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AGRICULTURAE
CONSPECTUS SCIENTIFICUS
Volume 65, No 4, 2000 (229-236)
ORIGINAL SCIENTIFIC
PAPER
Identification of Indigenous Bradyrhizobium japonicum Strains
Isolated from Different Soil Types in Western Slavonia
Sanja SIKORA
Sulejman REDŽEPOVIĆ
SUMMARY
Fast and reliable strain identification methods are needed
for studying Bradyrhizobium japonicum field population as well
as for the selection the most efficient strains for commercial inoculant
production. The main aim of the present investigation was to compare different
methods for identification of indigenous B. japonicum strains isolated
from different soil types in western Slavonia. Physiological tests, intrinsic
antibiotic resistance, SDS-PAGE (sodium dodecil sulphate polyacrilamide
gel electrophoresis) of total cell proteins and RAPD (random amplified
polymorphic DNA) analysis were used for strain identification and the
assessment of variability within natural B. japonicum population. The
results of each method were converted to two-dimensional binary matrix
and dendrograms, showing relative similarity among B. japonicum
strains, were obtained by using biostatistical NTSYS programe. The results
showed that among all the methods used in this work, that RAPD analysis
was the most sensitive and reliable for strain identification. The lowest
level of differentiation among B. japonicum strains were determined
by using intrinsic antibiotic resistance. All the methods used in this
work, with the exception of intrinsic antibiotic resistance, revealed
that all field isolates essentially differed from commercial strains and
so can be regarded as indigenous strains for that area. Protein and RAPD
profiles very clearly indicated that among natural field population two
highly divergent group of strains can be determined.
KEY WORDS
Bradyrhizobium japonicum, indigenous strains,
nitrogen fixation, strain identification
Department of Microbiology
Faculty of Agriculture University of Zagreb
Svetošimunska 25, 10000 Zagreb, Croatia
E-mail: ssikora@agr.hr
Received: September 20, 2000
ACKNOWLEDGEMENT
We gratefully acknowledge the help of prof.dr. Jasna Kniewald and Mihela
Jakominić, M.S. (Department for Chemistry and Biochemostry- Laboratory
for Toxicology, Faculty of Food Technology and Biotechnology University
of Zagreb) with the strain identification by using SDS-PAGE of total cell
proteins.
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