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Ste´phane Uroz,1 Cathy D’Angelo-Picard,1 Aure´ lien Carlier,1 Miena Elasri,1

Microbiology (2003), 149, 1981–1989. Novel bacteria degrading N-acylhomoserine lactones and their use as quenchers of quorum-sensing-regulated functions of plant-pathogenic bacteria. Ste´phane Uroz,1 Cathy D’Angelo-Picard,1 Aure´ lien Carlier,1 Miena Elasri,1

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Ste´phane Uroz,1 Cathy D’Angelo-Picard,1 Aure´ lien Carlier,1 Miena Elasri,1

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  1. Microbiology (2003), 149, 1981–1989 Novel bacteria degrading N-acylhomoserinelactones and their use as quenchers ofquorum-sensing-regulated functions ofplant-pathogenic bacteria Ste´phane Uroz,1 Cathy D’Angelo-Picard,1 Aure´ lien Carlier,1 Miena Elasri,1 Carine Sicot,1 Annik Petit,1 Phil Oger,1,2 Denis Faure1 and Yves Dessaux1

  2. Quorum-Sensing定額感應 • 早期的科學家們發現，細菌藉由菌數來調控基因表現的現象，我們稱作quorum-sensing(QS)。 • 這種調控的方式在Gram-上比較常見，其有利於微生物在不同的環境中生存。 • quorum-sensing regulation system首先在深海魚共生菌photobacterium fischeri(發光桿菌)中被發現。 • 細菌分泌N-AHSL → N-AHSL突破門檻值 → 開啟基因表現。

  3. N-acylhomoserine lactone(N-AHSL(QS signal))

  4. Novel bacteria degrading N-acylhomoserinelactones and their use as quenchers ofquorum-sensing-regulated functions ofplant-pathogenic bacteria • 分解植物病原菌N-AHSL和抑制其定額感應調控的新種細菌

  5. Abstract • Quorum-Sensing定額感應 • Quorum-quenchers 定額抑制 • 從菸草根部附近土壤，分離出了可抑制quorum-sensing的訊息分子(N-AHSL)的25株菌。並分析各株菌能作用N-AHSL的範圍及其分解效率，再從其中篩選出分解N-AHSL種類最廣且最迅速的菌株Rhodococcus erythropolis (W2)。並對其做干擾其他quorum-sensing regulation 的效果作評估。

  6. Materials • AT medium就是一般的Luria-Bertani medium再加上少量的必需的物質，如mannitol NH4(SO4)2和cycloheximide。而這次的AT medium加入N-AHSL當做唯一碳源。 • Chromobacterium violaceum CV026這株菌當做Biosensors。這株菌會產生violacein這種紫色色素，一株qs regulation的菌，要是他的N-AHSL被分解的時候紫色色素也不會產生。

  7. Isolation of bacteria degrading N-AHSL (紫色色桿菌)

  8. Identification of the N-AHSL-degrading bacteria

  9. The N-AHSL-degrading bacteria exhibit differentsubstrate specificity

  10. R. erythropolis strain W2 as a quencher of theQS signal • 篩選出W2這株菌對N-AHSL有較廣的分解能力，且有迅速分解N-AHSL的活性。我們將進一步對W2干擾其他菌quorum-sensingregulation能力作觀察。 • C. violaceaum紫色色桿菌 • A. tumefaciens根癌農桿菌 • P. carotovorum果膠桿菌

  11. Quenching of violacein production in Chromobacteriumby R. erythropolis strain W2 (紫色色桿菌)

  12. Quenching of violacein production inA. tumefaciens(根癌農桿菌)by R. erythropolis strain W2 • Ti plasmid • A. tumefaciens A. tumefaciensstrainR10 (pTi donor) • A. tumefaciensstrainC58.00RS(pTi recipient) • Conjugation frequencies(per donor) were 1.5X10-3when the conjugation was performed without the quencher strain W2 • Conjugation frequencies(per donor) were 1.5X10-5when in the presence of the quencher strain W2

  13. Quenching of pectinolytic activities in Pectobacterium strain Pcc797 by R. erythropolis strain W2 (果膠桿菌)

  14. Discussion • <1>分離鑑定出可分解N-AHSL的菌株 • Pseudomonas sp. about 64 %(假單胞菌) • Comamonas 16 %(叢毛單胞菌) • Variovorax 12 %(貪噬菌) • Rhodococcus 8 %(紅球菌) • QS regulation並不局限在某些種類的菌屬中，因此具有開發的價值。

  15. Discussion • <2>探索Quorum-quenchers菌株用來對抗QS-regulation的潛力 • R. erythropolis strain W2(紅球菌)具有迅速分解N-AHSL的活性，且可作用的N-AHSL也較廣。在之前實驗證實可干擾QS regulation，且不影響菌的生長。 • 未來可朝向不汙染環境生物控制劑，或不具有副作用的抗生素開發。

  16. Thank you

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