caa a22 4500 47574652X CHVBK 20180406123515.0 cr unu---uuuuu 170329e20001201xx s 000 0 eng 10.1007/s002840010158 doi (NATIONALLICENCE)springer-10.1007/s002840010158 Crossing the Limits of Rhizobium Existence in Extreme Conditions [Elektronische Daten] [Suneeta Kulkarni, Sanjay Surange, Chandra Shekhar Nautiyal] An ecological survey was conducted to characterize 5000 Rhizobium sp. sesbania strains of diverse geographical origin, isolated from the root nodules of Sesbania aculeata growing in neutral (pH 7) and alkaline (pH 8.5 and above) soils. The rhizobia from the alkaline soil showed significantly higher salt tolerance than those isolated from neutral soil. Upper limits of stress survival of rhizobial isolates, Rhizobium sp. NBRI0102 sesbania selected from neutral soil, and Rhizobium sp. NBRI2505 sesbania selected from alkaline soil, were studied under free living conditions. Rhizobium sp. NBRI0102 sesbania and Rhizobium sp. NBRI2505 sesbania tolerated yeast extract mannitol broth (YEB) containing 10% and 28% salt (NaCl, wt/vol) for up to 18 h of incubation at 30°C. Growth of Rhizobium sp. NBRI0102 sesbania and Rhizobium sp. NBRI2505 sesbania at pH 7, 11, and 12 was identical, except for a lag period of about 10 h in the growth of Rhizobium sp. NBRI0102 sesbania at pH 11 and 12, as compared with pH 7. Rhizobium sp. NBRI0102 sesbania and Rhizobium sp. NBRI2505 sesbania survived at 50°C and 65°C, in YEB at pH 7 for up to 4 and 2 h, respectively. To our knowledge, this is the first report of rhizobia demonstrating survival of Rhizobium sp. NBRI2505 sesbania, estimated by counting viable cells, to such extreme conditions of salt and temperature, individually. In contrast to Rhizobium sp. NBRI0102 sesbania, high temperature was tolerated efficiently by Rhizobium sp. NBRI2505 sesbania, in the presence of salt at higher pH. Our results suggest that the possession of the trait of high salt tolerance might be of some evolutionary significance for the survival of rhizobia in alkaline soils, at high pH and temperature. Springer-Verlag New York Inc., 2000 Kulkarni Suneeta Microbiology Group, National Botanical Research Institute, P.B. No. 436, Rana Pratap Marg, Lucknow 226 001, India, India aut Surange Sanjay Microbiology Group, National Botanical Research Institute, P.B. No. 436, Rana Pratap Marg, Lucknow 226 001, India, India aut Shekhar Nautiyal Chandra Microbiology Group, National Botanical Research Institute, P.B. No. 436, Rana Pratap Marg, Lucknow 226 001, India, India aut Current Microbiology Springer-Verlag 41/6(2000-12-01), 402-409 0343-8651 41:6<402 2000 41 284 https://doi.org/10.1007/s002840010158 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s002840010158 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kulkarni Suneeta Microbiology Group, National Botanical Research Institute, P.B. No. 436, Rana Pratap Marg, Lucknow 226 001, India, India aut NATIONALLICENCE 700 1- Surange Sanjay Microbiology Group, National Botanical Research Institute, P.B. No. 436, Rana Pratap Marg, Lucknow 226 001, India, India aut NATIONALLICENCE 700 1- Shekhar Nautiyal Chandra Microbiology Group, National Botanical Research Institute, P.B. No. 436, Rana Pratap Marg, Lucknow 226 001, India, India aut NATIONALLICENCE 773 0- Current Microbiology Springer-Verlag 41/6(2000-12-01), 402-409 0343-8651 41:6<402 2000 41 284 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer