Sequences of Landomycin E and Carotenoid Biosynthetic Gene Clusters, and Molecular Structure of Transcriptional Regulator of Streptomyces globisporus 1912.

Streptomyces globisporus 1912 and its derivatives 1912-2 and 1912-4Crt are the producers of the landomycin E, carotenoids and the regulator of antibiotics biosynthesis and morphogenesis of streptomycetes. The genome DNA of two mutant strains, 1912-2, the more effective producer of the landomycin E and the regulator, and 1912-4Crt, the producer of beta-carotene and lycopene, was sequenced by Illumina. Comparative analysis of the DNA sequences using GenBank data allowed localization of 36 landomycin E biosynthetic genes lnd of S. globisporus 1912 in one cluster. Twenty of these lnd genes have been sequenced for the first time. The new regulatory responce gene lndRR and the sensor kinase gene lndY1 were proposed as the members of the putative two-component system. High identity (94 ­ 95 %) was determined for the lnd genes of the 1912 strain and those of the metagenomic clone AZ97. Seven carotenoid biosynthetic genes crt of the strain 1912-4Crt were sequenced and localized in one cluster consisting of two convergent operons from 4 and 3 crt genes. High homology (93 %) of the crt gene clusters of S. globisporus 1912 and S. griseus IFO 13350 was shown. Two non-punctual repeats (NPRs) of 21 bp were identified in the sequence of crtY gene coding lycopene cyclase. It was shown that the deletion of 117 bp including the sequence between NPRs of 96 bp and one NPR from 5`-side activated the crt gene cluster and increased the production of beta carotene (6.91 mg/l) and lycopene (3.24 mg/l) by the strain 1912-4Crt. Deletion of 86 bp was revealed in the regulatory gene lndRR resulting in the deficiency of landomycin E production in the strain 1912-4Crt. The DNA sequences of crt and lnd genes of S. globisporus 1912 were submitted to the NCBI database with accession numbers KM349312 and KJ645792, respectively. S. globisporus 1912 produced a low-molecular-weight compound that, like A-factor, restored the landomycin E and streptomycin biosynthesis and sporulation of the defective mutants S. globisporus 1912-B2 and S. griseus 1439, respectively. The compound was purified by thin layer chromatography and HPLC. It had an absorption maximum at λmax= 245 nm and a molecular mass m/z 244. On the basis of NMR spectroscopy the chemical structure of the transcriptional regulator was elucidated as the new (L)-N-methylphenylalanyl-dehydrobutyrine diketopiperazine.

Isolation of Streptomyces globisporus and Blakeslea trispora mutants with increased carotenoid content.

Hyperpigmented mutants of Streptomyces globisporus 1912-Hp7 and Blakeslea trispora 18(+), 184(-) were isolated by action of hydrogen peroxide and nitrosoguanidine, correspondingly, from initial strains S. globisporus 1912-4Lcp and B. trispora 72(-), 198(+). The carotenoids of dry biomass of obtained strains, rubbed thoroughly with glass powder by a pestle in porcelain mortar were extracted by acetone and purified by TLC. Identification of the individual carotenoids was performed by means of HPLC and LC/MS spectrometry. It was shown that strain S. globisporus 1912-4Crt produced beta-carotene/lycopene (6.91/3.24 mg/L), mutants 1912-4Lcp and 1912-7Hp synthesized only lycopene (26.05 and 50.9 mg/L, respectively), and strains B. trispora 18(+) and 184(-)-beta-carotene (6.2% in dry biomass or more 2.5 g/L) without illumination in shake flasks. It is the first example of high constitutive production of the carotenoids by the representative of genus Streptomyces without photoinduction or increased synthesis of sigma factor The improved strains of B. trispora 18(+) and 184(-) can be used for biotechnological production of beta-carotene in industrial conditions.