No abstract

The objective of this study was to digest okara in high yield by food-processing enzymes. Autoclaving of okara was effective in increasing cellulase digestion for the primary cell wall, and the digestion was accelerated by the formation of single cells by stirring. Most of the residual okara after autoclaving and cellulase digestion was found to be the secondary cell walls compared with the cellulase-treated soybean single cells. The secondary cell wall was found to be composed of galacturonic acid, neutral sugars, and protein and was considered to be a complex of these compositions. Many cellulolytic and proteolytic enzymes could not digest the secondary cell wall; however, it was found that two pectinases could digest the secondary cell wall. A series of digestions resulted in yields of 83-85% from the raw okara, and the final residues were identified as oil body complexes in the soybean cells and fiber-like organ between the cells.

Single cells prepared from autoclaved soybeans and cellulase treatment of the cells were effective in digesting the cell walls of and extracting the oil from soybeans. The first cell wall of the soybean single cell was completely removed using cellulases; the thin and transparent second cell wall of the cell was swollen. Oil in the cell formed spherical or hemispherical oil drops, and oil leaking from the oil bodies was observed. The oil was almost retained within the second cell wall. Water-extractable substances were obtained at approximately >60% of the weight. Flotation of oil drops by centrifugation was easily done. Ambient n-hexane extraction was also possible; however, residual oil remained in the oil bodies. Protease or peptidase digested the structure of the oil bodies; however, separation of the oil and the hydrolysates was impossible. The oil from the oil bodies was obtained effectively (>85%) by pressing the single cells and/or cellulase-treated single cells.

An arabinoxylan arabinofuranohydrolase (AXS5) was purified from the culture filtrate of Penicillium chrysogenum 31B. A cDNA encoding AXS5 (axs5) was isolated by in vitro cloning using the N-terminal amino acid sequence of the native enzyme as a starting point. The deduced amino acid sequence of the axs5 gene has high similarities with those of arabinoxylan arabinofuranohydrolases of Aspergillus niger, Aspergillus tubingensis, and Aspergillus sojae. Module sequence analysis revealed that a "Glyco_hydro_62" was present at position 28-299 of AXS5. This is a family of α-L-arabinofuranosidases which are all members of glycoside hydrolase family 62. Recombinant AXS5 (rAXS5) expressed in Escherichia coli was highly active on arabinoxylan but not on branched sugar beet arabinan. (1)H-NMR analysis revealed that the rAXS5 cleaved arabinosyl side-chains linked to C-2 and C-3 of single-substituted xylose residues in arabinoxylan. Semi-quantitative RT-PCR analysis indicated that expression of the axs5 gene in P. chrysogenum 31B was strongly induced by adding D-xylose and arabinoxylan to the culture medium. Moreover, two binding sites of XlnR, a transcriptional activator that regulates the expression of the genes encoding xylanolytic enzymes, are present in the upstream region of the axs5 gene. These results suggest that AXS5 is involved in xylan degradation.

No abstract

A bacterium that assimilates 2,3-dichloro-l-propanol was isolated from soil by enrichment culture. The strain was identified as Pseudomonas sp. by the taxonomic studies. The strain converted 2,3-dichloro-l-propanol to 3-chloro-l,2-propanediol, releasing chloride ion. The conversion was stereospecific because the residual 2,3-dichloro-l-propanol and formed 3-chloro-l,2-propanediol gave optical rotation. The resting cells converted various halohydrins to the dehalogenated alcohols, and cell-free extracts had strong epoxyhydrolase activity. These results indicated that the strain assimilated 2,3-dichloro-l-propanol via 3-chloro-l,2-propanediol, glycidol, and glycerol. The possibility to manufacture optically active 2,3-dichloro-l-propanol is discussed. Large amounts of halogenated compounds have been widely used for solvents, starting materials for resins, polymers, agrochemicals, and Pharmaceuticals.1} Microorganisms capable of degradation of various halogenated compounds have been isolated and characterized.2) However, studies on interaction of low halogenated aliphatic compounds and microorganisms are rather limited. Brunner et al. isolated a bacterium using dichloromethane as the sole carbon source,3) and Stucki et al. have reported bacterial growth on 1,2-dichloro-ethane,4) but there is a little known in this field yet. Further study is needed to understand these interactions.

No abstract

In this review, the principles to detect flaws with uniform eddy currents were presented based on the shape and orientation of the excitation coils and detection coils of the probe. Techniques are applied to detect flaws like cracks, especially on the weld zone surface, of test pieces of non-magnetic and ferromagnetic materials, and have unique features which are immune to the effects of lift-off. In the technique of interest, almost all the probe models developed are the type with tangential rectangular excitation coils. The induction condition and the flaw signal for each probe were discussed based on the shape and orientation of the excitation coils and detection coils of the probe. Finally, the challenge of increasing sensitivity to detect flaws with a uniform eddy current was also presented.