Genomic DNA was extracted from 13 samples of Sargassum polycystum and S. siliquosum collected from various localities around Peninsular Malaysia and Singapore by using four different extraction methods. The yields and the suitability of the DNA to be used as template for the polymerase chain reaction (PCR) was compared. DNA samples were subjected to PCR analysis by using random primers. Only DNA samples that were extracted using the CTAB method were successfully amplified by random amplified polymorphic DNA (RAPD)-PCR. Five of 31 random primers (OPA02, OPA03, OPA04, OPA13 and OPM10) tested amplified sequences of DNA from the DNA samples. Reproducible, amplified products were obtained using these primers and showed some potential to be useful in discriminating individual samples within the genus, in determining relationships between species within a genus and in developing individual fingerprints for individual samples.

Palm and palm-kernel oils and their olein and stearin fractions were suitable as the main carbon sources for growth and production of clavulanic acid by Streptomyces clavuligerus. However, oleic and lauric acids were not utilized for growth. A spontaneous mutant, which was selected for higher cephamycin C production, also produced more clavulanic acid with these oils in the medium.

The random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) was used for the molecular characterisation and identification of Sargassum spp. A total of 17 samples of Sargassum (Sargassaceae, Fucales) was obtained from various localities around Peninsular Malaysia and Singapore. On the basis of morphological characteristics, the samples were tentatively grouped into five species: Sargassum baccutaria, S. glaucescens, S. aligacystum, S. polycystum and S. siliquosum. By RAPD-PCR, five of 31 random primers tested generated reproducible amplification products, and polymorphic loci were detected by four of them (OPA02, OPA03, OPA04, OPAI3). The RAPD-PCR profiles did not correlate with the morphological grouping into five species and extensive variation was detected between different isolates of the same species. A 450 base pair fragment generated using OPAI3 was detected in 12 of 17 samples of Sargassum. This fragment was also present in profiles from Turbinaria (Sargassaceae). This study suggests that RAPD-PCR is useful in discriminating individual samples of the genus Sargassum and in developing fingerprints for them.

A circular genetic map was constructed of Streptomyces peucetius var. caesius, the producer of the anti-cancer antibiotic adriamycin. For the mapping, auxotrophic mutations were used to block the synthesis of various amino acids, adenine and nicotinamide. These auxotrophic mutants were obtained by mutagenic treatment of sporulating derivatives of the original strain (IMRU 3920 hereby called H3502). Most of these derivatives utilized the purple (accumulating -rhodomycinone) and white mutants with a defective adriamycin biosynthetic pathway. The location of the markers on the genetic map was based on haploid recombinant selection following the experimental and analytical procedures developed with Streptomyces rimosus. Crosses were made resulting in the unambiguous placement of the markers phe-ser-met-ade-leu phe in the anti-clockwise direction. This preliminary genetic map can be used for future mapping of the genes involved in adriamycin biosynthesis.Streptomyces peucetius var. caesius produces adriamycin, a clinically important anti-cancer antibiotic (1). This anthracycline antibiotic is biosynthesized via the polyketide pathway followed later by glycosidation of various aglycones to biologically-active glycosides, the anthracyclines. As a first step towards the location of the genes involved in this biosynthesis, a chromosomal map with markers is required. The method used here for the mapping involved haploid recombinant selection following conjugation using procedures developed for Streptomyces rimosus (2). Three four-factor crosses were studied with the parents of each cross carrying four auxotrophic markers (two auxotrophic mutations in each strain).Strains. MATERIALS AND METHODSThe origins of the various strains used for the crosses are given in 231

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