Evaluation of xenobiotics biodegradation potential, shown here for benzotriazoles (corrosion inhi... more Evaluation of xenobiotics biodegradation potential, shown here for benzotriazoles (corrosion inhibitors) and sulfamethoxazole (sulfonamide antibiotic) by microbial communities and/or pure cultures normally requires time intensive and money consuming LC/GC methods that are, in case of laboratory setups, not always needed. The usage of high concentrations to apply a high selective pressure on the microbial communities/pure cultures in laboratory setups, a simple UV-absorbance measurement (UV-AM) was developed and validated for screening a large number of setups, requiring almost no preparation and significantly less time and money compared to LC/GC methods. This rapid and easy to use method was evaluated by comparing its measured values to LC-UV and GC-MS/MS results. Furthermore, its application for monitoring and screening unknown activated sludge communities (ASC) and mixed pure cultures has been tested and approved to detect biodegradation of benzotriazole (BTri), 4- and 5-tolyltriazole (4-TTri, 5-TTri) as well as SMX. In laboratory setups, xenobiotics concentrations above 1.0 mg L(-1) without any enrichment or preparation could be detected after optimization of the method. As UV-AM does not require much preparatory work and can be conducted in 96 or even 384 well plate formats, the number of possible parallel setups and screening efficiency was significantly increased while analytic and laboratory costs were reduced to a minimum.
The corrosion inhibitor 5-tolyltriazole (5-TTri) can have a detrimental impact on aquatic systems... more The corrosion inhibitor 5-tolyltriazole (5-TTri) can have a detrimental impact on aquatic systems thus implying an acute need to reduce the effluent concentrations of 5-TTri. In this study, 5-TTri biodegradation was enhanced through acclimation and nutrient supply. Activated sludge communities (ASC) were setup in nine subsequent ASC generations. While generation two showed a lag phase of five days without biodegradation, generations four to nine utilized 5-TTri right after inoculation, with biodegradation rates from 3.3 to 5.2 mg L(-1)d(-1). Additionally, centrifuged AS supernatant was used to simulate the nutrient conditions in wastewater. This sludge supernatant (SS) significantly enhanced biodegradation, resulting in removal rates ranging from 3.2 to 5.0 mg L(-1)d(-1) without acclimation while the control groups without SS observed lower rates of ⩽ 2.2 mg L(-1)d(-1).
Three benzotriazoles (benzotriazole, BTri; 5-methylbenzotriazole, 5-TTri; 4-methylbenzotriazole, ... more Three benzotriazoles (benzotriazole, BTri; 5-methylbenzotriazole, 5-TTri; 4-methylbenzotriazole, 4-TTri) and sulfamethoxazole (SMX) were studied for their aerobic biodegradation potential by activated sludge communities (ASC) and by pure cultures, respectively. With adsorption being negligible ASC were able to remove 100 mg/L 5-TTri within 14 days while only 10 mg/L BTri were removed within the same time. 4-TTri was not removed at all. For assessment of changes in ASC during biodegradation, DGGE was applied. For SMX degradation 9 pure cultures could be isolated from ASC showing the potential to utilize SMX (1) as a co-substrate with carbon/nitrogen being provided as well as (2) with SMX as sole carbon/nitrogen source. From these 9 isolates five different strains of Pseudomonas spp., two Microbacterium spp., one Variovorax sp. and one Brevundimonas sp. were found. SMX biodegradation was faster with additional carbon/nitrogen, i.e. 10 mg/L SMX in 2 days compared to 10 days with SMX as...
Benzotriazole (BTri), 4- and 5-tolyltriazole (4-TTri, 5-TTri) were monitored over 1 year in three... more Benzotriazole (BTri), 4- and 5-tolyltriazole (4-TTri, 5-TTri) were monitored over 1 year in three wastewater treatment plants (WWTPs) with a membrane bioreactor (MBR-MH) and two conventional activated sludge systems (CAS-E, CAS-M). The influent/effluent concentrations and treatment stages removal efficiencies were monitored. 5-TTri was removed best (mean removal 80%) in the WWTP mainly by biodegradation followed by BTri (mean removal 45%) and 4-TTri (mean removal 15%) that showed a significant lower elimination. High removal fluctuations for all three benzotriazoles occurred over the four seasons with lowest removal during winter. All three WWTPs constituted a point source for BTs in the aquatic environment as concentration measurements in the receiving rivers upstream and downstream of the WWTP proved. While MBR-MH and CAS-M significantly increased the downstream concentrations, CAS-E only slightly increased the downstream concentrations as the receiving river was already contaminated with benzotriazoles from hydropower. 5-TTri was detected in lowest concentrations due to its good removal compared to BTri and 4-TTri that contribute to high effluent concentrations with the potential to accumulate due to insufficient self-purification.
The aerobic biodegradation of 5-methyl-benzotriazole (5-TTri) was optimized using lab-scale setup... more The aerobic biodegradation of 5-methyl-benzotriazole (5-TTri) was optimized using lab-scale setups and activated sludge communities (ASC) collected from three wastewater treatment plants (WWTP) MBR-MH, CAS-E and CAS-M being different in their treatment technologies. ASC inocula were diluted to rule out non-biodegrading species and incubated under two nutrient conditions: A) mineral salt media (MSM) and B) carbon and nitrogen supplied MSM giving MSM-CN. 5-TTri removal with the ASC ranged from 60% to 100% in only 10 days. 100 μL suspended biomass from the biodegrading setups was subsequently plated on solid media to eliminate possible activated sludge remnants. After growth occurred, mixed colonies were harvested and inoculated in fresh liquid MSM containing 20 mg L(-1) 5-TTri. These bacterial consortia showed good 5-TTri removal in MSM-CN rather than in MSM, indicating nutrient supply being required for efficient biodegradation. In addition, experiments with high 5-TTri concentrations ranging from 20 to 1,000 mg L(-1) were conducted in both, MSM and MSM-CN and the maximal 5-TTri removal capacity of the ASC evaluated. 50 mg L(-1) 5-TTri was still removed in both media whereas 100 mg L(-1) was solely removed in MSM-CN. 5-TTri biodegradation patterns also indicated that 5-TTri might be co-metabolized by microbial consortia. Furthermore, experiments with gradient-solid-media-plates showed 5-TTri to be inhibitory for the ASC in concentrations above 50 mg L(-1) and revealed the optimal conditions regarding carbon and nitrogen concentration and pH value for effective 5-TTri biodegradation by ASC. Nitrogen proved a crucial factor for enhancing organisms' biodegradation capacity with an optimal pH around 7 while carbon showed no such effect.
Environmental Science and Pollution Research, 2014
The intensive use of benzotriazoles as corrosion inhibitors for various applications and their ap... more The intensive use of benzotriazoles as corrosion inhibitors for various applications and their application in dishwasher detergents result in an almost omnipresence of benzotriazole (BTri), 4-methyl- and 5-methyl-benzotriazole (4-TTri and 5-TTri, respectively) in aquatic systems. This study aims on the evaluation of the biodegradation potential of activated sludge communities (ASCs) toward the three benzotriazoles regarding aerobic, anoxic, and anaerobic conditions and different nutrients. ASCs were taken from three wastewater treatment plants with different technologies, namely, a membrane bioreactor (MBR-MH), a conventional activated sludge plant CAS-E (intermittent nitrification/denitrification), and CAS-M (two-stage activated sludge treatment) and used for inoculation of biodegradation setups. All ASCs eliminated up to 30 mg L(-1) 5-TTri and BTri under aerobic conditions within 2-7 and 21-49 days, respectively, but not under anoxic or anaerobic conditions. 4-TTri was refractory at all conditions tested. Significant differences were observed for BTri biodegradation with non-acclimated ASCs from MBR-MH with 21 days, CAS-E with 41 days, and CAS-M with 49 days. Acclimated ASCs removed BTri within 7 days. Furthermore, different carbon and nitrogen concentrations revealed that nitrogen was implicitly required for biodegradation while carbon showed no such effect. The fastest biodegradation occurred for 5-TTri with no need for acclimatization, followed by BTri. BTri showed sludge-specific biodegradation patterns, but, after sludge acclimation, was removed with the same pattern, regardless of the sludge used. Under anaerobic conditions in the presence of different electron acceptors, none of the three compounds showed biological removal. Thus, presumably, aerobic biodegradation is the major removal mechanism in aquatic systems.
Keratinases are enzymes that have the ability to degrade the insoluble protein keratin. Keratin, ... more Keratinases are enzymes that have the ability to degrade the insoluble protein keratin. Keratin, solely produced by animals, is the main structural protein of hair (mainly alpha keratin), skin and feathers (mainly beta keratin). It has a high stability and observes a slow biodegradation. This study focuses on the identification of a keratinase being highly specific for hair and skin keratin. Thus, an application might be to soften/remove hair and as active ingredient in anti-aging products to reduce wrinkles. Therefore, environmental samples as well as known bacteria strains are screened for their keratin biodegradation potential by using modified hair as a nutrient that releases colored degradation products. This allows to photometrically screening a large number of setups for keratin degradation. Promising setups are then further characterized regarding the responsible organism(s), the activity of the keratinase, and the feasibility of the organism/enzyme for its potential applica...
Evaluation of xenobiotics biodegradation potential, shown here for benzotriazoles (corrosion inhi... more Evaluation of xenobiotics biodegradation potential, shown here for benzotriazoles (corrosion inhibitors) and sulfamethoxazole (sulfonamide antibiotic) by microbial communities and/or pure cultures normally requires time intensive and money consuming LC/GC methods that are, in case of laboratory setups, not always needed. The usage of high concentrations to apply a high selective pressure on the microbial communities/pure cultures in laboratory setups, a simple UV-absorbance measurement (UV-AM) was developed and validated for screening a large number of setups, requiring almost no preparation and significantly less time and money compared to LC/GC methods. This rapid and easy to use method was evaluated by comparing its measured values to LC-UV and GC-MS/MS results. Furthermore, its application for monitoring and screening unknown activated sludge communities (ASC) and mixed pure cultures has been tested and approved to detect biodegradation of benzotriazole (BTri), 4- and 5-tolyltriazole (4-TTri, 5-TTri) as well as SMX. In laboratory setups, xenobiotics concentrations above 1.0 mg L(-1) without any enrichment or preparation could be detected after optimization of the method. As UV-AM does not require much preparatory work and can be conducted in 96 or even 384 well plate formats, the number of possible parallel setups and screening efficiency was significantly increased while analytic and laboratory costs were reduced to a minimum.
The corrosion inhibitor 5-tolyltriazole (5-TTri) can have a detrimental impact on aquatic systems... more The corrosion inhibitor 5-tolyltriazole (5-TTri) can have a detrimental impact on aquatic systems thus implying an acute need to reduce the effluent concentrations of 5-TTri. In this study, 5-TTri biodegradation was enhanced through acclimation and nutrient supply. Activated sludge communities (ASC) were setup in nine subsequent ASC generations. While generation two showed a lag phase of five days without biodegradation, generations four to nine utilized 5-TTri right after inoculation, with biodegradation rates from 3.3 to 5.2 mg L(-1)d(-1). Additionally, centrifuged AS supernatant was used to simulate the nutrient conditions in wastewater. This sludge supernatant (SS) significantly enhanced biodegradation, resulting in removal rates ranging from 3.2 to 5.0 mg L(-1)d(-1) without acclimation while the control groups without SS observed lower rates of ⩽ 2.2 mg L(-1)d(-1).
Three benzotriazoles (benzotriazole, BTri; 5-methylbenzotriazole, 5-TTri; 4-methylbenzotriazole, ... more Three benzotriazoles (benzotriazole, BTri; 5-methylbenzotriazole, 5-TTri; 4-methylbenzotriazole, 4-TTri) and sulfamethoxazole (SMX) were studied for their aerobic biodegradation potential by activated sludge communities (ASC) and by pure cultures, respectively. With adsorption being negligible ASC were able to remove 100 mg/L 5-TTri within 14 days while only 10 mg/L BTri were removed within the same time. 4-TTri was not removed at all. For assessment of changes in ASC during biodegradation, DGGE was applied. For SMX degradation 9 pure cultures could be isolated from ASC showing the potential to utilize SMX (1) as a co-substrate with carbon/nitrogen being provided as well as (2) with SMX as sole carbon/nitrogen source. From these 9 isolates five different strains of Pseudomonas spp., two Microbacterium spp., one Variovorax sp. and one Brevundimonas sp. were found. SMX biodegradation was faster with additional carbon/nitrogen, i.e. 10 mg/L SMX in 2 days compared to 10 days with SMX as...
Benzotriazole (BTri), 4- and 5-tolyltriazole (4-TTri, 5-TTri) were monitored over 1 year in three... more Benzotriazole (BTri), 4- and 5-tolyltriazole (4-TTri, 5-TTri) were monitored over 1 year in three wastewater treatment plants (WWTPs) with a membrane bioreactor (MBR-MH) and two conventional activated sludge systems (CAS-E, CAS-M). The influent/effluent concentrations and treatment stages removal efficiencies were monitored. 5-TTri was removed best (mean removal 80%) in the WWTP mainly by biodegradation followed by BTri (mean removal 45%) and 4-TTri (mean removal 15%) that showed a significant lower elimination. High removal fluctuations for all three benzotriazoles occurred over the four seasons with lowest removal during winter. All three WWTPs constituted a point source for BTs in the aquatic environment as concentration measurements in the receiving rivers upstream and downstream of the WWTP proved. While MBR-MH and CAS-M significantly increased the downstream concentrations, CAS-E only slightly increased the downstream concentrations as the receiving river was already contaminated with benzotriazoles from hydropower. 5-TTri was detected in lowest concentrations due to its good removal compared to BTri and 4-TTri that contribute to high effluent concentrations with the potential to accumulate due to insufficient self-purification.
The aerobic biodegradation of 5-methyl-benzotriazole (5-TTri) was optimized using lab-scale setup... more The aerobic biodegradation of 5-methyl-benzotriazole (5-TTri) was optimized using lab-scale setups and activated sludge communities (ASC) collected from three wastewater treatment plants (WWTP) MBR-MH, CAS-E and CAS-M being different in their treatment technologies. ASC inocula were diluted to rule out non-biodegrading species and incubated under two nutrient conditions: A) mineral salt media (MSM) and B) carbon and nitrogen supplied MSM giving MSM-CN. 5-TTri removal with the ASC ranged from 60% to 100% in only 10 days. 100 μL suspended biomass from the biodegrading setups was subsequently plated on solid media to eliminate possible activated sludge remnants. After growth occurred, mixed colonies were harvested and inoculated in fresh liquid MSM containing 20 mg L(-1) 5-TTri. These bacterial consortia showed good 5-TTri removal in MSM-CN rather than in MSM, indicating nutrient supply being required for efficient biodegradation. In addition, experiments with high 5-TTri concentrations ranging from 20 to 1,000 mg L(-1) were conducted in both, MSM and MSM-CN and the maximal 5-TTri removal capacity of the ASC evaluated. 50 mg L(-1) 5-TTri was still removed in both media whereas 100 mg L(-1) was solely removed in MSM-CN. 5-TTri biodegradation patterns also indicated that 5-TTri might be co-metabolized by microbial consortia. Furthermore, experiments with gradient-solid-media-plates showed 5-TTri to be inhibitory for the ASC in concentrations above 50 mg L(-1) and revealed the optimal conditions regarding carbon and nitrogen concentration and pH value for effective 5-TTri biodegradation by ASC. Nitrogen proved a crucial factor for enhancing organisms' biodegradation capacity with an optimal pH around 7 while carbon showed no such effect.
Environmental Science and Pollution Research, 2014
The intensive use of benzotriazoles as corrosion inhibitors for various applications and their ap... more The intensive use of benzotriazoles as corrosion inhibitors for various applications and their application in dishwasher detergents result in an almost omnipresence of benzotriazole (BTri), 4-methyl- and 5-methyl-benzotriazole (4-TTri and 5-TTri, respectively) in aquatic systems. This study aims on the evaluation of the biodegradation potential of activated sludge communities (ASCs) toward the three benzotriazoles regarding aerobic, anoxic, and anaerobic conditions and different nutrients. ASCs were taken from three wastewater treatment plants with different technologies, namely, a membrane bioreactor (MBR-MH), a conventional activated sludge plant CAS-E (intermittent nitrification/denitrification), and CAS-M (two-stage activated sludge treatment) and used for inoculation of biodegradation setups. All ASCs eliminated up to 30 mg L(-1) 5-TTri and BTri under aerobic conditions within 2-7 and 21-49 days, respectively, but not under anoxic or anaerobic conditions. 4-TTri was refractory at all conditions tested. Significant differences were observed for BTri biodegradation with non-acclimated ASCs from MBR-MH with 21 days, CAS-E with 41 days, and CAS-M with 49 days. Acclimated ASCs removed BTri within 7 days. Furthermore, different carbon and nitrogen concentrations revealed that nitrogen was implicitly required for biodegradation while carbon showed no such effect. The fastest biodegradation occurred for 5-TTri with no need for acclimatization, followed by BTri. BTri showed sludge-specific biodegradation patterns, but, after sludge acclimation, was removed with the same pattern, regardless of the sludge used. Under anaerobic conditions in the presence of different electron acceptors, none of the three compounds showed biological removal. Thus, presumably, aerobic biodegradation is the major removal mechanism in aquatic systems.
Keratinases are enzymes that have the ability to degrade the insoluble protein keratin. Keratin, ... more Keratinases are enzymes that have the ability to degrade the insoluble protein keratin. Keratin, solely produced by animals, is the main structural protein of hair (mainly alpha keratin), skin and feathers (mainly beta keratin). It has a high stability and observes a slow biodegradation. This study focuses on the identification of a keratinase being highly specific for hair and skin keratin. Thus, an application might be to soften/remove hair and as active ingredient in anti-aging products to reduce wrinkles. Therefore, environmental samples as well as known bacteria strains are screened for their keratin biodegradation potential by using modified hair as a nutrient that releases colored degradation products. This allows to photometrically screening a large number of setups for keratin degradation. Promising setups are then further characterized regarding the responsible organism(s), the activity of the keratinase, and the feasibility of the organism/enzyme for its potential applica...
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