Degradation of amoxicillin by newly isolated Bosea sp. Ads-6

Monitoring Ammonium Polyphosphate (APP) Biodegradation by Acinetobacter nosocomialis D-3 Using DAPI

Ammonium polyphosphate (APP), a pivotal constituent within environmentally friendly flame retardants, exhibits notable decomposition susceptibility and potentially engenders ecological peril. Consequently, monitoring the APP concentration to ensure product integrity and facilitate the efficacious management of wastewater from production processes is of great significance. A fluorescent assay was devised to swiftly discern APP utilizing 4',6'-diamino-2-phenylindole (DAPI). With increasing APP concentrations, DAPI undergoes intercalation within its structure, emitting pronounced fluorescence. Notably, the flame retardant JLS-PNA220-A, predominantly comprising APP, was employed as the test substrate. Establishing a linear relationship between fluorescence intensity (F-F0) and JLS-PNA220-A concentration yielded the equation y = 76.08x + 463.2 (R2 = 0.9992), with a LOD determined to be 0.853 mg/L. The method was used to assess the degradation capacity of APP-degrading bacteria. Strain D-3 was isolated, and subsequent analysis of its 16S DNA sequence classified it as belonging to the Acinetobacter genus. Acinetobacter nosocomialis D-3 demonstrated superior APP degradation capabilities under pH 7 at 37 °C, with degradation rates exceeding 85% over a four-day cultivation period. It underscores the sensitivity and efficacy of the proposed method for APP detection. Furthermore, Acinetobacter nosocomialis D-3 exhibits promising potential for remediation of residual APP through environmental biodegradation processes.

Arsenic effectively improves the degradation of fluorene by Rhodococcus sp. 2021 under the combined pollution of arsenic and fluorene

The performance of bacterial strains in executing degradative functions under the coexistence of heavy metals/heavy metal-like elements and organic contaminants is understudied. In this study, we isolated a fluorene-degrading bacterium, highly arsenic-resistant, designated as strain 2021, from contaminated soil at the abandoned site of an old coking plant. It was identified as a member of the genus Rhodococcus sp. strain 2021 exhibited efficient fluorene-degrading ability under optimal conditions of 400 mg/L fluorene, 30 °C, pH 7.0, and 250 mg/L trivalent arsenic. It was noted that the addition of arsenic could promote the growth of strain 2021 and improve the degradation of fluorene - a phenomenon that has not been described yet. The results further indicated that strain 2021 can oxidize As3+ to As5+; here, approximately 13.1% of As3+ was converted to As5+ after aerobic cultivation for 8 days at 30 °C. The addition of arsenic could greatly up-regulate the expression of arsR/A/B/C/D and pcaG/H gene clusters involved in arsenic resistance and aromatic hydrocarbon degradation; it also aided in maintaining the continuously high expression of cstA that codes for carbon starvation protein and prmA/B that codes for monooxygenase. These results suggest that strain 2021 holds great potential for the bioremediation of environments contaminated by a combination of arsenic and polycyclic aromatic hydrocarbons. This study provides new insights into the interactions among microbes, as well as inorganic and organic pollutants.

Bacterial response to the combined pollution of benzo[a]pyrene and decabromodiphenyl ether in soil under flooding anaerobic condition

This study investigated the interaction between the co-pollutants of Benzo[a]pyrene (BaP) and decabromodiphenyl ether (BDE-209) and the bacterial community in soil under flooding anaerobic condition. Three levels of combined pollution (at nominal concentrations of 1, 5, and 25 mg/kg, respectively, for each pollutant), their corresponding sterilized controls, and a blank control (CK) were set up. During the incubation time of 270 days, BaP attenuated more easily than BDE-209. The second-order rate constant of BaP attenuation was negatively correlated with the Ln value of initial BaP concentration. Maximal difference in bacterial community occurred between the CK soil and the highly polluted soil. Desulfomonilaceae, Parcubacteria and Rhodanobacter were probably involved in BaP and BDE-209 degradation, while Nitrosomonadaceae, Phenylobacterium and Mitochondria were significantly suppressed by BaP and BDE-209 or their degrading products. Genes narI, bcrC, fadJ, had, dmpC, narG and CfrA were involved in the degradation of BaP and BDE-209. Impacts of BaP and BDE-209 on metabolisms of carbon, nitrogen and sulfur were not significant. The results provide guidance for the management and remediation of the contaminated soil.

Applied potential assisted biodegradation of amoxicillin (AMX) using bacterial consortium isolated from a waste dump site

Antibiotics have revolutionized modern day living with their ability to effectively treat infectious diseases in humans and animals. However, the release of antibiotic compounds into the environment has led to toxic consequences. To reduce this environmental impact, it is important to employ an inexpensive and rational technology to reduce the amount of antibiotics released into the ecosystem. This study aims to explore the potential of using a bio-electrochemical system (BES) to remove Amoxicillin (AMX) from artificially contaminated soil using a microbial consortium and pure culture isolates. Under desired conditions, including an initial AMX concentration of 150 mg/L, 5 mg/L tryptone as the nitrogen source, pH of 7, temperature of 29 °C, an applied potential of 0.8 V, and an inoculum dose of 1% w/v, the BES showed a maximum degradation of 97.9% of AMX with the microbial consortium (HP03, HP09, and HP10). High performance liquid chromatography-mass spectrometry was used to analyse the intermediates formed during the degradation process, and the pathway elucidated revealed complete degradation of AMX. Phytotoxicity studies and degradation efficiency against multiple antibiotics confirmed the environmental significance of the BES with microbial consortium. Overall, this study highlights the potential of BES as a cost-effective and efficient method for reducing the release of antibiotics into the environment and provides valuable insights into the mechanisms and pathways of antibiotic degradation.

Direct and gut microbiota-mediated toxicities of environmental antibiotics to fish and aquatic invertebrates

The accumulation of antibiotics in the environment has ecological impacts that have received less attention than the human health risks of antibiotics, although the effects could be far-reaching. This review discusses the effects of antibiotics on the health of fish and zooplankton, manifesting in direct or dysbiosis-mediated physiological impairment. Acute effects of antibiotics in these organism groups are usually induced at high concentrations (LC₅₀ at ∼100-1000 mg/L) that are not commonly present in aquatic environments. However, when exposed to sub-lethal, environmentally relevant levels of antibiotics (ng/L-μg/L) disruption of physiological homeostasis, development, and fecundity can occur. Antibiotics at similar or lower concentrations can induce dysbiosis of gut microbiota which can affect the health of fish and invertebrates. We show that the data about molecular-level effects of antibiotics at low exposure concentrations are limited, hindering environmental risk assessment and species sensitivity analysis. Fish and crustaceans (Daphnia sp.) were the two groups of aquatic organisms used most often for antibiotic toxicity testing, including microbiota analysis. While low levels of antibiotics impact the composition and function of gut microbiota in aquatic organisms, the correlation and causality of these changes to host physiology are not straightforward. In some cases, negative or lack of correlation have occurred, and, unexpectedly, gut microbial diversity has been unaffected or increased upon exposure to environmental levels of antibiotics. Efforts to incorporate functional analyses of gut microbiota are beginning to provide valuable mechanistic information, but more data is needed for ecological risk assessment of antibiotics.

Insights into the role of prechlorination in algae-laden raw water distribution process: Algal organic matter and microcystin-LR release, extracellular polymeric substances (EPS) aggregation, and pipeline biofilm communities

Prechlorination routinely applied for the treatment of algae-laden raw water has received extensive attention due to its influence on water quality and aquatic microbes. In this study, prechlorination experiments with different doses were conducted in sets of model raw water distribution systems. With the elevated dose of chlorine and prolonged hydraulic retention time (HRT), the ratio of intact algal cells decreased, and the stability of water enhanced. Dissolved organic carbon (DOC) and nitrogen (DON) increased when chlorine dose elevated from 0 to 0.5 mg/L but decreased with elevations from 0.5 to 2.0 mg/L, while UV₂₅₄ showed a monotonically increasing tendency. DOC, DON and extracellular microcystin-LR increase initially and decrease thereafter with the prolonged HRT. Notably, the effects of prechlorination on extracellular polymeric substances aggregation behavior on pipe walls and microbial community composition was revealed, providing more profound understanding of the community dynamics in this engineered system. This study helped optimize strategies to improve the stability and efficiency of pretreatment of algae-laden water.

Factors affecting the hydrolysis of the antibiotic amoxicillin in the aquatic environment

The environmental fate of the frequently used broad-spectrum β-lactam antibiotic amoxicillin (AMX) is of high concern regarding the potential evolution of antimicrobial resistance (AMR). Moreover, it is known that AMX is prone to hydrolysis, yielding a variety of hydrolysis products (HPs) with yet unknown effects. Studies to identify those HPs and investigate their formation mechanisms have been reported but a long-term study on their stability in real water samples was missing. In this regard, we investigated the hydrolysis of AMX at two concentration levels in four distinct water types under three different storage conditions over two months. Concentrations of AMX and four relevant HPs were monitored by an LC-MS/MS method revealing pronounced differences in the hydrolysis rate of AMX in tap water and mineral water on the one hand (fast) and surface water on the other (slow). In this context, the occurrence, relative intensities, and stability of certain HPs are more dependent on the water type than on the storage condition. As clarified by ICP-MS, the main difference between the water types was the content of the metals copper and zinc which are supposed to catalyze AMX hydrolysis demonstrating an effective method to degrade AMX at ambient conditions.

Removal of oxytetracycline and ofloxacin in wastewater by microalgae-bacteria symbiosis for bioenergy production

The development of microalgae-bacteria symbiosis for treating wastewater is flourishing owing to its high biomass productivity and exceptional ability to purify contaminants. A nature-selected microalgae-bacteria symbiosis, mainly consisting of Dictyosphaerium and Pseudomonas, was used to treat oxytetracycline (OTC), ofloxacin (OFLX), and antibiotic-containing swine wastewater. Increased antibiotic concentration gradually reduced biomass productivity and intricately changed symbiosis composition, while 1 mg/L OTC accelerated the growth of symbiosis. The symbiosis biomass productivity reached 3.4-3.5 g/L (5.7-15.3 % protein, 18.4-39.3 % carbohydrate, and 2.1-3.9 % chlorophyll) when cultured in antibiotic-containing swine wastewater. The symbiosis displayed an excellent capacity to remove 76.3-83.4 % chemical oxygen demand, 53.5-62.4 % total ammonia nitrogen, 97.5-100.0 % total phosphorus, 96.3-100.0 % OTC, and 32.8-60.1 % OFLX in swine wastewater. The microbial community analysis revealed that the existence of OTC/OFLX increased the richness and evenness of microalgae but reduced bacteria species in microalgae-bacteria, and the toxicity of OFLX to bacteria was stronger than that of OTC.

Degrading Characterization of the Newly Isolated Nocardioides sp. N39 for 3-Amino-5-methyl-isoxazole and the Related Genomic Information

3-amino-5-methyl-isoxazole (3A5MI) is a persistent and harmful intermediate in the degradation of antibiotic sulfamethoxazole. It was accumulated in the environments day by day and has caused great environmental risks due to its refractory characteristic. Microbial degradation is economic and environmentally friendly and a promising method to eliminate this pollutant. In this study, a bacterial strain, Nocardioides sp. N39, was isolated. N39 can grow on 3A5MI as the sole carbon, nitrogen and energy resource. The effect of different factors on 3A5MI degradation by N39 was explored, including initial 3A5MI concentration, temperature, pH value, dissolved oxygen and additional carbon or nitrogen source. The degradation ability of N39 to various 3A5MI analogs was also explored. Nevertheless, the degrading ability of N39 for 3A5MI is not permanent, and long-term storage would lead to the loss of this ability. This may result from the mobile genetic elements in the bacterium according to the genomic comparison of N39 and its degrading ability-lost strain, N40. Despite this, N39 could support a lot of useful information about the degradation of 3A5MI and highlight the importance of studies about the environmental effects and potential degradation mechanism.