Patulibacter defluvii sp. nov., Isolated from a Wastewater Treatment Plant in Guangzhou City, China.

A novel Gram-stain-positive, aerobic, catalase-positive, oxidase-negative, non-motile, and rod-shaped bacterium with ibuprofen-degrading capacity, designated DM4T, was isolated from the sewage of a wastewater treatment plant (WWTP) in Guangzhou city, China. Strain DM4T grew optimally at 0% (w/v) NaCl, pH 5.0-7.0, and 30 °C, forming white colonies on trypticase soy agar. C18:1ω9c, C18:2ω9.12c and C15:1ω10c were the predominant fatty acids. Results of 16S rRNA gene alignment and phylogenetic analysis indicated that strain DM4T belonged to the genus Patulibacter, was closely related to Patulibacter medicamentivorans DSM 25692T (98.5%) and P. brassicae KCTC 39817T (98.1%). Strain DM4T had a genome size of 5.33Mbp, and the DNA G + C content was 75.0%. The average nucleotide identity (ANI), average amino acid identity (AAI), and digital DNA-DNA hybridisation (dDDH) values between strain DM4T and P. medicamentivorans were 85.2%, 83.9%, and 29.0% respectively, while those between strain DM4T and P. brassicae were 78.5%, 71.3%, and 22.2%, respectively. Strain DM4T could significantly degrade ibuprofen by almost 80% after 84 h of incubation, and the degradation kinetics was well fitted with the first-order kinetics. Evidence from phenotypic, phylogenetic and chemotaxonomic analyses support that strain DM4T (= GDMCC 1.4574T = KCTC 59145T) represents a new species of the genus Patulibacter, for which the name Patulibacter defluvii sp. nov. is proposed.

Microbiomes on microplastics versus natural microcarriers: Stability and transformation during aquatic travel from aquaculture ponds to adjacent stream.

Microplastics (MPs) with different physical-chemical properties are considered as vectors for the propagation of microbes in aquatic environments. It remains unclear how plastic types impact on the plastisphere and whether different MPs spread microbes more rapidly than natural materials in microbes across distinct water bodies as proposed previously. We used in-situ incubation to investigate the microbes attached on MPs of polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC), versus that on two natural microcarriers (quartz sands and bamboo) during the travel from aquaculture ponds with impacted by fish farming to adjacent freshwater stream. The results showed that the microbial communities on the carriers were shaped not only by environmental conditions, which were primary determinants but also by carrier types. All the tested plastics did not carry more microbes than the natural carriers during the journey. The biofilm community composition on PVC is distinct from that on PE and PP MPs and natural carriers. The plastisphere of PE and PP kept microbial proportions as natural materials did but PVC retained less than nature materials. Bamboo carried more potential pathogens than plastic polymers and quartz. The results indicated that the communities of plastisphere is polymer-type dependent, and, compared with the natural materials, MPs did not show enhanced propagation of microbes, including pathogens, cross distinct environments.

Impacts of MnO2 on tomato (Lycopersicon esculentum Mill.) growth: A study with MnO2-amended organic fertilizer.

Manganese dioxide (MnO2), as a catalyst in composting processes, can accumulate in soil over multiple fertilizations. However, its impact on crop growth remains to be explored. In this study, a pot experiment was conducted to investigate the impacts of MnO2 on the tomato plant performance across various growth stages. Results showed that MnO2 reduced the plant height, leaf number and length by 35.53 %, 27.61 %, and 37.00 %, respectively, and decreased the fruit weight (23.16 %) and sugar-acid ratio (29.7 %) of fruits compared to the MnO2-free control. The adverse impacts of MnO2 on plant growth might be attributed to the inhibition of microbial activity in soil reflected by the reduction of soil urease (9.30 %) and acid phosphatase (12.52 %) activities, which decreased the efficiency of nutrients conversion and uptake. The decrease of nutrient elements in roots resulted in oxidative stress in the plant, inhibiting the plasma membrane H+-ATPase activity thereby reducing the translocation of nutrients (e.g., calcium, magnesium, and phosphorus) translocation from roots to leaves. Furthermore, the phytohormones indolebutyric acid, gibberellin, and jasmonic acid of leaves were disturbed. This study reveals the risks associated with the application of MnO2-containing organic fertilizers.

Unraveling the important role of comammox Nitrospira to nitrification in the coastal aquaculture system.

Increasing nitrogen (N) input to coastal ecosystems poses a serious environmental threat. It is important to understand the responses and feedback of N removal microbial communities, particularly nitrifiers including the newly recognized complete ammonia-oxidizers (comammox), to improve aquaculture sustainability. In this study, we conducted a holistic evaluation of the functional communities responsible for nitrification by quantifying and sequencing the key functional genes of comammox Nitrospira-amoA, AOA-amoA, AOB-amoA and Nitrospira-nxrB in fish ponds with different fish feeding levels and evaluated the contribution of nitrifiers in the nitrification process through experiments of mixing pure cultures. We found that higher fish feeding dramatically increased N-related concentration, affecting the nitrifying communities. Compared to AOA and AOB, comammox Nitrospira and NOB were more sensitive to environmental changes. Unexpectedly, we detected an equivalent abundance of comammox Nitrospira and AOB and observed an increase in the proportion of clade A in comammox Nitrospira with the increase in fish feeding. Furthermore, a simplified network and shift of keystone species from NOB to comammox Nitrospira were observed in higher fish-feeding ponds. Random forest analysis suggested that the comammox Nitrospira community played a critical role in the nitrification of eutrophic aquaculture ponds (40-70 µM). Through the additional experiment of mixing nitrifying pure cultures, we found that comammox Nitrospira is the primary contributor to the nitrification process at 200 µM ammonium. These results advance our understanding of nitrifying communities and highlight the importance of comammox Nitrospira in driving nitrification in eutrophic aquaculture systems.

Reduction of selenite to selenium nanoparticles by highly selenite-tolerant bacteria isolated from seleniferous soil.

The microbial reduction of selenite to elemental selenium nanoparticles (SeNPs) is thought to be an effective detoxification process of selenite for many bacteria. In this study, Metasolibacillus sp. ES129 and Oceanobacillus sp. ES111 with high selenite reduction efficiency or tolerance were selected for systematic and comparative studies on their performance in selenite removal and valuable SeNPs recovery. The kinetic monitoring of selenite reduction showed that the highest transformation efficiency of selenite to SeNPs was achieved at a concentration of 4.24 mM for ES129 and 4.88 mM for ES111. Ultramicroscopic analysis suggested that the SeNPs produced by ES111 and ES129 had been formed in cytoplasm and subsequently released to extracellular space through cell lysis process. Furthermore, the transcriptome analysis indicated that the expression of genes involved in bacillithiol biosynthesis, selenocompound metabolism and proline metabolism were significantly up-regulated during selenite reduction, suggesting that the transformation of selenite to Se0 may involve multiple pathways. Besides, the up-regulation of genes associated with nucleotide excision repair and antioxidation-related enzymes may enhance the tolerance of bacteria to selenite. Generally, the exploration of selenite reduction and tolerance mechanisms of the highly selenite-tolerant bacteria is of great significance for the effective utilization of microorganisms for environmental remediation.

Trace analysis of 47 psychotropic medications in environmental samples by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS).

Psychotropic medications are one of the most prescribed pharmaceuticals in the world. Given their frequent detection and ecotoxicity to the no-target organism, the emission of these medications into environments has gradually draw attention. The study developed a sensitive and reliable analytic method to simultaneously investigate 47 psychotropic medications in four matrices: wastewater, surface water, activated sludge, and sediment by ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS). These 47 target analytes include 24 antidepressants, 17 antianxiety drugs, 5 anticonvulsants, and 1 relevant hormone. Solid phase extraction (SPE) was employed to extract analytes from water-phase samples. Ultrasonic Solvent Extraction method with Enhanced Matrix Removal clean-up (USE-EMR) was utilized to extract target compounds from solid-phase samples, which requires more straightforward and convenient procedures than previous methods. The extraction recoveries of all analytes ranged from 80 % to 120 % in these four sample matrices. In this study, The limit of quantitation for 47 psychotropic medications were 0.15 ng/L (estazolam) to 2.27 ng/L (lorazepam), 0.08 ng/L (desvenlafaxine) to 2 ng/L (mianserin), 0.22 ng/g (dry weight, dw) (nordiazepam) to 3.65 ng/g (dw) (lorazepam), and 0.07 ng/g (dw) (carbamazepine) to 2.85 ng/g (lorazepam), in wastewater, surface water, sludge, and sediment, respectively. In addition, the developed method was employed to analyse actual samples in two wastewater treatment plants and their receiving rivers. Carbamazepine, escitalopram, clozapine, desvenlafaxine, diazepam, lamotrigine, sertraline, temazepam, and venlafaxine were nearly ubiquitous in all matrices. Moreover, this study indicated that the inadequate removal efficiencies of psychotropic medications in wastewater treatment plants (WWTPs) had resulted in a persistent discharge of these contaminants from human sources into environments.

Cable bacteria: widespread filamentous electroactive microorganisms protecting environments.

Cable bacteria have been identified and detected worldwide since their discovery in marine sediments in Aarhus Bay, Denmark. Their activity can account for the majority of oxygen consumption and sulfide depletion in sediments, and they induce sulfate accumulation, pH excursions, and the generation of electric fields. In addition, they can affect the fluxes of other elements such as calcium, iron, manganese, nitrogen, and phosphorous. Recent developments in our understanding of the impact of cable bacteria on element cycling have revealed their positive contributions to mitigating environmental problems, such as recovering self-purification capacity, enhancing petroleum hydrocarbon degradation, alleviating phosphorus eutrophication, delaying euxinia, and reducing methane emission. We highlight recent research outcomes on their distribution, state-of-the-art findings on their physiological characteristics, and ecological contributions.

Relationships Among Demographic Factors, Stigma, Social Support, and Self-Management in Individuals With Bipolar Disorder in Remission.

The current cross-sectional study aimed to investigate the extent to which demographic characteristics, stigma, and social support impact the self-management abilities of individuals with bipolar disorder in remission. Participants (N = 114) completed a demographic questionnaire, Self-Stigma Scale-Short Form, Social Support Rating Scale, and Self-Management Scale for Patients With Bipolar Disorder. Mean scores were 60.65 (SD = 10.42) for self-management, 35.76 (SD = 7.14) for social support, and 21.38 (SD = 5.06) for stigma. In the univariate analysis, age, educational level, method of payment for care, illness duration, and number of hospitalizations demonstrated significant associations with self-management (p < 0.05). Correlation analysis revealed a positive correlation between self-management and social support (r = 0.574, p < 0.01) and negative correlations between self-management and stigma (r = -0.489, p < 0.01) and stigma and social support (r = -0.476, p < 0.01). Multiple linear regression analysis included number of hospitalizations (ß = -3.818), social support (ß = 0.436), literacy (ß = 2.132), and stigma (ß = -0.397). Individuals in remission from bipolar disorder exhibit moderate levels of self-management. Follow-up interventions should prioritize enhancing social support and addressing stigma to promote improved self-management and overall well-being. [Journal of Psychosocial Nursing and Mental Health Services, xx(xx), xx-xx.].

The variations of native plasmids greatly affect the cell surface hydrophobicity of sphingomonads.

IMPORTANCE: Microbial cell surface hydrophobicity (CSH) reflects nonspecific adhesion ability and affects various physiological processes, such as biofilm formation and pollutant biodegradation. Understanding the regulation mechanisms of CSH will contribute to illuminating microbial adaptation strategies and provide guidance for controlling CSH artificially to benefit humans. Sphingomonads, a common bacterial group with great xenobiotic-degrading ability, generally show higher CSH than typical Gram-negative bacteria, which plays a positive role in organic pollutant capture and cell colonization. This study verified that the variations of two native plasmids involved in synthesizing outer membrane proteins and polysaccharides greatly affected the CSH of sphingomonads. It is feasible to control their CSH by changing the plasmid copy number and sequences. Additionally, considering that plasmids are likely to evolve faster than chromosomes, the CSH of sphingomonads may evolve quickly to respond to environmental changes. Our results provide valuable insights into the CSH regulation and evolution of sphingomonads.

Explaining nitrogen turnover in sediments and water through variations in microbial community composition and potential function.

Anthropogenic activities greatly impact nitrogen (N) biogeochemical cycling in aquatic ecosystems. High N concentrations in coastal aquaculture waters threaten fishery production and aquaculture ecosystems and have become an urgent problem to be solved. Existing microbial flora and metabolic potential significantly regulate N turnover in aquatic ecosystems. To clarify the contribution of microorganisms to N turnover in sediment and water, we investigated three types of aquaculture ecosystems in coastal areas of Guangdong, China. Nitrate nitrogen (NO3--N) was the dominant component of total nitrogen in the sediment (interstitial water, 90.4%) and water (61.6%). This finding indicates that NO3--N (1.67-2.86 mg/L and 2.98-7.89 mg/L in the sediment and water) is a major pollutant in aquaculture ecosystems. In water, the relative abundances of assimilation nitrogen reduction and aerobic denitrifying bacteria, as well as the metabolic potentials of nitrogen fixation and dissimilated nitrogen in fish monoculture, were only 61.0%, 31.5%, 47.5%, and 27.2% of fish and shrimp polyculture, respectively. In addition, fish-shrimp polyculture reduced NO3--N content (2.86 mg/L) compared to fish monoculture (7.89 mg/L), which was consistent with changes in aerobic denitrification and nitrate assimilation, suggesting that polyculture could reduce TN concentrations in water bodies and alleviate nitrogen pollution risks. Further analysis via structural equation modeling (SEM) revealed that functional pathways (36% and 31%) explained TN changes better than microbial groups in sediment and water (13% and 11%), suggesting that microbial functional capabilities explain TN better than microbial community composition and other factors (pH, O2, and aquaculture type). This study enhances our understanding of nitrogen pollution characteristics and microbial community and functional capabilities related to sediment-water nitrogen turnover in three types of aquaculture ecosystems, which can contribute to the preservation of healthy coastal ecosystems.

Species' functional traits and interactions drive nitrate-mediated sulfur-oxidizing community structure and functioning.

IMPORTANCE: Understanding the processes and mechanisms governing microbial community assembly and their linkages to ecosystem functioning has long been a core issue in microbial ecology. An in-depth insight still requires combining with analyses of species' functional traits and microbial interactions. Our study showed how species' functional traits and interactions determined microbial community structure and functions by a well-controlled laboratory experiment with nitrate-mediated sulfur oxidation systems using high-throughput sequencing and culture-dependent technologies. The results provided solid evidences that species' functional traits and interactions were the intrinsic factors determining community structure and function. More importantly, our study established quantitative links between community structure and function based on species' functional traits and interactions, which would have important implications for the design and synthesis of microbiomes with expected functions.

Identification of significant live bacterial community shifts in different reclaimed waters during ozone and chlorine disinfection.

Ozone and chlorine are the most widely used disinfectants for water and wastewater disinfection. They play important role in microbial inactivation but could also pose a considerable selection effect on the microbial community of reclaimed water. Classical culture-based methods that rely on the assessment of conventional bacterial indicators (e.g., coliform bacteria) could hardly reflect the survival of disinfection residual bacteria (DRB) and hidden microbial risks in disinfected effluents. Hence, this study investigated the shifts of live bacterial community during ozone and chlorine disinfection in three reclaimed waters (i.e., two secondary effluents and one tertiary effluent), adopting Illumina Miseq sequencing technology in combination with a viability assay, propidium monoazide (PMA) pretreatment. Notably, statistical analyses of Wilcoxon rank-sum test confirmed the existance of distinct differences in bacterial community structure between samples with or without PMA pretreatment. On the phylum level, Proteobacteria commonly dominated in three undisinfected reclaimed waters, while ozone and chlorine disinfection posed varied effects on its relative abundance among different influents. On the genus level, ozone and chlorine disinfection significantly changed the bacterial composition and dominant species in reclaimed waters. Specifically, the typical DRB identified in ozone disinfected effluents were Pseudomonas, Nitrospira and Dechloromonas, while for chlorine disinfected effluents, Pseudomonas, Legionella, Clostridium, Mycobacterium and Romboutsia were recognized as typical DRB, which call for much attention. The Alpha and Beta diversity analysis results also suggested that different influent compositions greatly affected the bacterial community structure during disinfection processes. Since the experiments in present study were conducted in a short period and the dataset was relatively limited, prolonged experiment under different operational conditions are needed in future to illustrate the potential long-term effects of disinfection on the microbial community structure. The findings of this study could provide insights into microbial safety concern and control after disinfection for sustainable water reclamation and reuse.

Effectiveness of pharmacological cardioversion of new-onset atrial fibrillation during thoracic surgery operations: a single-centre experience.

OBJECTIVE: Prophylactic pharmacological conversion agents could reduce the incidence of postoperative atrial fibrillation (AF) in patients undergoing thoracic operations. The current study examined whether the use of pharmacological conversion agents could help to restore sinus rhythm in patients with AF newly developed during thoracic operations. METHODS: Medical records of 18,605 patients from January 1, 2015 to December 31, 2019, at the Shanghai Chest Hospital were reviewed. Patients with non-sinus rhythm prior to the surgery (n = 128) were excluded from data analysis. The final analysis included 18,477 patients (n = 16,292 undergoing lung operations; n = 2,185 undergoing esophageal operations). RESULTS: Intraoperative AF (defined as AF lasting for at least 5 min) occurred in 646 out of a total of 18,477 subjects (3.49%). Within the 646 subjects, 258 received pharmacological conversion agents during the surgery. sinus rhythm was restored in 20.15% (52/248) of patients treated with pharmacological cardioversion and in 20.87% (81/399) patients not receiving pharmacological intervention. In a subgroup analysis of the 258 patients receiving pharmacological conversion agents, recovery of sinus rhythm was highest in beta-blocker group (35.59%, 21/59 vs. 15.78%, 15/95 in amiodarone group, p = 0.008, 5.55%, and 1/18 in amiodarone plus beta-blockers group, p = 0.016). The incidence of hypotension was higher in pharmacological conversion (27.5% vs. 9.3% in patients not receiving pharmacological intervention, p < 0.001). In subjects not recovering to sinus rhythm during the surgery (n = 513), electrical cardioversion in post-anesthesia care unit (PACU) restored sinus rhythm in > 98% of the cases (155/158 vs. 63/355 in subjects not receiving cardioversion; p < 0.001). CONCLUSIONS: Our experience shows that pharmacological conversion, in general, failed to show better treatment effectiveness on intraoperative new-onset AF within period of surgery except for beta-blockers. Patients with AF persisting beyond the surgery could be effectively managed with electrical cardioversion.

Protection of electroactive biofilms against hypersaline shock by quorum sensing.

Quorum sensing (QS) is an ideal strategy for boosting the operating performance of electroactive biofilms (EABs), but its potential effects on the protection of electroactive biofilms against environmental shocks (e.g., hypersaline shock) have been rarely revealed. In this study, a QS signaling molecule, the N-(3-oxo-dodecanoyl)-L-homoserine lactone, was employed to promote the anti-shock property of the EABs against extreme saline shock. The maximum current density of the QS-regulated biofilm recovered to 0.17 mA/cm2 after 10% salinity exposure, which was much higher than those of its counterparts. The laser scanning confocal microscope confirmed a thicker and more compact biofilm with the presence of the QS signaling molecule. The extracellular polymeric substances (EPS) might play a crucial role in the anti-shocking behaviors, as the polysaccharides in EPS of QS-biofilm had doubled compared to the groups with acylase (the QS quencher). The microbial community analysis indicated that the QS molecule enriched the relative abundance of key species including Pseudomonas sp. and Geobacter sp., which were both beneficial to the stability and electroactivity of the biofilms. The functional genes related to the bacterial community were also up-regulated with the presence of the QS molecule. These results highlight the importance of QS effects in protecting electroactive biofilm under extreme environmental shock, which provides effective and feasible strategies for the future development of microbial electrochemical technologies.

Effects of various COD/NO ratios on NOx removal performance and microbial communities in a BTF-ABR integrated system.

In this study, we investigated the removal performance of NOx and stability of the biotrickling filter-anaerobic baffled reactor (BTF-ABR) integrated system at various chemical oxygen demand (COD)/NO ratios (12.18, 6.71, and 4.63 in stages 1, 2, and 3, respectively) under 3.5% O2 and 50 ± 0.5 °C conditions for the first time. The results showed that the maximum elimination capacity of NOx was 4.46, 8.16, and 11.58 g/(m3·h) in stages 1, 2, and 3, respectively. The minimum operating cost in terms of glucose was 4.79 g of glucose/g of NO. However, a COD/NO ratio of 12.18 resulted in a wastage of carbon sources, while a COD/NO ratio of 4.63 led to about 20 mg/m3 N2O emission at the end of the study. Highly bacteria diversity and positive co-occurrence networks at the COD/NO ratio of 6.71 were the main reasons for no intermediate accumulation or N2O emission. Analysis of real-time polymerase chain reaction (PCR) indicated that nirS and norB were more sensitive to the changes in the COD/NO ratios than other denitrifying genes, and the denitrifiers with nirS filled more ecological niches as the NOx increased. Furthermore, although the decrease in COD/NO ratio significantly impacted the microbial community structure, the NOx RE was stabilized at over 90% because the micro-aerobic environment produced by ABR combined highly diverse microbes and functions in BTF, as well as the coordinated expression of denitrifying genes. Achieving efficient, stable, and low-cost denitrification is feasible in this BTF-ABR integrated system.

Quantitative models and potential surrogates for rapid evaluation and surveillance of chlorine disinfection efficacy in reclaimed water.

Chlorine disinfection has become the most widely applied and indispensable technology in wastewater treatment and reuse to mitigate microbial risk and guarantee water safety. However, owing to complexities and high concentrations of contaminants in reclaimed water, rapid evaluation of chlorine disinfection efficacy is a crucial but challenging issue. Based on intensive experimental and statistical analyses, this study has established kinetic models and potential surrogates for rapid indication of the inactivation of microbial indicators and opportunistic pathogens during chlorine disinfection in different reclaimed waters. Overall, the constructed Selleck models performed very well to simulate log removal values (LRVs) of fecal coliforms, Pseudomonas aeruginosa and heterotrophic plate counts in all reclaimed water samples (R2 = 0.877-0.990). Moreover, total and Peak A fluorescence intensity as well as fluorescence integral intensities in Regions II and IV were found to have high response sensitivities during the chlorination process. Nevertheless, their effectiveness to act as potential surrogates of LRVs of microbial indicators needs to be further validated. The results from this study can provide valuable information on microbial safety surveillance of disinfection toward sustainable and long-term water reuse.

Complexing agents-free bioelectrochemical trickling systems for highly-efficient mesothermal NO removal: The role of extracellular polymer substances.

The biological treatments are promising for nitric oxide (NO) reduction, however, the biotechnology has long suffered from high demands of NO-complexing agents (i.e., Fe(II)EDTA), leading to extra operation costs. In this study, novel complexing agents-free bioelectrochemical systems have been developed for direct NO reduction. The electricity-driven bioelectrochemical trickling system (ED-BTS, a denitrifying biocathode driven by the external electricity and an acetate-consuming bioanode) achieved approximately 68% NO removal without any NO-complexing agents, superior to the bioanode-driven BTS and open-circuit BTS. The extracellular polymeric substances from the biofilms of ED-BTS contained more polysaccharides, humic substrates, and hydrophobic tryptophan that were beneficial for NO reduction. Additionally, the external electricity altered the microbial community toward more denitrifying bacteria and a higher abundance of NO reduction genes (nosZ and cnorB). This study provides a comprehensive understanding of microbial behaviors on the adsorption and reduction of NO and proposes a promising strategy for mesothermal NO biotreatment.

A novel antimony-selective ArsR transcriptional repressor and its specific detection of antimony trioxide in environmental samples via bacterial biosensor.

Extensively industrial applications and ever-accelerated anthropogenic activities have resulted in the dramatic accumulation of Sb2O3 contaminant in the environment, leading to adverse health effects on humans and ecosystems. Although arsenite has been subjected to numerous studies and ArsR-based whole-cell biosensors have been successfully applied in field testing of arsenite, there is limited information on the biological recognition element of Sb2O3 and its actual application in biosensor construction and environmental monitoring. In this study, we identified a specific recognition element of Sb2O3, SxArsR, in Sphingobium xenophagum C1 by the induced bioluminescent signal analysis of gene expression in response to Sb2O3 exposure. Compared to the other four groups of characterized ArsRs, the novel SxArsR lacks the third cysteine residue for binding of arsenite and has a conserved histidine-cysteine "HCXC" binding site that directly and specifically binds for Sb2O3. Sb2O3 can remove SxArsR from the core operator/promoter binding sequence in the -79 region upstream of the start codon of sxarsR. Based on the specificity of SxArsR protein and the sensitivity of SxArsR-binding DNA sequence, SxArsR-based whole-cell biosensor was constructed and showed a linear relationship (R2 = 0.99) from 0.01 to 6.0 µM of Sb2O3 with a detection limit of 0.01 µM. The novel bacterial biosensor also exhibited a good performance in the detection of Sb2O3 in environmental water and sediment samples. Overall, SxArsR-based biosensor represents a promising strategy for Sb2O3 detection and may have a profound impact on further practical application of ArsR biosensor in the dual-signal simultaneous detection of arsenite and Sb2O3.

Cable bacteria accelerate the anaerobic removal of pyrene in black odorous river sediments.

Cable bacteria play an essential role in biogeochemical processes in sediments by long-distance electron transport (LDET). A potential relationship has been found between cable bacteria and organic contaminant removal; however, the mechanisms remain unclear. In this study, the response of cable bacteria to pyrene was investigated in sediments with and without pyrene, and the effect of cable bacteria on pyrene removal was explored by connecting and blocking the paths of cable bacteria to the suboxic zones. The results showed that pyrene significantly influenced the microbial community structure and the composition of cable bacteria. The pyrene removal efficiencies significantly increased with the enrichment of cable bacteria, while sulfur-reducing microorganisms and aromatic compound degraders were also significantly enriched and correlated with cable bacteria abundance. Metagenomic analysis showed that cable bacteria have a potential LDET-bound acetate/formate respiratory pathway to gain energy. The presence of pyrene probably selects and enriches cable bacteria with a high tolerance to organic contaminants and changes the related functional microbial community, leading to the acceleration of pyrene removal. This study provides new insights into the interaction mechanisms between contaminants and cable bacteria, shedding light on the applications of cable bacteria in the bioremediation of contaminants in sediments.

Cysteine-Mediated Extracellular Electron Transfer of Lysinibacillus varians GY32.

Microbial extracellular electron transfer (EET) is essential in many natural and engineering processes. Compared with the versatile EET pathways of Gram-negative bacteria, the EET of Gram-positive bacteria has been studied much less and is mainly limited to the flavin-mediated pathway. Here, we investigate the EET pathway of a Gram-positive filamentous bacterium Lysinibacillus varians GY32. Strain GY32 has a wide electron donor spectrum (including lactate, acetate, formate, and some amino acids) in electrode respiration. Transcriptomic, proteomic, and electrochemical analyses show that the electrode respiration of GY32 mainly depends on electron mediators, and c-type cytochromes may be involved in its respiration. Fluorescent sensor and electrochemical analyses demonstrate that strain GY32 can secrete cysteine and flavins. Cysteine added shortly after inoculation into microbial fuel cells accelerated EET, showing cysteine is a new endogenous electron mediator of Gram-positive bacteria, which provides novel information to understand the EET networks in natural environments. IMPORTANCE Extracellular electron transport (EET) is a key driving force in biogeochemical element cycles and microbial chemical-electrical-optical energy conversion on the Earth. Gram-positive bacteria are ubiquitous and even dominant in EET-enriched environments. However, attention and knowledge of their EET pathways are largely lacking. Gram-positive bacterium Lysinibacillus varians GY32 has extremely long cells (>1 mm) and conductive nanowires, promising a unique and enormous role in the microenvironments where it lives. Its capability to secrete cysteine renders it not only an EET pathway to respire and survive, but also an electrochemical strategy to connect and shape the ambient microbial community at a millimeter scale. Moreover, its incapability of using flavins as an electron mediator suggests that the common electron mediator is species-dependent. Therefore, our results are important to understanding the EET networks in natural and engineering processes.