Streptomyces kasugaensis, a producer of kasugamycin, is listed as a particularly safe Streptomyces host in the Japan Guidelines for Recombinant DNA Experiments. In search of a chromogenic selectable marker usable for S. kasugaensis, melanin-synthesizing melE was constructed by placement of the operon for the melanin-synthesizing gene (melC) from Streptomyces antibioticus under the control of the promoter of the erythromycin-resistance gene (ermE) from Saccharopolyspora erythraea. Combined use of melE and the thiostrepton-resistance gene from Streptomyces azureus yielded vectors pSK216 and pSK221, derivatives of pSK2 from S. kasugaensis MB273. In S. kasugaensis and Streptomyces lividans, melE-harboring pSK216 and pSK221 induced detectable amounts of melanin pigment on agar media in marked contrast to pSK2-based pSK212 carrying melC, thereby establishing an efficient cloning system for S. kasugaensis.
A comparative analysis was performed on the taxonomy of actinomycete isolates of Malaysia and Japan. The taxonomical positions of isolates were determined using a simple identification method based on 16S rDNA partial sequence homology. The 16S rDNA partial sequence determination was made by direct PCR and direct sequencing. Simple identification was attempted for each of the 1128 actinomycete isolates for each country. We succeeded in simple identification of 790 Malaysian and 981 Japanese isolates. Malaysian isolates belonged to 9 families, 23 genera, and 185 species, including one genus as yet undescribed. The Japanese isolates belonged to 9 families, 22 genera, and 207 species. There was little taxonomical overlap between Malaysian isolates and Japanese isolates. Only 14% of the species and only 50% of the genera occurred in both groups. These results indicate that a group of actinomycetes of greater taxonomic diversity can be obtained when gathered from both regions, rather than from one or the other. Among Malaysian isolates, two strains were found that apparently do not belong to any known genus. Phylogenetic analysis indicates that they belong to the suborder Sreptosporangineae. The existence of candidate strains of a novel genus suggests that Malaysian actinomycetes have not been thoroughly investigated and therefore has promising potential as a source for novel bioactive compounds.
We investigated the taxonomic diversity of Nocardia strains freshly isolated from six sediment samples taken from Lake Suwa, Nagano Prefecture, and from the moat surrounding Takeda Shrine, Yamanashi Prefecture, Japan. A restriction fragment length polymorphism (RFLP) analysis of 16S rDNA was used for species-level identification. Of the 25 test isolates, 23 strains were identified as N. asteroides, N. carnea, N. flavorosea, N. nova, N. uniformis, or identified as belonging to the N. africana-N. veterana group. Based on RFLP patterns, the remaining two strains were differentiated from the known Nocardia species.
S-Adenosylmethionine caused overproduction of streptomycin (by Streptomyces griseus) and bicozamycin (by Streptomyces griseoflavus) when added to the medium at an appropriate concentration. The enhancement of streptomycin production was accompanied by a 1.35-fold increase in transcript of strR (a pathway-specific positive regulatory gene), and a 1.9-fold increase in activity of streptomycin kinase (an enzyme for streptomycin biosynthesis). These results, together with the previous works dealing with Streptomyces coelicolor (J. Bacteriol. 185, 601–609, 2003) and Streptomyces lividans (J. Bacteriol, 185, 592–600, 2003), implicate the significance of S-adenosylmethionine as an intracellular signal molecule for onset of secondary metabolism in the Streptomyces species.
Malaysia is one of the countries blessed with rich flora and fauna, which is a heritage that all Malaysians are proud of. The Country is concerned and determined to ensure the preservation of this unique biological heritage for the benefit of present and future generations. Malaysia was among the more than 150 countries that signed the CBD at the Earth Summit in Rio de Janeiro in 1992 and ratified the convention and became a party to it in 1994. The National Policy on Biological Diversity for Malaysia was developed and launched in 1998. This national policy aims to provide direction for the nation to implement strategies, action plans and programmes on biological diversity for the conservation and sustainable utilization of the resources. This paper therefore discusses the issues and policies on the biological diversity, bioprospecting and international collaboration in line with CBD using some already available case histories in Malaysia.
In 1995, we discovered new antiherpetic antibiotics, called fattiviracins. The producing organism was classified as a strain belonging to Streptomyces microflavus. The strain produced at least 13 fattiviracin derivatives (FV-1 to FV-13). Fattiviracins were obtained as a white amorphous powder, and their molecular weights are in the range of 1400 to 1500. They are readily soluble in water, methanol, pyridine and DMSO, but insoluble in other organic solvents. Fattiviracins have macrocyclic diesters formed by the binding of two trihydroxy fatty acids and two D-glucose residues in the molecule, and they can be divided into 5 families, according to the length of fatty acid moiety. Fattiviracins have a potent activity against enveloped DNA viruses such as the herpes family, HSV-1 and VZV and enveloped RNA viruses such as influenza A and B viruses, and three strains of HIV-1, in the order of a few μg/ml of EC50. The biosynthetic pathway of fattiviracins is also becoming clearer. Using bacitracin-resistant strains, enhanced and astringent production of fattiviracin was recognized: fattiviracin FV-13, having the longest fatty acid chains in the molecule was dramatically enhanced by a C55-isoprenyl phosphate metabolism.