Isolation and characterization of polyacrylamide-degrading bacteria from dewatered sludge.
16 Apr 2015-International Journal of Environmental Research and Public Health (Int J Environ Res Public Health)-Vol. 12, Iss: 4, pp 4214-4230
TL;DR: High-molecular-weight PAM was partly cleaved to small molecular oligomer derivatives and part of the amide groups of PAM had been converted to carboxyl groups by a PAM-induced extracellular enzyme from the aliphatic amidase family.
Abstract: Polyacrylamide (PAM) is a water-soluble polymer that is widely used as a flocculant in sewage treatment. The accumulation of PAM affects the formation of dewatered sludge and potentially produces hazardous monomers. In the present study, the bacterial strain HI47 was isolated from dewatered sludge. This strain could metabolize PAM as its sole nutrient source and was subsequently identified as Pseudomonas putida. The efficiency of PAM degradation was 31.1% in 7 days and exceeded 45% under optimum culture condition (pH 7.2, 39 °C and 100 rpm). The addition of yeast extract and glucose improved the bacterial growth and PAM degradation. The degraded PAM samples were analyzed by gel-filtration chromatography, Fourier transform infrared and high-performance liquid chromatography. The results showed that high-molecular-weight PAM was partly cleaved to small molecular oligomer derivatives and part of the amide groups of PAM had been converted to carboxyl groups. The biodegradation did not accumulate acrylamide monomers. Based on the SDS-PAGE and N-terminal sequencing results, the PAM amide groups were converted into carboxyl groups by a PAM-induced extracellular enzyme from the aliphatic amidase family.
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07 Sep 2018
TL;DR: A short review of current applications of high molecular weight polyacrylamide (PAM) can be found in this paper, where the potential for PAM degradation by chemical, mechanical, thermal, photolytic, and biological processes are discussed along with issues related to the potential toxicity and mobility of PAM in the environment after disposal or accidental release.
Abstract: High molecular weight (106–3 × 107 Da) polyacrylamide (PAM) is commonly used as a flocculant in water and wastewater treatment, as a soil conditioner, and as a viscosity modifier and friction reducer in both enhanced oil recovery and high volume hydraulic fracturing. These applications of PAM can result in significant environmental challenges, both in water management and in contamination of local water supplies after accidental spills. This paper provides a short review of current applications of high molecular weight PAM, including the potential for PAM degradation by chemical, mechanical, thermal, photolytic, and biological processes. Methods for treating wastewater containing partially degraded PAM are then discussed along with issues related to the potential toxicity and mobility of PAM in the environment after disposal or accidental release.
243 citations
TL;DR: Future research should focus on elucidating the exact pathways and the enzymes involved in the biodegradation process, especially by fungi and anaerobic bacteria, as well as utilizing PAM-degrading microbes for bioremediation purposes.
Abstract: Although polyacrylamide (PAM) and its derivatives have many useful applications, their release in nature can have impacts on the environment and human health, thus bioremediation approaches for residual PAM are urgently needed. Biodegradation of PAM and its derivatives has been studied only in the last two decades, with most emphasis on acrylamide biodegradation. Microorganisms have been shown to utilize, not only acrylamide, but also PAM and its derivatives as the sole source of nitrogen and/or carbon under aerobic as well as anaerobic conditions. Microbial degradation lowered the molecular weight of the polymer, the viscosity, and the amide nitrogen was degraded to ammonia. Few species belonging to the bacterial genera Enterobacter sp., Azomonas sp., Bacillus sp., Acinetobacter sp., Pseudomonas sp., and Clostridium sp., were able to degrade 16–91% of PAM/HPAM under aerobic or anaerobic conditions. The monomer acrylamide is toxic to most microorganisms, however, some bacteria and fungi could degrade it using amidases that deaminate acrylamide to acrylic acid and ammonium, and further utilize acrylic acid to produce CO2 and water. Some fungi and yeasts could degrade 60–80% of acrylamide. The biodegradation of PAM and its derivatives are initiated by the enzyme amidase, either under aerobic or anaerobic conditions, and are further degraded partially or completely by an array of different enzymes. Future research should focus on elucidating the exact pathways and the enzymes involved in the biodegradation process, especially by fungi and anaerobic bacteria, as well as utilizing PAM-degrading microbes for bioremediation purposes.
65 citations
Cites background or methods from "Isolation and characterization of p..."
...The improper disposal of this sludge in landfills influences both terrestrial and aquatic ecosystems, as well as the health of all types of living organisms (Yu et al. 2015)....
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...In the last years, there has been a tremendous progress in the methods used to analyze PAM/HPAM and many studies have demonstrated their biodegradation by microbes (Yu et al. 2015; Zhao et al. 2016)....
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...SEC was used to investigate the molecular weight distribution of PAM, whereas the degradation products were determined using HPLC....
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...The changes in molecular weights after PAM degradation were also determined by using gelfiltration chromatography, Fourier transform infrared (FTIR) spectroscopy, and HPLC (Yu et al. 2015), where changes in the side chain functional groups before and after degradation could be analyzed....
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...High performance liquid chromatography (HPLC) method using ‘C18’ and ‘ion-exchange’ columns in series was used for the determination of acrylamide and acrylic acid monomers in polymeric samples (VerVers 1999)....
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TL;DR: The use of water hyacinth, a notorious weed in Kenyan waters, to produce cellulose-based polymer hydrogels has not been explored and yet, it could form an effective and beneficial way of utilizing this plant.
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TL;DR: In this paper, the authors investigated the degradation of polyacrylamide by single microbial species as well as mixed populations and suggested some hypothetical pathways for the bacterial degradation, although enzymology of bacterial degradation is largely unknown.
40 citations
References
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TL;DR: This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr with little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose.
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TL;DR: This work used human plasma to find the most efficient method for sample preparation and compared four widely applied precipitation methods, using trichloroacetic acid, acetone, chloroform/methanol and ammonium sulfate, as well as ultrafiltration.
467 citations
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TL;DR: Anionic polyacrylamide (PAM) has been sold since 1995 to reduce irrigation-induced erosion and enhance infiltration as mentioned in this paper, which has been shown to improve runoff water quality by reducing sediments, N, dissolved reactive phosphorus (DRP), pesticides, weed seeds and microorganisms in runoff.
Abstract: Anionic polyacrylamide (PAM) has been sold since 1995 to reduce irrigation‐induced erosion and enhance infiltration. Its soil stabilizing and flocculating properties improve runoff water quality by reducing sediments, N, dissolved reactive phosphorus (DRP) and total P, chemical oxygen demand (COD), pesticides, weed seeds, and microorganisms in runoff. PAM used for erosion control is a large (12–15 Mg mol −1 ) water‐soluble (non‐cross‐linked) anionic molecule, containing by PAM or can be slightly reduced. Typical seasonal application totals in furrow irrigation vary from 3 to 7 kg ha −1 . Research has shown little or no consistent adverse effect on soil microbial populations. Some evidence exists for PAM‐related yield increases where infiltration was crop‐limiting, especially in field portions having irregular slopes, where erosion prevention eliminated deep furrow cutting that deprives shallow roots of adequate water delivery. Modified water management with PAM shows great promise for water conservation. High effectiveness and low cost of PAM for erosion control and infiltration management, coupled with easier implementation than traditional conservation measures, has resulted in rapid adoption. About 800,000 ha of US irrigated land use PAM for erosion and/or infiltration management. In recent years, PAM has been deployed for uses beyond agricultural erosion control, including construction site erosion control, use in storm water runoff ponds to accelerate water clarification, soil stabilization and dust prevention in helicopter‐landing zones, and various other high‐traffic military situations. Among the newest topics being researched is the use of PAM to reduce ditch, canal, and pond seepage, using specific application protocols that take advantage of its increase of water viscosity at higher concentrations.
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TL;DR: A series of mutant strains derived from P. putida F1 that are defective in the todC gene, which encodes the oxygenase component of toluene dioxygenase, failed to degrade trichloroethylene and to oxidize indole to indigo, and a spontaneous revertant selected from a tod C culture regained simultaneously the abilities to oxidizing toluenes, to form indigo and to degradetrichlorOethylene.
Abstract: Toluene-induced cells of Pseudomonas putida F1 removed trichloroethylene from growth media at a significantly greater initial rate than the methanotroph Methylosinus trichosporium OB3b. With toluene-induced P. putida F1, the initial degradation rate varied linearly with trichloroethylene concentration over the range of 8 to 80 microM (1.05 to 10.5 ppm). At 80 microM (10.5 ppm) trichloroethylene and 30 degrees C, the initial rate was 1.8 nmol/min per mg of total cell protein, but the rate decreased rapidly with time. A series of mutant strains derived from P. putida F1 that are defective in the todC gene, which encodes the oxygenase component of toluene dioxygenase, failed to degrade trichloroethylene and to oxidize indole to indigo. A spontaneous revertant selected from a todC culture regained simultaneously the abilities to oxidize toluene, to form indigo, and to degrade trichloroethylene. The three isomeric dichloroethylenes were degraded by P. putida F1, but tetrachloroethylene, vinyl chloride, and ethylene were not removed from incubation mixtures.
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...Thus, PAM is commonly used as a flocculant to improve sedimentation in sewage treatment [2], oil recovery [3], paper manufacturing [4], mining, and other fields [5–7]....
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