Aggregation inAzospirillum brasilense Cd: Conditions and factors involved in cell-to-cell adhesion
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Aggregation of the root-inhabiting, asymbiotic N-fixingAzospirillum brasilense Cd (ATCC-29729), was studied. Aggregation occurred towards the end of the exponential phase and during the stationary phase. More aggregates were formed in media supplemented with organic acids than in those containing sugars as a sole carbon source. Maximum growth with no aggregation was obtained in a medium containing both fructose and malate as carbon sources. Aggregation was increased by poly-L-lysine and carbodiimide as well as by increasing the C/N ratio and decreasing combined nitrogen in the growth medium. Aggregates were stable at pH levels of >8 and <6, but dispersed at pH 7.1. Treatment of Azospirillum with NaEDTA resulted in loss of both aggregative capacity and the ability of adsorb to wheat roots without losing cell viability. When extracted bacteria were suspended in their dialysed NaEDTA extract, both their aggregative and adsorptive capacities were restored.
The dialysed NaEDTA extract agglutinated bacterial cells and red blood cells, especially of type O. When the extract was run through a sepharose gel, it separated into three main fractions, of which only one showed agglutinating capacity. Gel electrophoresis of this fraction revealed a single band (MW 97,000) which reacted positively to Schiff's reagent and Coomassie brilliant blue R-250, typical to a glycoprotein. Bacterial agglutination by this fraction was strongly inhibited by D-glucose, melibiose and α-metyl glucoside. No evidence as to the involvement of cellulose fibrils in aggregation was found. It is suggested that glycoprotein(s) and glucose residues located on the outer surface of the cells are involved in aggregation of Azospirillum.
Key wordsagglutination aggregation cellulose fibrils C/N ratio flocculation NaEDTA
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- Barak R, Elad D, Mirelman D and Chet I 1985 Lectins: A possible basis for specific recognition in the interaction of Trichoderma andSclerotium rolfsii. Phytopathology 75, 458–462.Google Scholar
- Calleja G B 1984 Microbial Aggregation. CRC Press, Florida, 276 p.Google Scholar
- Das A and Mishra A K 1983 Utilization of fructose byAzospirillum brasilense. Can. J. Microbiol. 78, 42–57.Google Scholar
- Deguid J P and Wilkinson J P 1961 Environmental induced change in bacterial morphology.In Microbial Reaction to Environment, Eleventh Symposium of the Society For General Microbiology. Eds. G G Meynell and H Gooder. pp 69–99. Cambridge University Press, London.Google Scholar
- Eggest G, Stenberg E and Kjosbakken J 1983 Flocculation of methanol-oxidizing bacteria. J. Gen. Microbiol. 129, 3610–3617.Google Scholar
- Foster R C and Bowen G D 1982 Plant surfaces bacterial growth: The rhizosphere and rhizoplane.In Phytopathogenic Prokaryots. Vol 1 Eds. M S Mount and G H Lacy. pp 159–185. Academic Press, New York.Google Scholar
- Ohyama K, Pelcer L E and Schaefer A 1979In vitro binding ofAgrobacterium tumefaciens to plant cells from suspension culture. Plant Physiol. 63, 382–387.Google Scholar
- Okon Y, Albrecht S L and Burris R H 1977 Methods for growingSpirillum lipoferum and for counting it in pure culture and in association with plants. Appl. Environ. Microbiol. 33, 85–88.Google Scholar
- Okon Y, Albrecht S L and Burris R H 1976 Carbon and ammonia metabolism ofSpirillum lipoferum. J. Gen. Bacteriol. 128, 592–597.Google Scholar