Abstract:环境微生物学作为微生物学与环境科学相结合的交叉学科，已经在环境污染物质降解、废弃物资源化利用和元素生物地球化学循环等方面发挥着重要作用。《微生物学通报》本期推出的“环境微生物学主题刊”报道了研究报告11篇、专论与综述12篇，内容涵盖环境微生物与环境工程、环境微生物生理学及生物制剂、环境微生物资源的发掘与利用、环境微生物学方法学、环境微生物遗传与生理、环境污染修复与微生物多样性、环境微生物与环境健康、环境微生物学研究前沿等应用领域，期望该主题刊的出版有助于加强我国环境微生物学研究者间的交流与合作，推动环境微生物学学科的进一步发展。

Abstract:[Background] The accumulation of nitrogenous substances in water bodies will cause problems such as eutrophication and death of aquatic organisms, which seriously threatens the aquatic environment and restricts the environmental protection for the sustainable development of China. [Objective] To study the nitrogen removal performance and metabolic pathway of Acinetobacter johnsonii sp. N26, a bacterial strain with heterotrophic nitrifying-aerobic denitrifying function and screened out from sheep manure compost, for the removal of nitrogen pollutants in domestic sewage. [Methods] The growth and nitrogen removal curves of N26 in the media with ammonia nitrogen and nitrate nitrogen were established. The nitrogen removal performance of the strain was optimized by single factor experiment, and the metabolic pathway was studied by nitrogen balance analysis and functional gene identification. [Results] The growth and nitrogen removal curves illustrated that N26 rapidly removed ammonia nitrogen and nitrate nitrogen (initial concentration of 50 mg/L) with high efficiency. For the removal of ammonia nitrogen, the strain showed the removal efficiency of 95.5% and the maximum removal rate of 5.330 mg/(L·h) within 9 h. For the removal of nitrate nitrogen, the strain showed the removal efficiency of 93.6% and the maximum removal rate of 3.147 mg/(L·h) within 15 h, and only a small amount of nitrate and nitrite were accumulated in the end. The strain had the optimum nitrogen removal performance in the medium with ammonium chloride as the nitrogen source and sodium succinate as the carbon source at 30 ℃, the inoculum amount of 15%, pH 8.0–9.0, C/N ratio of 15, rotating speed of 120 r/min, and nitrogen load ≤300 mg/L (ammonia nitrogen). The results of nitrogen balance analysis and functional gene identification indicated that the nitrogen removal process of this strain was not only in line with heterotrophic nitrification-aerobic denitrification but also a short-range nitrification-denitrification process. The metabolic pathways of this strain for nitrogen removal were NH₄⁺-N→NO₂^--N→NO→N₂O→N₂ and NO₃^--N→NO₂^--N→NO→ N₂O→N₂. [Conclusion] A. johnsonii sp. N26 has excellent performance of heterotrophic nitrification-aerobic denitrification and application potential in the treatment of ammonia nitrogen pollution in water bodies. The results can provide a theoretical basis for the application of heterotrophic nitrifying-aerobic denitrifying microorganisms to the biological removal of nitrogen in domestic sewage.

Abstract:[Background] Unlike general acetogenic bacteria which usually reduce two molecules of CO₂ into one molecule of acetyl-CoA via Wood-Ljungdahl pathway, the formate dehydrogenase-lacking acetogen Clostridium bovifaecis reduces one molecule of formate and one molecule of CO₂ into acetyl-CoA and conducts acetogenic utilization of glucose only in the presence of formate. Nitrate is the preferred electron acceptor for acetogens which vary in their ability to utilize this alternative electron acceptor. However, the effect of nitrate on the carbon fixation by formate dehydrogenase-lacking Wood-Ljungdahl pathway remains unclear. [Objective] To investigate the effect of nitrate on the carbon fixation by formate-dependent acetogenesis in C. bovifaecis. [Methods] We measured the growth, substrate consumption, and product yield of C. bovifaecis cultured in the medium containing 10 mmol/L or 30 mmol/L nitrate and using glucose + formate + CO₂ as substrates. The medium without nitrate was taken as the control. [Results] The main product was ethanol with the concentrations of 5.80 mmol/L and 1.66 mmol/L, respectively, in the media with 10 mmol/L and 30 mmol/L nitrate, which were significantly lower than that (7.13 mmol/L) of the control. In addition, the glucose consumption significantly decreased in the presence of nitrate. Formate consumption decreased with the increase in nitrate concentration and became zero at the nitrate concentration of 30 mmol/L. [Conclusion] Nitrate of 30 mmol/L inhibited carbon fixation by formate-dependent acetogenesis, and that of 10 mmol/L decreased the glycolysis in C. bovifaecis.

Abstract:[Background] Due to the wide spread of drug-resistant bacteria, new antibiotics are urgently needed. Actinomycetes are major antibiotic-producing pharmaceutical resources. Saline lakes are special water bodies with high concentrations of dissolved salts. Studies have demonstrated that actinomycetes with high diversity, rich novel metabolites, and a wide range of biological activities from saline lakes are potential resource for drug discovery. [Objective] This study aims to reveal the composition of actinomycete species in the soil samples collected from Chahan Nur and identify the strains with antibacterial activities, which will accumulate strains for the discovery of novel antibacterial compounds. [Methods] The actinomycetes were isolated by dilution coating method in 19 selective culture media. The diversity and novelty of the isolates were analyzed by comparison of 16S rRNA genes. According to the taxa and novelty, representative isolates were selected for detection of the genes involved in the biosynthesis of type Ⅰ, type Ⅱ polyketide synthases (PKS) and non-ribosomal polypeptide synthases (NRPS) by PCR. The fermented broths and mycelia of representative isolates were extracted with ethyl acetate and acetone, respectively, and then antibacterial tests were carried out with the disk diffusion method. [Results] A total of 250 actinomycete strains were isolated from nine soil samples, belonging to 28 genera, 16 families of 9 orders, and Streptomyces (88 isolates, 35.2%) and Nocardiopsis (68 isolates, 27.2%) were the dominant genera. Fifteen Streptomyces isolates showed the highest 16S rRNA gene similarities below 98.65% to relative strains, which implied they might belong to four novel Streptomyces species. Meanwhile, novel species of Nocardiopsis and Nocardioides were discovered. Among the 75 tested strains, 66 strains were detected with at least one gene involved in antibiotic biosynthesis, and 20 strains carried all the three functional genes. Seven actinomycete strains with strong antibacterial activities were screened out, including five isolates of Streptomyces, one isolate of Nocardiopsis, and one isolate of Promicromonospora. [Conclusion] Soil samples from Chahan Nur have abundant culturable actinomycetes, and the active substances from some strains have strong antibacterial activities. Therefore, the secondary metabolites of these strains are worthy of further study.

Abstract:[Background] Waste plastic polyethylene (PE) is refractory due to its high chemical inertness, resulting in long-term pollution. [Objective] To investigate the effects of common plastic foam (PE) on the growth and development of Zophobas atratus and provide a theoretical basis for the application of Z. atratus as an insect in the degradation of PE plastic foam. [Methods] Z. atratus larvae were fed with four different diets: T1 (wheat bran), T2 (plastic foam), T3 (plastic foam+wheat bran), and T4 (no diet). After 30 days of feeding, the larvae were dissected and the gut contents were enriched in LB medium. The obtained culture was added to the medium with PE as the only carbon source for selective culture, from which the strains capable of degrading PE plastics were isolated. [Results] After feeding on plastic foam and wheat bran for 30 days, the Z. atratus larvae showed a survival rate of 76%. Fourier transform infrared (FTIR) spectroscopy detected significant changes in the peaks corresponding to the main functional groups of compounds in the feces, which indicated a break in the long chains of PE. Three strains causing significant erosion on the edges of PE films were isolated from the gut. [Conclusion] Z. atratus can feed on and digest PE plastics, and the gut microorganisms play a key role in the degradation of PE plastics. The findings of this study provide scientific evidence for the bioremediation of plastic pollution.

Abstract:[Background] Per-and poly-fluoroalkyl substances (PFAS), a class of organic pollutants with high surface activity, thermal stability, chemical stability, hydrophobicity, and lipophobicity, are difficult to be degraded. Due to the long-distance migration, strong environmental persistence, and bioaccumulation, PFAS has brought serious harm to the environment and organisms. [Objective] To isolate an efficient perfluorooctane sulfonamide (PFOSA)-degrading bacterium from a sewage treatment plant and analyze the degradation characteristics and mechanism. [Methods] An aerobic PFOSA-degrading bacterium was screened out from wastewater by enrichment, isolation, and purification with PFOSA as the sole carbon source. The strain was identified by morphological observation and 16S rRNA gene and whole-genome sequencing. The degradation rate and degradation products of PFOSA were analyzed by a triple quadrupole mass spectrometer. [Results] An aerobic PFOSA-degrading bacterium C11 was isolated and identified as Comamonas testosteroni. The single factor experiments for degradation condition optimization showed that the degradation rate of PFOSA by strain C11 reached 64.6% under the optimal conditions of 30 ℃, pH 7.0, and PFOSA concentration of 30 mg/L. The degradation products of PFOSA were perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFHpA), and perfluorohexanoic acid (PFHxA). According to the degradation products, we preliminarily hypothesized the degradation pathway of strain C11. Specifically, PFOS generated from the deamination of PFOSA was desulfonated and oxidized to PFOA, which was then converted into PFHpA and PFHxA after the cleavage of C–F bond. [Conclusion] Strain C11 has a strong ability of degrading PFOSA, which provides theoretical support for deciphering the biodegradation mechanism of PFOSA and exploring the bioremediation path of PFAS-contaminated environment.

Abstract:[Background] The residues of acetamiprid and other neonicotinoid insecticides have adverse effects on non-target beneficial organisms, and bacteria can promote the degradation of them. [Objective] To isolate acetamiprid-degrading strain from drilosphere and optimize the degradation conditions to improve the degradation rate. [Methods] The acetamiprid-degrading strain was isolated from drilosphere and identified based on 16S rRNA gene sequencing and physiological and biochemical characteristics. The degradation conditions were optimized by single factor test, Plackett-Burman design, steepest ascent path design, and Box-Behnken design. [Results] Strain D35 could degrade more than 55.46% of 50 mg/L acetamiprid within 72 h, and was identified as Pseudomonas sp. The optimized conditions were tryptone 10.19 g/L, 30 ℃, inoculum size 5.24%, pH 7.0, and acetamiprid at initial concentration of 50 mg/L. The degradation rate of D35 under the optimized conditions hit 80.21% within 72 h, 24.75% higher than that before the optimization. [Conclusion] We screened the neonicotinoids-degrading bacteria and strain D35 could efficiently degrade acetamiprid, which provided microbial resource for rapidly eliminating acetamiprid in the environment.

Abstract:[Background] The high temperature of textile wastewater inhibits the degradation of azo dyes by microorganisms. Little is known about the degradation of azo dyes by thermophiles. [Objective] To enrich the thermophilic microbiota that can degrade azo dyes at high temperature and study their degradation potential and genomic characteristics. [Methods] We obtained a thermophilic bacterial consortium by the enrichment method and then studied its degradation characteristics by spectrophotometry. The degradation mechanism was analyzed by full-wavelength scanning, Fourier transform infrared spectroscopy (FTIR), and gas chromatography-mass spectrometry (GC-MS). The phytotoxicity of azo dyes before and after degradation was compared. The functional genes and structure were analyzed by high-throughput sequencing. [Results] A bacterial consortium (SD1) was enriched, which can degrade azo dye at 65 ℃. SD1 was mainly composed of Caldibacillus, unclassified_f__Bacillaceae, and Geobacillus. It could degrade acid red GR within pH 5.0–9.0, 50–75 ℃, dye concentration of 100–500 mg/L, and salinity of 1%–5%. Azo reductase and NADH-DCIP were the main degrading enzymes. The results of GC-MS and FTIR demonstrated that the azo bond was broken by SD1. The phytotoxicity of acid red GR decreased after degradation. The genes encoding NADH-dependent flavin mononucleotide (FMN) azo reductase and FMN-dependent reductase involved in the degradation were detected. [Conclusion] The thermophilic bacterial consortium SD1 has great potential to be applied in the treatment of high-temperature textile wastewater.

Abstract:[Background] Tris-(1-chloro-2-propyl) phosphate (TCIPP), as an emerging organic pollutant of global wide concern, has the characteristics of high environmental concentration, difficult biodegradation, etc. It is urgent to develop efficient removal technology for TCIPP. [Objective] To obtain a new strain with high TCIPP degradation efficiency that can be used for TCIPP pollution remediation.[Methods] The strain which could degrade TCIPP with high concentration (up to 100 mg/L) in liquid was isolated from the TCIPP-contaminated soil by gradually increasing the concentration of TCIPP in the mineral salt medium. The strain was preliminarily identified according to 16S rRNA gene sequence analysis, and its characteristics of degrading TCIPP in liquid were further investigated. [Results] The strain DT-6 was identified as Ochrobactrum sp., and it could utilize TCIPP as the only carbon and energy source. When the initial concentration of TCIPP was 50 mg/L and the incubation time was 7 d, the biomass of the DT-6 strain was the largest and the degradation rate of TCIPP reached the highest (34.6%). The addition of sucrose significantly promoted the growth of the DT-6 strain but inhibited the degradation of TCIPP. [Conclusion] This study reported a highly efficient TCIPP-degrading strain, Ochrobactrum sp. DT-6, which could provide new germplasm resources for the bioremediation of TCIPP pollution in the environment.

Abstract:[Background] Microcystis aeruginosa is ubiquitous in temperate lakes and has aroused wide concern since it is a dominant bloom-forming cyanobacterium capable of producing microcystins. [Objective] To elucidate the central metabolic pathways and the efficient phosphorus-utilizing mechanism in M. aeruginosa Chao 1910 (termed Chao 1910 for short) isolated from Chaohu Lake based on the whole-genome sequence analysis and transcription verification. [Methods] The whole genome sequence was obtained by the third-generation sequencing technique, and the genes encoding the central metabolic pathways, especially the phosphorus metabolic pathways, were annotated. [Results] Chao 1910 had the closest phylogenetic relationship with M. aeruginosa NIES-843 among the Microcystis strains with known full-length genome sequences. The genes involved in the metabolic pathways such as glycolysis, pentose phosphate pathway, and nucleotide synthesis were highly conserved in Chao 1910. The genome of Chao 1910 encoded the complete pathways of phosphate transport, phosphate absorption, polyphosphate synthesis/decomposition, and other efficient phosphorus utilization pathways. Unlike other strains of M. aeruginosa, Chao 1910 did not possess the gene cluster for microcystin synthesis, which indicated that it relied on efficient phosphorus utilization to gain the competitive advantage. [Conclusion] Chao 1910 is the first M. aeruginosa strain with completed sequencing of the whole genome isolated from Chaohu Lake. It helps us to reveal the molecular mechanism of competitive advantage for the bloom-forming cyanobacteria in Chaohu Lake.

Abstract:[Background] Reed wetland is one of the main methane emission sources, and methanogenic archaea are the only known organisms producing ample methane. Whereas, the dominant methane-production pathways in the rhizosphere soil of reed in saline-alkali wetland are unknown. [Objective] To reveal the dominant methanogenic pathway in the saline-alkaline Zhalong wetland. [Methods] High-throughput sequencing of 16S rRNA gene was employed to study the diversity of methanogenic archaea and bacteria in the rhizosphere soil (0–20 cm depth) of reed in Zhalong wetland. The known methanogenic substrates including trimethylamine (TMA), methanol, betaine, acetate, and H₂/CO₂ were used to enrich the methanogenic microorganisms in the wetland soil. The methanogenic rate of each microorganism was measured to determine the predominant methanogenic pathway in the rhizosphere soil, and qPCR was employed to quantify the bacterial and archaeal groups and further predict the bacteria and archaea that jointly convert betaine to CH₄. [Results] The dominant methanoarchaea were determined to be the CO₂-reducing Methanobacterium (36.42%) and Rice Cluster II (11.55%), the methane anaerobic oxidizer Candidatus Methanoperedens (35.06%), the aceticlastic methanogen Methanosaeta (11.29%), methylotrophic Methanosarcina (6.53%), and the H₂-dependent methylotrophic methanogen Methanomassiliicoccus(4.05%). The predominant bacteria were Chloroflexi (21.55%), Proteobacteria (16.88%), Actinobacteria (13.37%), and Acidobacteria (10.00%). The highest methane-producing rate was observed in the media with the addition of TMA and betaine. The dominant bacteria reducing betaine to TMA included Sporomusaceae, Sedimentibacteraceae, Hungateiclostridiaceae, and Clostridiaceae and the dominant archaea producing CH₄ from TMA included Methanosarcina and Methanomassiliicoccus. [Conclusion] Methylotrophic methanogenesis based on the TMA from betaine reduction is the dominant methanogenic pathway in the rhizosphere soil of reed in the low-temperature Zhalong wetland.

Abstract:[Background] Pseudomonas is genus of bacteria ubiquitous in soil and water environments, among which Pseudomonas plecoglossicida NyZ12 is a Gram-negative bacterium that can grow on cyclohexylamine as the sole carbon and nitrogen source, with the genome up to 7.0 Mb. [Objective] To investigate whether the genome of P. plecoglossicida NyZ12 has plasticity and variability. [Methods] P. plecoglossicida NyZ12 was continuously cultured with succinic acid or the intermediate cyclohexanone as the carbon source for natural mutation, and then the mutants incapable of growing on cyclohexylamine as the sole carbon and nitrogen source were isolated. The whole genomes of the mutants T₁ and T₂ were sequenced and compared with that of the wild-type P. plecoglossicida NyZ12. [Results] The genomes of mutants T₁ and T₂ presented a large number of deletions and mutations compared with the wild type. A large number of repeats, transposons, and prophages were present in the two missing large gene fragments. [Conclusion] The genome of P. plecoglossicida NyZ12 is characterized with plasticity and variability. This study explores the possible mechanism and gives insight into the adaptation and evolution of microorganisms.

Abstract:The development and spread of antibiotic resistance in the environment pose potential risks to human health. With the advances in high-throughput sequencing and bioinformatics, metagenomics has been widely used in the study of antibiotic resistomes in different environmental samples. This paper introduces two metagenomic methods for environmental resistome screening, summarizes the current mainstream bioinformatic tools and databases, and describes the risk assessment framework of environmental resistome and the related practice based on metagenomic technology. We aim to provide a feasible roadmap for the monitoring, risk assessment, and control of environmental resistome.

Abstract:Medium and long-chain alkanes are key parts of petroleum hydrocarbons. They are the main cause of the high viscosity of underground crude oil, low oil recovery, and long-term pollution of the ecological environment after leakage due to their strong hydrophobicity, high viscosity, low chemical activity, and difficulty in degradation. As a result, they are important degradation targets in terms of improving oil recovery and treating petroleum pollution in the environment. As a new and efficient green technology, microbial degradation of medium and long-chain alkanes has gained popularity. This paper summarized the interphase adaptation and transport process of medium and long-chain alkanes in microbial degradation, membrane proteins related to the transport process, metabolic pathways of aerobic and anaerobic microorganism degradation, gene regulation mechanism in aerobic degradation, and putative gene regulation mechanism in anaerobic degradation. Furthermore, prospects for the research direction of microbial degradation of medium and long-chain alkanes were presented, serving as references for subsequent related research.

Abstract:Organohalide-respiring bacteria (OHRB) play a key role in the in-situ bioremediation of chlorinated ethenes-contaminated groundwater. Improving the abundance and activity of OHRB is of great significance for the complete removal of chlorinated ethenes. Given that OHRB tend to coexist with multifarious microorganisms, metabolic interaction among microbial species has been considered to be a common phenomenon. The complete innocuity of organic pollutants requires the cooperative metabolism of microbial flora. Therefore, from the perspective of interspecific metabolic interaction of microorganisms, this paper presented a brief review of the current dechlorinating microbial resources as well as the mechanism of the dechlorination, particcularly the interspecific metabolic interaction of obligate OHRB, non-obligate OHRB and non-OHRB, and the mechanisms. Moreover, we proposed to construct the synthetic microbial community based on interspecific interaction to improve the anaerobic biodegradation efficiency of chlorinated ethenes, hoping to guide the rapid and complete innocuity of chlorinated ethenes in the environment.

Abstract:Estrogen is an important class of environmental endocrine disruptors. Microbial degradation is considered as one of the most greenest, environmentally friendly, and economical methods to remove estrogens and remediate polluted environment. This paper analyzed the main sources and hazards of estrogens, reviewed the reported estrogen-degrading microorganisms, summarized the progress of genetic and genomics related to estrogen degradation, and described the estrogen degradation pathways and mechanisms. Finally, the microbial degradation of environmental estrogens was summarized, and future research directions of estrogen degradation was prospected.

Abstract:Nitrifiers are omnipresent in drinking water systems. While being capable of degrading nitrogenous contaminants in drinking water treatment process, nitrifiers accelerate the consumption of disinfectant in drinking water distribution systems, thus posing a serious threat to public health. This paper introduces the methodological techniques currently used in the detection of nitrifiers and summarizes the distribution characteristics of nitrifiers in filters, drinking water distribution systems, and secondary water supply systems. Further, it elucidates the influencing mechanism of environmental and engineering factors on nitrifiers, discusses the augmentation and suppression of nitrification in drinking water system and prospects the future research and application of nitrifiers.

Abstract:Partial nitrification (PN) is a novel low-carbon technology for biological nitrogen removal from wastewater. With the application of anaerobic ammonia oxidation (anammox), PN, as the essential electron acceptor (i.e., NO₂^-) supplier for anammox, has become a hot topic in the field of wastewater nitrogen removal. Ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) are the two key groups of microorganisms involved in PN. To achieve a stable and efficient PN process, we need to clarify the microbial ecology of AOB and NOB for the washout of NOB and regulation of AOB and strengthen the predictability of microbial community. From the viewpoint of microbial ecology, this review introduced the taxonomic status, physiological properties, and niche separation of AOB and NOB, and highlighted the growth kinetics, community assembly, environmental factors, and mutual interactions of AOB and NOB in the PN process. Finally, we propose the future research directions involving the two groups of microorganisms, aiming to provide theoretical guidance for the rapid start-up and stable operation of the PN process.

Abstract:Removal of microorganisms in soil and groundwater environments is closely related to groundwater resource protection, groundwater pollution treatment, and soil pollution prevention. Due to complex structures and spatial heterogeneity of porous media in nature, the removal of microorganisms is susceptible to multiple environmental factors. This paper summarized several models, theories, and research methods of typical removal of microorganisms in porous media, and sorted out three factors (physical, chemical, and biological factors) affecting the removal of microorganisms in porous media. The physical factors included the particle size, surface roughness, saturation, ambient temperature, and flow rate in porous media. The chemical factors include pH, ionic species and strength, soluble organic matter content, and chemical properties of porous media. The biological factors involve not only the microbial species, cell size, and cell surface properties, but also the secretion of extracellular polymers, flagellar mediated motility, and chemotaxis. The purpose of this paper is to improve the understanding of the removal of microorganisms in porous media by reviewing the related research in recent years, to provide a theoretical basis for its practical application in the remediation of polluted groundwater and soil.

Abstract:Plant endophytes, important microbial resources that can produce novel biomolecules and various enzymes through metabolism, have broad application prospects in such fields as agriculture, plant protection, and pharmaceutical industries. It is currently an important way to understand the relationships between endophytes and medicinal plants, for the improvement of both medicinal plants’ growth and quality. Thanks to their rich diversity, plant endophytes play a variety of important roles in host plants’ growth, such as nitrogen fixation, phosphorus solubilization, siderophore production, plant hormone IAA (indole-3-acetic acid) secretion, ACC (1-aminocyclopropane-1-carboxylate) deaminase production, stress resistance enhancement, and secondary metabolites production. Through a review of relevant literature, this paper focused on the relationship between endophytes and medicinal plants, mainly exploring the growth-promoting mechanism of endophytes of medicinal plants in host plants and envisioning the application of new techniques in the study of plant endophytes. This paper is expected to effectively elucidate the growth-promoting effect of endophytes on medicinal plants by adopting molecular means and to provide theoretical references for their applications in related fields.

Abstract:Cadmium (Cd) is one of the major hazardous pollutants threatening grain production. Cd(II) with good dissolubility and high mobility tends to be absorbed and accumulated by plants. Microorganisms have evolved detoxification mechanisms under Cd(II) stress, which include the inhibition of Cd(II) uptake, activation of Cd(II) efflux, and sequestration of Cd(II) into cells. A variety of microorganisms have been reported to immobilize Cd(II) by biosorption and extracellular precipitation. These microorganisms exhibit great potential to bioremediate cadmium-contaminated soils. This review summarizes the molecular mechanisms of microbial detoxification of cadmium, microbial interaction, and microorganism-plant interaction, and then introduces the latest research progress in the bioremediation of cadmium contamination by microorganisms.

Abstract:Unreasonable treatment and leakage of petrochemical products lead to massive release of petroleum hydrocarbons into the environment. Petroleum pollution has been a global concern. Being cost-efficient and environmentally friendly, bioremediation has been widely used for the removal and degradation of products in petroleum industry. Accumulation evidence has shown that functional microbial communities play an important role in the bioremediation of petroleum-contaminated environment, particularly bacteria. However, the ex-situ and in-situ bioremediation faces the following challenges: ease of functional microflora imbalance and unclear degradation pathway of petroleum hydrocarbons. Thus, this review summarizes the structures, metabolic pathways of petroleum hydrocarbons, and functional genes of bacterial communities in different types of petroleum-contaminated environments and microcosmic bioremediation experimental systems. Moreover, the trends of research on microbial treatment of petroleum pollution are summarized. Thereby, this study is expected to serve as a reference for the formulation and implementation of microbial remediation schemes for petroleum-contaminated sites.

Abstract:Global climate change affects the processes and functions of terrestrial ecosystems where soil microbial community plays a crucial role in almost all of the biogeochemical cycles. Here, we reviewed the direct and indirect responses of soil microbial activities (e.g., soil respiration and enzyme activities) and community structure to individual and multiple global change factors, including elevated CO₂ concentration, warming, altered precipitation, and nitrogen deposition. Besides, we summarized the mechanisms for the adaptation of soil microbial community and the responses of functional microorganisms involved in soil carbon and nitrogen cycle to climate change. Generally, these global change factors may have positive, negative, or insignificant effects on soil microbial communities, and different functional microorganisms also showed different sensitivity to them. Moreover, the interactive effect of multiple global change factors on soil microbial community structure may be additive, synergistic, or antagonistic. However, there is a paucity of research on the combined effects of multiple global change factors, such as three, four, and even more factors. In addition, the distribution of the studied areas is uneven, and studies involving various ecosystems with large spatial and temporal scale are scarce. No comprehensive ecosystem model is available to simulate and predict the effects of global change on soil microbial communities. Finally, we summarized the research trends: (1) dynamic monitoring of soil microbial communities in multiple ecosystems in large spatial scale for a long time involving multiple global change factors, (2) the interaction of multiple global change factors, and (3) development of comprehensive ecosystem model to accurately estimate the impact of global climate change and factors’ interaction on soil microbial community. These will help to accurately predict the response of ecosystem, especially soil microbial ecosystems, under future global climate change scenarios, and lay a basis for the sustainable development of ecosystems.

Abstract:The accelerated industrialization has aggravated the water pollution in China. The discharge of high-salinity organic wastewater will lead to further deterioration of the environment. The effective treatment of wastewater is essential for the recycle of water resources. This paper reviews the research progress in microbial treatment of high-salinity organic wastewater through typical cases and introduces the survival and tolerance mechanisms of microorganisms in high-salinity environment and the research and application of microbial treatment of high-salinity industrial organic wastewater. Furthermore, this paper puts forward the existing problems and the prospect of the research and application in this field, which can provide references for the development of biological treatment of high-salinity industrial organic wastewater.