Gas-phase pyrolysis of methyl glucosides and levoglucosan

Levoglucosan, the major intermediate in cellulose pyrolysis, is stable up to around 500?°C in the gas phase. To study whether this stability is a characteristic property of levoglucosan, the gas-phase reactivity was compared with those of methyl α- and β-glucosides at 200–500?°C (residence time 1.2–2.0 s). The methyl glucosides decomposed even at 200 and 300?°C to form levoglucosan exclusively. This selective transglycosylation was explained with a concerted mechanism. Fragmentation of the glucosides forming C1–C3 carbonyl compounds started at 400?°C, a temperature lower than that of levoglucosan (500?°C). Thus, levoglucosan is a special carbohydrate that is stable in the gas phase, and the stability is explained by the steric hindrance of the bicyclic ring. Formation of the anhydrofuranose isomer and furans was negligible from the gas-phase pyrolysis of these compounds, suggesting that these are produced mainly from the molten-phase pyrolysis. These results show the roles of gas- and molten-phase reactions during carbohydrate pyrolysis, providing insights for upgrading biomass pyrolysis/gasification processes.     

Changes in proline-14C metabolism in barley seedlings germinating at low temperature

Changes in the metabolic pattern of proline-¹⁴C were examined in barley seedlings germinated at the low temperature of 2°C (LT) and compared with those germinated at 25°C (HT). In the LT shoots. proline-¹⁴C incorporation was higher in the cationic fraction and lower in the acid-neutral fraction than that of HT, respectively. More proline-¹⁴C of LT was converted to other amino acids, especially to acidic amino acids in free amino acid state, than was the HT proline-¹⁴C which had a comparatively wide distribution.

In the LT protein fractions. more proline-¹⁴C was incorporated into the cytoplasmic protein than into the cell wall protein. On the contrary, the radioactivity of the lIT cell wall increased more distinctively. proline-¹⁴C in the two proteins of LT was a little less converted to other amino acids than in those of HT. A little higher radioactivity was found in the aspartate and glutamate of the LT protein hydrolysates. The hydroxyproline which is closely related with proline had a little lower level of radioactivity in the LT cell wall.     

Impact of fumigation with metam sodium upon soil microbial community structure in two Japanese soils

The effects of fumigation with sodium methyl dithiocarbamate (metam sodium) on the microbial community structure and function in 2 soils were investigated using a variety of techniques. In both soils ca. 50% and 90% of the populations of total and culturable bacteria, respectively, were killed by fumigation, with recovery to levels prevailing in control soils 26 d after cessation of fumigation. The size of the ammonium and nitrite oxidiser populations was reduced by up to 4 orders of magnitude by fumigation, with the latter showing a slight recovery 105 d later. There were substantial changes in the C-utilisation (Biolog GN) profiles in the fumigated soils even 105 d later. The number and pattern of amplified 16S ribosomal DNA restriction analysis (ARDRA) fragments was changed by fumigation, and there was a shift in the %G+C profile toward a greater proportion of lower %G+C classes in treated soils. It appeared that DNA released from killed cells remained for some time after fumigation, and masked the apparent community DNA profiles. This study demonstrates that the effects of fumigation on the soil microbial community structure and function were pronounced and for some parameters very persistent. However, the effects on broad-scale properties such as total or culturable bacterial numbers were less enduring.     

At5g54160 gene encodes <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> 5-hydroxyconiferaldehyde <Emphasis Type="Italic">O</Emphasis>-methyltransferase

The function of an Arabidopsis thaliana gene, At5g54160 annotated as a caffeic acid O-methyltransferase CAOMT gene was characterized. The recombinant enzyme of this gene (AtOMT1) catalyzed the O-methylation of phenylpropanoid and flavonoid substrates. The specificity constants (k _cat/K _m) for 5-hydroxyconiferaldehyde (5-HCAld) and quercetin were both 0.11 μM⁻¹·min⁻¹. On the other hand, lignins of At5g54160-knockout Arabidopsis mutants lacked syringyl units. In addition, we showed that the gene silencing also resulted in significant accumulation of caffeyl alcohol (CaAlc). These results strongly suggested that At5g54160 gene is involved in syringyl lignin synthesis for the methylation of both 5-hydroxyconiferaldehyde and 3,4-dihydroxyphenyl compound(s). Part of this work was presented at the Annual Meeting of Japan Society for Bioscience, Biotechnology, and Agrochemistry, March 24–27, 2007     

Comparison of rDNA-ITS Sequences between Potato and Tobacco Strains in <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> AG-3

Genetic diversity among 51 isolates of Rhizoctonia solani AG-3, representing potato and tobacco populations, was inferred from the sequences of the internal transcribed spacer (ITS) and 5.8S ribosomal RNA (rRNA) gene. The 5.8S rDNA sequence was completely conserved not only in AG-3, but across all the AG isolates examined, whereas the rDNA-ITS sequence was found to be variable among the isolates. The nucleotide sequence similarity in the ITS 1 region was high (96-100%) for isolates within each of the two populations, but was 91-92% for isolates from different populations. The AG-3 isolates had 56 to 91% sequence similarities in the ITS 1 region with R. solani isolates of the other AGs. Phylogenetic analysis based on the ITS-5.8S rDNA sequence data indicated that the different populations in AG-3 are distantly related to each other. Genetic divergence between the two populations was also supported by the results of DNA-DNA hybridization studies. This study suggests that AG-3 consists of two genetically isolated groups corresponding to separate subgroups: AG-3 PT (potato type) and AG-3 TB (tobacco type). Specific primer sets for the detection of the two AG-3 subgroups were developed from the aligned rDNA-ITS sequences. Received 22 April 1999/ Accepted in revised form 2 July 1999     

Studies on the effect of humic acid on availability of phosphorus

It is believed that some organic compounds form complexes with iron and aluminum and prevent the fixation of phosphate applied to soils.     

First report of white leaf rot on Chinese chives caused by Rhizoctonia solani AG-2-1

Delayed sprouting and white rot of leaf tips were found on Chinese chives in a greenhouse in Hokkaido, Japan, in the spring of 2006 and 2007. The causal fungus was identified as Rhizoctonia solani anastomosis group (AG)-2-1 and discriminated from the leaf rot pathogen R. solani AG-4 HG-I in terms of pathogenicity. Symptoms and the time of year that the disease occurs also apparently differ for the two pathogens. This is the first report of white leaf rot on Chinese chive caused by R. solani AG-2-1.     

The first report of tomato foot rot caused by <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> AG-3 PT and AG-2-Nt and its host range and molecular characterization

Foot rot of mature tomato plants was found in four cities of Hokkaido, Japan, from 2004 to 2007. Six of eight isolates obtained from damaged tissues were identified as Rhizoctonia solani anastomosis group (AG)-3, and the remaining two isolates belonged to AG-2-1. We compared these isolates with nine reference isolates including the different subgroups in AG-3 (PT, TB and TM) and AG-2-Nt (pathogen of tobacco leaf spot) within AG-2-1 in terms of pathogenicity to tomato, tobacco and potato. All eight isolates caused foot rot on tomato. The six AG-3 isolates caused stem rot on young potato plants. While, all reference isolates of AG-3 PT causing stem rot of young potato plants incited foot rot on tomato. The two AG-2-1 isolates and an AG-2-Nt reference isolate caused severe leaf spot on tobacco leaves. The sequences of rDNA- ITS region and rDNA-IGS1 region of the AG-3 isolates showed high similarity to that of AG-3 PT isolates. Phylogenetic tree based on ITS and IGS1 regions of rDNA indicated that the AG-2-1 isolates from tomato formed a single clade with AG-2-Nt isolates and that they were separate from Japanese AG-2-1 isolates (culture type II). Pathogenicity tests and DNA sequence evaluation of the causal fungi revealed that the present isolates of AG-3 and AG-2-1 belonged to AG-3 PT and AG-2-Nt, respectively. This is the first report of tomato foot rot caused by R. solani in Japan.     

Process integration of ethanol production from Japanese beech as treated with hot-compressed water followed by enzymatic treatment

Ethanol was produced from the hydrolysate collected as a water-soluble (WS) portion and a residue after hot-compressed water (HCW) treatment of Japanese beech with and without fractionation. Simultaneous saccharification with β-xylosidase and isomerization with xylose isomerase followed by fermentation with Saccharomyces cerevisiae were applied to the WS portion; simultaneous saccharification with cellulase and fermentation with S. cerevisiae was applied to the residue. Integration of the processes for the WS portion and the residue was investigated to improve the conversion efficiency throughout the whole process. The ethanol yield in the integrated process without fractionation was comparable with that for the process with fractionation. Ethanol yields were improved for both of the processes by modifying the operation pattern in which cellulase was added prior to fermentation of the residue.     

New lignan, isoactifolin, fromChamaecyparis obtusa cv. Breviramea

A new lignan isoactifolin was isolated from young shoots (with leaves) ofChamaecyparis obtusa cv. Breviramea. The structure of the compound was determined based on spectroscopic evidence.Parts of this report were presented at the 44th lignin symposium, Gifu, October 1999