Biomedical subjects

Jiti Zhou

Publications and source records attributed to Jiti Zhou.

6 recordsLinked to original sources

PubMed2006

Biocalalyst effects of immobilized anthraquinone on the anaerobic reduction of azo dyes by the salt-tolerant bacteria.

The accelerating effect of dissolved redox mediators has been studied in details in the bio-decolorization processes, but there are little literatures about the non-dissolved redox mediators. Here we describe the accelerating effect of anthraquinone as a redox mediator in the bio-decolorization. Decolorization of azo dyes was carried out experimentally using the salt-tolerant bacteria under immobilized anthraquinone and high salt conditions. Anthraquinone as a redox mediator was able to increase the decolorization rate of azo dyes, and was immobilized by entrapment in calcium alginate (CA), Polyvinyl alcohol (PVA)-H(3)BO(3) and agar, respectively. The effects of various operating conditions such as anthraquinone bead number, dissolved oxygen, temperature and pH on microbial decolorization were investigated experimentally. The reusability of the anthraquinone immobilization beads was evaluated with repeated-batch decolorization experiments. After four repeated experiments, the decolorization rate of CA immobilized anthraquinone retained over 90% of their original value. The experiments explored a great improvement of the redox mediator application and the new bio-treatment concept.

Alginates↗

PubMed2006

Bioaugmentation of bromoamine acid degradation with Sphingomonas xenophaga QYY and DNA fingerprint analysis of augmented systems.

One high-effective bromoamine acid (1-amino-4-bromoanthraquinone-2-sulfonic acid, BAA) degrading strain was isolated previously with the ability to use BAA as sole source of carbon and nitrogen. It was identified as Sphingomonas xenophaga QYY by 16S rDNA sequence analysis and physio-biochemical tests. In this study, bioaugmentation of BAA degradation with suspended and immobilized cells of strain QYY was investigated. The optimal degradation conditions were as follows: temperature 30 degrees C, pH 6.0-7.0, 150 rev min(-1) and the immobilized cells maintained degradation activity to BAA after 60 days storage at 4 degrees C. The structure of BAA was evidently changed according to the analysis of total organic carbon removal of BAA (about 50%) and the UV-VIS spectra changes during the biodegradation. Bioaugmented systems exhibited stronger abilities degrading BAA than the non-bioaugmented control ones. And microbial community dynamics of augmented systems was revealed by amplified ribosomal DNA restriction analysis (ARDRA), a modern DNA fingerprint technique. The results indicated that the microbial community dynamics was substantially changed throughout the augmentation process. This study suggests that it is feasible and potentially useful to enhance BAA degradation using bioaugmentation with the immobilized cells of BAA-degrading bacterium.

Anthraquinones↗

PubMed2005

Correlation of anaerobic biodegradability and the electrochemical characteristic of azo dyes.

Some experiments were conducted to study some electrochemical factors affecting the bacterial reduction (cleavage) of azo dyes, knowledge of which will be useful in the wastewater treatments of azo dyes. A common mixed culture was used as a test organism and the reductions of Acid Yellow 4, 11, 17 and Acid Yellow BIS were studied. It was found that the azo dyes were reduced at different rates, which could be correlated with the reduction potential of the azo compounds in cyclic voltammetric experiments. Acid Yellow BIS (E (r)--616.75 mV) was reduced at the highest rate of 0.0284 mol g dry cell weight(-1) h(-1), Acid Yellow 11 (E (r)--593.25 mV) at 0.0245 mol g dry cell weight(-1) h(-1) and Acid Yellow 4 (E (r)--513 mV) at 0.0178 mol g dry cell weight(-1) h(-1). At the same time, the decolorization rate of Acid Yellow 17 (E (r)--627.5 mV) was 0.0238 mol g dry cell weight(-1) h(-1), which was affected by the nature of chlorine substituent. Reduction of these azo dyes did not occur under aeration conditions. These studies with a common mixed culture indicate that the reduction of azo dyes may be influenced by the chemical nature of the azo compound. The reduction potential is a preliminary tool to predict the decolorization capacity of oxidative and reductive biocatalysts.

Azo Compounds↗

PubMed2005

Microbial community dynamics in bioaugmented sequencing batch reactors for bromoamine acid removal.

Sphingomonas xenophaga QYY with the ability to degrade bromoamine acid (BAA) was previously isolated from sludge samples. The enhancement of BAA removal by strain QYY in sequencing batch reactors (SBRs) was investigated in this study. The results showed that augmented SBRs exhibited stronger abilities to degrade BAA than the non-augmented control one. In order to estimate the relationship between community dynamics and function of augmented SBRs, a combined method based on fingerprints (ribosomal intergenic spacer analysis, RISA) and 16S rRNA gene sequencing was used. The results indicated that the microbial community dynamics were substantially changed, and the introduced strain QYY was persistent in the augmented systems. This study suggests that it is feasible and potentially useful to enhance BAA removal using BAA-degrading bacteria, such as S. xenophaga QYY.

Anthraquinones↗

PubMed2005

Performance and microbial structure of a combined biofilm reactor.

A novel combined biofilm reactor was established and applied as a single treatment unit for carbon and nitrogen removal of wastewater. The nitrogen removal performance of the reactor at different levels of organic carbon (COD) loading was investigated when the influent total nitrogen (TN) loading was 0.74 g TN/m2 day. Continuous experimental results demonstrated that 80% nitrogen was eliminated when the influent COD loading ranged between 2.06 g and 3.92 g COD/m2 day. Microbial composition in the reactor was analyzed using fluorescent in situ hybridization (FISH) and conventional batch tests. The relative abundance of ammonia-oxidizing bacteria in the aerobic zone of the reactor measured by FISH was consistent with the result from conventional batch tests.

Ammonia↗

PubMed2003

Construction of a genetically engineered microorganism for CO2 fixation using a Rhodopseudomonas/Escherichia coli shuttle vector.

The CO2 fixation ability of Rhodopseudomonas palustris DH was enhanced by introducing the recombinant plasmid pMG-CBBM containing the form II ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) gene (cbbM) isolated from Rps. palustris NO. 7. Sequencing of a 3.0-kb PstI fragment containing the cbbM gene revealed an open reading frame encoding 461 amino acids, homologous to known cbbM genes, with a ribosome binding site upstream of cbbM and a terminator downstream of cbbM, without promoter. pMG-CBBM, a Rhodopseudomonas/Escherichia coli shuttle expression plasmid, was derived from the Rhodopseudomonas/E. coli shuttle cloning vector pMG105, by inserting the promoter of the pckA gene and the cbbM gene into its multiple cloning site. Plasmid pMG-CBBM was transformed into Rps. palustris DH by electroporation, and was stably maintained when transformants were grown either photoheterotrophically or photolithoautotrophically in the absence of antibiotics. This is the first report of an expression plasmid containing a Rps. palustris-specific promoter that allows stable expression of a foreign gene in the absence of antibiotic selection.

Amino Acid Sequence↗