Chemotaxonomy of some nitrogen-fixing bacteria isolated from the rhizosphere of rice (Oryza sativa L.) grown in Thailand
1986
Anchan Choonhahirun
R15, R17 and R25 are strains of Nitrogen fixing bacteria to be studied. Their DNA base composition and DNA sequence homology were indicated that they should be classified in two distinct groups; R15 and R17 were Klebsiella-liked (mol % G+C, 52-56 %) but R25 was most fitted in Azospirillum sp. (mol % G+C, 69-71 %). Several biochemical properties together with growth condition and acetylene reduction activity under specific conditionsal also supported that R15 and R17 were Klebsiella-liked strains because of their ability to produce indole, to utilize malonate as sole carbon source and positive test to Voges-Proskauer reaction. As for R25, which requires biotin for growth and forms pink-colony when grown on nutrient agar plate whereas it forms yellow-colony on rich agar plate, together with ability to grown in nitrogen fixing bacteria semisolid medium supplied with 0.5 % glucose in place of malate, thus R25 is identified as A. lipoferum strain. In addition, glucose was the preferential carbon source for growth and nitrogen fixation under either aerobic or microaerobic condition of both K. R15 and K. R17 in contrast to A. R25 that malate was preferred for growth and nitrogen fixation under microaerobic condition only.
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