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. 1985 Aug;163(2):716–723. doi: 10.1128/jb.163.2.716-723.1985

Flocculation in Azospirillum brasilense and Azospirillum lipoferum: exopolysaccharides and cyst formation.

L Sadasivan, C A Neyra
PMCID: PMC219180  PMID: 3894333

Abstract

The phenomena of flocculation and floc formation by Azospirillum brasilense Sp7 (ATCC 29145) and Azospirillum lipoferum Sp59b (ATCC 29707) were studied in aerobic liquid cultures. Carbon sources representative of various entry pathways in combination with various nitrogen sources induced flocculation in both species of azospirilla. Noticeably, the combination of fructose and nitrate was the most effective in terms of floc yields. Phase-contrast microscopic observations revealed a transition in cell morphology from freely motile, vibrioid cells to nonmotile, highly refractile encysting forms during the formation of flocs. The nonmotile forms in flocs appeared to be entangled within a fibrillar matrix, and the cells were highly resistant to desiccation. Dried flocs kept for almost 6 months still maintained the highly refractile encysting forms, and their viability was confirmed by pellicle formation and acetylene reduction in semisolid malate medium. Electron microscopic observations of the desiccated flocs revealed the presence of cell forms containing abundant poly beta-hydroxybutyrate granules within a central body and surrounded by a thick layer of exopolysaccharides. The latter were characterized by alkali and acid digestion, crude cellulase hydrolysis, and calcofluor staining. It was concluded that the overproduction of exocellular polymers induces the flocculent growth and is associated with the concomitant transformation of vegetative cells to the desiccation-resistant encysting forms under limiting cultural conditions.

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Selected References

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  1. Berg R. H., Tyler M. E., Novick N. J., Vasil V., Vasil I. K. Biology of azospirillum-sugarcane association: enhancement of nitrogenase activity. Appl Environ Microbiol. 1980 Mar;39(3):642–649. doi: 10.1128/aem.39.3.642-649.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Deinema M. H., Zevenhuizen L. P. Formation of cellulose fibrils by gram-negative bacteria and their role in bacterial flocculation. Arch Mikrobiol. 1971;78(1):42–51. doi: 10.1007/BF00409087. [DOI] [PubMed] [Google Scholar]
  3. Dimitrov M., Doncheva I., Nikolcheva M. Vidovaia prinadlezhnost' gribov roda Fusarium Lk. ex Fr. -- produtsentov zearalenona, izolirovannykh iz pshenitsy, kukuruzy i fasoli. Mikrobiol Zh. 1982;44(6):33–37. [PubMed] [Google Scholar]
  4. Eklund C., Pope L. M., Wyss O. Relationship of encapsulation and encystment in Azotobacter. J Bacteriol. 1966 Dec;92(6):1828–1830. doi: 10.1128/jb.92.6.1828-1830.1966. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Friedman B. A., Dugan P. R., Pfister R. M., Remsen C. C. Structure of exocellular polymers and their relationship to bacterial flocculation. J Bacteriol. 1969 Jun;98(3):1328–1334. doi: 10.1128/jb.98.3.1328-1334.1969. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Goebel E. M., Krieg N. R. Fructose catabolism in Azospirillum brasilense and Azospirillum lipoferum. J Bacteriol. 1984 Jul;159(1):86–92. doi: 10.1128/jb.159.1.86-92.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. LAYNE J. S., JOHNSON E. J. NATURAL FACTORS INVOLVED IN THE INDUCTION OF CYST FORMATION IN AZOTOBACTER. J Bacteriol. 1964 Mar;87:684–689. doi: 10.1128/jb.87.3.684-689.1964. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Magalhães L. M., Neyra C. A., Döbereiner J. Nitrate and nitrite reductase negative mutants of N2-fixing Azospirillum spp. Arch Microbiol. 1978 Jun 26;117(3):247–252. doi: 10.1007/BF00738542. [DOI] [PubMed] [Google Scholar]
  9. Martinez-Drets G., Del Gallo M., Burpee C., Burris R. H. Catabolism of carbohydrates and organic acids and expression of nitrogenase by azospirilla. J Bacteriol. 1984 Jul;159(1):80–85. doi: 10.1128/jb.159.1.80-85.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Matthysse A. G., Holmes K. V., Gurlitz R. H. Elaboration of cellulose fibrils by Agrobacterium tumefaciens during attachment to carrot cells. J Bacteriol. 1981 Jan;145(1):583–595. doi: 10.1128/jb.145.1.583-595.1981. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Napoli C., Dazzo F., Hubbell D. Production of cellulose microfibrils by Rhizobium. Appl Microbiol. 1975 Jul;30(1):123–131. doi: 10.1128/am.30.1.123-131.1975. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Neyra C. A., Döbereiner J. Denitrification by N2-fixing Sprillum lipoferum. Can J Microbiol. 1977 Mar;23(3):300–305. doi: 10.1139/m77-044. [DOI] [PubMed] [Google Scholar]
  13. Neyra C. A., Van Berkum P. Nitrate reduction nitrogenase activity in Spirillum lipoferum1. Can J Microbiol. 1977 Mar;23(3):306–310. doi: 10.1139/m77-045. [DOI] [PubMed] [Google Scholar]
  14. Okon Y., Albrecht S. L., Burris R. H. Factors affecting growth and nitrogen fixation of Spirillum lipoferum. J Bacteriol. 1976 Sep;127(3):1248–1254. doi: 10.1128/jb.127.3.1248-1254.1976. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Sadoff H. L. Encystment and germination in Azotobacter vinelandii. Bacteriol Rev. 1975 Dec;39(4):516–539. doi: 10.1128/br.39.4.516-539.1975. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Stevenson L. H., Socolofsky M. D. Cyst formation and poly-beta-hydroxybutyric acid accumulation in Azotobacter. J Bacteriol. 1966 Jan;91(1):304–310. doi: 10.1128/jb.91.1.304-310.1966. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Tarrand J. J., Krieg N. R., Döbereiner J. A taxonomic study of the Spirillum lipoferum group, with descriptions of a new genus, Azospirillum gen. nov. and two species, Azospirillum lipoferum (Beijerinck) comb. nov. and Azospirillum brasilense sp. nov. Can J Microbiol. 1978 Aug;24(8):967–980. doi: 10.1139/m78-160. [DOI] [PubMed] [Google Scholar]
  18. Vela G. R. Survival of Azotobacter in dry soil. Appl Microbiol. 1974 Jul;28(1):77–79. doi: 10.1128/am.28.1.77-79.1974. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Westby C. A., Cutshall D. S., Vigil G. V. Metabolism of various carbon sources by Azospirillum brasilense. J Bacteriol. 1983 Dec;156(3):1369–1372. doi: 10.1128/jb.156.3.1369-1372.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]

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