A bacteria strain for the degradation of hydrolyzed polyacrylamide （HPAM） was isolated from a curing pot in HPAM distribution station of Daqing Oilfield using Hungate anaerobic technique. The isolate was investigate...A bacteria strain for the degradation of hydrolyzed polyacrylamide （HPAM） was isolated from a curing pot in HPAM distribution station of Daqing Oilfield using Hungate anaerobic technique. The isolate was investigated from morphological, physiological, biochemical and molecular characterization. It is a Gram-negative, shortbacillus, non-spore-forming anaerobic bacteria with an optimum growth at 8.0 pH at 40℃. It can reduce sulfate to I-I2S. Alignment of 16S ribosomal DNA and 16S-23S ribosomal DNA intergenic spacer sequences suggests that this isolate is closely related to the Enterobacter cloacae. The isolate is identified as a new strain belonging to Enterobacter genus, temporarily named as Enterobacter cloacae 17. Analysis results of infrared spectroscopy （IR） show that the bacteria can use HPAM as the only carbon source, change the structure of HPAM polymer surface, and realize the hydrolysis of amide to carboxyl group by hydrolysis mechanism. It can degrade the side chain and change some functional groups, which obviously decreases the viscosity. GC-MS analysis indicates that the determined low-molecular weight degradation products of HPAM are polyacrylamide fragments with duplet bond, epoxy as well as carbonyl group, but most of them are acrylamide oligomer derivatives.展开更多
Salmonella can invade non-phagocytic cells through its type Ⅲ secretion system （T3SS-1）, which induces a Trigger entry process. This study showed that Salmonella enterica, subspecies enterica serovar Enteritidis ca...Salmonella can invade non-phagocytic cells through its type Ⅲ secretion system （T3SS-1）, which induces a Trigger entry process. This study showed that Salmonella enterica, subspecies enterica serovar Enteritidis can also invade cells via the Rck outer membrane protein. Rck was necessary and sufficient to enable non-invasive E. coli and Rckcoated beads to adhere to and invade different cells. Internalization analysis of latex beads coated with different Rck peptides showed that the peptide containing amino acids 140-150 promoted adhesion, whereas amino acids between 150 and 159 modulated invasion. Expression of dominant-negative derivatives and use of specific inhibitors demonstrated the crucial role of small GTPases Racl and Cdc42 in activating the Arp2/3 complex to trigger formation of actin-rich accumulation, leading to Rck-dependent internalization. Finally, scanning and transmission electron microscopy with Rck-coated beads and E. coli expressing Rck revealed microvillus-like extensions that formed a Zipper-like structure, engulfing the adherent beads and bacteria. Overall, our results provide new insights into the Salmonella T3SS-independent invasion mechanisms and strongly suggest that Rck induces a Zipper-like entry mechanism. Consequently, Salmonella seems to be the first bacterium found to be able to induce both Zipper and Trigger mechanisms to invade host cells.展开更多
This report details an assessment of an integrated low-technology phytodisinfectant-sand filter drum for household water and waste water treatment for sub-Saharan Africa, using bacterial culture tests, total solids, a...This report details an assessment of an integrated low-technology phytodisinfectant-sand filter drum for household water and waste water treatment for sub-Saharan Africa, using bacterial culture tests, total solids, and turbidity amongst others is presented. A hundred litres of very dirty/turbid water （130.3 NTU） was pretreated with 100 seeds of Moringa olieferaand further filtered through a sand filter drum （120 litres carrying capacity） made of fine, coarse sand, charcoal and gravel. The mean total aerobic mesophilic bacterial counts, E coli, coliform, pseudomonas, and yeast counts, as well as turbidity of untreated water drastically reduced to wealth health organization acceptable standards for potable water. The results indicated that the mean values of the same parameters for sand filtered pond water alone was significantly lower than the corresponding mean values obtained for Moringa treated pond water. The findings from this study suggest strongly that an integral of two natural water purification technologies （phytodisinfectant-sand filter drum） could be applied for the treatment of all types of contaminated water rendering it free from pathogens for potable and non potable uses.展开更多
基金Sponsored by the Country from Branch Fund Significant International Cooperation Item(Grant No.50521140075)
文摘A bacteria strain for the degradation of hydrolyzed polyacrylamide （HPAM） was isolated from a curing pot in HPAM distribution station of Daqing Oilfield using Hungate anaerobic technique. The isolate was investigated from morphological, physiological, biochemical and molecular characterization. It is a Gram-negative, shortbacillus, non-spore-forming anaerobic bacteria with an optimum growth at 8.0 pH at 40℃. It can reduce sulfate to I-I2S. Alignment of 16S ribosomal DNA and 16S-23S ribosomal DNA intergenic spacer sequences suggests that this isolate is closely related to the Enterobacter cloacae. The isolate is identified as a new strain belonging to Enterobacter genus, temporarily named as Enterobacter cloacae 17. Analysis results of infrared spectroscopy （IR） show that the bacteria can use HPAM as the only carbon source, change the structure of HPAM polymer surface, and realize the hydrolysis of amide to carboxyl group by hydrolysis mechanism. It can degrade the side chain and change some functional groups, which obviously decreases the viscosity. GC-MS analysis indicates that the determined low-molecular weight degradation products of HPAM are polyacrylamide fragments with duplet bond, epoxy as well as carbonyl group, but most of them are acrylamide oligomer derivatives.
文摘Salmonella can invade non-phagocytic cells through its type Ⅲ secretion system （T3SS-1）, which induces a Trigger entry process. This study showed that Salmonella enterica, subspecies enterica serovar Enteritidis can also invade cells via the Rck outer membrane protein. Rck was necessary and sufficient to enable non-invasive E. coli and Rckcoated beads to adhere to and invade different cells. Internalization analysis of latex beads coated with different Rck peptides showed that the peptide containing amino acids 140-150 promoted adhesion, whereas amino acids between 150 and 159 modulated invasion. Expression of dominant-negative derivatives and use of specific inhibitors demonstrated the crucial role of small GTPases Racl and Cdc42 in activating the Arp2/3 complex to trigger formation of actin-rich accumulation, leading to Rck-dependent internalization. Finally, scanning and transmission electron microscopy with Rck-coated beads and E. coli expressing Rck revealed microvillus-like extensions that formed a Zipper-like structure, engulfing the adherent beads and bacteria. Overall, our results provide new insights into the Salmonella T3SS-independent invasion mechanisms and strongly suggest that Rck induces a Zipper-like entry mechanism. Consequently, Salmonella seems to be the first bacterium found to be able to induce both Zipper and Trigger mechanisms to invade host cells.
文摘This report details an assessment of an integrated low-technology phytodisinfectant-sand filter drum for household water and waste water treatment for sub-Saharan Africa, using bacterial culture tests, total solids, and turbidity amongst others is presented. A hundred litres of very dirty/turbid water （130.3 NTU） was pretreated with 100 seeds of Moringa olieferaand further filtered through a sand filter drum （120 litres carrying capacity） made of fine, coarse sand, charcoal and gravel. The mean total aerobic mesophilic bacterial counts, E coli, coliform, pseudomonas, and yeast counts, as well as turbidity of untreated water drastically reduced to wealth health organization acceptable standards for potable water. The results indicated that the mean values of the same parameters for sand filtered pond water alone was significantly lower than the corresponding mean values obtained for Moringa treated pond water. The findings from this study suggest strongly that an integral of two natural water purification technologies （phytodisinfectant-sand filter drum） could be applied for the treatment of all types of contaminated water rendering it free from pathogens for potable and non potable uses.
