Yoshio Hirose

Application of immobilized lipase to regio-specific interesterification of triglyceride in organic solvent

SummaryLipase from Rhizopus delemar was immobilized by entrapment with photo-crosslinkable resin prepolymers or urethane prepolymers or by binding to various types of porous silica beads. The immobilized lipase preparations thus obtained were examined for their activity in converting olive oil to an interesterified fat (cacao butter-like fat), whose oleic acid moieties at 1- and 3-positions were replaced with stearic acid moieties, in the reaction solvent n-hexane. Although all of the immobilized preparations exhibited some activity, lipase adsorbed on Celite and then entrapped with a hydrophobic photo-crosslinkable resin prepolymer showed the highest activity, about 75% of that of lipase simply adsorbed onto Celite. Entrapment markedly enhanced the operational stability of lipase.

Production of adenine arabinoside by gel-entrapped cells of Enterobacter aerogenes in water-organic cosolvent system

SummaryGel-entrapped whole cells of Enterobacter aerogenes, which has a transglycosylation activity, were used to produce adenine arabinoside from uracil arabinoside and adenine, in an appropriate water-organic cosolvent system. Cells of E. aerogenes entrapped with a hydrophilic photo-crosslinkable resin prepolymer, ENT-4000, or a urethane prepolymer, PU-6, had a high and stable transglycosylation activity. To improve the poor solubility in water of the substrate (adenine) and product (adenine arabinoside), dimethyl sulfoxide was selected as the cosolvent based on the criteria of operational stability of the immobilized biocatalyst and solubility of both substrate and product. Addition of 40% dimethyl sulfoxide to the reaction mixture permitted use of a high substrate concentration range which gave high productivity under homogeneous reaction conditions. The immobilized cells of E. aerogenes exhibited a markedly improved operational stability, retaining their initial level of activity during repeated use for at least 35 days at 60°C in 40% dimethyl sulfoxide. When the reaction was carried out with 150 mM uracil arabinoside and 50 mM adenine as the substrates, the yield of adenine arabinoside was maintained at 100% based on the molar ratio of adenine, throughout the reaction.

Spore fatty acid composition in Bacillus natto, a food microorganism

Abstract The levels of fatty acids and their distribution were determined in spores from twenty-five strains of Bacillus natto isolated from a fermented soybean food, natto, or subcultured from the culture collection. The major fatty acid components of spores, consisting of about 80 to 90% of the total, were anteiso -C 15 , anteiso -C 17 , iso -C 15 and iso -C 17 ; the other fatty acids, at a level of 10 to 20% of the total, were iso -C 14 , iso -C 16 , n -C 14 , n -C 16 and n -C 18 . The amount of fatty acid in spores was highest with anteiso -C 15 , followed in order by iso -C 15 . In addition to the nine fatty acids, some of the strains produced six extra fatty acids, three branched ( anteiso -C 13 , iso -C 12 and iso -C 13 ) and three normal ( n -C 12 , n -C 15 and n -C 17 ).

Photoautotrophic growth of Marchantia polymorpha L. cells in suspension culture

A cell line of M. polymorpha was grown photoautotrophically in liquid suspension culture using 1% CO2 in air as sole carbon source. The growth rate in terms of cell dry-weight during the exponential phase was 0.171 and the doubling time was 1.76 d. The rate of increase in chlorophyll was 1.6 times higher than the growth rate. The highest content of chlorophyll was 24 mg g-1 dry weight, and the photosynthetic activity of the cells in the exponential phase, as calculated from the growth rate, was at least 60 μmol mg-1 chlorophyll h-1.

Basic Aspects of Electrode Potential Change in Submerged Fermentation

The platinum electrode potentials relative to the standard half cell depended on a pH value, dissolved oxygen concentration, equilibrium constant and oxidation reduction potentials of the liquid The overall potential change in submerged fermentation gave no independent information on these individual factors A thermostatic and pH-static apparatus excluded influences of temperatures and pH values on the electrode pontentials If the determination was completed for short time duration, potentials were governed by the dissolved oxygen tension. While the oxygen concentration was maintained at a same level, redox potential changes became a dominant. This measurement of redox potential, which gave the concentration of extremely low dissolved oxygen that could not be detected by the membrane-coated oxygen electrode, was practically useful for the control of aerobic fermentation

Ptychanolide, a sesquiterpenoid with a new type skeleton from the liverwort ptychanthus striatus (lehm. et lindenb.) nees

Abstract The structure of ptychanolide, isolated from the liverwort Ptychanthus striatus , has been determined by spectroscopic analysis and chemical transformation.

Effect of glycine betaine, an osmoprotective compound on the growth of Brevibacterium lactofermentum

SummaryOsmoregulation of Brevibacterium lactofermentum was examined. Exogenous glycine betaine was found to stimulate the growth rate of the bacterium in media of inhibitory osmotic strength. The stimulation was independent of any specific solute, electrolyte, or non-electrolyte. The bacterium did not utilize glycine betaine as a sole carbon source or nitrogen source, or degrade it even in complete medium. The changes in intracellular proline and glycine betaine concentrations were measured in media of different osmolarity. Brevibacterium lactofermentum grown in media without glycine betaine did not accumulate it, but synthesized several hyndred millimoles of proline inside the cells. On the other hand, when glycine betaine was added to the growth media, it accumulated in the cell instead of proline. These data indicate that glycine betaine is an osmoprotective compound for B. lactofermentum.

Stimulatory effect of glycine betaine on l-lysine fermentation

SummaryThe growth rate, sugar consumption rate, and production rate of an l-lysine producing Brevibacterium lactofermentum mutant were stimulated by addition of exogenous glycine betaine. Glycine betaine stimulated the growth rate especially in media of inhibitory osmotic stress, and the stimulation was independent of any specific solute. Therefore growth stimulation by glycine betaine was considered to be an osmoprotective effect. A strong enhancement of the sugar consumption rate and the l-lysine production rate was observed even with resting cells under osmotic stress as well as in a fermentation with growing cells. These data indicated that the osmoprotective effects of glycine betaine on l-lysine production can be independent of protein synthesis.

Effect of Glycine and L-Isoleucine on Protein Production by Bacillus brevis No. 47

Among factors affecting the protein production by Bacillus brevis No. 47, glycine and l-isoleucine were found to be prominent in stimulating protein production. The simultaneous addition of appropriate amount of these amino acids resulted in the largest accumulation of proteins; namely, 12 g/liter.The mode of action of glycine and isoleucine appeared different. Isoleucine stimulated the synthesis of both extracellular and intracellular proteins, while glycine caused a considerable increase of extracellular protein accumulation with a concomitant decrease in the amount of intracellular protein. Therefore, glycine may have a function in stimulating protein excretion. Glycine made cells more sensitive to lysozyme and caused a large decrease in alanine content of the cell wall fraction. These findings supported the possibility that glycine alters cell wall structure in such a way so as to facilitate protein excretion.The proteins produced in the presence of glycine as a whole were smaller in molecular weight ...

Molecular breeding of a Brevibacterium lactofermentum l-phenylalanine producer using a cloned prephenate dehydratase gene

SummaryThe prephenate dehydratase gene was cloned from a mutant of Brevibacterium lactofermentum, AJ11957 that produced enzyme free from feedback inhibition. The recombinant plasmids pPH11 and pPH14 complemented a phenylalanine auxotroph of B. lactofermentum, A-15, provided the transformant with the desensitized enzyme and caused an increased level of the enzyme compared to that of a wild strain. Plasmid pPH14 was introduced into l-phenylalanine producers genetically induced from B. lactofermentum; MF358 and FP-1 excreting l-tyrosine and anthranilate, respectively, as by-products. Both transformants predominantly accumulated l-phenylalanine at the expense of by-product formation. Co-existence of pPH14 and pTAR16, a recombinant plasmid expressing desensitized 3-deoxy-d-arabino-hepturosonate-7-phosphate synthase had a marked effect on further improvement in l-phenylalanine productivity, accompanied by an increase in the corresponding enzyme activity. The parent, MF358, accumulating 5.5 g/l l-phenylalanine, 6.8 g/l l-tyrosine and 0.3 g/l anthranilate turned into a potent l-phenylalanine producer producing 18.2 g/l l-phenylalanine and 1.0 g/l l-tyrosine by-product.