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

Isolation, Identification, and Selection of Bacteria With Proof-of-Concept for Bioaugmentation of Whitewater From Wood-Free Paper Mills

In the wood-free paper industry, whitewater is usually a mixture of additives for paper production. We are currently lacking an efficient, cost-effective purification technology for their removal. In closed whitewater cycles the additives accumulate, causing adverse production problems, such as the formation of slime and pitch. The aim of our study was to find an effective bio-based strategy for whitewater treatment using a selection of indigenous bacterial isolates. We first obtained a large collection of bacterial isolates and then tested them individually by simple plate and spectrophotometric methods for their ability to degrade the papermaking additives, i.e., carbohydrates, resin acids, alkyl ketene dimers, polyvinyl alcohol, latex, and azo and fluorescent dyes. We examined correlation between carbon source use, genera, and inoculum source of isolates using two multivariate methods: principal component analysis and FreeViz projection. Of the 318 bacterial isolates, we selected a consortium of four strains (Xanthomonadales bacterium sp. CST37-CF, Sphingomonas sp. BLA14-CF, Cellulosimicrobium sp. AKD4-BF and Aeromonas sp. RES19-BTP) that degrade the entire spectrum of tested additives by means of dissolved organic carbon measurements. A proof-of-concept study on a pilot scale was then performed by immobilizing the artificial consortium of the four strains and inserting them into a 33-liter, tubular flow-through reactor with a retention time of < 15 h. The consortium caused an 88% reduction in the COD of the whitewater, even after 21 days.

Draft Genome Sequence of the Plant Growth-Promoting Sphingobium sp. Strain AEW4, Isolated from the Rhizosphere of the Beachgrass Ammophila breviligulata

Sphingobium sp. strain AEW4 is a novel isolate from rhizosphere soil attached to the root of the American beachgrass Ammophila breviligulata The genomic sequence consisted of 4,678,518 bp and 4,428 protein-coding sequences. Here we report the draft genome sequence of this strain and some initial insights on its plant growth-promoting capabilities.

Bioaugmentation: An Emerging Strategy of Industrial Wastewater Treatment for Reuse and Discharge

A promising long-term and sustainable solution to the growing scarcity of water worldwide is to recycle and reuse wastewater. In wastewater treatment plants, the biodegradation of contaminants or pollutants by harnessing microorganisms present in activated sludge is one of the most important strategies to remove organic contaminants from wastewater. However, this approach has limitations because many pollutants are not efficiently eliminated. To counterbalance the limitations, bioaugmentation has been developed and consists of adding specific and efficient pollutant-biodegrading microorganisms into a microbial community in an effort to enhance the ability of this microbial community to biodegrade contaminants. This approach has been tested for wastewater cleaning with encouraging results, but failure has also been reported, especially during scale-up. In this review, work on the bioaugmentation in the context of removal of important pollutants from industrial wastewater is summarized, with an emphasis on recalcitrant compounds, and strategies that can be used to improve the efficiency of bioaugmentation are also discussed. This review also initiates a discussion regarding new research areas, such as nanotechnology and quorum sensing, that should be investigated to improve the efficiency of wastewater bioaugmentation.

Genome Sequence of Sphingomonas xenophaga QYY, an Anthraquinone-Degrading Strain

Sphingomonas xenophaga QYY is an efficient anthraquinone-degrading strain. Here, we present a 4.2-Mb assembly of the first genome sequence of S. xenophaga. We have annotated 36 coding sequences (CDSs) encoding aromatic catabolism and 216 CDSs responsible for toxic resistance and stress response, which may provide insights into the degradation of complex aromatics.

Microbial community structures in mixed bacterial consortia for azo dye treatment under aerobic and anaerobic conditions

Thirteen pure strains that possessed high methyl red (MR)-decolorizing ability were isolated from dye-contaminated water. Each isolate was identified by 16S rDNA sequencing. The results reveal that all of the isolated strains were facultative anaerobic bacteria. Two novel bacterial consortia (AE and AN), which could decolorize MR under aerobic and anaerobic conditions, respectively, were developed. Azo dye decolorization rate was significantly higher with the use of consortia compared to that with the use of individual strains. Both of the consortia can decolorize different azo dyes effectively in a short time, and tolerate MR with high concentrations. To provide further insight into the microbial diversity of the bacteria consortia under aerobic and anaerobic conditions, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analyses were performed. PCR-DGGE profiles revealed that the microbial community had changed significantly with varying initial concentrations of MR. Phylogenetic analysis indicated that microbial populations in the aerobic compartment belong to Klebsiella, Buttiauxella and Bacillus, whereas Klebsiella, Escherichia, Bacillus and Clostridium were present in the anaerobic compartment. Klebsiella, which was the majority genus in both of the consortia, may play an important role in azo dye removal.

Biodegradation of bromoamine acid using combined airlift loop reactor and biological activated carbon

The biodegradation of bromoamine acid (BAA) in a combined airlift loop reactor (ALR) and biological activated carbon (BAC) system was investigated. The results showed that the ALR using Sphingomonas xenophaga as inoculum and granular activated carbon (GAC) as carrier, could run steadily for over 3 months at less than 950 mg L(-1) BAA. And the efficiencies of BAA decolorization and COD removal in ALR reached about 90% and 50% within 12h, respectively. When it was further aerated for another 12h, the ALR effluent gradually became yellow due to the auto-oxidation of BAA decolorization products which were identified by HPLC-MS. Further biotreatment of the ALR effluent using BAC showed that the efficiency of TOC removal could reach 90%. Moreover, the release efficiencies of Br(-) and SO(4)(2-) were 73.5% and 67.4%, respectively. It indicated that BAC system was effective in the biodegradation of the auto-oxidative BAA decolorization products.

The application of molecular techniques to the study of wastewater treatment systems

Wastewater treatment systems tend to be engineered to select for a few functional microbial groups that may be organized in various spatial structures such as activated sludge flocs, biofilm or granules and represented by single coherent phylogenic groups such as ammonia-oxidizing bacteria (AOB) and polyphosphate-accumulating organisms (PAO). In order to monitor and control engineered microbial structure in wastewater treatment systems, it is necessary to understand the relationships between the microbial community structure and the process performance. This review focuses on bacterial communities in wastewater treatment processes, the quantity of microorganisms and structure of microbial consortia in wastewater treatment bioreactors. The review shows that the application of molecular techniques in studies of engineered environmental systems has increased our insight into the vast diversity and interaction of microorganisms present in wastewater treatment systems.

Bioaugmentation of activated sludge towards 3-chloroaniline removal with a mixed bacterial population carrying a degradative plasmid

A bioaugmentation approach combining several strategies was applied to achieve degradation of 3-chloroaniline (3CA) in semicontinuous activated sludge reactors. In a first step, a 3CA-degrading Comamonas testosteroni strain carrying the degradative plasmid pNB2 was added to a biofilm reactor, and complete 3CA degradation together with spread of the plasmid within the indigenous biofilm population was achieved. A second set of reactors was then bioaugmented with either a suspension of biofilm cells removed from the carrier material or with biofilm-containing carrier material. 3CA degradation was established rapidly in all bioaugmented reactors, followed by a slow adaptation of the non-bioaugmented control reactors. In response to variations in 3CA concentration, all reactors exhibited temporary performance breakdowns. Whereas duplicates of the control reactors deviated in their behaviour, the bioaugmented reactors appeared more reproducible in their performance and population dynamics. Finally, the carrier-bioaugmented reactors showed an improved performance in the presence of high 3CA influent concentrations over the suspension-bioaugmented reactors. In contrast, degradation in one control reactor failed completely, but was rapidly established in the remaining control reactor.

Bioaugmentation on decolorization of C.I. Direct Blue 71 by using genetically engineered strain Escherichia coli JM109 (pGEX-AZR)

The study showed that Escherichia coli JM109 (pGEX-AZR), the genetically engineered microorganism (GEM) with higher ability to decolorize azo dyes, bioaugmented successfully the dye wastewater bio-treatment systems to enhance C.I. Direct Blue 71 (DB 71) decolorization. The control and bioaugmented reactors failed at a around pH 5.0. However, the bioaugmented one succeeded at around pH 9.0, the influent DB 71 concentration was 150 mg/L, DB 71 concentration was decreased to 27.4 mg/L in 12h. The 1-3% NaCl concentration of bioaugmented reactors had no definite influence on decolorization, DB 71 concentration was decreased to 12.6 mg/L in 12h. GEM was added into anaerobic sequencing batch reactors (AnSBRs) to enhance DB 71 decolorization. Continuous operations of the control and bioaugmented AnSBRs showed that E. coli JM109 (pGEX-AZR) could bioaugment decolorization. The concentrations of activated sludge and GEM were still more than 2.80 g/L and 1.5 x 10(6)cells/mL, respectively, in the bioaugmented AnSBR. All the microbial communities changed indistinctively with time. The microbial community structures of the control AnSBR were similar to those of the bioaugmented one.

Population dynamics in bioaugmented membrane bioreactor for treatment of bromoamine acid wastewater

The performances and microbial population changes in laboratory-scale membrane bioreactor (MBR) augmented with Sphingomonas xenophaga QYY were investigated in the present study. It was demonstrated that after 30 days acclimation, the non-augmented MBR system were able to degrade bromoamine acid (BAA) well. However, the efficiency of the system decreased with BAA concentration increasing. While the augmented MBR showed higher capability, in which the color and COD removal were more than 90% and 50%, respectively. By ribosomal intergenic spacer analysis (RISA), it was found that BAA-utilizing populations gradually increased to become the dominant species in the non-augmented MBR. However, the augmented MBR possessed relatively stable treatment abilities, in which the introduced strain QYY could be persistent and co-exist well with the indigenous populations.

Enhancement of nitroaromatic compounds anaerobic biotransformation using a novel immobilized redox mediator prepared by electropolymerization

Functionalized polypyrrole (PPy) composites were prepared by incorporation of a model redox mediator, anthraquinonedisulphonate (AQDS), as doping anion during the electropolymerization of pyrrole (Py) monomer on active carbon felt (ACF) electrode. Then, the resulting composite, ACF/PPy/AQDS as a novel immobilized redox mediator for catalyzing anaerobic biotransformation of the model nitroaromatic compounds (NACs), such as nitrobenzene (NB), 2,4- and 2,6-dinitrotoluene (DNT), were investigated in detail. The results showed that ACF/PPy/AQDS exhibited good catalytic activity and stability, and its addition effectively accelerated the NACs anaerobic reduction to the corresponding amino compounds. In order to estimate the relationship between community dynamics and the function of immobilized redox mediator, a combined method based on fingerprints (ribosomal intergenic spacer analysis, RISA) and 16S rRNA gene sequencing was used. The results indicated that the existence of ACF/PPy/AQDS made the potent AQDS-reducing bacteria keeping predominant in the catalytic systems. Based on the results above, it can be concluded that this novel immobilized redox mediator is feasible and potentially useful to enhance NACs anaerobic reduction.

Effects of the inoculant strain Sphingomonas paucimobilis 20006FA on soil bacterial community and biodegradation in phenanthrene-contaminated soil

The effects of the inoculant strain Sphingomonas paucimobilis 20006FA (isolated from a phenanthrene-contaminated soil) on the dynamics and structure of microbial communities and phenanthrene elimination rate were studied in soil microcosms artificially contaminated with phenanthrene. The inoculant managed to be established from the first inoculation as it was evidenced by denaturing gradient gel electrophoresis analysis, increasing the number of cultivable heterotrophic and PAH-degrading cells and enhancing phenanthrene degradation. These effects were observed only during the inoculation period. Nevertheless, the soil biological activity (dehydrogenase activity and CO(2) production) showed a late increase. Whereas gradual and successive changes in bacterial community structures were caused by phenanthrene contamination, the inoculation provoked immediate, significant, and stable changes on soil bacterial community. In spite of the long-term establishment of the inoculated strain, at the end of the experiment, the bioaugmentation did not produce significant changes in the residual soil phenanthrene concentration and did not improve the residual effects on the microbial soil community.

The new incorporation bio-treatment technology of bromoamine acid and azo dyes wastewaters under high-salt conditions

The accelerating effect of quinones has been studied in the bio-decolorization processes, but there are no literatures about the incorporation bio-treatment technology of the bromoamine acid (BA) wastewater and azo dyes wastewaters under high-salt conditions (NaCl, 15%, w/w). Here we described the BA wastewater as a redox mediator in the bio-decolorization of azo dye wastewaters. Decolorization of azo dyes was carried out experimentally using the salt-tolerant bacteria under the BA wastewater and high-salt conditions. The BA wastewater used as a redox mediator was able to increase the decolorization rate of wastewater containing azo dyes. The effects of various operating conditions such as dissolved oxygen, temperature, and pH on microbial decolorization were investigated experimentally. At the same time, BA was tested to assess the effects on the change of the Oxidation-Reduction Potential (ORP) values during the decolorization processes. The experiments explored a great improvement of the redox mediator application and the new bio-treatment concept.

Bacterial community structure of a pesticide-contaminated site and assessment of changes induced in community structure during bioremediation

The introduction of culture-independent molecular screening techniques, especially based on 16S rRNA gene sequences, has allowed microbiologists to examine a facet of microbial diversity not necessarily reflected by the results of culturing studies. The bacterial community structure was studied for a pesticide-contaminated site that was subsequently remediated using an efficient degradative strain Arthrobacter protophormiae RKJ100. The efficiency of the bioremediation process was assessed by monitoring the depletion of the pollutant, and the effect of addition of an exogenous strain on the existing soil community structure was determined using molecular techniques. The 16S rRNA gene pool amplified from the soil metagenome was cloned and restriction fragment length polymorphism studies revealed 46 different phylotypes on the basis of similar banding patterns. Sequencing of representative clones of each phylotype showed that the community structure of the pesticide-contaminated soil was mainly constituted by Proteobacteria and Actinomycetes. Terminal restriction fragment length polymorphism analysis showed only nonsignificant changes in community structure during the process of bioremediation. Immobilized cells of strain RKJ100 enhanced pollutant degradation but seemed to have no detectable effects on the existing bacterial community structure.