For lindane degradation, a cell suspension of Clostridium rectum strain S-17 demands the addition of substrates such as leucine, alanine, pyruvate, a leucine-proline mixture, and molecular hydrogen. In the presence of leucine-proline mixture, lindane decomposed in parallel with isovaleric acid formation, and both lindane degradation and isovaleric acid formation were inhibited by monoiodoacetic acid, suggesting a close relation between lindane degradation and the Stickland reaction. Lindane was degraded by cell-free extracts of C. rectum in the presence of dithiothreitol (DTT). Radiogaschromatograms of n-hexane soluble metabolites from [14C] lindane showed the presence of monochlorobenzene and gamma-3,4,5,6-tetrachlorocyclohexene. Leucine, NADH, and NADPH were somewhat less active than DTT for lindane degradation in cell-free extracts. Reductive dechlorination seemed the major route of lindane degradation in cell-free extracts as well as in the intact cells of C. rectum.

Cereal Chem. 82(2):228-232The effects of autoclave and oven treatments on the gelatinization of rice flour and on the rheological characteristics of its pastes were studied by differential scanning calorimetry (DSC), rapid viscoanalysis (RVA), and rotational viscometry. Flours from autoclave-treated rice (ATR) and oven-treated rice (OTR) were prepared, respectively, by heating at 120°C for 60 min and 160°C for 60 min followed by drying (ATR sample), and grinding at 2.2-12.9% moisture content. The rice flour dispersions were adjusted between pH 6.3 and 2.8 using 0.2M citrate buffer. The retort processing of rice flour in water pastes were done at 120°C for 20 min either once or twice. The gelatinization peak temperature (PT and T o ) and the peak temperature corresponding to the amylose-lipid complexes (T p3 ) of ATR increased at pH 6.3 and 2.8 compared with OTR and UTR flour. This indicates that the internal structures of the starch granules in ATR became more stable to heat and acid, even though the damaged starch content of ATR was 23% compared with 16 and 7%, respectively, for untreated rice flour (UTR) and OTR. The OTR flour pastes showed a gellike behavior at pH 4.5 after retort processing in water at 120°C for 20 min; however, the ATR mixture behaved more like a liquid paste. Decreases in the reducing sugar content of OTR and ATR pastes suggested that enzymes in the heat-treated rice were denatured, which retarded the hydrolysis of glucose chains and the rupture of starch granules during pasting.

A BHC decomposer isolated from a paddy field soil of Shiga prefecture was identified to be Clostridium rectum. The most dominant degradation intermediate from T-BHC was identified to be ƒÁ-3,4,5,6-tetrachlorocyclohexene (ƒÁ-TCCH) by gas chromatography-mass spectrometry. Degradation of r-BHC took place rapidly in the early growth phase of C. rectum, but was remarkably reduced in the resting state, e.g., spore-formed cell or washed cell sus

Clostridium rectum strain S-17 converts gamma-1,2,3,4,5,6-hexachlorocyclohexane (HCH) related compounds to chlorobenzenes. The metabolites from gamma-1,2,3,4,5,6-hexachlorocyclohexene and gamma-1,3,4,5,6-pentachlorocyclohexene are identified as 1,2,4-trichlorobenzene and 1,4-dichlorobenzene, respectively. ATP synthesis, converting these chlorinated compounds, is observed in the cell suspension of C.rectum as indicated by luciferase-luciferin reaction and phosphorylation of 32P-labeled phosphate. These observation lead to the conclusion that HCH and related compounds serve as artificial electron acceptors of the Stickland reaction, and therefore, the reductive dechlorination is associated with ATP synthesis.

Chemical properties and textures of cooked rice prepared with aged rice grains were investigated and compared with those of cooked rice prepared with new rice grains. Di#erences in stickiness/hardness (S/ H) ratios between new rice and aged rice were eliminated by the removal of the external layer of rice grains. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the proteins of the external layer in aged rice grains were oxidized to a greater extent than those of new rice grains. Addition of a reducing agent to cooking water increased the S/H ratio of aged rice to approximately that of new rice. The reducing agent cleaves the disulfide linkages of the proteins. Therefore, textural changes in aged rice were inferred to be due to oxidation of proteins in the external layers of grains.