Understanding Comorbidity Between Non-Suicidal Self-Injury and Depressive Symptoms in a Clinical Sample of Adolescents: A Network Analysis.

Background: Non-suicidal self-injury (NSSI) and depression often co-occur among adolescents with more severe clinical symptoms. This study examined the network structures of NSSI and depressive symptoms in adolescents. Methods: Participants were recruited in the psychiatric outpatient clinics of three tertiary hospitals between April 10 and July 10, 2023. All participants been already found with self-injury behaviors in outpatient when enrolled. NSSI diagnostic criteria and Patient Health Questionnaire-9 (PHQ-9) were utilized to collect NSSI and depressive symptoms separately. We performed a network analysis to visualize the correlation between each symptom and to identify core and bridging symptoms in comorbidities. Results: A total of 248 patients were enrolled in the study, with a mean age of 15.48 (SD = 1.62). Based on the PHQ-9 scores and grades, our results showed that the incidence of depression in adolescents with non-suicidal self-injury behavior was relatively high (N=235, 94.76%), with the majority having severe depression. The network analysis revealed that nodes D-6 "feeling bad, failing or letting yourself or your family down", D-1 "little interest or pleasure" and D-4 "feeling tired" were the most vital and most central symptoms. The most crucial bridging symptom is the node NSSI-8 "frequent thinking about self-injury", which connects the NSSI to the depression comorbid network. Conclusion: This study offers a significant symptom-level conceptualization of the association between NSSI and depressive symptoms in a clinical sample of adolescents, which not only enhances our understanding of the comorbid but also identifies potential treatment targets to prevent and treat comorbidity between adolescent NSSI and depression.

Gut microbiota and its relation to inflammation in patients with bipolar depression: a cross-sectional study.

BACKGROUND: To explore the gut microbiota characteristics in depressed patients with bipolar disorder (BD) as well as the connection between the gut microbiota and inflammatory markers. METHODS: Totally 72 depressed BD patients and 16 healthy controls (HCs) were enrolled in the study. Blood and feces samples were taken from each subject. With the help of 16S-ribosomal RNA gene sequencing, the characteristics of the gut microbiota in each participant were examined. Correlation analysis was then utilized to assess the relationship between the gut microbiota and clinical parameters. RESULTS: We found the taxonomic composition of the gut microbiota, but not its diversity, was significantly different in BD patients compared to HCs. We found the abundance of Bacilli, Lactobacillales and genus Veillonella were higher in BD patients than in HCs, while genus Dorea was more abundant in HCs. Additionally, correlation analysis showed that the bacterial genera' abundance in BD patients was strongly correlated with the severity of depression and inflammatory markers. CONCLUSIONS: According to these results, the gut microbiota characteristics were changed in depressed BD patients, which may have been associated with the severity of depression and the inflammatory pathways.

QSP: An open sequence database for quorum sensing related gene analysis with an automatic annotation pipeline.

Quorum sensing (QS) has attracted great attention due to its important role in the bacterial interactions and its relevance to water management. With the development of high-throughput sequencing technology, a specific database for QS-related sequence annotation is urgently needed. Here, Hidden Markov Model (HMM) profiles for 38 types of QS-related proteins were built using a total of 4024 collected seed sequences. Based on both homolog search and keywords confirmation against the non-redundant database, we established a QS-related protein (QSP) database, that includes 809,721 protein sequences and 186,133 nucleotide sequences, downloaded available at: https://github.com/chunxiao-dcx/QSP. The entries were classified into 38 types and 315 subtypes among 91 bacterial phyla. Furthermore, an automatic annotation pipeline, named QSAP, was developed for rapid annotation, classification and abundance quantification of QSP-like sequences from sequencing data. This pipeline provided the two homolog alignment strategies offered by Diamond (Blastp) or HMMER (Hmmscan), as well as a data cleansing function for a subset or union set of the hits. The pipeline was tested using 14 metagenomic samples from various water environments, including activated sludge, deep-sea sediments, estuary water, and reservoir water. The QSAP pipeline is freely available for academic use in the code repository at: https://github.com/chunxiao-dcx/QSAP. The establishment of this database and pipeline, provides a useful tool for QS-related sequence annotation in a wide range of projects, and will increase our understanding of QS communication in aquatic environments.

Succession of function, assembly, and interaction of microbial community in sequencing biofilm batch reactors under selenite stress.

The mechanism of interaction between selenite, a toxic substance, and the microbial community in wastewater is still not well understood. Herein, nine sequencing biofilm batch reactors were used to systematically investigate the response of the microbial community to the continuous selenite stress. The results showed that selenite affected the reactor performance and reduced the biofilm mass. Also, it increased the proportion of the living cells, and changed the protein and polysaccharide composition of the biofilm as well as cellular secretions. Selenite facilitated the removal of NO3-N, according to water-quality and bioinformatics analyses. As such, the selenite was converted into selenium nanoparticles. α-diversity analysis further revealed that 20 µM selenite enhanced the microbial community resilience, while 200 µM selenite had the reverse effect. Community composition analysis showed that Variovorax, Rhizobium, and Simkania had positive correlations with selenite (P < 0.05). Functional prediction suggested that selenite changed the C, N, and S cycle functions. Furthermore, determinism dominated the community assembly process, and the deterministic proportion increased with the increase of selenite concentration. Network analysis showed that selenite improved the stability and positive correlation ratio of the overall microbial network, and accelerated the communication between microorganisms. However, when compared with the 20 µM selenite, the 200 µM selenite boosted the competition and parasitism/predation among microorganisms. Low-abundance genera played a key role in the network of selenite-reducing microbial community. In addition, under selenite stress, biofilm network exhibited better stability and faster information exchange than suspended network, and the positive association between biofilm and suspended microorganisms increased. All in all, this research sheds light on the interaction between selenite and microbial community, as well as provides crucial information on selenium-containing wastewater.

Different toxicity to liver and gill of zebrafish by selenium nanoparticles derived from bio/chemical methods.

With the wide application of selenium nanoparticles (SeNPs) in pharmaceutical fields, the toxicity assessment is of great significance. In this study, zebrafish were selected as model organisms to compare the toxicity of SeNPs derived from biological and chemical methods. The results showed that the size of bio-SeNPs was about 5-fold bigger than chem-SeNPs. When exposed to SeNPs for 96 h, LC50 of bio-SeNPs and chem-SeNPs was 1.668 mg/L and 0.699 mg/L, respectively. Compared with the control, the results showed a significant increase in oxidative toxicity index (P < 0.05), such as glutathione (GSH), superoxide dismutase (SOD) of the liver, and gill in SeNPs-treated group. The neurotoxicity index, such as acetylcholinesterase (AchE) and Na+-K+-ATP enzyme activity, was significantly decreased both in the liver and gill (P < 0.05). It was found that the toxicity of bio-SeNPs to the liver and gill of zebrafish was lower than chem-SeNPs and the toxicity to the liver was higher than gill. In this study, the toxicity of chem-SeNPs and bio-SeNPs to the target organs of zebrafish were systematically evaluated, which provided the basis for the safe application of SeNPs synthesized by different pathways.

Indole metabolism by phenol-stimulated activated sludges: Performance, microbial communities and network analysis.

Indole and phenol often coexist in the coking wastewater, while the effects of phenol on microbial communities of indole metabolism were less explored. In this study, the microbial interactions within activated sludge microbial communities stimulated by indole (group A) or by indole and phenol (group B) were systematically investigated in sequencing batch reactors (SBRs). The results showed that the removal of indole was increased by adding phenol. By using high-throughput sequencing technology, it was found that α-diversity was reduced in both groups. According to the relative abundance analysis, the indole-degrading genus Comamonas was the core genus in both groups (33.94% and 61.40%). But another indole-degrading genus Pseudomonas was only enriched in group A with 12.22% relative abundance. Meanwhile, common aromatic degrading genus Dyella and Thermomonas were enriched only in group B. It was found that the relative abundance of cytochrome P450 and styrene degradation enzymes were increased in group B by PICRUSt analysis. Based on the phylogenetic molecular ecological networks (pMENs), module hub OTU_1149 (Burkholderia) was only detected in group B, and the positive interactions between the key functional genus Burkholderia and other bacteria were increased. This study provides new insights into our understanding of indole metabolism communities stimulated by phenol, which would provide useful information for practical coking wastewater treatment.

Investigation of indole biodegradation by Cupriavidus sp. strain IDO with emphases on downstream biotransformation and indigo production.

Indole, as a typical N-heterocyclic aromatic pollutant, poses risks to living things; however, indole-biotransformation mechanisms remain under-discussed, especially those related to its downstream biotransformation. Here, we systematically investigated the characteristics of indole degradation by strain Cupriavidus sp. IDO. We found that Cupriavidus sp. IDO could utilize 25 to 150 mg/L indole within 40 h and identified three intermediates (2-oxindole, indigo, and isatin). Additionally, integrated genomics and proteomics analysis of the indole biotransformation mechanism in strain IDO revealed 317 proteins showing significant changes (262 upregulated and 55 downregulated) in the presence of indole. Among these, three clusters containing indole oxidoreductase, CoA-thioester ligase, and gentisate 1,2-oxidoreductase were identified as potentially responsible for upstream and downstream indole metabolism. Moreover, HPLC-MS and -omics analysis offered insight into the indole-degradation pathway in strain IDO. Furthermore, the indole oxidoreductase IndAB, which initiates indole degradation, was heterologously expressed in Escherichia coli BL21(DE3). Optimization by the response surface methodology resulted in a maximal production of 135.0 mg/L indigo by the recombination strains in tryptophan medium. This work enriches our understanding of the indole-biodegradation process and provides new insights into multiple indole-degradation pathways in natural environments.

Succession of diversity, functions, and interactions of the fungal community in activated sludge under aromatic hydrocarbon stress.

Although fungi are regarded as the important degraders of aromatic hydrocarbons (AHs) in various environments, the dynamic succession and interaction of their community under aromatic hydrocarbon stress has been rarely reported. In this study, we systematically investigated the responses of the fungal community and the associations among fungal species when facing the continuous stress of two typical AHs, benzene and naphthalene. Using high-throughput sequencing technology, we demonstrated that fungal diversity displayed a significant downward trend during six weeks of continuous aromatic hydrocarbon treatment. Community succession was observed during the operational period, and the relative abundance of some typical degraders, such as Exophiala sp. and Candida sp., increased during the later period of operation. Meanwhile, by predicting the functions of the fungal community through PICRUSt2, we found that some relevant enzymes, such as peroxidase, dioxygenase, and monooxygenase, may play an important role in the degradation process and maintaining overall community multifunctionality. Furthermore, the measurement of modified normalized stochasticity ratio (MST) indicated that continuous aromatic hydrocarbon stress resulted in a stronger deterministic process in community assembly over time, suggesting environmental selection dominated succession of the fungal community in activated sludge. Finally, molecular ecological network analysis (MENA) demonstrated that, the cooperative behaviors among members, the network keystone genera related to biodegradation, such as Exophiala sp. and Haglerozyma sp., and a well-organized topological structure, together, maintained the structural stability of the fungal community under AH stress. Our study provides new insights for understanding the stability of fungal communities during the degradation of contaminants in activated sludge.

Selenium nanoparticles with photocatalytic properties synthesized by residual activated sludge.

The treatment and disposal of residual activated sludge is a worldwide problem and the research on its reuse is still only in the earliest stages. Selenite is a toxic pollutant, while selenium nanoparticles (SeNPs) are environmentally friendly and have promising application prospects. At present, the reduction mechanism of selenite under the complex system is still poorly understood. In order to explore the mechanism of SeNPs synthesis by activated sludge resource utilization, SeNPs were synthesized by activated sludge extracts of domestic sewage (DSeNPs) and coking sewage (CSeNPs), respectively. The synthesis process, zeta potential and morphology size of SeNPs were changed by pH value, extract concentration and extract composition. Under the same synthesis conditions, the morphologies of DSeNPs and CSeNPs were mainly spherical and pseudo-spherical, while CSeNPs also contained pseudo-rod shape particles. The sizes and crystal grains of CSeNPs were smaller than those of DSeNPs. Compared with DSeNPs, a specific protein (~35 kDa) was found on the surface of CSeNPs using SDS-PAGE. By analyzing the fluorescence images of the two SeNPs, it was found that the relative contents of proteins, α-d-glucopyranose polysaccharides, and ß-d-glucopyranose polysaccharides on their surfaces were obviously different (P < 0.05). The present study demonstrated that proteins, polysaccharides, humic-like and fulvic acid-like substances cooperated in the formation and stabilization of SeNPs. Furthermore, CSeNPs (bandgap: 1.68 eV) had more desirable photocatalytic performance than DSeNPs (bandgap: 1.84 eV). Under the light condition, CSeNPs could degrade Rhodamine B faster without adding hydrogen peroxide. This experiment provided a new insight into the resource utilization of activated sludge and a reference for the synthesis of nanometer selenium with excellent performance.

Antibacterial properties and mechanism of selenium nanoparticles synthesized by Providencia sp. DCX.

Selenium nanoparticles (SeNPs) have attracted great interest as a potential antimicrobial agent. However, there is limited research on the antibacterial activity and possible mechanisms of biosynthesized SeNPs. In this study, spherical bio-SeNPs with an average size of 120 nm were synthesized by strain Providencia sp. DCX. The SeNPs were further applied to investigate the antibacterial properties of model bacteria, including Gram-positive (Staphylococcus aureus, Bacillus cereus and Bacillus subtilis) and Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Vibrio parahemolyticus). The biosynthesized SeNPs demonstrated strong inhibition activity against the growth of these pathogens. When treated with 500 mg/L SeNPs, most of the tested bacteria were destructed within 12 h, among which the mortality rates of Gram-negative bacteria were much better. The leakage tests illustrated that there existed more proteins and polysaccharides outside the cells after reacted with bio-SeNPs. It was indicated that the leakages of proteins and polysaccharides were caused by permeability changes of membranes and the disruption of cell walls. And the change of reactive oxygen species (ROS) intensity indicated that oxidative damage may play the significant role in the antibacterial processes. The results showed that several bacteria could be effectively inhibited and destructed, suggesting the potential of using the biosynthesized SeNPs as antibacterial agents for bacterial infectious diseases.

Bacteria mediated Fenton-like reaction drives the biotransformation of carbon nanomaterials.

Carbon nanomaterials (CNs), which gain heightened attention as novel materials, are increasingly incorporated into daily products and thus are released into the environment. Limited research on CNs environmental fates lags their industry growth, only few bacteria have been confirmed to biotransform CNs and the mechanism behind has not been revealed yet. In this study, four types of commercial CNs, i.e. graphene oxide (GO), reduced graphene oxide (RGO), single walled carbon nanotubes (SWCNTs), and oxidized (carboxylated) SWCNTs, were selected for investigation. The biotransformation of CNs by Labrys sp. WJW, which could grow with these CNs as the sole carbon source, was investigated. The bacterial transformation was proved by qPCR, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, liquid chromatography/time-of-flight/mass spectrometry, and gas chromatograph-mass spectrometry analyses. The biotransformation resulted in morphology change, defect increase and functional group change of these CNs. Furthermore, the underlying mechanism of CNs biodegradation mediated by extracellular Fenton-like reaction was demonstrated. In this reaction, the OH production was mediated by reduction of H2O2 involved a continuous cycle of Fe(II)/Fe(III). These findings reveal a novel degradation mechanism of microorganism towards high molecular weight substrate, which will provide a new insight into the environmental fate of CNs and the guidance for their safer use.

Interaction of graphene-family nanomaterials with microbial communities in sequential batch reactors revealed by high-throughput sequencing.

The accelerated development and application of graphene-family nanomaterials (GFNs) have increased their release to various environments and converged in wastewater treatment plants (WWTPs). However, little is known about the interactions between GFNs and microbes in WWTPs. In this study, the interaction of graphene oxide (GO) or graphene (G) at different concentrations with microbial communities in sequential batch reactors was investigated. Transmission electron microscopy and Raman spectroscopy analyses showed that the structures of GFNs were obviously changed, which suggested GFNs could be degraded by some microbes. Significantly higher DNA concentration and lower cell number in high-concentration GO group were detected by DNA leakage test and qPCR analysis, which confirmed the microbial toxicity of GO. The chemical oxygen demand and ammonia nitrogen removals were significantly affected by G and GO with high concentrations. Further, high-throughput sequencing confirmed the composition and dynamic changes of microbial communities under GFNs exposure. Saccharibacteria genera incertae sedis (12.55-28.05%) and Nakamurella (20.45-29.30%) were the predominant genera at two stages, respectively. FAPROTAX suggested 12 functional groups with obvious changes related to the biogeochemical cycle of C, N and S. Molecular ecological network analysis showed that the networks were more complex in the presence of GFNs, and the increased negative interactions reflected more competition relationships in microbial communities. This study is the first to report the effect of GFNs on network of microbial communities, which provides in-depth insights into the complex and highlights concerns regarding the risk of GFNs to WWTPs.

[A new interspecies and interkingdom signaling molecule-Indole].

Indole, as a typical N-heterocyclic aromatic compound, is widespread in natural environment. A growing number of researches have proved that indole is a new interspecies and interkingdom signal molecule with certain biological activities. Indole could regulate virulence, biofilm formation, antibiotic tolerance and quorum sensing of bacteria. Indole not only modulates plant growth and defense system, but also affects intestinal inflammation, oxidative stress and hormone secretion in animals. Hence indole plays important roles in diverse aspects such as microbial metabolism, human health and plant growth, holding important significance both in biology and ecology. This review presents the history of indole from biological metabolism to signal transmission, the current knowledge on indole as an intercellular and interspecies signal of microorganisms, and interkingdom signal between bacteria and plants or animals. This review will help to explore the biological significant and ecological mechanism of indole metabolic and signal regulation in complex environment.

Application of an efficient indole oxygenase system from Cupriavidus sp. SHE for indigo production.

Indigo, one of the most widely used dyes, is mainly produced by chemical processes, which generate amounts of pollutants and need high energy consumption. Microbial production of indigo from indole has attracted much attention; however, the indole oxygenase has never been explored and applied for indigo production. In the present study, the indole oxygenase indAB genes were successfully cloned from Cupriavidus sp. SHE and heterologously expressed in Escherichia coli BL21(DE3) (designated as IND_AB). Strain IND_AB produced primarily indigo in tryptophan medium by high-performance liquid chromatography-mass spectroscopy (HPLC-MS) analysis. The preferable conditions for indigo production were pH 6.5 (normal pH), 30 °C, 150 rpm, strain inoculation concentration OD600 0.08, and induction with 1 mM IPTG at the time of inoculation. The optimal culture medium compositions were further determined as tryptophan 1.0 g/L, NaCl 3.55 g/L, and yeast extract 5.12 g/L based on single-factor experiment and response surface methodology. The highest indigo yield was 307 mg/L, which was 4.39-fold higher than the original value. This is the first study investigating indigo production using the indole oxygenase system and the results highlighted its potential in bio-indigo industrial application.

Biosynthesis of gold nanoparticles using fungus Trichoderma sp. WL-Go and their catalysis in degradation of aromatic pollutants.

An efficient green method of gold nanoparticles (AuNPs) biosynthesis was achieved by cell-free extracts of fungus Trichoderma sp. WL-Go. Based on UV-Vis spectra, AuNPs biosynthesised by cell-free extracts with 90 mg/l protein exhibited a characteristic absorption band at 556 nm and was stable for 7 days. Transmission electron microscopy images revealed that the as-synthesised AuNPs were spherical and pseudo-spherical, and the average size was calculated to be 9.8 nm with a size range of 1-24 nm. The AuNPs illustrated their good catalytic activities for reduction of nitro-aromatics (2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2-nitroaniline, 3-nitroaniline) with catalytic rate constants of 7.4 × 10-3 s-1, 10.3 × 10-3 s-1, 4.9 × 10-3 s-1, 5.8 × 10-3 s-1, 15.0 × 10-3 s-1, respectively. Meanwhile, the AuNPs also showed excellent catalytic performance in decolourisation of azo dyes with decolourisation efficiency from 82.2 to 97.5%. This study provided a green gentle method for AuNPs synthesis as well as exhibiting efficient catalytic capability for degradation of aromatic pollutants.

Inhibition of LPS-induced brain injury by NR2B antagonists through reducing assembly of NR2B-CaMKII-PSD95 signal module.

Background: Accumulating evidence suggests that inflammation is a contributor to the cause and progression of neurodegenerative disease, such as Alzheimer's disease (AD) and Parkinson disease (PD). However, the exact mechanisms of neuroinflammation are still unclear. Here, we discussed the potential mechanisms of lipopolysaccharide (LPS)-induced brain injury via NR2B antagonists (Ro25-6981) treatment in mice. Methods: Neuroinflammation was induced in mice by virtue of LPS (1 mg/kg) by intraperitoneal injection. Immunoprecipitation was performed to measure the assembly of NR2B-calmodulin dependent protein kinase II (CaMKII)-Postsynaptic density protein 95 (PSD95) signal module in the hippocampus and frontal cortex. Nissl's staining was employed to access neuron injury in the brain. Results: Data demonstrated that LPS could induce neuron damage, and promote the assembly of NR2B-CaMKII-PSD95 signal module and increase the expression of phosphorylated CaMKII and c-Jun N-terminal kinase (JNK) in the frontal cortex and hippocampus. However, NR2B antagonists could protect neuron injury against LPS-induced inflammation, inhibit the assembly of NR2B-CaMKII-PSD95 signal module and decrease the level of phosphorylated CaMKII and JNKs in mice. Conclusions: These findings indicated that the assembly of NR2B-CaMKII-PSD95 signal module is related to LPS-induced neuroinflammation, NR2B plays a key role in the assembly of NR2B-CaMKII-PSD95 signal module and NR2B antagonists could alleviate LPS-related inflammation through the reduced assembly of NR2B-CaMKII-PSD95 signal module in frontal cortex and hippocampus.

Performance and Microbial Community Analysis of Bioaugmented Activated Sludge System for Indigo Production from Indole.

Indole is a typical nitrogen-containing aromatic pollutant in coking wastewater, and it can be used for the microbial production of indigo, one of the oldest dyestuffs. In this study, the activated sludge system bioaugmented with two indigo-producing bacterial strains, wild strain Comamonas sp. MQ and recombinant Escherichia coli (ND_IND), was constructed to investigate indigo bioproduction from indole. During the operation, the bioaugmentation could promote the production of indigo, especially in early stages, and the indigo yields gradually increased from 17.5 ± 0.4 to 44.3 ± 0.5 mg/L with the increase of influent indole (80 to 282 mg/L). Illumina MiSeq sequencing revealed that the microbial community could have a noticeable shift driven by the bioaugmentation and high indole pressure. The indigenous bacteria could be more responsible for indigo production, and the dominant genera Comamonas, Diaphorobacter, Paracoccus, Aquamicrobium, Pseudomonas, and Truepera could be the key functional taxa. Based on FAPROTAX (Functional Annotation of Prokaryotic Taxa) analysis, the nitrogen metabolism-related functional groups could play important roles in indole biotransformation and indigo biosynthesis. This study should provide insights into microbial production of indigo by microbial communities.

The potential role of HO-1 in regulating the MLK3-MKK7-JNK3 module scaffolded by JIP1 during cerebral ischemia/reperfusion in rats.

Heme oxygenase (HO-1), which may be induced by Cobaltic protoporphyrin IX chloride (CoPPIX) or Rosiglitazone (Ros), is a neuroprotective agent that effectively reduces ischemic stroke. Previous studies have shown that the neuroprotective mechanisms of HO-1 are related to JNK signaling. The expression of HO-1 protects cells from death through the JNK signaling pathway. This study aimed to ascertain whether the neuroprotective effect of HO-1 depends on the assembly of the MLK3-MKK7-JNK3 signaling module scaffolded by JIP1 and further influences the JNK signal transmission through HO-1. Prior to the ischemia-reperfusion experiment, CoPPIX was injected through the lateral ventricle for 5 consecutive days or Ros was administered via intraperitoneal administration in the week prior to transient ischemia. Our results demonstrated that HO-1 could inhibit the assembly of the MLK3-MKK7-JNK3 signaling module scaffolded by JIP1 and could ultimately diminish the phosphorylation of JNK3. Furthermore, the inhibition of JNK3 phosphorylation downregulated the level of p-c-Jun and elevated neuronal cell death in the CA1 of the hippocampus. Taken together, these findings suggested that HO-1 could ameliorate brain injury by regulating the MLK3-MKK7-JNK3 signaling module, which was scaffolded by JIP1 and JNK signaling during cerebral ischemia/reperfusion.

Characterization and functional gene analysis of a newly isolated indole-degrading bacterium Burkholderia sp. IDO3.

Indole is a common N-heterocyclic pollutant as well as a signaling molecule widespread in various environmental matrices. Several bacterial strains have been reported to be able to degrade indole, while the degradation capacity and functional enzymes are poorly documented. Herein, the degradation characteristics of a newly-isolated indole-degrading strain Burkholderia sp. IDO3 were carefully investigated. Strain IDO3 exhibited superior degradation ability which could completely remove 100 mg/L indole within 14 h in mineral salt medium. It maintained comparable degradation performance under conditions of pH 4.0-9.0, temperature 25-35 °C and rotary speed 0-250 r/min, and most of the tested heavy metals and organic pollutants did not significantly affect the degradation process. Two important intermediates, i.e. isatin and anthranilate, were identified in indole degradation process. The genomic clone library technique with indigo-based screening method was successfully applied to screen the functional genes. Heterologous expression assay proved that recombinant E. coli strain carrying indole oxygenase and reductase genes iifCD could transform indole to indigo. Bioinformatic analyses indicated that the newly obtained enzyme IifC_IDO3 formed a phylogenetically separate branch from other related aromatic oxygenases. This study provides new insights into our understanding of indole degradation by Burkholderia strains and offers efficient bacterial resource for indole bioremediation.