Motoko Matsufuji

High production of rhamnolipids by Pseudomonas aeruginosa growing on ethanol

Pseudomonas aeruginosa IFO 3924 produced 32 g rhamnolipid biosurfactant/l when grown on 55.3 g ethanol/l in fed-batch culture for 7 days. The conversion rate was 58%.

High production of pyoluteorin and 2,4-diacetylphloroglucinol by Pseudomonas fluorescens S272 grown on ethanol as a sole carbon source

Pseudomonas fluorescens S272 newly isolated from a soil sample produced a considerable amount of pyoluteorin and 2,4-diacetylphloroglucinol when grown on ethanol as a single carbon source. The coproduction of approximately 150 μg/ml of pyoluteorin and approximately 500 μg/ml of 2,4-diacyl-phloroglucinol was achieved by flask cultutivation in a medium containing approximately 2% ethanol. A high CN ratio and inorganic phosphate limitation in the medium were also important factors to be considered for optimization of production of the antibiotics.

Protective effects of bacterial glyceroglycolipid M874B against cell death caused by exposure to heat and hydrogen peroxide

It was revealed by bioassay using sodA and katA mutants of Bacillus subtilis that the bacterial monogalactosyldiacylglycerol M874B, previously characterized as an alkyl peroxyl radical scavenger, was also capable of protecting cells from death caused by heating and exogenous H2O2. Chemical assays using the Fenton reaction and xanthine-xanthine oxidase revealed that M874B could quench hydroxyl radicals but not superoxide anions. Wheat monogalactosyldiacylglycerol, but neither digalactosyldiacylglycerol nor synthetic diacylglycerol, also had the same activities as those of M874B, although it was less efficient than M874B. These results suggest that monogalactosyldiacylglycerols such as M874B are a new type of oxygen radical scavengers capable of quenching some reactive oxygen species.

Glyceroglycolipids preventing tert-butylhydroperoxide-induced cell death from Microbacterium sp. and Corynebacterium aquaticum strains.

Galactosyl diacylglycerols M874B and S365B obtained from the recently isolated bacteria identified as Microbacterium sp. M874 and Corynebacterium aquaticum S365 were found to prevent oxidative cell death induced by tert-butylhydroperoxide. Their structures were determined to be 1,2-di-O-(12-methyltetradecanoyl)-3-O-beta-D-galactopyranosyl-sn-glycerol and 1-O-(14-methylhexadecanoyl)-2-O-(12-methyltetradecanoyl)-3-O-beta-D-galactopyranosyl-sn-glycerol, respectively.

Streptomyces Serine Protease (DHP-A) as a New Biocatalyst Capable of Forming Chiral Intermediates of 1,4-Dihydropyridine Calcium Antagonists

ABSTRACT Streptomyces viridosporus A-914 was screened as a producer of an enzyme to effectively form chiral intermediates of 1,4-dihydropyridine calcium antagonists. The supernatant liquid of the growing culture of this strain exhibited high activity for enantioselective hydrolysis of prochiral 1,4-dihydropyridine diesters to the corresponding (4R) half esters. The responsible enzyme (termed DHP-A) was purified to apparent homogeneity and characterized. Cloning and sequence analysis of the gene for DHP-A (dhpA) revealed that the enzyme was a serine protease that is highly similar in both structural and enzymatic feature to SAM-P45, which is known as a target enzyme of Streptomyces subtilisin inhibitor (SSI), from Streptomyces albogriseolus. In a batch reaction test, DHP-A produced a higher yield of a chiral intermediate of 1,4-dihydropyridine than the commercially available protease P6. Homologous or heterologous expression of dhpA resulted in overproduction of the enzyme in culture supernatants, with 2.4- to 4.2-fold higher specific activities than in the parent S. viridosporus A-914. This indicates that DHP-A is suitable for use in reactions forming chiral intermediates of calcium antagonists and suggests the feasibility of developing DHP-A as a new commercial enzyme for use in the chiral drug industry.