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Characterization of Five Filamentous Phages from Xanthomonas campestris pv. citri

柑桔潰瘍病菌五種絲狀噬菌體之特性

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摘要


Cf29、Cf32、Cf99、Cf117和Cf134等五個噬菌體分別從柑桔潰瘍病菌的XW29、XW32、XW99、XW117和XW134等潛溶菌株分離而得。此等噬菌體皆為絲狀,大小在1250-1228 X 8-10nm之間;在XW47指示菌株的頂層培養基上,形成直徑1.0-1.5毫米稍混濁或混濁的溶菌斑;每一溶菌斑含有約10^7-10^8 PFU的噬菌體;其基因組為環狀的單股去氧核醣核酸。使用Apal, Aval, BamHI. BgIII, EcoRI, HindIll, Kpnl, Notl, PstI, StuI, XhoI等限制酶切割此五噬菌體之基因組,發現其大小為7.4 kb。此等噬菌體能感染柑桔潰瘍病菌70個菌株中之56個菌株,但不能感染所供試的其他植物病原細菌及土壤、臨床、環境等細菌。這些噬菌體分別可以69-100%的頻率將XW47菌株的細胞潛溶化。潛溶菌株經五年來的長期更新培養,或吖啶橙、紫外線照射、軟瓊脂培養基五年穿刺保存、或接種至柳橙葉片二星期後,皆仍具有潛溶性。所有潛溶菌株在牛肉煎汁液培養過程中皆自然地釋放噬菌體,0小時測得10^3-10^4 PFU/ml,而48小時後達10^5-10^6 PFU/ml的噬菌體顆粒。XW47 (Cf29)-69、XW47 (Cf32)-16、XW47 (Cf99)-22、XW47 (Cf117)-13及XW47 (Cf134)-24等潛溶菌株對於潛溶化自己本身的Cf29、Cf32、Cf99、Cf117與Cf134等噬菌體皆具有免疫性。潛溶化後,此五等噬菌體的DNA存在於其寄主細胞內,但其位置還未確定。

關鍵字

絲狀噬菌體

並列摘要


Phages Cf29, Cf32, Cf99, Cf117 and Cf134 were isolated from the lysogenic strains XW29, XW32, XW99, Xw117 and XW134 of Xanthomomas campestris pv. citri, respectively. They were filamentous and measured 1250-1288 X 8-10 nm, produced small turbid plaques on the lawn of X. campestris pv. citri XW47, diameter of which ranged from 1.0 to 1.5 mm; each of the plaques contained approximately 10^7-10^8 PFU of phage particles; their genomes consisted of circular sigle-stranded DNA. Based on the size of the fragments produced by digestion with restriction endonucleases Apal, Aval, BamHI. BgIII, EcoRI, HindIll, Kpnl, Notl, PstI, StuI, XhoI, the DNAs of these five phages were estimated to have about 7.4 kilobase pairs. These five phages infected 56 out of the 70 X. campestris pv. citri strains tested, but not other species of phytopathogenic, soil, clinical and environmental bacteria tested. All of these phages lysogenized strain XW47 of X. campestris pv. citri at the frequencies of 69-100%. The resulting lysogens of X. campestris pv. citri XW47, after a long series of subcultures for 5 years on the nutrient agar plates, retained lysogeny for their lysogenizing phages and, after treated with acridine orange at the concentrations of 0.4, 0.8 and 1.0μg/ml and at pH7.6, 7.2 and 6.7, irradiated under a 15-W UV light at a distance of 60 cm for 10 seconds, preserved in soft-agar stabs for 5 years, or inoculated into the leaves of Liucheng sweet orange (Citrus sinensis cv. Liucheng) within 2 weeks, were still lysogenic for each of their lysogenizing phages. During their growth in the nutrient broth, all of the X. campestris pv. citri XW47 lysogens spontaneously liberated phages at approximately 10^3-10^4 PFU/ml at 0 hr and 10^5-10^6 PFU/ml at 48 hr, and they were immune to each of their own lysogenizing phages.

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