A novel alkaline esterase from Sporosarcina sp. nov. strain eSP04 catalyzing the hydrolysis of a wide variety of aryl-carboxylic acid esters.

A novel esterase showing activity specific for esters of aryl-carboxylic acids was discovered in Sporosarcina sp. nov., which was identified by the 16S rDNA sequencing method in addition to morphological and physiological analyses. The aryl-carboxylesterase (named EstAC) was purified 780-fold from crude cell extracts by a 5-step procedure. EstAC was characterized as a monomeric protein with a molecular weight of 43,000, an optimum pH of around 9.0, and an optimum temperature of 40 °C. The pH optimum and the effects of inhibitors together with an internal amino acid sequence suggested that EstAC is a member of family VIII esterases. EstAC was found to be highly active on a wide variety of substrates such as alkyl benzoates, alkyl phenylacetates, ethyl α- or ß-substituted phenylpropionates, dialkyl terephthalates, dimethyl isophthalate, and ethylene glycol dibenzoate. However, monomethyl terephthalate was not hydrolyzed. It was suggested that EstAC had 4-hydroxybenzoyl and cinnamoyl esterase activities as well.

High-yield production of short chain length poly(epsilon-L-lysine) consisting of 5-20 residues by Streptomyces aureofaciens, and its antimicrobial activity.

Poly(epsilon-L-lysine) (epsilon-PL) is a naturally-occurring L-lysine homopolymer having antimicrobial activity. A newly-isolated strain of Streptomyces aureofaciens produced a short chain length epsilon-PL consisting of 5-20 residues at the highest production level of 4.5 g l(-1). This epsilon-PL had different spectra in terms of antimicrobial activity from the epsilon-PL that is now used as a food preservative. The high productivity was based on multiple metabolic pathways for L-lysine synthesis, and a great flux from L-lysine to epsilon-PL. The usefulness of this new epsilon-PL and its producing strain was discussed.

Poly(gamma-L-diaminobutanoic acid), a novel poly(amino acid), coproduced with poly(epsilon-L-lysine) by two strains of Streptomyces celluloflavus.

Two poly(epsilon-L-lysine) (epsilon-PL) producer strains of Streptomyces celluloflavus secreted a novel polymeric substance into their culture broths along with epsilon-PL. Three types of HPLC analysis plus one- and two-dimensional 1H and 13C nuclear magnetic resonance experiments revealed that the secreted substance was poly(gamma-L-diaminobutanoic acid) (gamma-PAB), an L-alpha,gamma-diaminobutanoic acid (L-DAB) homopolymer linking between y-amino and alpha-carboxylic acid functional groups. The gamma-PABs from the two strains had an identical chemical structure, and the same number-average molecular weight of 2100-2200. No copolymers composed of the two amino acids L-DAB and L-lysine were found in either of the broths from the producers. Both strains coproduced high levels of the two poly(amino acid)s in the presence of SO4(2-) at pH 4.0 and 4.5 L min(-1) aeration in a 5-L jar fermentor. gamma-PAB exhibited strong inhibitory activities against various yeasts and weaker actions against bacteria than epsilon-PL. gamma-PAB may have various biological functions similar to epsilon-PL, and the use of gamma-PAB along with epsilon-PL would be advantageous for technical applications in various fields.

Biosynthesis of nearly monodispersed poly(epsilon-L-lysine) in Streptomyces species.

Poly(epsilon-L-lysine) (epsilon-PL) is a naturally occurring poly(amino acid) characterized by a unique structure linking epsilon-amino and carboxyl groups of L-lysine. Due to its various functions and its biodegradability and non-toxicity, the epsilon-PL polymer has attracted increasing attention in recent years. epsilon-PL is frequently found in various strains of Streptomyces sp. This review gives an up-to-date overview regarding the biosynthesis of epsilon-PL focussing mainly on results obtained from ten newly isolated producer strains, using the two-stage culture method of cell growth and epsilon-PL production cultures. The production of nearly monodispersed epsilon-PL is covered together with the development of epsilon-PL specific hydrolases and the release of synthesized epsilon-PL into the culture broth. From these results, coupled with the termination of polymerization through nucleophilic chain transfer, the biosynthetic mechanism of the polymer is discussed.

Substantially monodispersed poly(epsilon-L-lysine)s frequently occurred in newly isolated strains of Streptomyces sp.

The presence of poly(epsilon-L-lysine) (epsilon-PL) was found quite frequently by screening various strains of Streptomyces sp. Most of the ten newly obtained epsilon-PLs, when they were produced from glucose, showed a polydispersity index of Mw/Mn = 1.01 using ion-pair chromatography analysis. The polymers were classified into five groups according to their chain lengths. The average numbers of residues in the five groups were 32, 28, 25, 19, and 16, respectively. The use of glycerol instead of glucose resulted in decreases of 10 to 20% in the Mn and slight increases in the Mw/Mn. These observations indicated the chain length and polydispersity of epsilon-PL were primarily determined by each producer strain. Proton and 13C NMR analysis revealed the signals of glycerol-derived ester at the C terminus of the polymer from several producers including the first discovered S. albulus strain, although the percentages of the ester were low under our culture conditions. These results, coupled with the previous observation that SO4(2-) was essential for the polymer production, led to discussion on the mechanistic aspects of monomer activation, elongation, and termination in the biosynthesis of epsilon-PL.

Biosynthesis of poly(epsilon-L-lysine)s in two newly isolated strains of Streptomyces sp.

The biosynthesis of poly(epsilon-L-lysine) (epsilon-PL) in the two newly isolated strains of Streptomyces lydicus USE-11 (USE-11) and Streptomyces sp. USE-51 (USE-51) was studied by a newly developed two-stage culture method of cell growth at pH 6.8 and epsilon-PL production at pH 4.5. USE-11 synthesized epsilon-PL consisting of about 28 residues at a high production level, whereas USE-51 did the polymer with 15 ones at a low level. The secreted epsilon-PLs in culture media were digested in a neutral pH range with a peptide hydrolase(s) produced by the epsilon-PL producers. The optimum production levels were presumed to be dependent upon the inherent epsilon-PL synthesis machinery of each producer. The production in USE-51 was sharply dependent upon cell density as was often observed in the production of antibiotics, whereas that in USE-11 was scarcely affected by the density. The SO(4)(2-) was found to be essential for the epsilon-PL production in both strains. This might suggest the involvement of a thiol group in the polymerization reactions including the activation of L-lysine. This study indicates that USE-11 is a most suitable strain for the exploration of the epsilon-PL biosynthesis at the molecular level as well as for the technical applications.

Chemical Study and Absolute Configuration of a New Marine Secospatane from the Brown Alga Dilophus okamurae.

A new diterpene, dilkamural (1), of the secospatane class has been isolated from the brown alga Dilophus okamurae Dawson, and its structure, including absolute stereochemistry, has been determined by NMR spectroscopic and chemical means.