How halogenated aromatic compounds affect the electron supply and consumption in glucose supported denitrification?

Halogenated aromatic compounds possess bidirectional effects on denitrifying bio-electron behavior, providing electrons and potentially interfering with electron consumption. This study selected the typical 4-chlorophenol (4-CP, 0-100 mg/L) to explore its impact mechanism on glucose-supported denitrification. When COD(glucose)/COD(4-CP)=28.70-3.59, glucose metabolism remained the dominant electron supply process, although its removal efficiency decreased to 73.84-49.66 %. When COD(glucose)/COD(4-CP)=2.39-1.43, 4-CP changed microbial carbon metabolism priority by inhibiting the abundance of glucose metabolizing enzymes, gradually replacing glucose as the dominant electron donor. Moreover, 5-100 mg/L 4-CP reduced adenosine triphosphate (ATP) by 15.52-24.67 % and increased reactive oxygen species (ROS) by 31.13-63.47 %, causing severe lipid peroxidation, thus inhibiting the utilization efficiency of glucose. Activated by glucose, 4-CP dechlorination had stronger electron consumption ability than NO2--N reduction (NO3--N > 4-CP > NO2--N), combined with the decreased nirS and nirK genes abundance, resulting in NO2--N accumulation. Compared with the blank group (0 mg/L 4-CP), 5-40 mg/L and 60-100 mg/L 4-CP reduced the secretion of cytochrome c and flavin adenine dinucleotides (FAD), respectively, further decreasing the electron transfer activity of denitrification system. Micropruina, a genus that participated in denitrification based on glucose, was gradually replaced by Candidatus_Microthrix, a genus that possessed 4-CP degradation and denitrification functions after introducing 60-100 mg/L 4-CP.

A 4.43-Kb deletion of chromosomal segment containing an ovate family protein confers long capsule in sesame (Sesamum indicum L.).

KEY MESSAGE: A 4.43-Kb structural variation in the sesame genome results in the deletion of the Siofp1 gene and induces the long capsule length trait. Capsule length (CL) has a positive effect on seed weight and yield in various agronomically important species; however, the molecular mechanism underlying long capsule trait regulation in sesame remains unknown. The inheritance analysis showed that long capsule traits (CL > 4.0 cm) were dominant over normal length (average CL = 3.0 cm) and were controlled by a single gene pair. Association mapping with a RIL population and 259 natural sesame germplasm accessions indicated that the target interval was 52,830-730,961 bp of SiChr.10 in sesame. Meanwhile, the structural variation (SV) of the association mapping revealed that only SV_414325 on chromosome 10 was significantly associated with the CL trait, with a P value of 1.1135E-19. SV_414325 represents a 4430-bp deletion from 414,325 to 418,756 bp on SiChr.10, covering Sindi_2155000 (named SiOFP1). In the normal length type, Siofp1 encodes 411 amino acids of the ovate family proteins and is highly expressed in the leaf, stem, bud, and capsule tissues of sesame. In accordance with the transcriptional repressor character, Siofp1 overexpression in transgenic Arabidopsis (T0 and T1 generations) induced a 25-39% greater shortening of silique length than the wild type (P < 0.05), as well as round cauline leaves and short carpels. These results confirm that SiOFP1 plays a key role in regulating CL trait in sesame and other flowering plants. These findings provide a theoretical and material basis for sesame capsule development and high-yield breeding research.

Polydopamine and calcium functionalized fiber carrier for enhancing microbial attachment and Cr(VI) resistance.

The formation of biofilm determines the performance and stability of biofilm system. Increasing the hydrophilicity of the carrier surface could efficiently accelerate the attachment and growth of microorganisms. Here, the surface of polypropylene (PP) fiber carrier was modified with polydopamine (PDA) and calcium (Ca(II)) to enhance microbial attachment and toxicity resistance. The results of surface characteristic confirmed the self-polymerization of PDA and the chelation mechanism of Ca(II). Subsequently, the biofilm formation experiments were conducted in sequencing batch biofilm reactors using both normal and chromium-containing wastewater. The biofilm on the surface of the modified carrier exhibited better nitrogen removal and Cr(VI) reduction ability. The biomass of the modified carrier was significantly increased, and the maximum microbial attachment amounts in normal wastewater and chrome-containing wastewater were 1153.34 and 511.78 mg/g carrier, respectively. Furthermore, the confocal laser scanning microscope (CLSM) indicated that the modified carrier coated with PDA and Ca(II) were both biocompatible, and the cell activity was significantly increased. 16S rRNA sequencing results showed that the modified carrier efficiently enriched both denitrification bacteria (Thauera and Flavobacterium) and chrome-reducing bacteria (Simplicispira and Arenimonas) to improve system stability and Cr(VI) resistance. Microbial phenotype prediction based on BugBase analysis further verified the enrichment effect of modified carriers on microorganisms responsible for biofilm formation and oxidative stress resistance. Overall, this work proposed a novel functional carrier that could provide references for advancing the application of biofilm systems in wastewater treatment.

Evaluation of an identification method for the SARS-CoV-2 Delta variant based on the amplification-refractory mutation system.

The Delta variant of SARS-CoV-2 dominated the COVID-19 pandemic due to its high viral replication capacity and immune evasion, causing massive outbreaks of cases, hospitalizations, and deaths. Currently, variant identification is performed mainly by sequencing. However, the high requirements for equipment and operators as well as its high cost have limited its application in underdeveloped regions. To achieve an economical and rapid method of variant identification suitable for undeveloped areas, we applied an amplification-refractory mutation system (ARMS) based on PCR for the detection of novel coronavirus variants. The results showed that this method could be finished in 90 min and detect as few as 500 copies/mL and not react with SARS-Coronavirus, influenza A H1N1(2009), and other cross-pathogens or be influenced by fresh human blood, α- interferon, and other interfering substances. In a set of double-blind trials, tests of 262 samples obtained from patients confirmed with Delta variant infection revealed that our method was able to accurately identify the Delta variant with high sensitivity and specificity. In conclusion, the ARMS-PCR method applied in Delta variant identification is rapid, sensitive, specific, economical, and suitable for undeveloped areas. In our future study, ARMS-PCR will be further applied in the identification of other variants, such as Omicron.

Insights into heavy metals shock on anammox systems: Cell structure-based mechanisms and new challenges.

Anaerobic ammonium oxidation (anammox) as a low-carbon and energy-saving technology, has shown unique advantages in the treatment of high ammonia wastewater. However, wastewater usually contains complex heavy metals (HMs), which pose a potential risk to the stable operation of the anammox system. This review systematically re-evaluates the HMs toxicity level from the inhibition effects and the inhibition recovery process, which can provide a new reference for engineering. From the perspective of anammox cell structure (extracellular, anammoxosome membrane, anammoxosome), the mechanism of HMs effects on cellular substances and metabolism is expounded. Furthermore, the challenges and research gaps for HMs inhibition in anammox research are also discussed. The clarification of material flow, energy flow and community succession under HMs shock will help further reveal the inhibition mechanism. The development of new recovery strategies such as bio-accelerators and bio-augmentation is conductive to breaking through the engineered limitations of HMs on anammox. This review provides a new perspective on the recognition of toxicity and mechanism of HMs in the anammox process, as well as the promotion of engineering applicability.

Systematical analysis of sludge treatment and disposal technologies for carbon footprint reduction.

This study aims to comprehensively analyze the Greenhouse Gases (GHGs) emissions from current sewage sludge treatment and disposal technologies (building material, landfill, land spreading, anaerobic digestion, and thermochemical processes) based on the database of Science Citation Index (SCI) and Social Science Citation Index (SSCI) from 1998 to 2020. The general patterns, spatial distribution, and hotspots were provided by bibliometric analysis. A comparative quantitative analysis based on life cycle assessment (LCA) put forward the current emission situation and the key influencing factors of different technologies. The effective GHG emissions reduction methods were proposed to mitigate climate change. Results showed that incineration or building materials manufacturing of highly dewatered sludge, and land spreading after anaerobic digestion have the best GHG emissions reduction benefits. Biological treatment technologies and thermochemical processes have great potential for reducing GHGs. Enhancement of pretreatment effect, co-digestion, and new technologies (e.g., injection of carbon dioxide, directional acidification) are major approaches to facilitate substitution emissions in sludge anaerobic digestion. The relationship between the quality and efficiency of secondary energy in thermochemical process and GHGs emission still needs further study. Solid sludge products generated by bio-stabilization or thermochemical processes are considered to have a certain carbon sequestration value and can improve the soil environment to control GHG emissions. The findings are useful for future development and processes selection of sludge treatment and disposal facing carbon footprint reduction.

LncRNA SNHG25 Promotes Glioma Progression Through Activating MAPK Signaling.

Numerous studies indicated that long non-coding RNAs (lncRNAs) play critical roles in glioma initiation and progression. SNHG25 is a newly identified lncRNA. And the functional role and molecular mechanism of SNHG25 in glioma cells have not been investigated. In this study, we found that SNHG25 was upregulated in glioma cells and tissues. CCK-8, EDU, and colony formation assays demonstrated that SNHG25 knockdown markedly inhibited glioma cell proliferation. In vivo studies showed that SNHG25 knockdown significantly inhibited tumor growth. Further studies indicated that SNHG25 positively regulated MAP2K2 through sponging miR-579-5p. High expression of SNHG25 activated MAPK signaling through MAP2K2. These data suggest that SNHG25 is a potential target and biomarker for glioma.

Effects of high ammonia loading and in-situ short-cut nitrification in low carbon­nitrogen ratio wastewater treatment by biocathode microbial electrochemical system.

The microbial electrochemical system (MES) has great advantages in wastewater treatment for rapid chemical oxygen demand (COD) removal and low sludge yield rate. Herein, biocathode MES was proposed to remove COD from high-ammonia wastewater with low carbon­nitrogen ratio and regulate the nitrogen forms in effluent for ANAMMOX process. The biocathode was more sensitive to ammonia nitrogen (NH4+-N) than anode and determined the power generation of MES. With COD of 500-550 mg L-1 in influent, increasing NH4+-N from 50 to 150 mg L-1 improved maximum power output (Pmax) from 3.0 ± 0.2 to 3.4 ± 0.1 W m-3, which was then reduced with further increase of NH4+-N from 300 to 600 mg L-1. However, for the cathodic reductive current, the negative effects of ammonia only revealed with NH4+-N ≥ 450 mg L-1. The cathodic equilibrium potential drop determined the power degradation, because the increased reductive compounds (NH4+ and COD) in catholyte. The high NH4+-N reduced the abundance of denitrifiers, exoelectrogens and organic-degrading bacteria on electrodes, while that of nitrogen-fixing bacteria increased. External alkalinity addition achieved in-situ short-cut nitrification and nitrite accumulation. With comparable NH4+ and NO2-, limited NO3- and low COD, the biocathode MES effluent was then suitable for subsequence ANAMMOX process.

Multi-omic approach provides insights into osmoregulation and osmoconformation of the crab Scylla paramamosain.

Osmoregulation and osmoconformation are two mechanisms through which aquatic animals adapt to salinity fluctuations. The euryhaline crab Scylla paramamosain, being both an osmoconformer and osmoregulator, is an excellent model organism to investigate salinity adaptation mechanisms in brachyurans. In the present study, we used transcriptomic and proteomic approaches to investigate the response of S. paramamosain to salinity stress. Crabs were transferred from a salinity of 25 ppt to salinities of 5 ppt or 33 ppt for 6 h and 10 days. Data from both approaches revealed that exposure to 5 ppt resulted in upregulation of ion transport and energy metabolism associated genes. Notably, acclimation to low salinity was associated with early changes in gene expression for signal transduction and stress response. In contrast, exposure to 33 ppt resulted in upregulation of genes related to amino acid metabolism, and amino acid transport genes were upregulated only at the early stage of acclimation to this salinity. Our study reveals contrasting mechanisms underlying osmoregulation and osmoconformation within the salinity range of 5-33 ppt in the mud crab, and provides novel candidate genes for osmotic signal transduction, thereby providing insights on understanding the salinity adaptation mechanisms of brachyuran crabs.

The role of bulk micro-nanobubbles in reagent desorption and potential implication in flotation separation of highly hydrophobized minerals.

Micro-nanobubbles (MNBs) generated during hydrodynamic cavitation (HC) have been extensively studied in mineral processing field in the past two decades. Many researchers have claimed that MNBs can effectively promote the collection of fine particles in flotation, while studies on MNBs assisted mineral separation are rare. In this study, the role of bulk MNBs in desorbing flotation reagent was investigated, with the aim of illustrating the potential effects of MNBs on minerals separation. The results showed that bulk MNBs could efficiently remove the sodium oleate (NaOl) from diaspore surfaces, reducing the residual concentration of NaOl on solids, which was more significant when the amount of NaOl pre-adsorbed was relatively small. Furthermore, lower residual concentration of NaOl on solids caused by MNBs cleaning made the particles less hydrophobic and flocs more friable. Given that gangue entrapment in flocs was one of the main limits for high-selective flotation, the roles of MNBs in enhancing reagent desorption and associated flocs breakup and reorganization probably contribute to higher separation efficiency of different minerals, which was confirmed by the flotation results of diaspore/kaolinite mixture.

A novel single chamber vertical baffle flow biocathode microbial electrochemical system with microbial separator.

A 10-liter single chamber vertical baffle flow biocathode microbial electrochemical system (MES) with microbial separator was designed for wastewater treatment. The anode and cathode compartments were incompletely isolated by the microbial separator, which enabled module integration and centralized sludge collection of MES. The effluent COD was <50 mg L-1 with COD removal of 86 ±â€¯2% and low sludge yield rate of 0.05 ±â€¯0.02 g-sludge g-1 -COD. The MES performance was mainly restricted by biocathodes and supporting matrixes with higher permeability resulted in better cathode performance. The MES obtained the maximum power density of 67.5 ±â€¯7.8 mW m-2 with two layers of filter cloth and one layer of polyurethane sponge (S2P1) and supporting matrix with moderate permeability was more suitable in overall power generation and anode stability. The influences on bio-community of both cathodes and separators by the permeability of supporting matrixes were observed.

Adsorption of bulk nanobubbles on the chemically surface-modified muscovite minerals.

Bulk nanobubbles (NBs) that are produced in the hydrodynamic cavitation (HC) process have been widely applied in mineral flotation for more than a decade, while how bulk NBs interact with minerals in the water-solid interface is still unclear. In this study, the adsorption behaviors of bulk NBs generated in the principle of HC on muscovite surfaces in the presence of dodecylamine (DDA) were investigated. The results show that NBs are likely coated with DDA in aqueous solutions. After attaching with muscovite, bulk NBs can adsorb on the mineral surfaces, probably following the three-contact line pinning theory. The adsorption of NBs increases the surface hydrophobicity of minerals, which can be inferred from the larger contact angles and the better flotation performances obtained in the presence of DDA/NBs. In addition, the adsorption of NBs is thought to be able to prevent the adsorption of DDA on the same space of the solid surfaces, which can be confirmed by the results of zeta potential measurements, contact angle measurements and AFM imaging results.

MicroRNA-96 is responsible for sevoflurane-induced cognitive dysfunction in neonatal rats via inhibiting IGF1R.

Sevoflurane is an experimental potent yet volatile anesthesia agent characterized by a low blood/gas partition coefficient. However, exposure to sevoflurane in neonatal mice has been speculated to result in learning deficits and abnormal social behavior. The aim of the present study was to investigate the relationship between sevoflurane and miR-96, in an attempt to identify the means by which it mediates IGF1R to influence the cognitive dysfunction (CD) in neonatal rats. Relationship between differentially expressed miRNAs and sevoflurane concentration was identified. The potential underlying regulatory mechanisms involved with sevoflurane were investigated through the administration of varying concentrations of the agent (1%, 2% and 4%), combined with miR-96 mimic or an inhibitor. A target prediction program was utilized, while the luciferase activity was determined in order to verify whether miR-96 targets IGF1R. The mRNA and protein levels of IGF1R, Bcl-2, Bax, and caspase-3 were measured followed by the determination of hippocampal neuron apoptosis. Learning and memory performance was assessed using the Morris water maze (MWM) test and step-down test. The obtained results highlighted a positive correlation between miR-96 and the concentration of sevoflurane, while miR-96 was confirmed to negatively target IGF1R. Our analyses indicated that 4% sevoflurane had a significantly stronger effect on reducing the levels of IGF1R and Bcl-2, while elevating the levels of miR-96, Bax and caspase-3 more so than that of 1% or 2% sevoflurane, which resulted in increased hippocampal neuron apoptosis but diminished the learning and memory performance of the rats. The addition of miR-96 mimic was demonstrated to exacerbate the influence of sevoflurane on hippocampal neurons as well as the cognitive function of the rats. The key findings of our study highlighted the role of miR-96 in the potential mechanism of sevoflurane anesthesia-induced CD in neonatal rats through the downregulation of IGF1R.

[Perioperative safety of Tibetan children with congenital heart disease undergoing cardiac surgery and anesthesia in low-altitude area].

OBJECTIVE: To observe the clinical parameters and short-term prognosis of Tibetan high-altitude area children with congenital heart disease undergoing surgery and anaesthesia in low-altitude area, and to investigate the perioperative safety of the treatment.
 Methods: From January, 2016 to December, 2016, 14 children with congenital heart disease who underwent surgery were assigned into 2 groups (n=7 each): the high-altitude area group (X group, children from Tibetan Autonomous Region) and the low-altitude area group (H group, children from Hunan Province). Echocardiography data, perioperative hemodynamic changes, postoperative recovery, complication and perioperative serum N terminal pro B type natriuretic peptide (NT-proBNP) levels were recorded.
 Results: There were no significant differences in cardiac structure and function between the 2 groups, while the incidence of pulmonary hypertension in the X group was significantly higher than that in the H group (P<0.05). There were no significant differences in perioperative hemodynamics between the 2 groups (P>0.05), while the duration in ICU in the X group was longer than that in the H group and the serum NT-proBNP level in the X group was higher than that in the H group (P<0.05).
 Conclusion: For children with congenital heart disease in Tibetan high-altitude area, undergoing surgery in low-altitude area contributes to a steady perioperative hemodynamics and helps to increase the perioperative safety. There may be a higher risk of postoperative cardiac dysfunction in Tibetan children than that in low-altitude area.

Effects of pyrite and sphalerite on population compositions, dynamics and copper extraction efficiency in chalcopyrite bioleaching process.

This study used an artificial microbial community with four known moderately thermophilic acidophiles (three bacteria including Acidithiobacillus caldus S1, Sulfobacillus thermosulfidooxidans ST and Leptospirillum ferriphilum YSK, and one archaea, Ferroplasma thermophilum L1) to explore the variation of microbial community structure, composition, dynamics and function (e.g., copper extraction efficiency) in chalcopyrite bioleaching (C) systems with additions of pyrite (CP) or sphalerite (CS). The community compositions and dynamics in the solution and on the ore surface were investigated by real-time quantitative PCR (qPCR). The results showed that the addition of pyrite or sphalerite changed the microbial community composition and dynamics dramatically during the chalcopyrite bioleaching process. For example, A. caldus (above 60%) was the dominant species at the initial stage in three groups, and at the middle stage, still dominated C group (above 70%), but it was replaced by L. ferriphilum (above 60%) in CP and CS groups; at the final stage, L. ferriphilum dominated C group, while F. thermophilum dominated CP group on the ore surface. Furthermore, the additions of pyrite or sphalerite both made the increase of redox potential (ORP) and the concentrations of Fe3+ and H+, which would affect the microbial community compositions and copper extraction efficiency. Additionally, pyrite could enhance copper extraction efficiency (e.g., improving around 13.2% on day 6) during chalcopyrite bioleaching; on the contrary, sphalerite restrained it.

Maize growth responses to soil microbes and soil properties after fertilization with different green manures.

The use of green manures in agriculture can provide nutrients, affect soil microbial communities, and be a more sustainable management practice. The activities of soil microbes can effect crop growth, but the extent of this effect on yield remains unclear. We investigated soil bacterial communities and soil properties under four different green manure fertilization regimes (Vicia villosa, common vetch, milk vetch, and radish) and determined the effects of these regimes on maize growth. Milk vetch showed the greatest potential for improving crop productivity and increased maize yield by 31.3 %. This change might be related to changes in soil microbes and soil properties. The entire soil bacterial community and physicochemical properties differed significantly among treatments, and there were significant correlations between soil bacteria, soil properties, and maize yield. In particular, abundance of the phyla Acidobacteria and Verrucomicrobia was positively correlated with maize yield, while Proteobacteria and Chloroflexi were negatively correlated with yield. These data suggest that the variation of maize yield was related to differences in soil bacteria. The results also indicate that soil pH, alkali solution nitrogen, and available potassium were the key environmental factors shaping soil bacterial communities and determining maize yields. Both soil properties and soil microbes might be useful as indicators of soil quality and potential crop yield.

Significant relationship between soil bacterial community structure and incidence of bacterial wilt disease under continuous cropping system.

Soil bacteria are very important in biogeochemical cycles and play significant role in soil-borne disease suppression. Although continuous cropping is responsible for soil-borne disease enrichment, its effect on tobacco plant health and how soil bacterial communities change are yet to be elucidated. In this study, soil bacterial communities across tobacco continuous cropping time-series fields were investigated through high-throughput sequencing of 16S ribosomal RNA genes. The results showed that long-term continuous cropping could significantly alter soil microbial communities. Bacterial diversity indices and evenness indices decreased over the monoculture span and obvious variations for community structures across the three time-scale tobacco fields were detected. Compared with the first year, the abundances of Arthrobacter and Lysobacter showed a significant decrease. Besides, the abundance of the pathogen Ralstonia spp. accumulated over the monoculture span and was significantly correlated with tobacco bacterial wilt disease rate. Moreover, Pearson's correlation demonstrated that the abundance of Arthrobacter and Lysobacter, which are considered to be beneficial bacteria had significant negative correlation with tobacco bacterial wilt disease. Therefore, after long-term continuous cropping, tobacco bacterial wilt disease could be ascribed to the alteration of the composition as well as the structure of the soil microbial community.

Insight into the effects of different cropping systems on soil bacterial community and tobacco bacterial wilt rate.

Rotation is an effective strategy to control crop disease and improve plant health. However, the effects of crop rotation on soil bacterial community composition and structure, and crop health remain unclear. In this study, using 16S rRNA gene sequencing, we explored the soil bacterial communities under four different cropping systems, continuous tobacco cropping (control group), tobacco-maize rotation, tobacco-lily rotation, and tobacco-turnip rotation. Results of detrended correspondence analysis and dissimilarity tests showed that soil bacterial community composition and structure changed significantly among the four groups, such that Acidobacteria and Actinobacteria were more abundant in the maize rotation group (16.6 and 11.5%, respectively) than in the control (8.5 and 7.1%, respectively). Compared with the control group (57.78%), maize and lily were effective rotation crops in controlling tobacco bacterial wilt (about 23.54 and 48.67%). On the other hand, tobacco bacterial wilt rate was increased in the turnip rotation (59.62%) relative to the control. Further study revealed that the abundances of several bacterial populations were directly correlated with tobacco bacterial wilt. For example, Acidobacteria and Actinobacteria were significantly negatively correlated to the tobacco bacterial wilt rate, so they may be probiotic bacteria. Canonical correspondence analysis showed that soil pH and calcium content were key factors in determining soil bacterial communities. In conclusion, our study revealed the composition and structure of bacterial communities under four different cropping systems and may unveil molecular mechanisms for the interactions between soil microorganisms and crop health.

The shift of microbial communities and their roles in sulfur and iron cycling in a copper ore bioleaching system.

Bioleaching has been employed commercially to recover metals from low grade ores, but the production efficiency remains to be improved due to limited understanding of the system. This study examined the shift of microbial communities and S&Fe cycling in three subsystems within a copper ore bioleaching system: leaching heap (LH), leaching solution (LS) and sediment under LS. Results showed that both LH and LS had higher relative abundance of S and Fe oxidizing bacteria, while S and Fe reducing bacteria were more abundant in the Sediment. GeoChip analysis showed a stronger functional potential for S0 oxidation in LH microbial communities. These findings were consistent with measured oxidation activities to S0 and Fe2+, which were highest by microbial communities from LH, lower by those from LS and lowest form Sediment. Moreover, phylogenetic molecular ecological network analysis indicated that these differences might be related to interactions among microbial taxa. Last but not the least, a conceptual model was proposed, linking the S&Fe cycling with responsible microbial populations in the bioleaching systems. Collectively, this study revealed the microbial community and functional structures in all three subsystems of the copper ore, and advanced a holistic understanding of the whole bioleaching system.

The succession pattern of soil microbial communities and its relationship with tobacco bacterial wilt.

BACKGROUND: The interaction mechanism between crop and soil microbial communities is a key issue in both agriculture and soil ecology. However, how soil microbial communities respond to crop planting and ultimately affect crop health still remain unclear. In this research, we explored how soil microbial communities shifted during tobacco cultivation under different rotation systems (control, maize rotation, lily rotation and turnip rotation). RESULTS: Our analyses showed that soil microbial communities had a general response pattern to tobacco planting, as the abundances of Proteobacteria and Planctomycetes increased while Acidobacteria and Verrucomicrobia decreased during tobacco cultivation, no matter which rotation system was adopted. Notably, tobacco decreased the diversity and co-occurrence of soil microorganisms, but maize rotation might suppress tobacco bacterial wilt by alleviating the decrease in biodiversity and co-occurrence. Molecular ecological network analysis indicated that there was stronger competition between potential disease suppressive (e.g., Acidobacteria) and inducible bacteria (e.g., Chloroflexi) in maize rotation systems. Both soil properties (e.g., pH, Ca content) and microbial communities of tobacco mature period depended on their counterparts of fallow period, and all these factors shaped tobacco disease comprehensively. CONCLUSIONS: Both soil microbial communities of fallow stage and tobacco selection shaped the communities of tobacco mature stage. And effective rotation crop (maize) could decrease the incidence of tobacco bacterial wilt by alleviating the decrease in diversity and co-occurrences of microbial populations. This study would deepen our understanding about succession mechanism of soil microbial communities during crop cultivation and their relationship with crop health.