Activity of aurisin A isolated from Neonothopanus nambi against methicillin-resistant Staphylococcus aureus strains.

Mycopharmaceuticals from basidiomycetes represent a promising source of new antimicrobials to overcome the challenges of multidrug-resistant bacteria. Here we report for the first time the in vitro activity of aurisin A, a dimeric sesquiterpenoid isolated from wild bioluminescent basidiomycetes Neonothopanus nambi DSM 24013, against methicillin-resistant Staphylococcus aureus (MRSA). Aurisin A revealed strong anti-MRSA activity with minimum inhibitory concentration 7.81 µg/mL against ATCC 33591 and ATCC 43300 reference strains, and BD 16876 and BD 15358 clinical strains. Activity against the clinical strains is 10- to 40-fold higher than that of the antibiotic fusidic acid. Furthermore, aurisin A proved to be more potent (MIC 3.91 µg/mL) in inhibiting growth of vancomycin-intermediate S. aureus (VISA) ATCC 700699 and displayed a rapid time-dependent bactericidal activity against MRSA (complete killing within 1 h). Additionally, aurisin A and oxacillin combination displayed synergy with notable decrease in the MICs of both compounds against MRSA. Notable synergism was also observed in combinations with linezolid and fusidic acid. Our findings indicate that aurisin A is a promising candidate for developing therapeutic agents against multidrug-resistant S. aureus and warrants further investigation.

Metabolic engineering of Corynebacterium glutamicum for cadaverine fermentation.

Cadaverine, the expected raw material of polyamides, is produced by decarboxylation of L-lysine. If we could produce cadaverine from the cheapest sugar, and as a renewable resource, it would be an effective solution against global warming, but there has been no attempt to produce cadaverine from glucose by fermentation. We focused on Corynebacterium glutamicum, whose L-lysine fermentation ability is superior, and constructed a metabolically engineered C. glutamicum in which the L-homoserine dehydrogenase gene (hom) was replaced by the L-lysine decarboxylase gene (cadA) of Escherichia coli. In this recombinant strain, cadaverine was produced at a concentration of 2.6 g/l, equivalent to up to 9.1% (molecular yield) of the glucose transformed into cadaverine in neutralizing cultivation. This is the first report of cadaverine fermentation by C. glutamicum.

Bispolides, novel 20-membered ring macrodiolide antibiotics from microbispora.

Seven new related compounds named bispolides A1, A2, A3, B1, B2a, B2b and B3, have been found in a culture of Microbispora sp. A34030, isolated from a Malaysian soil sample. The planar structures were elucidated to be new 20-membered ring macrodiolide antibiotics on the basis of MS and NMR spectroscopic analyses. These antibiotics showed a good anti-MRSA activity in vitro.

Quantification and diversity of the archaeal community in a landfill site.

At a sea-based, solid waste disposal site, methanogenic organisms were quantified by molecular approaches. The samples collected for analysis were from anaerobic leachate of the landfill site. When the DNA extracted from the leachate was examined by a quantitative PCR method using domain-specific 16S rDNA primers, archaeal DNA represented 2-3% of the total extracted DNA. On the basis of cloning and sequence comparison of the archaeal PCR products, more than half of the sequences belonged to Euryarchaeota, particularly relatives of the genus Methanosaeta. The cloning analysis suggested that the majority of methane emitted from the landfill site originated from the acetate-utilizing Methanosaeta.

A role of xylanase, alpha-L-arabinofuranosidase, and xylosidase in xylan degradation.

Renewable natural resources such as xylans are abundant in many agricultural wastes. Penicillium sp. AHT-1 is a strong producer of xylanolytic enzymes. The sequential activities of its xylanase, alpha-L-arabinofuranosidase, and beta-xylosidase on model hemicellulose oat-spelt xylan was investigated. Optimum production of the enzymes was found in culture containing oat-spelt xylan at 30 degrees C and initial pH 7.0 after 6 days. The enzymes were partially purified by ammonium sulphate fractionation and anion-exchange chromatography on DEAE-Toyopearl 650 S. The apparent molecular mass was 21 kDa, and the protein displayed an "endo" mode of action. The xylanase exhibited glycotansferase activity. It synthesized higher oligosaccharides from the initial substrates, and xylotriose was the shortest unit of substrate transglycosylated. Xylanolytic enzymes (enzyme mixture) produced by this Penicillium sp. interacted cooperatively and sequentially in the hydrolysis of oat-spelt xylan in the following order: alpha-L-arabinofuranosidase --> xylanase --> beta-xylosidase. All three enzymes exhibited optimal activity under the same conditions (temperature, pH, cultivation), indicating that they alone are sufficient to completely depolymerize the test xylan. Results indicate that the xylanolytic enzyme mixture of Penicillium sp. AHT-1 could be useful for bioconversion of xylan-rich plant wastes to value-added products.

Monitoring of Bacillus thermodenitrificans OHT-1 in compost by whole cell hybridization.

Thermophilic aerobic composting is a widely practiced method for the disposal of exhaust materials. We isolated a thermophilic bacteria strain from a compost sample under aerobic conditions at 60 degrees C. On the basis of its 16S rRNA sequence and physiological characteristics, this strain was identified as Bacillus thermodenitrificans OHT-1. An 18-subunit oligonucleotide probe for 16S rRNA, labeled with fluorescein isothiocyanate, was developed for the detection of B. thermodenitrificans. Spores and vegetative cells of B. thermodenitrificans OHT-1 were detected in liquid culture and laboratory compost by whole cell hybridization using this oligonucleotide probe. The results obtained by whole cell hybridization were evaluated in growth experiments of B. thermodenitrificans OHT-1 in laboratory compost and were used to enumerate spores and vegetative cells.