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Cellulosilyticum ruminicola H1 is a newly described bacterium isolated from yak (Bos grunniens) rumen and is characterized by its ability to grow on a variety of hemicelluloses and degrade cellulosic materials. In this study, we performed the whole-genome sequencing of C. ruminicola H1 and observed a comprehensive set of genes encoding the enzymes essential for hydrolyzing plant cell wall. The corresponding enzymatic activities were also determined in strain H1; these included endoglucanases, cellobiohydrolases, xylanases, mannanase, pectinases, and feruloyl esterases and acetyl esterases to break the interbridge cross-link, as well as the enzymes that degrade the glycosidic bonds. This bacterium appears to produce polymer hydrolases that act on both soluble and crystal celluloses. Approximately half of the cellulytic activities, including cellobiohydrolase (50%), feruloyl esterase (45%), and one third of xylanase (31%) and endoglucanase (36%) activities were bound to cellulosic fibers. However, only a minority of mannase (6.78%) and pectinase (1.76%) activities were fiber associated. Strain H1 seems to degrade the plant-derived polysaccharides by producing individual fibrolytic enzymes, whereas the majority of polysaccharide hydrolases contain carbohydrate-binding module. Cellulosome or cellulosomelike protein complex was never isolated from this bacterium. Thus, the fibrolytic enzyme production of strain H1 may represent a different strategy in cellulase organization used by most of other ruminal microbes, but it applies the fungal mode of cellulose production.The ruminant rumens are long believed to be the anaerobic environments efficiently degrading the plant-derived polysaccharides, which is attributed to the inhabited abundant rumen microorganisms. They implement the fibrolytic degradation by the combination of the enzymes comprising of cellulases, hemicellulases, and to a lesser extent pectinases and ligninases (12). The rumen bacteria are outnumbered of the other rumen microbes; however, only a few of cellulolytic bacteria have been isolated from rumens. Ruminococcus flavefaciens, Ruminococcus albus, and Fibrobacter succinogenes are considered to be the most important cellulose-degrading bacteria in the rumen (18), and they produce a set of cellulolytic enzymes, including endoglucanases, exoglucanases (generally cellobiohydrolase), and ␤-glucosidases, as well as hemicellulases. In addition, the predominant ruminal hemicellulose-digesting bacteria such as Butyrivibrio fibrisolvens and Prevotella ruminicola lack the ability to digest cellulose but degrade xylan and pectin and utilize the degraded soluble sugars as substrates (10,14). Although the robust cellulolytic species F. succinogenes degrades xylan, it cannot use the pentose product as a carbon source (24). Culture-independent approaches indicate that the three cellulolytic bacterial species represent only ϳ2% of the ruminal bacterial 16S rRNA (43). Therefore, many varieties of rumen microbes remain uncultured (2). In recent years, rumen metagenomics...

Proteiniclasticum ruminis gen. nov., sp. nov., a strictly anaerobic proteolytic bacterium isolated from yak rumen Two strictly anaerobic, proteolytic bacterial strains, designated strain D3RC-2 T and D3RC-3r, were isolated from a cellulose-degrading mixed culture enriched from yak rumen content. The strains were Gram-stain negative and non-spore-forming with cell sizes of 0.5-0.8¾0.6-2.0 mm. The temperature range for growth was 24-46 6C (optimum 38-39 6C) and the pH range was between 5.6 and 8.7 (optimum 7.0-7.3). Both strains used soya peptone, tryptone, Lphenylalanine, L-leucine, L-methionine, L-serine, L-valine, L-threonine and L-histidine as carbon and nitrogen sources, but did not use any of the saccharides tested. The major fermentation products from PY medium were acetate, propionate and iso-butyrate. The DNA G+C contents of strains D3RC-2 T and D3RC-3r were 41.0±0.1 mol% and 41.3±0.1 mol% (HPLC), respectively. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the two strains represented a new phyletic sublineage within the family Clostridiaceae, with ,93.8 % 16S rRNA gene sequence similarity to recognized species. On the basis of the phenotypic, genotypic and physiological evidence, strains D3RC-2 T and D3RC-3r are proposed as representing a novel species of a new genus, for which the name Proteiniclasticum ruminis gen. nov., sp. nov. is proposed. The type strain of the type species is D3RC-2 T (5AS 1.5057 T 5JCM 14817 T ).Yak (Bos grunniens) are ruminants that feed exclusively on grasses and live mainly on the Qinghai-Tibetan Plateau, China, at a height of 3000 m above sea level. Previous studies based on an uncultured approach in our laboratory have indicated that more than half of the microbes in yak rumen belong to as yet uncultured groups. The strains all showed ,90 % 16S rRNA gene sequence similarity levels with recognized species and 10.8 % of the sequences retrieved were related to known rumen fibrolytic bacteria. By using filter paper as the sole carbon source, a cellulose-degrading mixed culture enriched from yak rumen content was obtained. A few fibrolytic and nonfibrolytic bacterial strains were isolated from the mixed culture. In this paper, two proteolytic bacterial strains isolated from yak rumen are described.Strains D3RC-2 T and D3RC-3r were isolated from a fibrolytic mixed culture enriched from yak rumen. The yak rumen content was inoculated into a modified basal medium (Bryant & Burkey, 1953;Hungate, 1966) with filter paper as the sole carbon source and grown under a gas phase of N 2 /CO 2 (80 : 20). A fibrolytic mixed culture was obtained by subculturing the enrichment in the same medium. By means of serial dilution in peptone-yeast extract-glucose medium (PYG, Holdeman et al., 1977) and the Hungate roll-tube technique (Hungate, 1969), single colonies were picked and transferred to the same medium. The roll-tube procedure was repeated several times before strains D3RC-2 T and D3RC-3r were obtained. The purity of the isolates was examined by light microscopy. All i...

Herein, we present a comparative study of experimental and theoretical results on the inhibition of mild steel corrosion in hydrochloric acid using two novel pyridine Schiff base derivatives.

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Poly acrylic acid (PAA) and polyepoxysuccinic acid (PESA) were investigated as scale inhibitors. The static experiments certified that PAA was superior to PESA for the inhibition of calcium carbonate in the low molecular weight range. The X-ray diffraction patterns suggest that the effect of PAA on the calcite (1 0 4) and (1 1 0) crystal plane was more obvious. Scanning electron microscopy was used to study the surface morphology of the depositions, which indicated that the addition of scale inhibitors could disturb the normal growth of CaCO3 scale. The transmittance ratio of ferric oxide demonstrated that PAA had a better dispersion performance than PESA. The molecular dynamics simulation and quantum calculation were selected to theoretically explore the mechanism and structure of scale inhibitors, indicating that the interaction of PAA with (1 0 4) and (1 1 0) calcite crystal surfaces was stronger than PESA. In addition, the results indicated that the PAA with negative charge more easily adsorbed free Ca2+ in the aqueous phase. Based on these observations, PAA exhibited better scale inhibition and dispersion effects than PESA in the case of low molecular weight.

The aim of this study was to investigate the evolution of some physicochemical properties of fermented Zaopei throughout the fermentation. For each layer of Zaopei, the temperature gradually increased to a maximum after about 2 weeks, and then remained stable for about 15 days before it began to decrease; acidity tended to increase during the entire fermentation, while the starch content decreased throughout the fermentation. The reducing sugar content for all layers reached a maximum after one week and decreased afterwards. Ethanol accumulated with time and reached a peak after 5 weeks for each layer, then tended to decrease but rose again slightly after 7 weeks. The moisture content in the top and middle layers increased gradually and reached saturation after 5 weeks, then remained almost unchanged, while the moisture of the bottom layer increased throughout the fermentation. The ethyl caproate, ethyl acetate and ethyl butyrate content of all layers remained almost constant for the first 2 weeks, then increased gradually and reached a maximum after 6 weeks, and subsequently declined slightly. The ethyl lactate of each layer increased throughout the fermentation. The caproic acid, acetic acid, butyric acid and lactic acid in all of the layers reached the highest level on the sixth week, followed by a continuous decrease until week 8, thereafter followed by a slight increase in trend. Additionally, the qualities of the raw liquor distilled from the different layers of Zaopei were investigated and the results demonstrated that the bottom layer possessed the best quality.

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