Effects of nutritional factors on production of tabtoxin, a phytotoxin, by Pseudomonas syringae pv. tabaci.
Pseudomonas syringae pv. tabaci, the causal agent of the wildfire of tobacco, produces the phytotoxin tabtoxin. The effects of carbon, nitrogen sources and amino acids on growth and tabtoxin production by pv. tabaci, were examined by varying the components of a defined basal medium, which contained the following nutrients per liter: sucrose (10 g), KNO3 (5 g), MgSO(4).7H2O (0.2 g), CaCl(2).2H2O (0.11 g), FeSO(4).7H2O (20 mg), NaH2PO(4).2H2O (0.9 g) and H2PO(4).3HO (1 g). Bacterial growth was determined by cell density, and tabtoxin production was measured by the E. coli bioassay technique. Both growth and quantity of tabtoxin synthesized were significantly affected by carbon source, nitrogen source and amino acid supplements. Sorbitol, xylose and sucrose proved to be the best carbon sources for tabtoxin production. Specific toxin production was very low using glucose as a single carbohydrate source, although bacterial growth was well supported by glucose. Amount and type of nitrogen sources (NH4Cl or KNO3) affected the growth of pv. tabaci and quantities of tabtoxin produced. Nitrate was the best of these two forms of nitrogen for production of tabtoxin. Adding threonine to pv. tabaci grown in batch culture decreased the amount of tabtoxin production. Similar results were obtained with lysine, whereas, serine had no effects on quantities of tabtoxin production. The results of the present study were to formulate a medium which allowed for enhanced tabtoxin production by Pseudomonas syringae pv. tabaci.
Dehbi
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F
Institut National de la Recherche Agronomique d'Algerie, UR, Setif 19000, Algeria.
Harzallah
D
D
Larous
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L
D000596:Amino Acids / Q000378:metabolism; D001681:Biological Assay; D002244:Carbon / Q000378:metabolism; D003470:Culture Media; D004151:Dipeptides / Q000096:biosynthesis*; D009584:Nitrogen / Q000378:metabolism; D011549:Pseudomonas / Q000254:growth & development / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism; D013696:Temperature; D014026:Nicotiana / Q000382:microbiology*; D014118:Toxins, Biological / Q000096:biosynthesis
D000596:Amino Acids; D003470:Culture Media; D004151:Dipeptides; D014118:Toxins, Biological; D013395:Sucrose; D002244:Carbon; C003854:tabtoxin; D009584:Nitrogen