Serratia marcescens-Lytic Enzyme Produced by Micromonospora sp. Strain No. 152

A strain of Micromonospora sp. producing a lytic enzyme toward Serratia marcescens was isolated from soil. The lytic enzyme, called 152-enzyme, was purified from the culture filtrate by salting-out with ammonium sulfate, DEAE-cellulose column chromatography, and gel filtration on Sephadex G-75. The molecular weight of 152-enzyme was 17,000 and the isoelectric point was pH 7.3. The 152-enzyme showed lytic activity toward S. marcescens, Pseudomonas aeruginosa, Proteus vulgaris, Escherichia coli, and Bacillus subtilis, but was completely intert toward Staphylococcus aureus. The enzyme also showed caseinolytic activity. The lytic and caseinolytic activities of 152-enzyme were maximum around pH 11.0 and at 60°C. Both activities were inhibited by DFP and API-2c. Liberation of amino groups from cell walls of P. aeruginosa by incubation with 152-enzyme suggested that the enzyme was a kind of cell wall-lytic peptidase.     

Transformation of Maridomycin III by Maridomycin III-Insensitive Streptomycetes

Transformation of maridomycin III, a macrolide antibiotic, by maridomycin (MDM) III-insensitive streptomycetes was examined. Three main transformation products were obtained. In comparison with authentic samples, these transformation products were identified as 18-dihydro MDM III, 4′′-depropionyl MDM III and 18-dihydro-4′′-depropionyl MDM III. Reduction of the C–18 position of the macro lactone moiety of the antibiotic was thought to be a detoxication mechanism of the antibiotic by these insensitive strains.     

Neutral Sugar Fragments from Antibiotic K-52B

The neutral constituent sugars of antibiotic K-52B and their glycosidic linkages were examined by methylation analysis and Smith degradation. After partial acid hydrolysis of K-52B, neutral oligosaccharides I, II and III were isolated, and the constituent sugars of each oligosaccharide and their glycosidic linkages were similarly examined. K-52B was found to contain α-d-glc_p-(l → 4)-d-gal_p-(l → 4)-l-fuc and l-ara_f-(1 → 4)-d-gal-(l → as neutral sugar fragments.     

Isolation and Identification of a Hog Pancreatic α-Amylase Inhibitor (Haim) Producing Streptomyces

A screening test was carried out to obtain microbes which produce hog pancreatic α-amylase inhibitor and a new inhibitor was found in culture broth of an actinomycete, strain YM-25. This inhibitor was designated as Haim, an abbreviation for hog pancreatic α-amylase inhibitor from a microbe. The determined morphological and physiological properties of strain YM-25 led to the conclusion that the microorganism was Streptomyces griseosporeus.

When the microorganism was aerobically cultured at 30°C in a jar fermentor containing the most suitable medium for growth which consisted of 5% glycerol, 0.5% polypepton, 0.2% meat extract, 0.1% yeast extract, 0.4% Na₂HPO₄ ? 12H₂O, 0.1% KH₂PO₄, and 0.05% MgSO₄ ? 7H₂O (pH 7.3), the highest activity of Haim was obtained on 23~26hr cultivation.

Haim had specific inhibitory activities against animal α-amylases but not against microbial and plant α-amylases.     

Substitution Reaction on the Indole Ring of ( – )-Indolactam V,the Fundamental Structure of Teleocidins

We isolated a temperature-sensitive mutant which did not exhibit derepression of acid phosphatase and invertase at the restrictive temperature. The mutation was mapped in the cryl gene, the structural gene for the catalytic subunit of adenylate cyclase. On electron microscopic observation of the mutant cells at the restrictive temperature, it was observed that they accumulated carbohydrate particles in the cytoplasm. Isolated particles had a rosette-like structure of 40 to 60 nm in diameter, and were identified as glycogen. After 2 hr incubation at the restrictive temperature, glycogen particles occupied most of the cytoplasmic space and the vacuoles were observed to be fragmented.     

Comparative study for the effects of variable nutrient conditions on the biodegradation of microcystin-LR and concurrent dynamics in microcystin-degrading gene abundance

Microcystin-LR (MCLR) degradation capability of biofilm was investigated with and without additional nutrients (nitrate, ammonium, peptone and glucose) at concentrations of 100 and 1000 mg L(-1). The MCLR-degradation was stimulated with nitrate and inhibited with other nutrients, except for that glucose of low concentration had no obvious effect. Both stimulatory and inhibitory effects enhanced with increasing concentration of corresponding nutrient. Quantitative polymerase chain reaction (qPCR) indicated that enhanced inhibition in biodegradation correlated to increased inhibition in functional gene (mlrA) abundance, as nutrient concentration increased. Stimulated biodegradation under low nitrate concentration may result from more rapid increase in mlrA gene abundance. These suggested that MCLR-degradation largely depended upon responsible bacterial population, which was affected by population of other bacteria in biofilm according to 16S rDNA-targeting qPCR. However, inhibited mlrA gene abundance implied that the stimulated biodegradation under high nitrate concentration might be involved in the mechanisms not related to MCLRDB population.     

Perenniporiol derivatives six triterpenoids from the cultured mycelia of Perenniporia ochroleuca

Six new triterpenoids, (26S)-26-O-methylperenniporiol, (26S)-3-acetyl-26-O-methylperenniporiol, perenniporiol, 3-acetylperenniporiol, (26S-15-deacetoxy-7,11-dihydro-26-O-methylperenniporiol and 15-deacetoxy-7,11-dihydroperenniporiol were isolated from the cultured mycelia of Perenniporia ochroleuca. The structures of the first two compounds were determined using spectroscopic and X-ray analyses, and the structures of the other compounds were elucidated by spectroscopic data.