Development of a novel method for feeding a mixture of -lactic acid and acetic acid in fed-batch culture of Ralstonia eutropha for poly- -3-hydroxybutyrate production

Fermentative production of poly- -3-hydroxybutyrate [P(3HB)] from a mixture of -lactic acid and acetic acid by Ralstonia eutropha was investigated. For fed-batch culture with cell density, it is necessary to control the concentration of these organic acids in the culture medium below the inhibitory level for cell growth. Therefore, a novel feeding method, termed the computer-controlled pH-stat substrate feeding method, was developed using the rate of increase of the pH (pH-increasing rate) of the culture medium as an indicator for feed control. The pH-increasing rate, which was calculated every minute by a pH meter-linked computer, represented secondary information regarding substrate consumption by cells. When the pH-increasing rate decreased to 5% of the maximum increasing rate, acidic substrate solution was fed into the fermentor until the pH was reduced to 7.00. Using this feeding strategy, the cell concentration and PHA content obtained in 42 h were 75.0 g/l and 73.1% (w/w), respectively, resulting in a high P(3HB) productivity of 1.30 g/l·h.     

Production of new antioxidant compound from mycosporine-like amino acid,porphyra-334 by heat treatment

In this study, we evaluated the antioxidant activity (diphenylpicrylhydrazyl (DPPH)-radical scavenging activity) of the low-molecular weight fraction of water-soluble Susabinori (Porphyra yezoensis) extract (LMF). DPPH-radical scavenging activity of LMF (65.5 μmol-Trolox eq/ml) was enhanced at temperatures over 100 °C (1.4, 2.0 and 2.4 times higher at 100, 110 and 120 °C, respectively). As a result of HPLC separations, a newly produced peak was observed in heat treated LMF, while a marked decrease of another peak was found after heat treatment of LMF. The decreased peak was identified as porphyra-334, which is a typical mycosporine-like amino acid, by ESI/MSⁿ analysis (protonated molecule [M + H]⁺ at m/z 347.1 and its fragment ion 303.1). The newly produced compound with [M + H]⁺ at m/z 329.1 was found to be a dehydrated compound of porhyra-334. The compound exhibited an extremely high-IC₅₀ value of 10.1 μg/ml in DPPH-radical scavenging activity, compared to porphyra-334 (>1000 μg/ml).     

Thermal diffusivity of SiO2 and Y2O3 added AIN ceramics

The addition of both SiO₂ and Y₂O₃ to AIN led to decrease of 27R polytype in specimens sintered above 1600° C and also to an increase of thermal diffusivity of AIN ceramics. Furthermore, SiO₂ and Y₂O₃ added AIN ceramics were fully densified by liquid-phase sintering, and resulted in higher thermal diffusivity. The formation temperature of the liquid phase was lowered more by the addition of both SiO₂ and Y₂O₃ than only Y₂O₃ to AIN ceramics.     

Superconductive gigahertz power supply for Josephson multichipsystems

To confirm a gigahertz frequency power supply in a multichip system, three-stage superconductive filter-type powering device (SFPD) chips and a resistive load chip for a 500 gate Josephson device were designed and fabricated. Low-loss capacitors required for this gigahertz operation were also developed. The authors tested the operation of the three-stage SFPDs in a multichip configuration with resistive load. A superconductive power supply with frequencies as high as 2.0 GHz was demonstrated in a multichip system for the first time. For a 2.0-GHz SFPD, normal operation was confirmed with a resonant frequency of 2.1 GHz, a resonant level of -31 dB, and a current gain of 22.4. The 0.1-Ω input impedance of the device system was successfully transformed to 49.9 Ω     

Direct analysis of lipids in single zooplankter individuals by matrix-assisted laser desorption/ionization mass spectrometry

A highly sensitive method to analyze the intact lipids in a single zooplankter individual at the level of a few tenths of a microgram was developed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with a direct sampling technique. The sampling procedure involved (1) putting a zooplankter individual sample onto the MALDI sample plate, (2) cutting the sample into a few pieces by means of tweezers, (3) depositing aliquots of matrix and cationization reagent solutions on the zooplankter sample, and (4) irradiating with a N2 laser to cause MALDI. By using this technique, the mass spectra of the single zooplankter samples showed a series of ions generated from phospholipids with 34 or 36 carbons in the acyl groups and neutral lipids such as triglycerides and diacylglyceryl ethers with 50-54 carbons in their acyl and alkenyl groups. Accordingly, this method enabled us to estimate the relative quantity between "structured lipids" (phospholipids) and "storage lipids" (neutral lipids) in an individual zooplankter, which should give us a good clue to elucidate the roles of each class of lipids in its growth.     

Effect of pedological characteristics on aqueous soil extraction recovery and tert-butyldimethylsilylation yield for gas chromatography-mass spectrometry of nerve gas hydrolysis products from soils

Detection and identification of alkyl methylphosphonate (RMPA) and methylphosphonate (MPA) are performed to verify the existence of nerve gases by gas chromatography-mass spectrometry (GC-MS) after tert-butyldimethylsilylation (TBDMS). However, it is sometimes difficult to detect RMPA and MPA in soils. This study examines the relationship between the pedological characteristics and the aqueous extraction recoveries and TBDMS derivatization yields of ethyl-, isopropyl- and pinacolyl methylphosphonate and MPA for 21 soil samples. The aqueous extraction recoveries were measured directly by capillary electrophoresis. Andosols showed low extraction recoveries, while Regosols and Fluvisols showed high recoveries. RMPA were extracted with higher recoveries than MPA from all soils. MPA could not be extracted from Andosols. Within the pedological characteristics, phosphate absorption coefficients showed a strong negative correlation with the extraction recoveries of all phosphonates. The levels of RMPA and MPA in aqueous soil extracts were also determined for eight soils by GC-MS after TBDMS. Compared to the aqueous extraction recoveries, the yields of TBDMS derivatives were low. Strong anion exchange led to a significant improvement in derivatization yields. The efficiencies of TBDMS derivatization were inversely correlated with the levels of alkaline earth metals extractable from soils when the three soils that possessed high total carbon were excluded.     

Development of a novel method for feeding a mixture of L-lactic acid and acetic acid in fed-batch culture of Ralstonia eutropha for poly-D-3-hydroxybutyrate production

Fermentative production of poly-D-3-hydroxybutyrate [P(3HB)] from a mixture of L-lactic acid and acetic acid by Ralstonia eutropha was investigated. For fed-batch culture with cell density, it is necessary to control the concentration of these organic acids in the culture medium below the inhibitory level for cell growth. Therefore, a novel feeding method, termed the computer-controlled pH-stat substrate feeding method, was developed using the rate of increase of the pH (pH-increasing rate) of the culture medium as an indicator for feed control. The pH-increasing rate, which was calculated every minute by a pH meter-linked computer, represented secondary information regarding substrate consumption by cells. When the pH-increasing rate decreased to 5% of the maximum increasing rate, acidic substrate solution was fed into the fermentor until the pH was reduced to 7.00. Using this feeding strategy, the cell concentration and PHA content obtained in 42 h were 75.0 g/l and 73.1% (w/w), respectively, resulting in a high P(3HB) productivity of 1.30 g/l.h.