Isolation,identification, and acetochlor-degrading potential of a novel Rhodococcus sp. MZ-3

A new species of Rhodococcus, designated strain MZ-3, which could degrade acetochlor efficiently were isolated and identified. The isolate could degrade and utilize acetochlor as the sole source of carbon, nitrogen, and energy for growth. The optimal conditions for the degradation and growth of MZ-3 were pH 7.0 and 30°C. Under these conditions, this strain could completely degrade 200 mg/L of acetochlor within 12 h of incubation. During the biodegradation process, the enantioselectivity of the strain was investigated using a chiral high-performance liquid chromatography (HPLC) system. However, no obvious enantioselectivities were found. 2-chloro-N-(2-methyl-6-ethylphenyl) acetamide (CMEPA) was detected as the intermediate using liquid chromatography-mass spectrometry (LC-MS) analyses. Our results suggest that strain MZ-3 might be a promising microorganism for the bioremediation of acetochlor-contaminated environments because of its acetochlor-degrading performance.     

Biodegradation of acetochlor by a newly isolated Achromobacter sp. strain D-12

A highly effective acetochlor-degrading bacterial strain (D-12) was isolated from the soil of a pesticide factory. The strain was identified as Achromobacter sp. based on its 16S rRNA gene sequence. The strain D-12 optimally degrades acetochlor at a pH of 7.0 and a temperature of 30°C in a mineral salts medium (MSM). Approximately 95% of acetochlor was degraded by the stain treated at a concentration of 10 mg L^?1 after 5 days of incubation. A chiral high performance liquid chromatography (HPLC) system was used to study the enantioselectivity during the process. However, no obvious enantioselective biodegradation was observed. The primary biodegradation acetochlor products were identified by high-performance liquid chromatography-mass spectroscopy (HPLC-MS) and gas chromatography-mass spectrometry (GC-MS). The results indicated that the strain D-12 could be applied in the bioremediation of an acetochlor-polluted environment.     

Biodegradation of nicotine by a novel Strain Shinella sp. HZN1 isolated from activated sludge

The nicotine-degrading bacterium HZN1 was isolated from activated sludge and identified as Shinella sp. based on its physiological characteristics and analysis of 16S rDNA gene. Strain HZN1 is capable of using nicotine as the sole carbon source in the mineral salts medium. The optimum temperature and pH for strain HZN1 growth and nicotine degradation were 30°C and 7.0, respectively. It could degrade approximately 100 % of 0.5 g L^?1 of nicotine within 9 h. Three intermediate metabolites were produced by the strain HZN1 and identified as cotinine, myosmine and nicotyrine using gas chromatography-mass spectrometry. This is the first report of nicotine-degrading strain from the genus of Shinella. The results showed that strain HZN1 could be potentially employed in bioremediation of nicotine. Our findings would provide a new insight into the biodegradation of nicotine.     

Isolation and identification of 3-bromocarbazole-degrading bacteria

In this study, a bacterial strain, CH-1, capable of degrading 3-bromocarbazole (3-BCZ) was isolated from a polluted soil. Based on its physio-biochemical characteristics and 16S rRNA genes, strain CH-1 was identified as a Stenotrophomonas sp. Strain CH-1 was able to degrade 70% of 50 mg/L 3-BCZ within 8 d at pH 7.0 and 30°C in mineral salt medium (MSM). During the process, the main intermediate metabolite was identified as (2E, 4Z)-6-(2-amino-5-bromophenyl)-2-hydroxy-6-oxhexa-2, 4-dienoic by gas (2E, 4Z)-6-(2-amino-5-bromophenyl)-2-hydroxy-6-oxhexa-2,4-dienoic via gas chromatograph-mass spectrometry (GC-MS) analysis. The metabolite disappeared after 14 d, suggesting that the metabolite can also be degraded by strain CH-1. 3-BCZ is a new persistent organic pollutant. This is the first report of the biodegradation of 3-BCZ. The results indicated that strain CH-1 may be a promising bacterial candidate for the bioremediation of environments polluted with polyhalogenated carbazoles (PHCs).     

Biodegradation of methyl red by Bacillus sp. strain UN2: decolorization capacity,metabolites characterization,and enzyme analysis

Azo dyes are recalcitrant and refractory pollutants that constitute a significant menace to the environment. The present study is focused on exploring the capability of Bacillus sp. strain UN2 for application in methyl red (MR) degradation. Effects of physicochemical parameters (pH of medium, temperature, initial concentration of dye, and composition of the medium) were studied in detail. The suitable pH and temperature range for MR degradation by strain UN2 were respectively 7.0–9.0 and 30–40 °C, and the optimal pH value and temperature were respectively 8.0 and 35 °C. Mg²⁺ and Mn²⁺ (1 mM) were found to significantly accelerate the MR removal rate, while the enhancement by either Fe³⁺ or Fe²⁺ was slight. Under the optimal degradation conditions, strain UN2 exhibited greater than 98 % degradation of the toxic azo dye MR (100 ppm) within 30 min. Analysis of samples from decolorized culture flasks confirmed biodegradation of MR into two prime metabolites: N,N′dimethyl-p-phenyle-nediamine and 2-aminobenzoic acid. A study of the enzymes responsible for the biodegradation of MR, in the control and cells obtained during (10 min) and after (30 min) degradation, showed a significant increase in the activities of azoreductase, laccase, and NADH-DCIP reductase. Furthermore, a phytotoxicity analysis demonstrated that the germination inhibition was almost eliminated for both the plants Triticum aestivum and Sorghum bicolor by MR metabolites at 100 mg/L concentration, yet the germination inhibition of parent dye was significant. Consequently, the high efficiency of MR degradation enables this strain to be a potential candidate for bioremediation of wastewater containing MR.     

Biodegradation of fatty acylamino acids by fusarium culmorum

Abstract

Biodegradation of the fatty acylamino acids by Fusarium culmorum, measured in terms of the release of radioactive aspartate and lysine, occurred maximally at pH 6.5 and pH 7.0, respectively in 10 day cultures. Thirty‐six percent and twenty‐four percent of the total radioactivity recovered were in released aspartate and lysine, respectivley at 30°C. Twenty degrees (C) was the minimum temperature for biodegradation of these compounds by F. culmorum. Greater degradation was observed at 15°C and 30°C. The data suggest the activity of hydrolytic isoenzymes, with optima at different pH's and temperatures, operating in the biodegradation process.     

Simultaneous biodegradation of bifenthrin and chlorpyrifos by Pseudomonas sp. CB2

The degradation of bifenthrin (BF) and chlorpyrifos (CP), either together or individually, by a bacterial strain (CB2) isolated from activated sludge was investigated. Strain CB2 was identified as belonging to genus Pseudomonas based on the morphological, physiological, and biochemical characteristics and a homological analysis of the 16S rDNA sequence. Strain CB2 has the potential to degrade BF and CP, either individually or in a mixture. The optimum conditions for mixture degradation were as follows: OD_600nm = 0.5; incubation temperature = 30°C; pH = 7.0; BF-CP mixture (10 mg L^?1 of each). Under these optimal conditions, the degradation rate constants (and half-lives) were 0.4308 d^?1 (1.61 d) and 0.3377 d^?1 (2.05 d) for individual BF and CP samples, respectively, and 0.3463 d^?1 (2.00 d) and 0.2931 d^?1 (2.36 d) for the BF-CP mixture. Major metabolites of BF and CP were 2-methyl-3-biphenylyl methanol and 3,5,6-trichloro-2-pyridinol, respectively. No metabolite bioaccumulation was observed. The ability of CB2 to efficiently degrade BF and CP, particularly in a mixture, may be useful in bioremediation efforts.     

Batch and continuous biodegradation of Amaranth in plain distilled water by P. aeruginosa BCH and toxicological scrutiny using oxidative stress studies

Bacterium Pseudomonas aeruginosa BCH was able to degrade naphthylaminesulfonic azo dye Amaranth in plain distilled water within 6 h at 50 mg?l^?1 dye concentration. Studies were carried out to find the optimum physical conditions and which came out to be pH?7 and temperature 30 °C. Amaranth could also be decolorized at concentration 500 mg?l^?1. Presence of Zn and Hg ions could strongly slow down the decolorization process, whereas decolorization progressed rapidly in presence of Mn. Decolorization rate was increased with increasing cell mass. Induction in intracellular and extracellular activities of tyrosinase and NADH-DCIP reductase along with intracellular laccase and veratryl alcohol oxidase indicated their co-ordinate action during dye biodegradation. Up-flow bioreactor studies with alginate immobilized cells proved the capability of strain to degrade Amaranth in continuous process at 20 ml?h^?1 flow rate. Various analytical studies viz.—HPLC, HPTLC, and FTIR gave the confirmation that decolorization was due to biodegradation. From GC-MS analysis, various metabolites were detected, and possible degradation pathway was predicted. Toxicity studies carried out with Allium cepa L. through the assessment of various antioxidant enzymes viz. sulphur oxide dismutase, guaiacol peroxidase, and catalase along with estimation of lipid peroxidation and protein oxidation levels conclusively demonstrated that oxidative stress was generated by Amaranth.     

Biodegradation of imidacloprid in liquid media by an isolated wastewater fungus Aspergillus terreus YESM3

In the present study, a new fungal strain capable of imidacloprid degradation was isolated from agricultural wastewater drain. The fungal strain of YESM3 was identified as Aspergillus terreus based on ITS1-5.8S rDNA-ITS2 gene sequence by PCR amplification of a 500 bp sequence. Screening of A. terreus YESM3 to the insecticide imidacloprid tolerance was achieved by growing fungus in Czapek Dox agar for 6 days at 28°C. High values (1.13 and 0.94 cm cm^?1) of tolerance index (TI) were recorded at 25 and 50 mg L^?1 of imidacloprid, respectively in the presence and absence of sucrose. However, at 400 mg L^?1 the fungus did not grow. Effects of the imidacloprid concentration, pH, and inoculum size on the biodegradation percentage were tested using Box–Behnken statistical design and the biodegradation was monitored by HPLC analysis at different time intervals. Box–Behnken results indicated that optimal conditions for biodegradation were at pH 4 and two fungal discs (10 mm diameter) in the presence of 61.2 mg L^?1 of imidacloprid. A. terreus YESM3 strain was capable of degrading 85% of imidacloprid 25 mg L^?1 in Czapek Dox broth medium at pH 4 and 28°C for 6 days under static conditions. In addition, after 20 days of inoculation, biodegradation recorded 96.23% of 25 mg L^?1 imidacloprid. Degradation kinetics showed that the imidacloprid followed the first order kinetics with half-life (t₅₀) of 1.532 day. Intermediate product identified as 6-chloronicotinic acid (6CNA) as one of the major metabolites during degradation of imidacloprid by using HPLC. Thus, A. terreus YESM3 showed a potential to reduce pollution by pesticides and toxicity in the effected environment. However, further studies should be conducted to understand the biodegradation mechanism of this pesticide in liquid media.     

Studies on Biodegradation of Nicotine by Arthrobacter sp. Strain HF-2

A nicotine-degrading bacterium, strain HF-2, was isolated from tobacco waste-contaminated soil and identified as a member of Arthrobacter sp. based on morphology, physiological tests, 16S rDNA sequence and phylogenetic characteristics. At thermal denaturation test indicated that the G + C mol% of strain HF-1 was 63.5. The relationship between the growth of the isolate and the nicotine degradation suggested that strain HF-2 could utilize nicotine as sole sources of carbon, nitrogen and energy. Blue pigment was observed during the nicotine degradation by strain HF-2. The isolate grew well at 20 to 33°C, initial pH 6.5 to 8.0 and 0.5 to 2.0 g L^?1 of nicotine concentration in the nicotine inorganic salt media. The maximum growth and nicotine degradation occurred at 30°C, initial pH 7.0 and 0.7 g·L^?1 of nicotine concentration in media under natural incubation condition. Strain HF-2 could degrade 100% of nicotine under the optimized incubation conditions for 43 h. The concentrations of nicotine were monitored by high performance liquid chromatography. This study demonstrates Arthrobacter sp. strain HF-2 had a great ability to degrade nicotine, and it may be available for the application to the bioremediation of environments contaminated by tobacco waste.     

Biodegradation of nicotine by a novel Strain Shinella sp. HZN1 isolated from activated sludge

The nicotine-degrading bacterium HZN1 was isolated from activated sludge and identified as Shinella sp. based on its physiological characteristics and analysis of 16S rDNA gene. Strain HZN1 is capable of using nicotine as the sole carbon source in the mineral salts medium. The optimum temperature and pH for strain HZN1 growth and nicotine degradation were 30°C and 7.0, respectively. It could degrade approximately 100 % of 0.5 g L(-1) of nicotine within 9 h. Three intermediate metabolites were produced by the strain HZN1 and identified as cotinine, myosmine and nicotyrine using gas chromatography-mass spectrometry. This is the first report of nicotine-degrading strain from the genus of Shinella. The results showed that strain HZN1 could be potentially employed in bioremediation of nicotine. Our findings would provide a new insight into the biodegradation of nicotine.     

Biodegradation of triazine herbicide metribuzin by the strain Bacillus sp. N1

By enrichment culturing of soil contaminated with metribuzin, a highly efficient metribuzin degrading bacterium, Bacillus sp. N1, was isolated. This strain grows using metribuzin at 5.0% (v/v) as the sole nitrogen source in a liquid medium. Optimal metribuzin degradation occurred at a temperature of 30ºC and at pH 7.0. With an initial concentration of 20 mg L^?1, the degradation rate was 73.5% in 120 h. If the initial concentrations were higher than 50 mg L^?1, the biodegradation rates decreased as the metribuzin concentrations increased. When the concentration was 100 mg L^?1, the degradation rate was only 45%. Degradation followed the pesticide degradation kinetic equation at initial concentrations between 5 mg L^?1 and 50 mg L^?1. When the metribuzin contaminated soil was mixed with strain N1 (with the concentration of metribuzin being 20 mg L^?1 and the inoculation rate of 10¹¹ g^?1 dry soil), the degradation rate of the metribuzin was 66.4% in 30 days, while the degradation rate of metribuzin was only 19.4% in the control soil without the strain N1. These results indicate that the strain N1 can significantly increase the degradation rate of metribuzin in contaminated soil.     

一株高效MC—RR降解菌的分离鉴定及其降解特性

为了得到一株具有降解微囊藻毒素一RR（MC—RR）特性的产芽孢菌株，采用加热富集芽孢菌的方法，从太湖分离到一株MC．RR降解菌CMl，该菌对MC—RR具有强烈的降解特性。通过形态学特征、生理生化特征及16SrDNA序列分析鉴定该菌株属于耐硼赖氨酸芽孢杆菌（Lysinibacillusb oronitolerans）。通过研究温度和pH值对菌株CMl降解MC—RR能力的影响，发现菌株CMl在60h将MC—RR由12．77μg／mL降解到1．67μg／mL，降解率达86．90％，最适降解温度为37℃，最适pH值为7．0。CMl菌株的胞外物质和胞内物质均能降解MC—RR，但胞内物质具有更强烈的降解特性，12h可以将7．27μg／mL的MC-RR完全降解。为丰富MC-RR降解菌纯菌种研究以及在去除水体中MC—RR应用研究方面提供了理论基础。     

微囊藻毒素-LR降解菌的筛选及降解特性研究

从上海市淀山湖表层水体中筛选分离出了1株降解微囊藻毒素-LR(MC-LR)的细菌并研究了其降解特性。根据细胞形态结构、生理生化特征及其16S rDNA基因序列分析,鉴定分离菌株DHU-28(GenBank序列登录号为HM047512)属嗜麦芽寡养单胞菌(Stenotrophomonas maltophilia)。微囊藻毒素降解实验结果表明,该菌株能在以MC-LR为唯一碳源、氮源的无机盐培养基中生长,6 d内可将初始质量浓度为15 mg/L的MC-LR降解为8.12 mg/L,降解效率达到45.9%。菌株DHU-28的最适生长温度是30℃,最适生长pH为7.0。酵母粉、蛋白胨、葡萄糖等营养物质可以明显促进菌株对MC-LR的降解效率,尤其是加入50 mg/L酵母粉后,6 d降解率达到63.2%。     

Characterization and application of the enzyme peroxidase to the degradation of the mycotoxin DON

Deoxynivalenol (DON), one of the main mycotoxins found in food matrices, has high level of toxicity. This study aimed to characterize the peroxidase enzyme extracted from rice bran to be applied to the biodegradation of DON in order to evaluate the potential peroxidase (PO) from rice bran (RB) has to degrade DON in optimal conditions. Purification and recovery factors of PO extracted from RB and purified by three-phase partitioning were 5.7% and 50%, respectively. PO had the highest level of activity in the phosphate buffer 5 mM pH 5.5 in both crude and purified forms, whose reaction temperatures were 25°C and 10°C. At the end of production, purification and characterization steps, specific activities of the bran were 115.79 U mg^?1 and 4363 U g^?1. Reduction in the mycotoxin DON in optimal conditions determined for PO from RB was 20.3%, a promising result when the aim is to adequate mycotoxicological levels to foods.     

Isolation and characterization of a Rhodococcus strain with phenol-degrading ability and its potential use for tannery effluent biotreatment

Introduction

Wastewater derived from leather production may contain phenols, which are highly toxic, and their degradation could be possible through bioremediation technologies.

Materials, methods and results

In the present work, microbial degradation of phenol was studied using a tolerant bacterial strain, named CS1, isolated from tannery sediments. This strain was able to survive in the presence of phenol at concentrations of up to 1,000?mg/L. On the basis of morphological and biochemical properties, 16S rRNA gene sequencing, and phylogenetic analysis, the isolated strain was identified as Rhodococcus sp. Phenol removal was evaluated at a lab-scale in Erlenmeyer flasks and at a bioreactor scale in a stirred tank reactor. Rhodococcus sp. CS1 was able to completely remove phenol in a range of 200 to 1,000?mg/L in mineral medium at 30 ± 2?°C and pH 7 as optimal conditions. In the stirred tank bioreactor, we studied the effect of some parameters, such as agitation (200?C600 rpm) and aeration (1?C3?vvm), on growth and phenol removal efficiency. Faster phenol biodegradation was obtained in the bioreactor than in Erlenmeyer flasks, and maximum phenol removal was achieved at 400?rpm and 1 vvm in only 12?h. Furthermore, Rhodococcus sp. CS1 strain was able to grow and completely degrade phenols from tannery effluents after 9?h of incubation.

Conclusion

Based on these results, Rhodococcus sp. CS1 could be an appropriate microorganism for bioremediation of tannery effluents or other phenol-containing wastewaters.     

Pathways of reductive degradation of crystal violet in wastewater using free-strain Burkholderia vietnamiensis C09V

A new strain isolated from activated sludge and identified as Burkholderia vietnamiensis C09V was used to biodegrade crystal violet (CV) from aqueous solution. To understand the degradation pathways of CV, batch experiments showed that the degradation using B. vietnamiensis C09V significantly depended on conditions such as pH, initial dye concentration and media components, carbon and nitrogen sources. Acceleration in the biodegradation of CV was observed in presence of metal ions such as Cd and Mn. More than 98.86C of CV (30 mg l^?1) was degraded within 42 h at pH 5 and 30 °C. The biodegradation kinetics of CV corresponded to the pseudo first-order rate model with a rate constant of 0.046 h^?1. UV–visible and Fourier transform infrared spectroscopy (FTIR) were used to identify degradation metabolites. Which further confirmed by LC-MS analysis, indicating that CV was biodegraded to N,N-dimethylaminophenol and Michler’s ketone prior to these intermediates being further degraded. Finally, the ability of B. vietnamiensis C09V to remove CV in wastewater was demonstrated.     

Bioremediation of acidic oily sludge-contaminated soil by the novel yeast strain Candida digboiensis TERI ASN6

Background, aim, and scope

Primitive wax refining techniques had resulted in almost 50,000 tonnes of acidic oily sludge (pH 1–3) being accumulated inside the Digboi refinery premises in Assam state, northeast India. A novel yeast species Candida digboiensis TERI ASN6 was obtained that could degrade the acidic petroleum hydrocarbons at pH 3 under laboratory conditions. The aim of this study was to evaluate the degradation potential of this strain under laboratory and field conditions.

Materials and methods

The ability of TERI ASN6 to degrade the hydrocarbons found in the acidic oily sludge was established by gravimetry and gas chromatography–mass spectroscopy. Following this, a feasibility study was done, on site, to study various treatments for the remediation of the acidic sludge. Among the treatments, the application of C. digboiensis TERI ASN6 with nutrients showed the highest degradation of the acidic oily sludge. This treatment was then selected for the full-scale bioremediation study conducted on site, inside the refinery premises.

Results

The novel yeast strain TERI ASN6 could degrade 40 mg of eicosane in 50 ml of minimal salts medium in 10 days and 72% of heneicosane in 192 h at pH 3. The degradation of alkanes yielded monocarboxylic acid intermediates while the polycyclic aromatic hydrocarbon pyrene found in the acidic oily sludge yielded the oxygenated intermediate pyrenol. In the feasibility study, the application of TERI ASN6 with nutrients showed a reduction of solvent extractable total petroleum hydrocarbon (TPH) from 160 to 28.81 g kg^?1 soil as compared to a TPH reduction from 183.85 to 151.10 g kg^?1 soil in the untreated control in 135 days. The full-scale bioremediation study in a 3,280-m² area in the refinery showed a reduction of TPH from 184.06 to 7.96 g kg^?1 soil in 175 days.

Discussion

Degradation of petroleum hydrocarbons by microbes is a well-known phenomenon, but most microbes are unable to withstand the low pH conditions found in Digboi refinery. The strain C. digboiensis could efficiently degrade the acidic oily sludge on site because of its robust nature, probably acquired by prolonged exposure to the contaminants.

Conclusions

This study establishes the potential of novel yeast strain to bioremediate hydrocarbons at low pH under field conditions.

Recommendations and perspectives

Acidic oily sludge is a potential environmental hazard. The components of the oily sludge are toxic and carcinogenic, and the acidity of the sludge further increases this problem. These results establish that the novel yeast strain C. digboiensis was able to degrade hydrocarbons at low pH and can therefore be used for bioremediating soils that have been contaminated by acidic hydrocarbon wastes generated by other methods as well.     

Temperature influence on biological phosphorus removal induced by aerobic/extended-idle regime

Previous researches have demonstrated that biological phosphorus removal (BPR) from wastewater could be driven by the aerobic/extended-idle (A/EI) regime. This study further investigated temperature effects on phosphorus removal performance in six A/EI sequencing batch reactors (SBRs) operated at temperatures ranging from 5 to 30 °C. The results showed that phosphorus removal efficiency increased with temperature increasing from 5 to 20 °C but slightly decreased when temperature continually increased to 30 °C. The highest phosphorus removal rate of 97.1 % was obtained at 20 °C. The biomass cultured at 20 °C contained more polyphosphate accumulating organisms (PAO) and less glycogen accumulating organisms (GAO) than that cultured at any other temperatures investigated. The mechanism studies revealed that temperature affected the transformations of glycogen and polyhydroxyalkanoates, and the activities of exopolyphosphatase and polyphosphate kinase activities. In addition, phosphorus removal performances of the A/EI and traditional anaerobic/oxic (A/O) SBRs were compared at 5 and 20 °C, respectively. The results showed the A/EI regime drove better phosphorus removal than the A/O regime at both 5 and 20 °C, and more PAO and less GAO abundances in the biomass might be the principal reason for the higher BPR in the A/EI SBRs as compared with the A/O SBRs.     

Biodegradation of nicosulfuron by the bacterium Serratia marcescens N80

By enrichment culturing of the sludge collected from the industrial wastewater treatment pond, we isolated a highly efficient nicosulfuron degrading bacterium Serratia marcescens N80. In liquid medium, Serratia marcescens N80 grows using nicosulfuron as the sole nitrogen source, and the optimal temperature, pH values, and inoculation for degradation are 30–35°C, 6.0–7.0, and 3.0% (v/v), respectively. With the initial concentration of 10 mg L^?1, the degradation rate is 93.6% in 96 hours; as the initial concentrations are higher than 10 mg L^?1, the biodegradation rates decrease as the nicosulfuron concentrations increase; when the concentration is 400 mg L^?1, the degradation rate is only 53.1%. Degradation follows the pesticide degradation kinetic equation at concentrations between 5 mg L^?1 and 50 mg L^?1. Identification of the metabolites by the liquid chromatography/mass spectrometry (LC/MS) indicates that the degradation of nicosulfuron is achieved by breaking the sulfonylurea bridge. The strain N80 also degraded some other sulfonylurea herbicides, including ethametsulfuron, tribenuron-methyl, metsulfuron-methyl, chlorimuron-ethyl,and rimsulfuron.