Etiology of soft rot on fenel bulbs

Abstract

Soft rot bacterial strains were isolated from diseased fennel bulbs. They were characterised on the basis of its pathogenicity morphological, cultural and biochemical properties. All investigated strains caused the soft rot of inoculated fenel bulbs, pepper fruits as well as clices of potato and carrot. Results of bacteriological properties show that soft rot of fennel bulbs were caused by Gram negative, nonfluorescent, facultative anaerobic, levan and oxidase negative bacteria belonging to the genus Pectobacterium. The investigared strains utilised lactose, grew at 5% NaCl and weak growth was recorded on 37oC; they are resistent to erytromicin. Negative results were recorded in indol, phospathase, lecithinase and reducing compounds pf sucrose tests. These results as well as the characteristics growth on Logan differential medium indicated that sof rot of fenel bulbs was caused by Pectobacterium carotovorum subsp. carotovorum. This is the first report of this bacterium affecting fennel bulbs in Serbia.

U radu su proučene patogene i biohemijske odlike fitopatogenih bakterija izolovanih iz glavica komorača sa simptomima truleži. Proučavani sojevi prouzrokuju trulež glavica komorača, veštački inokulisanih, plodova paprike, kao i kriški mrkve i krompira i pri tome ispoljavaju izraženu pektolitičku aktivnost. Proučavanjem bakterioloških odlika utvrđeno je da su izolovani sojevi Gramnegativni, ne fluoresciraju na Kingovoj podlozi B, glukozu metabolišu i u aerobnim i anaerobnim uslovima, ne stvaraju levan i oksidazu. Na osnovu navedenih karakteristika zaključeno je da ispitivani sojevi pripadaju rodu Pectobacterium. Proučavani sojevi ne stvaraju fosfatazu, lecitinazu, indol, redukujuće supstance iz saharoze, a na Loganovoj podlozi formiraju karakteristične kolonije ružičaste boje sa tamnim centrom. Na osnovu ovih, ali i rezultata ostalih diferencijalnih testova za vrste roda Pectobacterium (metabolizam ugljenih hidrata, razvoj pri 5% NaCl, osetljivost prema eritromicinu), zaključeno je da vlažnu trulež komorača prouzrokuje bakterija Pectobacterium carotovorum subsp. carotovorum. Ovo je prvo saopštenje o nalazu ove bakterije kao patogena komorača u Srbiji.