Bioaugmentation of Bromoamine Acid Degradation with Sphingomonas xenophaga QYY and DNA Fingerprint Analysis of Augmented Systems

Methyl Orange Biodegradation by Immobilized Consortium Microspheres: Experimental Design Approach, Toxicity Study and Bioaugmentation Potential

Methyl orange (MO) is categorized among the recalcitrant and refractory xenobiotics, representing a significant burden in the ecosystem. To clean-up the surrounding environment, advances in microbial degradation have been made. The main objective of this study was to investigate the extent to which an autochthonous consortium immobilized in alginate beads can promote an efficient biodegradation of MO. By employing response surface methodology (RSM), a parametric model explained the interaction of immobilized consortium (Raoultella planticola, Ochrobactrum thiophenivorans, Bacillus flexus and Staphylococcus xylosus) to assimilate 200 mg/L of MO in the presence of 40 g/L of NaCl within 120 h. Physicochemical analysis, including UV-Vis spectroscopy and FTIR, and monitoring of the degrading enzymes (azoreductase, DCIP reductase, NADH reductase, laccase, LiP, MnP, nitrate reductase and tyrosinase) were used to evaluate MO degradation. In addition, the toxicity of MO-degradation products was investigated by means of phytotoxicity and cytotoxicity. Chlorella vulgaris retained its photosynthetic performance (>78%), as shown by the contents of chlorophyll-a, chlorophyll-b and carotenoids. The viability of normal lung and kidney cell lines was recorded to be 90.63% and 99.23%, respectively, upon exposure to MO-metabolic outcomes. These results reflect the non-toxicity of treated samples, implying their utilization in ferti-irrigation applications and industrial cooling systems. Moreover, the immobilized consortium was employed in the bioremediation of MO from artificially contaminated agricultural and industrial effluents, in augmented and non-augmented systems. Bacterial consortium remediated MO by 155 and 128.5 mg/L in augmented systems of agricultural and industrial effluents, respectively, within 144 h, revealing its mutual synergistic interaction with both indigenous microbiotas despite differences in their chemical, physical and microbial contents. These promising results encourage the application of immobilized consortium in bioaugmentation studies using different resources.

Statistical modeling of methylene blue degradation by yeast-bacteria consortium; optimization via agro-industrial waste, immobilization and application in real effluents

The progress in industrialization everyday life has led to the continuous entry of several anthropogenic compounds, including dyes, into surrounding ecosystem causing arduous concerns for human health and biosphere. Therefore, microbial degradation of dyes is considered an eco-efficient and cost-competitive alternative to physicochemical approaches. These degradative biosystems mainly depend on the utilization of nutritive co-substrates such as yeast extract peptone in conjunction with glucose. Herein, a synergestic interaction between strains of mixed-culture consortium consisting of Rhodotorula sp., Raoultella planticola; and Staphylococcus xylosus was recruited in methylene blue (MB) degradation using agro-industrial waste as an economic and nutritive co-substrate. Via statistical means such as Plackett-Burman design and central composite design, the impact of significant nutritional parameters on MB degradation was screened and optimized. Predictive modeling denoted that complete degradation of MB was achieved within 72 h at MB (200 mg/L), NaNO3 (0.525 gm/L), molasses (385 μL/L), pH (7.5) and inoculum size (18%). Assessment of degradative enzymes revealed that intracellular NADH-reductase and DCIP-reductase were key enzymes controlling degradation process by 104.52 ± 1.75 and 274.04 ± 3.37 IU/min/mg protein after 72 h of incubation. In addition, azoreductase, tyrosinase, laccase, nitrate reductase, MnP and LiP also contributed significantly to MB degradation process. Physicochemical monitoring analysis, namely UV-Visible spectrophotometry and FTIR of MB before treatment and degradation byproducts indicated deterioration of azo bond and demethylation. Moreover, the non-toxic nature of degradation byproducts was confirmed by phytotoxicity and cytotoxicity assays. Chlorella vulgaris retained its photosynthetic capability (˃ 85%) as estimated from Chlorophyll-a/b contents compared to ˃ 30% of MB-solution. However, the viability of Wi-38 and Vero cells was estimated to be 90.67% and 99.67%, respectively, upon exposure to MB-metabolites. Furthermore, an eminent employment of consortium either freely-suspended or immobilized in plain distilled water and optimized slurry in a bioaugmentation process was implemented to treat MB in artificially-contaminated municipal wastewater and industrial effluent. The results showed a corporative interaction between the consortium examined and co-existing microbiota; reflecting its compatibility and adaptability with different microbial niches in different effluents with various physicochemical contents.

Degradation pathways and kinetics of anthraquinone compounds along with nitrate removal by a newly isolated Rhodococcus pyridinivorans GF3 under aerobic conditions

A novel Rhodococcus pyridinivorans GF3 capable of degrading anthraquinone compounds (ACs) was isolated from 1-amino-4-bromoanthraquinone-2-sulfonic acid contaminated soil under aerobic conditions. Strain GF3 could degrade nine ACs at 150 rpm and 30 °C. LC-MS analysis showed that ACs were degraded via catechol and salicylic acid-produced pathways, which were different from previously reported phthalic acid-produced pathway. Strain GF3 could also completely remove ACs along with nitrate removal via aerobic denitrification. Further analysis found that the catechol as a metabolite of ACs could contribute to aerobic denitrification. The degradation of the mixture of five ACs used in 1-amino-4-bromoanthraquinone-2-sulfonic acid-producing process followed the modified Gompertz model under aerobic denitrification. During this process, except for anthraquinone (29.5% removal), the degradation efficiencies of hydrophilic and hydrophobic ACs reached over 90% and 60% in 48 h, respectively. These results show that strain GF3 is of potential application for the treatment of anthraquinone dye intermediates-containing wastewaters.

Bioaugmentation of membrane bioreactor with Achromobacter denitrificans strain PR1 for enhanced sulfamethoxazole removal in wastewater

Achromobacter denitrificans strain PR1, previously found to harbour specific degradation pathways with high sulfamethoxazole (SMX) degradation rates, was bioaugmented into laboratory-scale membrane bioreactors (MBRs) operated under aerobic conditions to treat SMX-containing real domestic wastewater. Different hydraulic retention times (HRTs), which is related to reaction time and loading rates, were considered and found to affect the SMX removal efficiency. The availability of primary substrates was important in both bioaugmented and non-bioaugmented activated sludge (AS) for cometabolism of SMX. High HRT (24 h) resulted in low food to microorganism ratio (F/M) and low SMX removal, due to substrate limitation. Decrease in HRT from 24 h to 12 h, 6 h and finally 4 h led to gradual increases in primary substrates availability, e.g. organic compounds and ammonia, resulted in increased SMX removal efficiency and degradation rate, and is more favorable for high-rate wastewater treatment processes. After inoculation into the MBRs, the bioaugmentation strain was sustained in the reactor for a maximum of 31 days even though a significant decrease in abundance was observed. The bioaugmented MBRs showed enhanced SMX removal, especially under SMX shock loads compared to the control MBRs. The results of this study indicate that re-inoculation is required regularly after a period of time to maintain the removal efficiency of the target compound.

Synthesis of a novel isatin and ethylenediamine modified resin and effective adsorption behavior towards Orange G

In this study, a novel crosslinked resin 135-I-EDA modified by isatin and ethylenediamine was synthesized through two continuous functionalization steps using chloromethylated styrene-divinylbenzene copolymer as the substrate. In the first step, the cross-linking reaction and isatin incorporation were realized in a creative one-pot reaction using Friedel-crafts reaction in the presence of isatin to give resin 135-I; in the second step, ethylenediamine was successfully introduced on the carbonyl of the modified isatin to further increase the chemically interacting sites. The double-modified resin 135-I-EDA displayed the best adsorption performance (113.38 mg g-1) towards Orange G, which is 1.99 times and 3.49 times as much as that of 135-I (56.94 mg g-1) and commercial resin H-103 (32.51 mg g-1) respectively. This is attributed to its superior porous structure formed in the Friedel-crafts reaction and multiple modified groups in isatin and ethylenediamine. π-π conjugation and hydrogen bonding are the main driving forces for the adsorption. The pseudo-second-order rate equation characterizes the adsorption kinetic curves well and 135-I-EDA displayed the fastest adsorption rate. The study also proved that the 135-I-EDA has a better adsorption capacity for OG in more acidic solution, at higher temperature and higher salinity, which provides a basis for the treatment of industrial dye wastewater.

The Comparative Study on the Rapid Decolorization of Azo, Anthraquinone and Triphenylmethane Dyes by Anaerobic Sludge

An anaerobic sludge (AS), capable of decolorizing a variety of synthetic dyes, was acclimated and is reported here. The sludge presented a much better dye decolorizing ability than that of different individual strains. A broad spectrum of dyes could be decolorized by the sludge. Continuous decolorization tests showed that the sludge exhibited the ability to decolorize repeated additions of dye. The chemical oxygen demand (COD) removal rate of the dye wastewater reached 52% after 12 h of incubation. Polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) profiles revealed that the microbial community changed as a result of varying initial concentrations of dyes. Phylogenetic analysis indicated that microbial populations in the sludge belonged to the phyla Acidobacteria, Firmicutes, Bacteroidetes, Chloroflexi and Proteobacteria. The degradation products of the three types of dye were identified. For azo dyes, the anaerobic sludge converted Methyl Orange to N,N-dimethylbenzene-1,4-diamine and 4-aminobenzenesulfonic acid; for triphenylmethane dyes, after Malachite Green was decolorized, the analyzed products were found to be a mixture of N,N-dimethylbenzenamine, 3-dimethyl-aminophenol and 4-dimethylaminobenzophenone; for anthraquinone dyes, two products (acetophenone and 2-methylbenzoic acid) were observed after Reactive Blue 19 decolorization. Together, these results suggest that the anaerobic sludge has promising potential for use in the treatment of industrial wastewater containing various types of dyes.

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.

Identification and characterization of Leucobacter sp. N-4 for Ni (II) biosorption by response surface methodology

In the present study, batch experiments were carried out to characterize and optimize the removal process of Ni (II) by a nickel tolerant strain Leucobacter sp. N-4, which was isolated from the soil samples. The effects of operating parameters with respect to initial solution pH (3.0-6.5), initial nickel concentration (50-100mg/L) and biomass dosage (1-10 g/L) on Ni (II) biosorption were investigated by response surface methodology (RSM). The maximal Ni (II) removal efficiency (nearly 99%) was achieved under the following conditions: pH 4.75, biomass dosage 5.38 g/L and initial Ni (II) concentration 53.6 mg/L. The adsorption-equilibrium data fitted well with both Langmuir and Freundlich isotherms. The monolayer adsorption capacity of biomass obtained from Langmuir isotherm was about 19.6 mg/g. Infrared spectrometer (IR) results showed that chemical functional groups (e.g. -NH(2), -OH and COO-M) of the biomass should be the active binding sites for Ni (II) biosorption from aqueous solutions.

Azo dye decolorization by a new fungal isolate, Penicillium sp. QQ and fungal-bacterial cocultures

A new azo dyes-decolorizing fungi strain QQ was isolated from activated sludge. It was identified as Penicillium sp. based on 26S rRNA gene sequence analysis. The study indicated that strain QQ could aerobically decolorize Reactive Brilliant Red X-3B by the way of bioadsorption, and nutrient-poor medium was more beneficial for adsorption. Decolorization rate was inversely proportional to the size of mycelial pellets. The optimum pH was observed at 4 or 5 for X-3B decolorization. There was still 70% color removal when salinity increased to 6%. By contrast with aerobic decolorization, the degradation of azo dyes occurred under anaerobic conditions, and some azo dyes could be absolutely decolorized. Furthermore, the decolorization of azo dyes by fungal-bacterial cocultures was investigated. The results demonstrated that strain QQ and Sphingomonas xenophaga QYY cocultures performed better than any single strain did. Weak acidity conditions and the presence of small amount of surfactant could enhance the ability of consortium to decolorize azo dyes.

Bioaugmentation with the nicotine-degrading bacterium Pseudomonas sp. HF-1 in a sequencing batch reactor treating tobacco wastewater: degradation study and analysis of its mechanisms

The highly effective nicotine-degrading bacterium Pseudomonas sp. HF-1 was augmented in an SBR system that is used to treat tobacco wastewater. Compared to the non-bioaugmented (non-BA) system, the bioaugmented (BA) system exhibited considerably stronger pollution disposal abilities, with 100% nicotine degradation and more than 84% chemical oxygen demand (COD) removal within 12h. Nicotine degradation had a significant effect on COD removal in SBRs (r=0.928, p<0.01). The mechanisms of bioaugmentation were systematically investigated using a combination of polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) and a toxicity assay (protein carbonyl (PC) and DNA-protein crosslinking (DPC)). DGGE fingerprint profiles showed that the number of bands and the Shannon-Wiener index decreased at a nicotine load of 250mg/L compared to a 40-130mg/L nicotine load in the non-BA system. However, a stepwise increase in the Shannon-Wiener index was found during all periods in the BA system. A comparison of sequences excised from DGGE gels demonstrated significant differences in the dominant microbial species between the two SBRs. This result suggested that bioaugmentation of strain HF-1 could select cooperators for treating complicated tobacco wastewater. The PC content and the DPC coefficient increased significantly at levels higher than 80mg/L in the non-BA system; nevertheless, no increase was observed in the BA system during the stepwise nicotine load. This indicated that bioaugmentation of strain HF-1 resulted in the maintenance of high treatment activity by minimizing the nicotine toxicity for other microbes in the BA system. In conclusion, the rapid nicotine degradation of strain HF-1 performed a vital function in SBR by influencing the microbial community structure, dynamics and activity of the activated sludge system.

Treatment of bromoamine acid wastewater using combined process of micro-electrolysis and biological aerobic filter

The wastewater originated from the production of bromoamine acid was treated in a sequential system of micro-electrolysis (ME) and biological aerobic filter (BAF). Decolorization and COD(Cr) removal rate of the proposed system was investigated with full consideration of the influence of two major controlling factors such as organic loading rate (OLR) and hydraulic retention time (HRT). The removal rate of COD(Cr) was 81.2% and that of chrominance could be up to 96.6% at an OLR of 0.56 kg m(-3)d(-1) when the total HRT was 43.4h. Most of the chrominance was removed by the ME treatment, however, the BAF process was more effective for COD(Cr) removal. The GC-MS and HPLC-MS analysis of the contaminants revealed that 1-aminoanthraquinone, bromoamine acid and mono-sulfonated 1,2-dichlorobenzene were the main organic components in the wastewater. The reductive transformation of the anthraquinone derivatives in the ME reactor improved the biodegradability of the wastewater, and rendered the decolorization. After long-term of operation, it was observed that the predominant microorganisms immobilized on the BAF carriers were rod-shaped and globular. Four bacterial strains with apparent 16S rDNA fragments in the Denaturing Gradient Gel Electrophoresis (DGGE) profiles of BAF samples were identified as Variovorax sp., Sphingomonas sp., Mycobacterium sp., and Microbacterium sp.

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.

Molecular characteristics of xenobiotic-degrading sphingomonads

The genus Sphingomonas (sensu latu) belongs to the alpha-Proteobacteria and comprises strictly aerobic chemoheterotrophic bacteria that are widespread in various aquatic and terrestrial environments. The members of this genus are often isolated and studied because of their ability to degrade recalcitrant natural and anthropogenic compounds, such as (substituted) biphenyl(s) and naphthalene(s), fluorene, (substituted) phenanthrene(s), pyrene, (chlorinated) diphenylether(s), (chlorinated) furan(s), (chlorinated) dibenzo-p-dioxin(s), carbazole, estradiol, polyethylene glycols, chlorinated phenols, nonylphenols, and different herbicides and pesticides. The metabolic versatility of these organisms suggests that they have evolved mechanisms to adapt quicker and/or more efficiently to the degradation of novel compounds in the environment than members of other bacterial genera. Comparative analyses demonstrate that sphingomonads generally use similar degradative pathways as other groups of microorganisms but deviate from competing microorganisms by the existence of multiple hydroxylating oxygenases and the conservation of specific gene clusters. Furthermore, there is increasing evidence for the existence of plasmids that only can be disseminated among sphingomonads and which undergo after conjugative transfer pronounced rearrangements.