Production of the Bioactive Compounds Violacein and Indolmycin Is Conditional in a maeA Mutant of Pseudoalteromonas luteoviolacea S4054 Lacking the Malic Enzyme
Production of the Bioactive Compounds Violacein and Indolmycin Is Conditional in a maeA Mutant of Pseudoalteromonas luteoviolacea S4054 Lacking the Malic Enzyme
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DOI：
10.3389/fmicb.2016.01461
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发表时间：
2016-09-16
影响因子：
5.2
通讯作者：
Gram, Lone
中科院分区：
文献类型：
--
作者：
Thogersen, Mariane S.;Delpin, Marina W.;Gram, Lone
以前曾有报道称，某些海洋细菌假异单胞菌（Pseudoalteromonas luteoviolacea）产生紫色生物活性色素紫素（violacein）和抗生素化合物吲哚霉素（indolmycin），迄今为止仅在链霉菌中发现。本研究的目的是确定这两种化合物在紫花苜蓿S4054中作为抗菌化合物的相对作用。利用In 10转座子诱变技术，建立了一种在含甘露糖底物中紫罗兰素产量显著降低的突变株。全基因组分析表明，该转座子不中断生物合成基因簇；相反，插入位置位于编码苹果酶的maeA基因上。突变菌株的上清液对鳗弧菌和金黄色葡萄球菌的抑制作用与野生型菌株相同。在共培养实验中，突变菌株与野生型一样有效地杀死了鳗鲡。通过UHPLC-UV/Vis分析，我们对紫紫素和吲哚霉素进行了定量分析，与野生型菌株相比，突变菌株的紫紫素含量仅为7-10%。相比之下，突变菌株产生的吲哚霉素量约为野生型的300%。由于突变菌株对鳗弧菌和金黄色葡萄球菌的抑制作用与野生型相似，因此得出结论，紫罗兰素不是紫花假单胞菌的主要抑菌化合物。我们进一步提出，紫紫素和吲哚霉素的产生可能与代谢有关，而尚未确定的抗菌化合物可能在紫花草的抗菌活性中发挥作用。
It has previously been reported that some strains of the marine bacterium Pseudoalteromonas luteoviolacea produce the purple bioactive pigment violacein as well as the antibiotic compound indolmycin, hitherto only found in Streptomyces. The purpose of the present study was to determine the relative role of each of these two compounds as antibacterial compounds in P. luteoviolacea S4054. Using In 10 transposon mutagenesis, a mutant strain that was significantly reduced in violacein production in mannose-containing substrates was created. Full genome analyses revealed that the vio-biosynthetic gene cluster was not interrupted by the transposon; instead the insertion was located to the maeA gene encoding the malic enzyme. Supernatant of the mutant strain inhibited Vibrio anguillarum and Staphylococcus aureus in well diffusion assays and in MIC assays at the same level as the wild type strain. The mutant strain killed V anguillarum in co-culture experiments as efficiently as the wild type. Using UHPLC-UV/Vis analyses, we quantified violacein and indolmycin, and the mutant strain only produced 7-10% the amount of violacein compared to the wild type strain. In contrast, the amount of indolmycin produced by the mutant strain was about 300% that of the wild type. Since inhibition of V anguillarum and S. aureus by the mutant strain was similar to that of the wild type, it is concluded that violacein is not the major antibacterial compound in P. luteoviolacea. We furthermore propose that production of violacein and indolmycin may be metabolically linked and that yet unidentified antibacterial compound(s) may be play a role in the antibacterial activity of P. luteoviolacea.