Isolation and Identification of Pseudomonas sp. Strain DY-1 from Agricultural Soil and Its Degradation Effect on Prometryne

Occurrence, ecological risk, and advanced removal methods of herbicides in waters: a timely review

Coastal pollution caused by the importation of agricultural herbicides is one of the main environmental problems that directly affect the coastal primary productivity and even the safety of human seafood. It is urgent to evaluate the ecological risk objectively and explore feasible removal strategies. However, existing studies focus on the runoff distribution and risk assessment of specific herbicides in specific areas, and compared with soil environment, there are few studies on remediation methods for water environment. Therefore, we systematically reviewed the current situation of herbicide pollution in global coastal waters and the dose-response relationships of various herbicides on phytoplankton and higher trophic organisms from the perspective of ecological risks. In addition, we believe that compared with the traditional single physical and chemical remediation methods, biological remediation and its combined technology are the most promising methods for herbicide pollution remediation currently. Therefore, we focus on the application prospects, challenges, and management strategies of new bioremediation systems related to biology, such as constructed wetlands, membrane bioreactor processes, and microbial co-metabolism, in order to provide more advanced methods for reducing herbicide pollution in the water environment.

Occurrence, spatiotemporal distribution patterns,partitioning and risk assessments of multiple pesticide residues in typical estuarine water environments in eastern China

The low terrain and the prosperous agriculture in the east of China, have caused the accumulation of pesticide residues in the estuaries. Therefore, this study analyzed the spatiotemporal distribution and partition tendency of 106 pesticides based on their abundance, frequencies, and concentrations in the aquatic environment of 16 river estuaries in 7 major basins in the eastern China by using solid-phase extraction (SPE) with high-performance liquid chromatography tandem mass spectrometry (HPLC‒MS/MS) and gas chromatography tandem mass spectrometry (GC‒MS/MS). In addition, potential risk of multiple pesticides was also evaluated. The results showed that herbicides were the dominant pesticide type, while triazines were the predominate substance group of pesticide. In addition, triadimenol, vinclozolin, diethylatrazine, prometryn, thiamethoxam, atrazine, and metalachlor were the major pesticides in the water, while prometryn, metalachlor, and atrazine were the main pesticides in the sediment. The average total concentration of pesticide was 751.15 ng/L in the dry season, 651.17 ng/L in the wet season, and 617.37 ng/L in the normal season, respectively. The estuaries of the Huai River Basin, the Yangtze River Basin, the Hai River Basin, and the Yellow River Basin have been affected by the low pollution treatment efficiency, weak infrastructure, and agricultural/non-agricultural activities in eastern China, resulting in relatively serious pesticide pollution. The estuaries of Huaihe River, Yangtze River, Xiaoqing River, and Luanhe River had large pesticide abundance and comparatively severe pesticide pollution, while the estuaries of Tuhai River and Haihe River had heavy pesticide contamination in the sediment, which might be induced by historical sedimentary factors. The log KOC values showed that except for thioketone, other pesticides were relatively stable due to the adsorption by sediment. The ecological risk assessment results indicated that insecticides had a high risk. Teenagers were the most severely affected by the noncarcinogenic risk of pesticides, while adults were mostly affected by the carcinogenic risk of pesticides. Therefore, pesticide hazards in the water environment of estuaries in eastern China needs to be further close supervision.

Isolation and Characterization of the Wastewater Micropollutant Phenacetin-Degrading Bacterium Rhodococcus sp. Strain PNT-23

Phenacetin, an antipyretic and analgesic drug, poses a serious health risk to both humans and aquatic organisms, which is of concern since this micropollutant is frequently detected in various aquatic environments. However, rare pure bacterial cultures have been reported to degrade phenacetin. Therefore, in this study, the novel phenacetin-degrading strain PNT-23 was isolated from municipal wastewater and identified as a Rhodococcus sp. based on its morphology and 16S rRNA gene sequencing. The isolated strain could completely degrade 100 mg/L phenacetin at an inoculum concentration of OD600 1.5 within 80 h, utilizing the micropollutant as its sole carbon source for growth. Strain PNT-23 exhibited optimal growth in LB medium at 37 °C and a pH of 7.0 with 1% NaCl, while the optimal degradation conditions in minimal medium were 30 °C and a pH of 7.0 with 1% NaCl. Two key intermediates were identified during phenacetin biodegradation by the strain PNT-23: N-acetyl-4-aminophenol and 4-aminophenol. This study provides novel insights into the biodegradation of phenacetin using a pure bacterium culture, expands the known substrate spectra of Rhodococcus strains and presents a potential new candidate for the microbial removal of phenacetin in a diverse range of environments.

Complete Genome Sequence and Function Gene Identify of Prometryne-Degrading Strain Pseudomonas sp. DY-1

The genus Pseudomonas is widely recognized for its potential for environmental remediation and plant growth promotion. Pseudomonas sp. DY-1 was isolated from the agricultural soil contaminated five years by prometryne, it manifested an outstanding prometryne degradation efficiency and an untapped potential for plant resistance improvement. Thus, it is meaningful to comprehend the genetic background for strain DY-1. The whole genome sequence of this strain revealed a series of environment adaptive and plant beneficial genes which involved in environmental stress response, heavy metal or metalloid resistance, nitrate dissimilatory reduction, riboflavin synthesis, and iron acquisition. Detailed analyses presented the potential of strain DY-1 for degrading various organic compounds via a homogenized pathway or the protocatechuate and catechol branches of the β-ketoadipate pathway. In addition, heterologous expression, and high efficiency liquid chromatography (HPLC) confirmed that prometryne could be oxidized by a Baeyer-Villiger monooxygenase (BVMO) encoded by a gene in the chromosome of strain DY-1. The result of gene knock-out suggested that the sulfate starvation-induced (SSI) genes in this strain might also involve in the process of prometryne degradation. These results would provide the molecular basis for the application of strain DY-1 in various fields and would contribute to the study of prometryne biodegradation mechanism as well.