Phage specificity and lipopolysaccarides of stem- and root-nodulating bacteria ( Azorhizobium caulinodans, Sinorhizobium
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S H O R T CO M MU N I C A T I O N
Phage speciWcity and lipopolysaccarides of stem- and root-nodulating bacteria (Azorhizobium caulinodans, Sinorhizobium spp., and Rhizobium spp.) of Sesbania spp. Radhey Shyam Sharma · Vandana Mishra · Asif Mohmmed · Cherukuri Raghavendra Babu
Received: 16 May 2007 / Revised: 2 October 2007 / Accepted: 24 October 2007 / Published online: 8 November 2007 © Springer-Verlag 2007
Abstract Phage susceptibility pattern and its correlation with lipopolysaccharide (LPS) and plasmid proWles may help in understanding the phenotypic and genotypic diversity among highly promiscuous group of rhizobia nodulating Sesbania spp.; 43 phages were from two stemnodulating bacteria of S. rostrata and 16 phages were from root-nodulating bacteria of S. sesban, S. aegyptica and S. rostrata. Phage susceptibility pattern of 38 Sesbania nodulating bacteria was correlated with their LPS rather than plasmid proWles. DiVerent species of bacteria (A. caulinodans- ORS571, SRS1-3 and Sinorhizobium saheliSRR907, SRR912) showing distinct LPS subtypes were susceptible to diVerent group of phages. Phages could also discriminate the strains of Si. saheli (SSR312, SAR610) possessing distinct LPS subtypes. Phages of Si. meliloti (SSR302) were strain-speciWc. All the strains of R. huautlense having incomplete LPS (insigniWcant O-chain) were phage-resistant. In in vitro assay, 100% of the phages were adsorbed to LPS of indicator bacterium or its closely related strain(s) only. These observations suggest the signiWcance of LPS in phage speciWcity of Sesbania nodulating rhizobia. Highly speciWc phages may serve as biological marker for monitoring the susceptible bacterial strains in culture collections and environment.
Communicated by Ercko Stackebrand. R. S. Sharma (&) · V. Mishra · C. R. Babu Centre for Environmental Management of Degraded Ecosystems (CEMDE), University of Delhi, Delhi 110007, India e-mail: [email protected]; [email protected] A. Mohmmed International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
Keywords Phage speciWcity · Lipopolysaccharide (LPS) · Sesbania · Sinorhizobium · Rhizobium · Azorhizobium caulinodans
Introduction Sesbania spp. can successfully colonize extremely diverse habitats and enrich the nutrient deWcient soils with nitrogen (146–267 kg N/ha) due to its association with the microsymbiont (rhizobia). Sesbania sesban, S. aegyptica and S. rostrata are among the major agro-forestry species in India. Among these S. rostrata also forms profuse stemnodules besides the root nodules (Dreyfus and Dommergues 1981). High-ecological amplitude and habitat processing ability of Sesbania spp. have been attributed to the highly promiscuous nature of the associated rhizobia (Sharma et al. 2005). Polyphasic methods might be useful to characterize this promiscuous group of rhizobia (Mohmmed et al. 2001). Phage sensitivity pattern has been suggested as one of the powerful methods to discriminate bacteria as: (1) it takes into account the phenotypic and genotypic traits (L
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