Dirammox (direct ammonia oxidation) to nitrogen (N): discovery, current status, and perspectives.

Microbial ammonia oxidation plays an important role in nitrogen (N) cycling in natural and man-made systems. Heterotrophic microorganisms that oxidize ammonia were observed more than a century ago; however, the underlying molecular mechanism of ammonia oxidation is still mysterious. Dirammox (direct ammonia oxidation to N) is a newly described heterotrophic ammonia oxidation process in which ammonia or its organic amine is oxidized into hydroxylamine and then directly converted to N gas without the involvement of nitrite and nitrate.

Identification of a chlorosalicylic acid decarboxylase (CsaD) involved in decarboxylation of 3,6-DCSA from an anaerobic dicamba-degrading sludge.

3,6-Dichlorosalicylic acid (3,6-DCSA) is the demethylation metabolite of herbicide 3,6-dichloro-2-methoxy benzoic acid (dicamba). Previous studies have shown that anaerobic sludge further transformed 3,6-DCSA through decarboxylation and dechlorination. However, the anaerobe, enzyme, and gene involved in the anaerobic degradation of 3,6-DCSA are still unknown.

DipR, a GntR/FadR-family transcriptional repressor: regulatory mechanism and widespread distribution of the dip cluster for dipicolinic acid catabolism in bacteria.

Dipicolinic acid is an essential component of bacterial spores for stress resistance, which is released into the environment after spore germination. In a previous study, a dip gene cluster was found to be responsible for the catabolism of dipicolinic acid in Alcaligenes faecalis JQ135. However, the transcriptional regulatory mechanism remains unclear.

Characterization of cotinine degradation in a newly isolated Gram-negative strain Pseudomonas sp. JH-2.

Cotinine, the primary metabolite of nicotine in the human body, is an emerging pollutant in aquatic environments. It causes environmental problems and is harmful to the health of humans and other mammals; however, the mechanisms of its biodegradation have been elucidated incompletely. In this study, a novel Gram-negative strain that could degrade and utilize cotinine as a sole carbon source was isolated from municipal wastewater samples, and its cotinine degradation characteristics and kinetics were determined.

Nocardioides imazamoxiresistens sp. nov. Isolated from the Activated Sludge.

A Gram-staining-positive actinomycete named YZH12 was isolated from the sediment of the Yangtze River in Nanjing, Jiangsu province, China. Cells were aerobic, non-spore forming, non-motile, short rod (0.4-0.

gen. nov., sp. nov., a novel taxon within the family isolated from sediment of Qiantang River.

A Gram-stain-negative bacterium, designated LG-4, was isolated from sediment of Qiantang River in Zhejiang Province, PR China. Cells were strictly aerobic, non-spore-forming, non-motile and short-rod-shaped (1.0-1.

Isolation and Characterization of the Wastewater Micropollutant Phenacetin-Degrading Bacterium 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 sp.

Crystal structures of herbicide-detoxifying esterase reveal a lid loop affecting substrate binding and activity.

SulE, an esterase, which detoxifies a variety of sulfonylurea herbicides through de-esterification, provides an attractive approach to remove environmental sulfonylurea herbicides and develop herbicide-tolerant crops. Here, we determined the crystal structures of SulE and an activity improved mutant P44R. Structural analysis revealed that SulE is a dimer with spacious binding pocket accommodating the large sulfonylureas substrate.

Cloning and expression of the phenazine-1-carboxamide hydrolysis gene pzcH and the identification of the key amino acids necessary for its activity.

Phenazine-1-carboxamide (PCN), a phenazine derivative, can cause toxicity risks to non target organisms. In this study, the Gram-positive bacteria Rhodococcus equi WH99 was found to have the ability to degrade PCN. PzcH, a novel amidase belonging to amidase signature (AS) family, responsible for hydrolyzing PCN to PCA was identified from strain WH99.

PcaR, a GntR/FadR Family Transcriptional Repressor Controls the Transcription of Phenazine-1-Carboxylic Acid 1,2-Dioxygenase Gene Cluster in Sphingomonas histidinilytica DS-9.

In our previous study, the phenazine-1-carboxylic acid (PCA) 1,2-dioxygenase gene cluster ( cluster) in Sphingomonas histidinilytica DS-9 was identified to be responsible for the conversion of PCA to 1,2-dihydroxyphenazine (Ren Y, Zhang M, Gao S, Zhu Q, et al. 2022. Appl Environ Microbiol 88:e00543-22).

Isolation and characterization of the 2,5-pyridinedicarboxylic acid-degrading bacterium Agrobacterium sp. strain YJ-5.

2,5-Pyridinedicarboxylic acid (2,5-PDA), a natural N-heterocyclic compound and a substitute for production in plastics, was widely distributed in industrial wastewater. However, the biodegradation of 2,5-PDA has been rarely reported. In this study, strain YJ-5, which could utilize 2,5-PDA as the sole carbon source for growth was isolated from pesticide-contaminated soil.

The MocR family transcriptional regulator DnfR has multiple binding sites and regulates Dirammox gene transcription in Alcaligenes faecalis JQ135.

Microbial ammonia oxidation is vital to the nitrogen cycle. A biological process, called Dirammox (direct ammonia oxidation, NH →NH OH→N ), has been recently identified in Alcaligenes ammonioxydans and Alcaligenes faecalis. However, its transcriptional regulatory mechanism has not yet been fully elucidated.

Comparative Genomic Analysis of Carbofuran-Degrading Sphingomonads Reveals the Carbofuran Catabolism Mechanism in sp. Strain CFD-1.

The worldwide use of the carbamate insecticide carbofuran has caused considerable concern about its environmental fate. Degradation of carbofuran by sp. strain CFD-1 is initiated via the hydrolysis of its ester bond by carbamate hydrolase CehA to form carbofuran phenol.

Sulfate-Dependent Anaerobic Degradation of Herbicide Acetochlor by a Sulfate-Reducing Bacterium sp. SRB-5.

Acetochlor, an important chloroacetamide herbicide (CAAH) widely used in agriculture, has resulted in environmental contamination, especially of anoxic habitats. In this study, a sulfate-reducing bacterium, designated as SRB-5, was isolated from anaerobic activated sludge and was identified as sp. This bacterium possesses a novel anaerobic pathway capable of degrading acetochlor.

Quinolinic acid catabolism is initiated by a novel four-component hydroxylase QuiA in Alcaligenes faecalis JQ191.

Quinolinic acid (QA) is an essential nitrogen-containing aromatic heterocyclic compounds in organisms and it also acts as an important intermediate in chemical industry, which has strong neurotoxicity and cytotoxicity. The wide range of sources and applications caused the release and accumulation of QA in the environment which might poses a hazard to ecosystems and human health. However, few research on the degradation of QA by microorganisms and toxicity of QA and its metabolites were reported.

Functional analysis, diversity, and distribution of carbendazim hydrolases MheI and CbmA, responsible for the initial step in carbendazim degradation.

Strains Rhodococcus qingshengii djl-6 and Rhodococcus jialingiae djl-6-2 both harbour the typical carbendazim degradation pathway with the hydrolysis of carbendazim to 2-aminobenzimidazole (2-AB) as the initial step. However, the enzymes involved in this process are still unknown. In this study, the previous reported carbendazim hydrolase MheI was found in strain djl-6, but not in strain djl-6-2, then another carbendazim hydrolase CbmA was obtained by a four-step purification strategy from strain djl-6-2.

The Novel Monooxygenase Gene in the Gene Cluster of JQ135 Is Essential for the Initial Catabolism of Dipicolinic Acid.

Dipicolinic acid (DPA), an essential pyridine derivative biosynthesized in spores, constitutes a major proportion of global biomass carbon pool. Alcaligenes faecalis strain JQ135 could catabolize DPA through the "3HDPA (3-ydroxyiicolinic cid) pathway." However, the genes involved in this 3HDPA pathway are still unknown.

PicR as a MarR Family Transcriptional Repressor Multiply Controls the Transcription of Picolinic Acid Degradation Gene Cluster in Alcaligenes faecalis JQ135.

Picolinic acid (PA) is a natural toxic pyridine derivative as well as an important intermediate used in the chemical industry. In a previous study, we identified a gene cluster, , that responsible for the catabolism of PA in Alcaligenes faecalis JQ135. However, the transcriptional regulation of the cluster remains known.

The Novel Amidase PcnH Initiates the Degradation of Phenazine-1-Carboxamide in Sphingomonas histidinilytica DS-9.

Phenazines are an important class of secondary metabolites and are primarily named for their heterocyclic phenazine cores, including phenazine-1-carboxylic acid (PCA) and its derivatives, such as phenazine-1-carboxamide (PCN) and pyocyanin (PYO). Although several genes involved in the degradation of PCA and PYO have been reported so far, the genetic foundations of PCN degradation remain unknown. In this study, a PCN-degrading bacterial strain, Sphingomonas histidinilytica DS-9, was isolated.

Biodegradation of Quinoline by a Newly Isolated Salt-Tolerating Bacterium Strain JH145.

Quinoline is a typical nitrogen-heterocyclic compound with high toxicity and carcinogenicity which exists ubiquitously in industrial wastewater. In this study, a new quinoline-degrading bacterial strain sp. JH145 was isolated from oil-contaminated soil.

Biodegradation of quinolinic acid by a newly isolated bacterium Alcaligenes faecalis strain JQ191.

Quinolinic acid (QA) is a pyridine derivative that can be found in many organisms and is widely used in the chemical industry. However, QA possesses excitotoxic properties. To date, the catabolism of QA mediated by microorganisms has rarely been reported.

The TetR Family Repressor HpaR Negatively Regulates the Catabolism of 5-Hydroxypicolinic Acid in Alcaligenes faecalis JQ135 by Binding to Two Unique DNA Sequences in the Promoter of Operon.

5-Hydroxypicolinic acid (5HPA), an important natural pyridine derivative, is microbially degraded in the environment. Previously, a gene cluster, , responsible for 5HPA degradation, was identified in Alcaligenes faecalis JQ135. However, the transcription regulation mechanism of the cluster is still unknown.

Anaerobic biodegradation and detoxification of chloroacetamide herbicides by a novel Proteiniclasticum sediminis BAD-10.

Chloroacetamide herbicides (CAAHs) are important herbicides that were widely used to control agricultural weeds. However, their mass applications have seriously contaminated environment, and they are toxic to living beings. CAAHs are easy to enter anoxic environments such as subsoil, wetland sediment, and groundwater, where CAAHs are mainly degraded by anaerobic organisms.