For over a decade, Streptomyces venezuelae has been used to study the molecular mechanisms that control morphological development in streptomycetes and is now a well-established model strain. Its rapid growth and ability to sporulate in a near-synchronised manner in liquid culture, unusual among streptomycetes, greatly facilitates the application of modern molecular techniques such as ChIP-seq and RNA-seq, as well as time-lapse fluorescence imaging of the complete Streptomyces life cycle. Here we describe a high-quality genome sequence of our isolate of the strain (Northern Regional Research Laboratory [NRRL] B-65442) consisting of an 8.2 Mb chromosome and a 158 kb plasmid, pSVJI1, which had not been reported previously. Surprisingly, while NRRL B-65442 yields green spores on MYM agar, the American Type Culture Collection (ATCC) type strain 10712 (from which NRRL B-65442 was derived) produces grey spores. While comparison of the genome sequences of the two isolates revealed almost total identity, it did reveal a single nucleotide substitution in a gene, vnz_33525, involved in spore pigment biosynthesis. Replacement of the vnz_33525 allele of ATCC 10712 with that of NRRL B-65442 resulted in green spores, explaining the discrepancy in spore pigmentation. We also applied CRISPR-Cas9 to delete the essential parB of pSVJI1 to cure the plasmid from the strain without obvious phenotypic consequences.

中文翻译：

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委内瑞拉链霉菌 NRRL B-65442：用于研究丝状放线菌形态分化的模型菌株的基因组序列

十多年来，委内瑞拉链霉菌一直被用于研究控制链霉菌形态发育的分子机制，现已成为一种成熟的模型菌株。它的快速生长和在液体培养中以近乎同步的方式形成孢子的能力，在链霉菌中是罕见的，极大地促进了现代分子技术（如 ChIP-seq 和 RNA-seq）的应用，以及完整的延时荧光成像链霉菌的生命周期。在这里，我们描述了我们的菌株分离株（北方区域研究实验室 [NRRL] B-65442）的高质量基因组序列，该菌株由 8.2 Mb 染色体和 158 kb 质粒 pSVJI1 组成，以前没有报道过。令人惊讶的是，当 NRRL B-65442 在 MYM 琼脂上产生绿色孢子时，美国典型培养物保藏中心 (ATCC) 的 10712 型菌株（NRRL B-65442 来源于此）产生灰色孢子。虽然比较两种分离株的基因组序列几乎完全一致，但它确实揭示了一个基因 vnz_33525 中的单核苷酸替换，该基因参与了孢子色素的生物合成。用 NRRL B-65442 替换 ATCC 10712 的 vnz_33525 等位基因产生绿色孢子，这解释了孢子色素沉着的差异。我们还应用 CRISPR-Cas9 删除 pSVJI1 的基本 parB 以治愈菌株中的质粒，而不会产生明显的表型后果。参与孢子色素的生物合成。用 NRRL B-65442 替换 ATCC 10712 的 vnz_33525 等位基因产生绿色孢子，这解释了孢子色素沉着的差异。我们还应用 CRISPR-Cas9 删除 pSVJI1 的基本 parB 以治愈菌株中的质粒，而不会产生明显的表型后果。参与孢子色素的生物合成。用 NRRL B-65442 替换 ATCC 10712 的 vnz_33525 等位基因产生绿色孢子，这解释了孢子色素沉着的差异。我们还应用 CRISPR-Cas9 删除 pSVJI1 的基本 parB 以治愈菌株中的质粒，而不会产生明显的表型后果。