Fungal assisted bio-treatment of environmental pollutants with comprehensive emphasis on noxious heavy metals: Recent updates.

In the present time of speedy developments and industrialization, heavy metals are being uncovered in aquatic environment and soil via refining, electroplating, processing, mining, metallurgical activities, dyeing and other several metallic and metal based industrial and synthetic activities. Heavy metals like lead (Pb), mercury (Hg), cadmium (Cd), arsenic (As), Zinc (Zn), Cobalt (Co), Iron (Fe), and many other are considered as seriously noxious and toxic for the aquatic environment, human, and other aquatic lives and have damaging influences. Such heavy metals, which are very tough to be degraded, can be managed by reducing their potential through various processes like removal, precipitation, oxidation-reduction, bio-sorption, recovery, bioaccumulation, bio-mineralization etc. Microbes are known as talented bio-agents for the heavy metals detoxification process and fungi are one of the cherished bio-sources that show noteworthy aptitude of heavy metal sorption and metal tolerance. Thus, the main objective of the authors was to come with a comprehensive review having methodological insights on the novel and recent results in the field of mycoremediation of heavy metals. This review significantly assesses the potential talent of fungi in heavy metal detoxification and thus, in environmental restoration. Many reported works, methodologies and mechanistic sights have been evaluated to explore the fungal-assisted heavy metal remediation. Herein, a compact and effectual discussion on the recent mycoremediation studies of organic pollutants like dyes, petroleum, pesticides, insecticides, herbicides, and pharmaceutical wastes have also been presented.

Unraveling disparate roles of organisms, from plants to bacteria, and viruses on built cultural heritage.

The different organisms, ranging from plants to bacteria, and viruses that dwell on built cultural heritage can be passive or active participants in conservation processes. For the active participants, particular attention is generally given to organisms that play a positive role in bioprotection, bioprecipitation, bioconsolidation, bioremediation, biocleaning, and biological control and to those involved in providing ecosystem services, such as reducing temperature, pollution, and noise in urban areas. The organisms can also evolve or mutate in response to changes, becoming tolerant and resistant to biocidal treatments or acquiring certain capacities, such as water repellency or resistance to ultraviolet radiation. Our understanding of the capacities and roles of these active organisms is constantly evolving as bioprotection/biodeterioration, and biotreatment studies are conducted and new techniques for characterizing species are developed. This brief review article aims to shed light on interesting research that has been abandoned as well as on recent (some ongoing) studies opening up new scopes of research involving a wide variety of organisms and viruses, which are likely to receive more attention in the coming years. KEY POINTS: • Organisms and viruses can be active or passive players in heritage conservation • Biotreatment and ecosystem service studies involving organisms and viruses are shown • Green deal, health, ecosystem services, and global change may shape future research.

Efficient degradation of rice straw through a novel psychrotolerant Bacillus cereus at low temperature.

BACKGROUND: Rice straw (RS) is one of the largest sources of lignocellulosic, which is an abundant raw material for biofuels and chemicals. However, the natural degradation of RS under a low temperature environment is the biggest obstacle to returning straw to the field. RESULTS: In the present study, one bacillus strain W118 was isolated. Strain W118 was identified as Bacillus cereus through morphological and physiological characterization and 16S rDNA sequencing. The optimum growth temperature and pH of strain W118 were 20 °C and 6.5, respectively. Simultaneously, it was found that the strain W118 grew well at low temperature, even at a temperature of 4 °C (OD600  = 1.40 ± 0.01). The decrease of various compositions of RS after the fermentation process at a temperature of 20 °C and 4 °C for 14 days was 27.00 ± 0.02% and 23.70 ± 0.04%, respectively. The composition of RS decreased to 50.71 ± 0.02% after being fermented at 4 °C for 25 days. The results of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction of RS showed that the compositions of RS were significant decreased. CONCLUSION: This test suggests that the strain W118 is efficient for degrading RS at low temperature, which has great application potential for straw degradation in a low temperature area. © 2022 Society of Chemical Industry.

Impacts of bioreactor operating parameters on removal efficiency, biodegradation rate, molecular distribution, and toxicity of commercial naphthenic acids.

Effects of naphthenic acids (NAs) concentration (50-200 mg NA L-1; 35-140 mg TOC L-1) and loading rate (1.4-1249 mg NA L-1 h-1; 1-874 mg TOC L-1 h-1) on removal efficiency, removal rate, and molecular distribution of NAs, and effluent toxicity were evaluated for biodegradation of commercial NAs mixture in circulating packed bed bioreactors (CPBBs). Increase of NAs concentration and loading rate (shorter residence times) increased the removal rate, while removal efficiency initially declined and then stabilized. The maximum biodegradation rates for 50, 100, 150, and 200 mg NA L-1 were 128.0, 321.7, 430.2, and 630.0 mg TOC L-1 h-1 at loading rates of 218.5, 455.6, 673.5 and 874.0 mg TOC L-1 h-1, respectively, with removal efficiencies of 58.6, 70.6, 63.9 and 72.1%. Analysis of influent and treated effluents with gas chromatography-mass spectrometry showed that molecular weight and cyclicity (C and Z numbers) affected the biodegradation, with low molecular weight acyclic NAs (C = 6-12) were the most amenable to biodegradation and those with intermediate and high molecular weights (C = 13-22) and moderate cyclicity (Z = - 4, - 6) were the most recalcitrant. In the biofilm, Proteobacteria and Actinobacteria were the most abundant phyla, and Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria were the dominant classes. Toxicity analyses with Artemia salina and Vibrio fischeri (Microtox) showed that high influent concentrations and loading rates (short residence times) led to higher NAs residual concentration and effluent toxicity. To design and operate large-scale CPBBs, intermediate loading rates and residence times that result in high removal efficiency, reasonable removal rates, and low toxicity are recommended.

Evaluation of eventual toxicities of treated textile wastewater using anoxic-aerobic algal-bacterial photobioreactor.

Water pollution is one of the major challenges and is of serious concern in the world. Toxicities generated by industrial activities severely deteriorate aquatic and terrestrial ecosystems during their uncontrolled discharge and accentuate water scarcity problems. An adequate treatment of released effluents seems to be mandatory. This study investigated the effect of synthetic textile wastewater (STWW) before and after an innovative algal-bacterial treatment occurred under anoxic-aerobic conditions on growth and mineral contents of radish plants. The health risk assessment was performed after the consumption of irrigated plants by rats. Results revealed a significant reduction in heavy metals content in plants irrigated with treated STWW, and rats fed with these plants showed normal health status. Rats fed with plants irrigated with raw STWW showed a disturbance of their homeostasis. The innovative treatment using algal-bacteria under anoxic-aerobic conditions succeeds to reduce the toxicity of raw STWW and provide an alternative water resource able to tackle water shortage.

Novel strains with superior degrading efficiency for lincomycin manufacturing biowaste.

As the antibiotic pollution source in the environment, a large amount of biowastes generated from antibiotic fermentation manufacture needs proper disposal. Recycling the biowaste as resources and nutrients is of great interest. Besides, degradation or removal of antibiotics is indispensable for the reclamation of antibiotic manufacturing biowaste. To establish environmentally friendly disposal strategies for lincomycin manufacturing biowaste (LMB), we screened the microbial strains that could efficiently degrade lincomycin from the antibiotic wastewater treatment plant. Among them, three novel strains were identified as Bacillus subtilis (strain LMB-A), Rhodotorula mucilaginosa (strain LMB-D) and Penicillium oxalicum (strain LMB-E), respectively. LMB-A and LMB-D could degrade 92.69% and 74.05% of lincomycin with an initial concentration of 1117.55 mg/L in 144 h, respectively. The lincomycin degradation products were formed by the breakage of amide bond or losing N-demethyl/thiomethyl group from the pyrrolidine/pyranose ringcata cata catalyzed by the strains. Moreover, LMB-A could decontaminate LMB, and the decontaminated LMB could be used as a nitrogen source to culture salt-resistant bacteria and other useful microorganisms. LMB-A and LMB-D have the potential to be used for the bioremediation of water and soil polluted by lincomycin and its analogs. LMB-E could degrade 88.20% LMB after 144-h cultivation. In summary, this study gives an insight into the green disposal of LMB, and the established strategy has potential application for biotreatment of other antibiotic fermentation manufacturing biowastes.

Recent development of advanced biotechnology for wastewater treatment.

The importance of highly efficient wastewater treatment is evident from aggravated water crises. With the development of green technology, wastewater treatment is required in an eco-friendly manner. Biotechnology is a promising solution to address this problem, including treatment and monitoring processes. The main directions and differences in biotreatment process are related to the surrounding environmental conditions, biological processes, and the type of microorganisms. It is significant to find suitable biotreatment methods to meet the specific requirements for practical situations. In this review, we first provide a comprehensive overview of optimized biotreatment processes for treating wastewater during different conditions. Both the advantages and disadvantages of these biotechnologies are discussed at length, along with their application scope. Then, we elaborated on recent developments of advanced biosensors (i.e. optical, electrochemical, and other biosensors) for monitoring processes. Finally, we discuss the limitations and perspectives of biological methods and biosensors applied in wastewater treatment. Overall, this review aims to project a rapid developmental path showing a broad vision of recent biotechnologies, applications, challenges, and opportunities for scholars in biotechnological fields for "green" wastewater treatment.

Bioremediation potential of a widespread industrial biowaste as renewable and sustainable biosorbent for synthetic dye pollution.

In this study, a model synthetic azo dye (Basic red 46) bioremoval by Carpinus betulus sawdust as inexpensive, eco-friendly, and sustainable biosorbent from aqueous solution was examined in a batch biosorption system. The effective environmental parameters on the biosorption process, such as the value of pH, amount of biosorbent, initial dye concentration and contact time were optimized using classical test design. The possible dye-biosorbent interaction was determined by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The equilibrium, thermodynamic, and kinetic studies for the biosorption of Basic red 46 onto the sawdust biomass were performed. In addition, a single-stage batch dye biosorption system was also designed. The dye biosorption yield of biosorbent was significantly influenced by the change of operating variables. The experimental data were best described by the Freundlich isotherm model and both the pseudo-first-order kinetic and the pseudo-second-order kinetic models. Thermodynamic research indicated that the biosorption of dye was feasible and spontaneous. Based on the Langmuir isotherm model, the biosorbent was found to have a maximum biosorption potential higher than many other biosorbents in the literature (264.915 mg g-1). Thus, this investigation presents a novel green option for the assessment of waste sawdust biomass as a cheap and effective biosorbent material.

Biosorptive application of defatted Laurus nobilis leaves as a waste material for treatment of water contaminated with heavy metal.

Defatted Laurus nobilis leaves as a natural biosorbent was first evaluated for elimination of toxic heavy metals such as Pb(II), Cd(II), Zn(II), Cu(II) from aqueous solutions for its wide availability as forest industry waste, in this study. The effects of solution pH, contact time, biosorbent dosage, initial metal ions concentration, ionic strength, humic acid effect, and their competitive effect on the biosorption of lead(II), cadmium(II), Copper(II), and zinc(II) by defatted Laurus nobilis leaves waste (LW) were studied for each metal. The biosorbent was characterized using FT-IR and SEM images. Comparative isotherm and kinetic studies were performed. The sorption of Cd(II) and Zn(II) on LW fitted better in the Freundlich model but Pb(II) and Cu(II) sorption fitted better in the Langmuir model. From the obtained results, the pseudo-second-order kinetic model described the biosorption of cadmium, lead, zinc copper ions the best. The biosorbent showed the maximum biosorption capacities (qm) of 96.2, 8.6, 8.7, and 6.0 mg g-1 for lead, cadmium, zinc, and copper, respectively. These results indicated that LW may be used as an effective and inexpensive heavy metal remediation material. Comparison to previous studies showed that LW is also comparable to (or better than) several other biosorbents.

Biotreatment of restaurant wastewater with an oily high concentration by newly isolated bacteria from oily sludge.

High concentration restaurant oily wastewater from restaurants and food processing industries discharged into water environment usually results in environment pollution and inhibits the activity of microorganisms in biological wastewater treatment systems. In this study, 75 strains from oily sludge were isolated with oil degradation activity for edible oil-contained wastewater. Eight isolates were able to grow well in liquid cultures with edible oil as the sole carbon source and discovered with high efficient oil-degrading ability. Seven out of eight isolates were identified as Acinetobacter and one isolate as Kluyvera cryocrescens, based on their 16S rRNA gene sequences. Three highly efficient oil degrading bacteria (Acinetobacter dijkshoorniae LYC46-2, Kluyvera cryocrescens LYC50-1a and Acinetobacter pittii LYC73-4b) were selected and their degradation characteristic were examined, the results showed that the three isolates were effective under pH range from 7.0 to 10.0, and temperature from 25 to 35 °C. For degradation of 2-4% (v/v) of vegetable oil, > 85% degradation percentage were obtained within 30 h. Degradation of the higher concentration oil (6-8%, v/v) result in 50-70% degradation percentage within 72 h, and the degradation percentage for the isolated strains were decreased about 50% for the degradation of 10% oil (< 45%) compared to 2% oil. Different type of oils were also tested, > 90% of degradation percentage were obtained by the three isolates, implied that these strains are capable of removing various oils efficiently. These results suggested that Acinetobacter dijkshoorniae LYC46-2, Kluyvera cryocrescens LYC50-1a and Acinetobacter pittii LYC73-4b are potential species could be efficiently used for high concentration restaurant oily wastewater treatment and might be applicable to a wastewater treatment system for the removal of oil.

Bacterial perspectives on the dissemination of antibiotic resistance genes in domestic wastewater bio-treatment systems: beneficiary to victim.

Domestic wastes, ranging from sewage and sludge to municipal solid waste, are usually treated in bioprocessing systems. These systems are regarded as main conduits for the elevated levels of antibiotic resistance genes (ARGs) observed in the environment. This paper mainly reviews recent studies on the occurrence and dynamics of ARGs in wastewater bio-treatment systems and discusses the ins and outs of ARG dissemination from the perspective of the microbial community. Our analysis shows that concentration of antibiotics through adsorption to microbial aggregates triggers the bacteria to acquire ARGs, which can be facilitated by the presence of mobile genetic elements. Notably, the acquisition and flow of ARGs during the rapid dissemination process is directed towards and for the best interests of the microbial community as a whole, and is influenced by surrounding nutrient levels, toxicant types, and sensitivities of the species in the prevailing antibiotic-stressed conditions. Furthermore, our review argues that predation of ARG-carrying bacteria by bacteriophages does periodically enhance the accessibility of ARGs to bacteria, which indirectly facilitates the recruitment of ARGs into environmental microbial communities.

Application of a novel phyco-composite biosorbent for the biotreatment of aqueous medium polluted with manganese ions.

A composite phyco-biomass including four different marine macroalgae species (Chaetomorpha sp., Polysiphonia sp., Ulva sp., and Cystoseira sp.) was evaluated as a novel biosorbent for the biosorption of manganese ions from aqueous solution. The experimental studies were performed to optimize the operational factors including solution pH, biosorbent amount, initial manganese concentration, and reaction time in a batch-mode biosorption system. The removal yield of the biosorbent for manganese ions increased with increasing pH, manganese ion concentration, and reaction time, while it decreased as the biosorbent dose increased. The obtained kinetic data indicated that the removal of manganese ions by the biosorbent was best described by the pseudo-second-order model and the pore diffusion also contributed to the biosorption process. The results of isotherm and thermodynamic studies showed that the Freundlich model represented the biosorption equilibrium data well and this biotreatment system was feasible, spontaneous, and physical. The maximum manganese uptake capacity of used biosorbent was found to be 55.874 mg g-1. Finally, a single-stage batch manganese biosorption system was designed and its kinetic performance was evaluated. All these findings revealed that the prepared composite macroalgae biosorbent has a fairly good potential for the removal of manganese ions from the aqueous medium.

Anaerobic degradation of glycol ether-ethanol mixtures using EGSB and hybrid reactors: Performance comparison and ether cleavage pathway.

The anaerobic biodegradation of ethanol-glycol ether mixtures as 1-ethoxy-2-propanol (E2P) and 1-methoxy-2-propanol (M2P), widely used in printing facilities, was investigated by means of two laboratory-scale anaerobic bioreactors at 25oC: an expanded granular sludge bed (EGSB) reactor and an anaerobic hybrid reactor (AHR), which incorporated a packed bed to improve biomass retention. Despite AHR showed almost half of solid leakages compared to EGSB, both reactors obtained practically the same performance for the operating conditions studied with global removal efficiencies (REs) higher than 92% for organic loading rates (OLRs) as high as 54 kg of chemical oxygen demand (COD) m-3 d-1 (REs of 70% and 100% for OLRs of 10.6 and 8.3 kg COD m-3 d-1 for E2P and M2P, respectively). Identified byproducts allowed clarifying the anaerobic degradation pathways of these glycol ethers. Thus, this study shows that anaerobic scrubber can be a feasible treatment for printing emissions.

Biotreatment of effluent from 'Adire' textile factories in Ibadan, Nigeria.

In this present study, bacteria were isolated from wastewater and polluted soil collected from two cottage textile factories in Ibadan. These bacteria isolates were used for the biotreatment of textile mill effluent. The physicochemical parameters of the textile mill effluent before treatment were carried out and percentage decolourisation of the effluent was analysed using ultraviolet-visible spectroscopy (UV-vis technique). The degradation products of the textile mill effluent characterised by Fourier transform infrared spectroscopy (FTIR). The pH values of the effluent were within the permissible limit of Federal Environmental Protection Agency (FEPA) and National Environmental Standards and Regulations Enforcement Agency (NESREA), while temperature and electric conductivity of the effluents were below the permissible limit of FEPA and NESREA. The BOD, COD, TSS, TDS and chloride of the textile mill effluent from the two cottage textile factories were above the permissible limits of FEPA and NESREA. Twelve bacteria isolates were screened, effective in decolourising commercial dyes and used to decolourise the textile mill effluent. The bacteria isolates were characterised and identified as Bacillus sp., Micrococcus sp., Erwinia sp., Acinetobacter sp. and Nocardia sp. The decolourisation of textile effluent was observed through the changes of spectra of UV-visible spectrophotometer. The following bacteria revealed different percentage proportion of decolouration profile:- Bacillus sp., had the highest percentage decolourisation of 57.7%, whereas Micrococcus sp. and Acinetobacter sp. had percentage decolourisation of 32.8 and 26.3%, respectively. The degradation profile of textile effluent was revealed through FTIR spectral analysis. The changes in the position of major peaks revealed from the textile effluent through FTIR spectral analysis, appearances of new peaks and the disappearances of existing peaks signify the degradation of the wastewater. Thus, some native microorganisms from the textile effluent could be enhanced to effectively degrade effluent from such environments.

Application of Pseudomonas flava WD-3 for sewage treatment in constructed wetland in winter.

Recently, constructed wetland was applied for sewage treatment globally due to its high efficiency and relatively low investment. However, operation of many constructed wetlands in cold winter is quite difficult due to the inhibition effect of low temperature. The objective of this experiment is to study the sewage treatment efficiency of Pseudomonas flava WD-3 in the integrated vertical-flow constructed wetland (IVCW) during winter with different dosages (bacterial suspension concentration: 4.575×10(8 )mL(-1)). Two treatments were designed, inoculation of P. flava WD-3 with different dosages and the control without bacterium incubation. A simplified Monod model was applied to simulate and evaluate the pollutant removal efficiency of this bacterial strain with respect to its dosages. Results indicated that P. flava WD-3 could degrade organic pollutants, nitrogen, and phosphorus nutrients from wastewater effectively. The optimal dosage of this strain was 6.0%, and the removal rates of chemical oxygen demand (COD), ammonium nitrogen (NH4+-N), and total phosphorous (TP) were 85.82-87.00%, 73.91-84.18%, and 82.04-87.00%, respectively. Furthermore, the average removal efficiencies of COD, NH4+-N, and TP were 1.46, 1.49, and 1.76 times, respectively, than the control. The simplified Monod model accurately predicted the pollutant removal efficiency of P. flava WD-3 in the IVCW system in winter.

Environmentally safe treatment of black liquor with Comamonas sp. B-9 under high-alkaline conditions.

The strain Comamonas sp. B-9 was isolated from steeping fluid of erosive bamboo slips derived from Kingdom Wu during the Three-Kingdoms Dynasty of ancient China (A.D. 220-280). It could be used to treat black liquor (BL) with high-alkaline pH and with an initial chemical oxygen demand (COD) of 18,000-25,000 mg L(-1) , without the addition of other carbon and nitrogen sources. The results revealed that Comamonas sp. B-9 was capable of reducing the COD, color, and lignin content of BL by up to 56.8, 35.3, and 43.5%, respectively. High levels of laccase, manganese peroxidase, cellulase, and xylanase enzymatic activities were also observed, and these enzymes could play an important role in the biotreatment of BL. Further, GC-MS analysis showed that most of the compounds detected in BL after biotreatment with Comamonas sp. B-9 were diminished, while 4-methyl benzaldehyde, 3,4,5-trihydroxybenzoic acid ethyl ester, and 4-hydroxy-3,5-dimethoxy benzaldehyde were produced as metabolites. The presented results indicate that Comamonas sp. B-9 has potential application for the treatment of wastewaters from pulp and paper processing with high COD load under high-alkaline conditions.

A local or a stranger? Comparison of autochthonous vs. allochthonous microalgae potential for bioremediation of coal mine drainage water.

Coal mining endangers the environment by contaminating of soil, surface, and ground water with coal mine drainage water (CMW) polluted by heavy metals. Microalgal cultures, hyper-accumulators of heavy metals, represent a promising solution for CMW biotreatment. A bottleneck of this approach is the availability of microalgal strains that combine a large capacity for heavy metal biocapture with a high resilience to their toxic effects. Biotopes contaminated with heavy metals are frequently inhabited by microalgae evolved to be resilient to heavy metal toxicity. Therefore, the autochthonous (locally isolated) microalgal strains are a priori considered to be superior for biotreatment of heavy metal-polluted waste streams. Still, strains from biocollections combine a high pollutant resilience with other biotechnologically important traits such as high productivity, high CO2 sequestration rate etc. Moreover, the strains available "off-the-shelf" would enable rapid development of bioprocesses. Here, we compared the efficiency of CMW biotreatment with autochthonous (isolated from the coal mine drainage sump) and allochthonous microalgae (from a geographically distant phosphate-polluted site). Both autochthonous strains and allochthonous strains turned to be interchangeable under our experimental conditions. Still, the autochthonous strains showed a higher capacity for sequestration of iron, zinc, and manganese, the specific pollutants of the studied CMW. It can be important when the duration of unattended exploitation of the CMW treatment facility is a priority or spikes of the heavy metal concentration in CMW are expected. Therefore, the "off-the-shelf" strains can be a plausible solution for rapid development of CMW treatment technologies from scratch (although screening for acute toxicity of CMW is imperative). On the other hand, locally isolated strains can offer distinct advantages and should be always considered if sufficient time and other resources are available for the development of microalgae-based process for CMW treatment.

Evaluation of Residual Yeast from Brewery Industry for Inactive Biosorption of Selenium from Industrial Wastewater: a Case Study.

In this study, the second-life application of Saccharomyces cerevisiae obtained from brewery wastewater was evaluated in the biosorption of Se(IV) (Na2SeO3) sorbate in residue generated from a fine chemical industry. Biosorption experiments were carried out with different Se(IV) concentrations (A = 7.5 to 30.0 mg L-1 dissolved in deionized water or industrial effluent) and different biosorbent concentrations (B = 2.0 to 52.5 g L-1, dry mass). Inactive microbial biomass was evaluated in a wet and dehydrated state. The highest selenium removal efficiency (biosorption efficiency-R = 97.5%) was achieved with the same concentrations of sorbate in deionized water, using 24.0 g L-1 of wet cells. In contrast, the industrial effluent treatment showed lower biosorption efficiency (R = 83.3%) due to a large amount of other salts in the medium, mainly sulphur. Overall, the use of smaller amounts of biosorbent had a biosorption capacity of approximately five times greater than when 24.0 g L-1 in industrial effluent treatment was used. However, as reducing the concentration of the contaminant contained in the wastewater is the primary goal of this study, a more significant amount of biosorbent is recommended.

Characterization and removal mechanism of fluoroquinolone-bioremediation by fungus Cladosporium cladosporioides 11 isolated from aquacultural sediments.

Antibiotics have been widely detected in aquatic environments, and fungal biotransformation receives considerable attention for antibiotic bioremediation. Here, a fungus designated Cladosporium cladosporioides 11 (CC11) with effective capacity to biotransform fluoroquinolones was isolated from aquaculture pond sediments. Enrofloxacin (ENR), ciprofloxacin (CIP) and ofloxacin (OFL) were considerably abated by CC11, and the antibacterial activities of the fluoroquinolones reduced significantly after CC11 treatment. Transcriptome analysis showed the removal of ENR, CIP and OFL by CC11 is a process of enzymatic degradation and biosorption which consists well with ligninolytic enzyme activities and sorption experiments under the same conditions. Additionally, CC11 significantly removed ENR in zebrafish culture water and reduced the residue of ENR in zebrafish. All these results evidenced the potential of CC11 as a novel environmentally friendly process for the removal of fluoroquinolones from aqueous systems and reduce fluoroquinolone residues in aquatic organisms.

Efficient bio-remediation of multiple aromatic hydrocarbons using different types of thermotolerant, ring-cleaving dioxygenases derived from Aeribacillus pallidus HB-1.

As toxic contaminants, aromatic compounds are widespread in most environmental matrices, and bioenzymatic catalysis plays a critical role in the degradation of xenobiotics. Here, a thermophillic aromatic hydrocarbon degrader Aeribacillus pallidus HB-1 was found. Bioinformatic analysis of the HB-1 genome revealed two ring-cleaving extradiol dioxygenases (EDOs), among which, EDO-0418 was assigned to a new subfamily of type I.1 EDOs and exhibited a broad substrate specificity, particularly towards biarylic substrate. Both EDOs exhibited optimal activities at elevated temperatures (55 and 65 °C, respectively) and showed remarkable thermostability, pH stability, metal ion resistance and tolerance to chemical reagents. Most importantly, simulated wastewater bioreactor experiments demonstrated efficient and uniform degradation performance of mixed aromatic substrates under harsh environments by the two enzymes combined for potential industrial applications. The unveiling of two thermostable dioxygenases with broad substrate specificities and stress tolerance provides a novel approach for highly efficient environmental bioremediation using composite enzyme systems.