Genomes of the Non-Clearing-Zone-Forming and Natural-Rubber- Degrading Species Gordonia polyisoprenivorans and Gordonia westfalica Harbor Genes Expressing Lcp Activity in Streptomyces Strains

The latex-clearing protein (LcpK₃₀) from the rubber-degrading bacterium Streptomyces sp. strain K30 is involved in the cleavage of poly(cis-1,4-isoprene), yielding isoprenoid aldehydes and ketones. Lcp homologues have so far been detected in all investigated clearing-zone-forming rubber-degrading bacteria. Internal degenerated oligonucleotides derived from lcp genes of Streptomyces sp. strain K30 (lcpK₃₀), Streptomyces coelicolor strain A3(2), and Nocardia farcinica strains IFM10152 and E1 were applied in PCR to investigate whether lcp homologues occur also in the non-clearing-zone-forming rubber-utilizing bacteria Gordonia polyisoprenivorans strains VH2 and Y2K, Gordonia alkanivorans strain 44187, and Gordonia westfalica strain Kb1, which grow adhesively on rubber. The 1,230- and 1,224-bp lcp-homologous genes from G. polyisoprenivorans strain VH2 (lcpVH₂) and G. westfalica strain Kb1 (lcpKb₁) were obtained after screening genomic libraries by degenerated PCR amplification, and their translational products exhibited 50 and 52% amino acid identity, respectively, to LcpK₃₀. Recombinant lcpVH₂ and lcpKb₁ harboring cells of the non-rubber-degrading Streptomyces lividans strain TK23 were able to form clearing zones and aldehydes on latex overlay-agar plates, thus indicating that lcpVH₂ and lcpKb₁ encode functionally active proteins. Analysis by gel permeation chromatography demonstrated lower polymer concentrations and molecular weights of the remaining polyisoprenoid molecules after incubation with these recombinant S. lividans strains. Reverse transcription-PCR analysis demonstrated that lcpVH₂ was transcribed in cells of G. polyisoprenivorans strain VH2 cultivated in the presence of poly(cis-1,4-isoprene) but not in the presence of sodium acetate. Anti-LcpK₃₀ immunoglobulin Gs, which were raised in this study, were rather specific for LcpK₃₀ and did not cross-react with LcpVH₂ and LcpKb₁. A lcpVH₂ disruption mutant was still able to grow with poly(cis-1,4-isoprene) as sole carbon source; therefore, lcpVH₂ seems not to be essential for rubber degradation in G. polyisoprenivorans.