Impacts of Irrigation with Reclaimed Water on Endophytic Bacteria in Chinese Cabbage in Urumqi City

[Objective] This study aimed to investigate the feasibility of agricultural irri- gation with reclaimed water in Urumqi City. [Method] Chinese cabbages were used as experimental materials and irrigated with control water, 50% reclaimed water and 100% reclaimed water, and then the number of endophytic bacteria in Chinese cab- bages was measured. [Result] Using 50% reclaimed water, the fresh weight of Chi- nese cabbage was improved by 68.94%; however, with the deepening internalization of exogenous microorganism internalization, the total number of endophytic bacteria and coliform flock in Chinese cabbages treated with 50% reclaimed water was sig- nificantly higher than the other two treatment groups （P〈0.05）. [Conclusion] Re- claimed water enhances both the weight of Chinese cabbage and the number of endophytic bacteria, which is unsuitable for irrigation of edible crops such as Chi- nese cabbage. Strengthening disinfection during the process of sewerage treatment could solve this problem.

Identification, Cloning and Characterization of Dictyoglomus Turgidum CelA, an Endoglucanase with Cellulase and Mannanase Activity

The discovery of new, highly active, biomass-degrading enzymes is important to the development of a sustainable biofuels industry. Dictyoglomus turgidum, a thermophilic, anaerobic eubacterium that ferments cellulose and produces ethanol and hydrogen, was chosen as a candidate to screen for novel enzymes. A novel thermostable endoglucanase, CelA, was identified and purified during screening of a shotgun library of Dic（yoglomus turgidum and subsequently subcloned and expressed in E. coli. The celA gene coding for a 312 amino acid protein showed low homology to proteins outside the genus Dictoglomi and lacked an apparent signal peptide. CelA had a broad substrate range, possessing both endo and exo activity on soluble and insoluble β-（1,4）-Iinked glucose-containing substrates as well as endo activity on soluble and insoluble β-（1,4）-linked mannose containing substrates. The specific activity of CelA was 226 U/rag using β-glucan, 66 U/mg using glucomannan, and 63 U/mg using CMC as substrates. The high temperature optimum of 70 ℃ to 80 ℃ and wide substrate range of the enzyme might make it an excellent tool for biomass degradation at high temperature.

Effects of fish meal and sodium butyrate on growth performance, gut development and glucagon-like peptide-2 secretion in weanling piglets

The experiment was conducted to study the effects of fish meal and sodium butyrate on growth performance, gut development and GLP-2 secretion in weanling piglets. A 2×2 factorial design was used with two fish meal levels （0, 5%）, and two sodium butyrate levels （0, 0.3%）. There were 4 dietary treatments： control diet （CD）; control diet supplemented with fish meal （CF）, control diet supplemented with sodium butyrate （CB）, control diet supplemented with fish meal and sodium butyrate （FB）. A total of 44 28-days-old Large White×Landrace weanling piglets were randomly allotted into 4 treatment averagely. The experiment period was 14 days. The results showed that sodium butyrate＇s addition increased average diary gain （ADG）, average diary feed intake （ADFI） and gain to feed intake ratio （G：F） of weanling piglets （all P〈0,05）, improved gut morphology （mucosa thickness, ratio of villous height to crypt depth） and sucrase activity, and fish meal＇s addition increased maltase activity （all P〈0.05）. Either sodium butyrate or fish meal addition decreased cecum colibacillus quantity, sodium butyrate increaded ratio of cecum lactobacilli to colibacillus （P〈0.05）. Consequently, diarrhea was reduced in diet supplemented with fish meal （P=-0.08） and diet supplemented with sodium butyrate （P=0.15） through 14 days of experiment, significant reduction of diarrhea rate was observed in diet supplemented with fish meal through the first 7 days （P〈0.05）. In addition, sodium butyrate and fish meal addition in diets tended to increase plasma GLP-2 concentration, however, GLP-2 concentration on the 4th day was consistently decreased in diet supplemented with fish meal relative to that on day 0 （P=0.08）. Overall, it could be concluded that both sodium butyrate and fish meal addition improve intestinal development and sodium butyrate addition significantly increase growth performance. The gut trophic response to sodium butyrate or may be in agreement with development. peptide GLP-2 increases in fish meal addition in diet and the alteration of intestinal

Improvement of the riboflavin production by engineering the precursor biosynthesis pathways in Escherichia coli

3,4-Dihydroxy-2-butanone 4-phosphate （DHBP） and GTP are the precursors for riboflavin biosynthesis. In this research, improving the precursor supply for riboflavin production was attempted by overexpressing ribB and engineering purine pathway in a riboflavin-producing Escherichia colt strain. Initially, ribB gene was overexpressed to increase the flux from ribulose 5-phosphate （Ru-5-P） to DHBP. Then ndk and grnk genes were overexpressed to enhance GTP supply. Subsequently, a R419L mutation was introduced into purA to reduce the flux from IMP to AMP. Finally, co-overexpression of mutant purF and prs genes further increased riboflavin production. The final strain RF18S produced 387.6 mg riboflavin · L-1 with a yield of 44.8 mg riboflavin per gram glucose in shake-flask fermentations. The final titer and yield were 72.2% and 55.6% higher than those of RF01S, respectively. It was concluded that simultaneously engineering the DHBP synthase and GTP biosynthetic pathway by rational metabolic engineering can efficiently boost riboflavin production in E. coll.

Theoretical shape analysis of tapered fibers using a movable large-zone furnace

To estimate the shape of tapered fibers using tapering machines with movable large-zone furnaces, a new calculation method is proposed based on the discrete deducing method and the principle of the volume conservation of the fiber materials. This method can estimate the tapering results, i.e., the shape of the tapered fibers, based on arbitrary moving parameters of the large-zone furnace and the fiber holders. The theoretical estimated results agree with the experimental measuring shape of the tapered fibers quite well.