The isolates were identified to genus level according to Bergey’s Manual of Determinative Bacteriology on the basis morphological, cultural and biochemical characteristics.
Results: The maximum endophytic population was recorded for vegetative stage at V5 and V4 (5.74 and 5.01 log10 CFU g-1 fresh weight) and for reproductive stage at R2, R1 and R3 (5.84, 5.80 and 5.74 log10 CFU g-1 fresh weight). A total of 572 (35.50 %) from vegetative growth stages and 1039 (64.50 %) from reproductive growth stages bacterial isolates were obtained. The endophytic isolates were identified as members belonging to the genera Pseudomonas, Bacillus, Enterobacter, Klebsiella, Acetobacter Burkholderia, Rhizobium and Xanthomonas.
Conclusion: As soybean development progresses endophytic population increased. At maturity, the high population density was observed and thereafter the population declined.