Isolation and Identification of NIF Gene Homologue of Locally Isolated Azorhizobium Strains from Stem Nodules of Sesbania Rostrata
Characterisation of UPMR 43, UPMR 44 and X was conducted. Morphological studies of colonies showed that all strains gave a relatively large gummy, watery, translucent or whitely opaque colour on a modified glutamate agar. Intrinsic antibiotic resistance (IAR) patterns of all strains indicated th...
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| Format: | Thesis |
| Language: | English English |
| Published: |
1997
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| Online Access: | http://psasir.upm.edu.my/id/eprint/10391/1/FP_1997_3_A.pdf http://psasir.upm.edu.my/id/eprint/10391/ |
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| Summary: | Characterisation of UPMR 43, UPMR 44 and X was conducted.
Morphological studies of colonies showed that all strains gave a relatively large
gummy, watery, translucent or whitely opaque colour on a modified glutamate agar.
Intrinsic antibiotic resistance (IAR) patterns of all strains indicated that they were
resistant to ampicillin of up to 50 mg/l but susceptible to streptomycin, tetracycline
and kanamycin at concentrations of 25, 15 and 10 mg/l, respectively. The growth
characteristics of UPMR.43 and UP"MR.44 (in a modified glutamate medium (GM) and peptone medium (PA)) was studied using shake flask method. UPMR43 grew
better in GM compared to PA but the reverse was true for UPMR44. PA
significantly reduced the cell concentration and affected growth characteristic. The
generation times for both strains in both media were less than 6 h indicating that
they were fast growers. The banding pattern of total DNA of three strains digested
with EcoRI showed that they were very similar.
A large plasmid, subject to confirmation was detected in UPMR44 using
Hirsch method and one small plasmid in UPMR43 using Casse method. A 13.5 kb
BamHI and a 7.0 kb EcoRI DNA fragment from total DNA extracts of all local
strains were detected in Southern blot experiments using probes carrying the
nifHDK genes of Klebsiella pneumoniae and Azotobacter vinelandii. The results
showed that the nif genes of the Azorhizobium strains were detectable using the
heterologous nif probes from K. pneumoniae and A. vinelandii. The similar results
obtained from colony morphology, generation time, IAR patterns, total DNA
restriction patterns and DNA-DNA hybridisation of the three strains studied suggests
that they may be the same strain. The obtained results also showed that local strains
have a similar characteristics with A. caulinodans ORS571. Strain X may be
considered a unique strain since S. rostrata was easily infected although it is not
native to Malaysia. It is postulated that this strain may have an alternative host plant. |
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