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To reduce the unpleasant odor during 1-deoxynojirimycin (DNJ) production, the genes of leucine dehydrogenase (bcd) and phosphate butryltransferase (ptb) were deleted from Bacillus amyloliquefaciens HZ-12, and the concentrations of branched-chain short fatty acids (BCFAs) and DNJ were compared.Results
By knockout of the ptb gene, 1.01 g BCFAs kg?1 was produced from fermented soybean by HZ-12Δptb. This was a 56% decrease compared with that of HZ-12 (2.27 g BCFAs kg?1). Moreover, no significant difference was found in the DNJ concentration (0.7 g kg?1). After further deletion of the bcd gene from HZ-12Δptb, no BCFAs was detected in fermented soybeans with HZ-12ΔptbΔbcd, while the DNJ yield decreased by 26% compared with HZ-12.Conclusions
HZ-12Δptb had decreased BCFAs formation but also maintained the stable DNJ yield, which contributed to producing DNJ-rich products with decreased unpleasant smell.4.
Xu L Luo M Yang L Wei X Lin X Liu H 《Journal of industrial microbiology & biotechnology》2011,38(10):1709-1718
Cr(VI) was efficiently reduced to Cr(III) by Pannonibacter phragmitetus LSSE-09 encapsulated in liquid-core alginate–carboxymethyl cellulose capsules under alkaline conditions. Taking into account
the physical properties of the capsules, the activity of encapsulated cells, and total Cr(III) concentration in the supernatant,
optimal conditions (0.5% w/v sodium alginate; 2% w/v sodium carboxymethyl cellulose; 0.1 M CaCl2; 30-min gelation time) for LSSE-09 encapsulation were determined. At optimal conditions, a relatively high reduction rate
of 4.20 mg g(dry weight)−1 min−1 was obtained. Total Cr(III) concentration in the supernatant was significantly decreased after reduction, because 63.7% of
the formed soluble organo-Cr(III) compounds compared with those of free cells were captured by the relatively smaller porous
structure of alginate capsules. The optimal pH value (9.0) for Cr(VI) reduction was not changed after encapsulation. In addition,
encapsulated LSSE-09 showed no appreciable loss in activity after eight repeated cycles at 37°C, and 85.7% of its initial
activity remained after 35-day storage at 4°C. The results suggest that encapsulated LSSE-09 in alginate–carboxymethyl cellulose
capsules has potential biotechnological applications for the detoxification of Cr(VI)-contaminated wastewater. 相似文献
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A 700 ml membrane-aerated, stirred glass reactor equipped with four vertical baffles was constructed. Biodesulfurization of
model oil (n-dodecane containing dibenzothiophene—DBT) and hydrodesulfurized diesel was carried out using Pseudomonas delafieldii strain R-8. Microbubble aeration gave an activity of 1.3 mg DBT removed g−1 h−1 and 277 μg sulfur g−1 h−1 for model oil and hydrodesulfurized diesel, respectively. These values were 1.9- and 1.6-times higher than using a traditional
bubble aeration process. This is a promising method for the biodesulfurization of petroleum feedstocks. 相似文献
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Yangtse W Zhou Y Lei Y Qiu Y Wei X Ji Z Qi G Yong Y Chen L Chen S 《Journal of bacteriology》2012,194(13):3561-3562
Bacillus licheniformis is an important bacterium that has been used extensively for large-scale industrial production of exoenzymes and peptide antibiotics. B. licheniformis WX-02 produces poly-gamma-glutamate increasingly when fermented under stress conditions. Here its genome sequence (4,270,104 bp, with G+C content of 46.06%), which comprises a circular chromosome, is announced. 相似文献
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Silver nanoparticles (AgNPs) were obtained by solar irradiation of cell-free extracts of Bacillus amyloliquefaciens and AgNO3. Light intensity, extract concentration, and NaCl addition influenced the synthesis of AgNPs. Under optimized conditions (solar intensity 70,000 lx, extract concentration 3 mg/mL, and NaCl content 2 mM), 98.23 ± 0.06% of the Ag+ (1 mM) was reduced to AgNPs within 80 min, and the ζ-potential of AgNPs reached −70.84 ± 0.66 mV. TEM (Transmission electron microscopy) and XRD (X-ray diffraction) analysis confirmed that circular and triangular crystalline AgNPs with mean diameter of 14.6 nm were synthesized. Since heat-inactivated extracts also mediated the formation of AgNPs, enzymatic reactions are likely not involved in AgNPs formation. A high absolute ζ-potential value of the AgNPs, possibly caused by interaction with proteins likely explains the high stability of AgNPs suspensions. AgNPs showed antimicrobial activity against Bacillus subtilis and Escherichia coli in liquid and solid medium. 相似文献
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Mi Le Qin Dandan Cheng Jie Wang Dan Li Sha Wei Xuetuan 《Journal of industrial microbiology & biotechnology》2017,44(3):419-430
Journal of Industrial Microbiology & Biotechnology - Two engineered Escherichia coli strains, DQ101 (MG1655 fadD −)/pDQTES and DQ101 (MG1655 fadD −)/pDQTESZ were constructed to... 相似文献
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