Abstract:[Objective] We are aiming to study the growth characteristics of Sphingomonas sp. YL-JM2C when triclocarban acts as carbon source; to mine putative genes encoding catechol 1,2-dioxygenase and catechol 2,3-dioxygenase from strain YL-JM2C; and to express, purify and functionally identify the putative catechol dioxygenase, then revealing the characters of catechol dioxygenases in this strain. [Methods] The growth of S. sp. YL-JM2C was measured at different pH values with different triclocarban concentrations on the optimized R2A medium containing extremely low amount of single carbon source. The putative catechol dioxygenase genes were cloned and heterologous expressed in E. coli BL21(DE3), and purified through AKTA purifier system. The purified proteins were functionally identified based on their abilities to catalyze the ring cleavage of catechol as well as its derivatives 3-chlorocatechol and 4-chlorocatechol. Their enzymatic characters were also determined through enzyme kinetics parameters. [Results] The optimal pH value was 7.0?7.5 for the growth of strain YL-JM2C, and this strain was able to utilize triclocarban as the carbon source and the optimum concentration for its growth was in the range of 4?8 mg/L. With adding 4 mg/L triclocarban, the biomass of strain YL-JM2C increased over time when this strain grew in the optimized R2A medium containing 0.01% of yeast extract and mineral salts. Six putative catechol dioxygenase genes (stcA1, stcA2, stcA3, stcE1, stcE2 and stcE3) were found through bioinformatics analysis. All exhibited catechol dioxygenase activities through assay using crude enzymes expressed in E. coli, except StcE3. Further, after purification, the substrate range analyses revealed that StcA1, StcA2 and StcA3 belonged to type II catechol 1,2-dioxygenase while StcE1 and StcE2 were identified as the novel type catechol 2,3-dioxygenase, which were all able to catalyze the ring cleavage of catechol and chlorocatechol. The kinetics parameters obtained from purified enzymes revealed that the enzymes exhibited highest affinity and catalytic efficiency to catechol, followed by 4-chlorocatechol. [Conclusion] In this research, five active catechol dioxygenase genes are functional identified from a single strain, which all have the ability to catalyze the ring cleavage of catechol and chlorocatechol. Among them, StcA1, StcA2, and StcA3 belong to type II catechol 1,2-dioxygenase, and StcE1 and StcE2 are new type catechol 2,3-diocygenase. This study will be greatly helpful to explore the diverse capability for the microbial aromatic degradation of microbes using catechol and chlorocatechol as ring-cleavage substrates.

Abstract:[Objective] Reconstituted tobacco technology has been one important method to treat and reuse the tobacco waste, in which ligini degradation in tobacco stem is a challenge key problem to resolve. To realize the flexible control of lignin, tobacco waste extract (TWE) was selected to screen high activity lignin-degrading strains for potential utilizaiton in recontituted tobacco process. [Methods] A lignin-degrading Bacillus subtilis SM isolated from tobacco waste extract (TWE), was inoculated into MSM (mineral salt medium) with kraft lignin (KL) as the sole carbon source and cultured at 30 °C, pH 7.0 for 4 days to detect the efficiency of lignin degradation. The results were analyzed by HPLC, TOC, GPC and chromaticity. The degradation of tobacco stem lignin by SM in MSM was also detected after 4 days culture at pH 7.0 and 30 °C. [Results] Degradation could be achieved for sodium lignosulfonate with Mw=534.5, while no significant degradation and a little compoition change were detected for kraft lignin. The decolorization rate reached 40.7%, while mineralization rate of lignin was only 5.4%. However, the weight loss rate of tobacco stem reached above 50% (while control group is 18.9%), and lignin content in tobacco stem reduced by about 70%. [Conclusion] Bacillus subtilis SM isoalted from tobacco waste extract (TWE) can grow on MSM with kraft lignin as the sole carbon source and degrade the lignin in tobacco stem effectively. It is potential for for liginin degradation of tobacco waste materials.

Abstract:[Objective] We isolated and identified alkane-degrading bacteria to provide microbial resources to remediate petroleum hydrocarbon pollution. [Methods] With n-hexadecane as sole carbon source, we identified strain LAM1007 isolated from Daqing oil-contaminated field by analysis of morphological, physiological and biochemical characteristics, cellular chemical composition, and 16S rRNA gene sequence. Furthermore, single factor experiment was used to evaluate various parameters including temperature, pH, biomass, shaking speed, concentration of n-hexadecane (0.1%, 0.3%, 0.5%, 1.0%, 1.5% and 2.0%, v/v). [Results] Strain LAM1007 was isolated and identified as a member of the genus Acinetobacter. Optimum condition of the strain was in an inorganic salt medium supplemented with n-hexadecane at 30 °C, pH 7.0, 1% (v/v) biomass and 180 r/min. The degradation of n-hexadecane (0.3% v/v) was 90% after 60 h under the optimum conditions. [Conclusion] Acinetobacter sp. LAM1007 has the potential to remediate petroleum hydrocarbon pollution.

Abstract:[Objective] The main objectives of this study were (i) to investigate the role of Mcc, a periplasmic monohemecytochrome c, in the extracellular electron transfer process of Shewanella decolorationis S12, and (ii) to provide new information for a complete understanding of bacterial extracellular electron transfer. [Methods] An mcc-mutant was created by using a suicide plasmid. The planktonic and biofilm growth of the mutant and wild type strains were compared by using cell optical density and confocal laser scanning microscope. Furthermore, the extracellular electron transfer capacities including electrode respiration, iron reduction and azo dye reduction of the two strains were analyzed. [Results] Although no significant difference was detected in iron and azo dye reduction between the wild type and mutant strains, mutant strain showed 34.1% decrease in electrode respiration capacity when using electrode as electron acceptor in microbial fuel cells in comparison with the wild type strain. In microbial fuel cells, the mcc-mutant showed similar planktonic growth profile but lower electrode biofilm forming capacity compared to the wild type strain. [Conclusion] The results demonstrated that Mcc played an important and specific role in the periplasmic electron transfer of S. decolorationis S12 electrode respiration, Mcc-deficiency caused significantly decrease in the electrode respiration and biofilm growth capacities of S. decolorationis S12.

Abstract:[Objective] To screen efficient dibutyl phthalate-degrading bacterium from the environment. [Methods] A bacterial strain ZJUTW that could degrade dibutyl phthalate was isolated from sludge of river of Hangzhou city, and identified by morphological, physiological characteristics and the analysis of 16S rRNA gene sequence. Its dibutyl phthalate-degrading characteristics were studied. [Results] Strain ZJUTW was identified as Arthrobacter sp. The optimal temperature was 30 °C and optimal pH between 7.0 and 8.0. The degradation was best fitted by first-order kinetic equation and the half-life was 10.47 h at 800 mg/L dibutyl phthalate of initial concentration. Dibutyl phthalate of 1 200 mg/L could be completely degraded by the resting cell (OD600=1.2) in 20 h. GC-MS analysis of the metabolites revealed that initial step of dibutyl phthalate degradation was transesterification. [Conclusion] Based on the high-tolerance ability and high removal rate of the isolated Arthrobacter sp. ZJUTW, this strain has a potential for remediation of hazardous phthalates.

Abstract:2016年11月，“第十九次全国环境微生物学学术研讨会”在重庆市召开。八百多名国内外与会者围绕环境微生物学前沿基础、污染物降解与微生物修复、废弃物资源化利用与环境生物技术、微生物生态、微生物资源与分布等五个主题进行了多种形式的交流讨论。会议充分展现了我国环境微生物学研究、应用进展和良好的发展前景，其中部分领域的研究工作国际领先。《微生物学通报》针对本次研讨会组织出版了本期《环境微生物学主题刊》，旨在展示我国环境微生物学最新的研究进展和成果，促进环境微生物学及相关学科的交流和发展。

Abstract:[Objective] This study focused on gene cloning, expression and functional characterization of 2,3-dihydroxybiphenyl-1,2-dioxygenase BphC encoded by bphC gene from Arthrobacter sp. strain YC-RL1 in the biodegradation process of polychlorinated biphenyls (PCBs). [Methods] Cloning bphC gene using the whole genome of YC-RL1 as a template and then transformed into Escherichia coli BL21(DE3) for prokaryotic expression. The recombinant enzyme BphC was purified through Ni2+ column based on affinity chromatography and its activity was measured in different ranges of pH and temperatures using 2,3-dihydroxybiphenyl as a substrate. We also assayed effects of different metal-ion on the enzyme and further detected the kinetic parameters according to the Michaelis equation. [Results] The bphC gene, size of 930 bp, was cloned by PCR and expressed in E. coli BL21(DE3). The 6-His tagged recombinant BphC was then purified and the optimum pH and temperature were pH 7.4 and 30 °C in vitro, respectively. Effects of metal ions on BphC differed from each other as Fe2+, Cu2+ and Cd2+ promoted the activity while others inhibited in varying degrees. Kinetic parameters of BphC acting on 2,3-DHBP were measured as below: Km: 8.67 mmol/L, Vmax: 27.32 μmol/s, kcat: 15.55 s–1, kcat/Km: 1.79 L/(mmol·s), respectively, of which the catalytic efficiency was much higher than some other homogeneous enzymes. [Conclusion] The gene bphC of strain YC-RL1 is vital in the process of PCBs biodegradation and the encoded enzyme BphC was revealed to be a very important aromatic ring lyase, which had high affinity to its substrates and could efficiently degrade them in vitro. This study showed a very good applicable value of bphC gene from Arthrobacter sp. strain YC-RL1.

Abstract:[Objective] We studied acetate production from H2/CO2 by mixed cultures from diverse ecosystems and applied the system for syngas fermentation. [Methods] Undefined mixed cultures from waste activate sludge, freshwater sediment, anaerobic methanogenic sludge and cow manure were used for the bioconversion of H2/CO2 and enriched H2/CO2-converting cultures from cow manure were applied as inoculums for syngas fermentation. Gas and volatile fatty acids contents were measured by a gas chromatograph. We used 454 pyrosequencing and qPCR assay to reveal the community structure during the bioconversion. [Results] Acetate, ethanol and butyrate accumulated in cow manure and waste activated sludge during the incubation under H2/CO2 headspace with final acetate concentrations of approximately 63 mmol/L and 40 mmol/L, respectively, significantly higher than that of 3 mmol/L and 16 mmol/L in freshwater sediment and anaerobic methanogenic sludge. Diverse types of acetogens were found in waste activated sludge and cow manure. The major putative acetogens belonged to the species Clostridium spp., Sporomusa malonica and Acetoanaerobium noterae in waste activated sludge, and to Clostridium spp., Treponema azotonutricium and Oxobacter pfennigii in cow manure. [Conclusion] Both the richness and the number of acetogens were important factors for the bioconversion of H2/CO2 by mixed cultures. Enriched H2/CO2-converting cultures can use syngas as carbon source to produce acetate and ethanol.

Abstract:[Objective] We studied the oil degradation pattern and the responses of cyanobacteria to crude oil at a series of concentrations, analyzed the resistance of cyanobacteria when treated with oil, explored the succession of cyanobacterial phylotypes under oil stress, and to provide scientific basis to judge if secondary environmental problems such as eutrophication would be caused by oil. [Methods] Microcosm experiments including untreated control (CK) and those treated with crude oil at a series of concentrations (25, 125 and 250 g/kg dry weight (wt), designated as, Light oil (LO), Medium oil (MO) and Heavy oil (HO), respectively) were set up in the laboratory. Gas chromatography-flame ionization detector (GC-FID) was adopted to analyze the degradation of crude oil. Cyanobacterial 16S rRNA genes were used to illustrate the diversity and richness of cyanobacteria and the alteration of genus during incubation period. [Results] A green mat appeared on the surfaces of sediments in the LO group on day 31 and didn’t occur in other groups. Clone libraries of cyanobacterial 16S rRNA genes revealed that the diversity of cyanobacteria reduced in the oiled sediments, while few genus such as Oscillatoria and Prochlorococcus increased at later stage. In addition, large proportion of sequences affiliated to uncultured genus might imply novel species. [Conclusion] This study indicated that cyanobacteria exhibited high resistance to crude oil. Oil could stimulate the cyanobacteria growth and might lead to cyanobacteria bloom in some situations. This study circumvents traditional cumbersome technologies, such as isolation and culture-based methods for cyanobacteria investigation, which is significant to molecular ecology analysis on cyanobacteria.

Abstract:[Objective] The archaea are recognized as key players participating in the global biogeochemical cycles in marine sediments. The knowledge upon community structure and metabolic functions of archaea is the basis to understand their potential contributions on the biogeochemical cycles globally. [Methods] Archaeal diversity in the sediments of three areas at the northern continental slope of SCS was surveyed using high-through sequencing for 16S rRNA gene. [Results] The major archaeal groups in the sediments was found to include Bathyarchaeota, Thermoplasmata, Woesearchaeota (DHVEG-6), Thaumarchaeota (Marine Group I), Lokiarchaeota and Marine Hydrothermal Vent Group (MHVG), also with low abundant of AK8, Marine Benthic Group A and Terrestrial Hot Spring Crenarchaeota Group (THSCG). Anaerobic methane oxidation (AOM) microbes (Anaerobic methanotrophic archaea, ANME), mainly ANME-1, ANME-2ab and ANME-2c were also found in the potential gas hydrate zone. Methyl coenzyme-M reductase alpha subunit (mcrA) gene, which encodes the key enzyme in methane metabolism, was also recovered from these sites, implying potentially active methane cycling. Quantitative PCR results showed that the abundance for bacterial 16S rRNA gene, archaeal 16S rRNA gene and mcrA gene were 105?107 copies/g (wet weight), 105?106 copies/g (wet weight) and 103?105 copies/g (wet weight), respectively. [Conclusion] These results revealed high diversity of archaea and rich microbial recourses in SCS sediments, layed the foundation for further analysis and understanding of archaeal mediated carbon cycling in the sediments of SCS.

Abstract:[Objective] Analysis and comparison of the bacterial community diversity in Suaeda roots rhizosphere and non-rhizosphere polycyclic aromatic hydrocarbons (PAHs) contaminated saline soil to provide the basis for plant-microbial remediation of PAHs contaminated saline soil. [Methods] Soil samples were collected from Suaeda roots rhizosphere and non rhizosphere at an oil well site in Shengli oil field. Bacterial community structures were analyzed by high throughput sequencing, and further the abundance of PAH-ring hydroxylating dioxygenase (PAH-RHDα) genes in soil was detected by Real-time PCR. [Results] The salt content of Suaeda roots rhizosphere soil is 22.51 g/kg, which is significantly lower than the salt content (40.03 g/kg) in non rhizosphere soil. The pH of rhizosphere and non-rhizosphere soil were basically the same, which were 8.20 and 8.22. The organic matter content and total nitrogen content of rhizosphere soil is 24.41 g/kg and 1.59 g/kg, respectively, which made C/N 15. These contents of non rhizosphere soil are 18.80 g/kg and 0.71 g/kg, respectively, which made C/N 26. The bacterial communities were analyzed and at least 53 854 and 30 312 sequencing were obtained for rhizosphere and non-rhizosphere soil samples. At 97% similarity level, the OTU number, Chao 1 index and ACE index are 5 934, 11 461 and 15 555 respectively in rhizosphere soil sample, which are higher than the index values in non-rhizosphere soil (4 262, 8 262 and 11 186). The rhizosphere soil contains 32 phyla and 758 genera of bacteria, more than those in the bare soil (28 phyla and 676 genera). Bacteria abundance and diversity of Suaeda roots rhizosphere soil were higher than that of the non-rhizosphere soil. There are rich resources of haloalkaliphilic microorganisms in PAHs-contaminated saline alkali soil, such as Thioalkalispira, Halothiobacillus, Thiohalophilus, and the PAH-RHDα genes were detected in the rhizosphere soil. [Conclusion] Haloalkaliphilic bacteria such as Thioalkalispira, Halothiobacillus, and Thiohalophilus were the dominant microorganism in PAHs-contaminated saline alkali soil. Suaeda can reduce the salt content and improve the C/N value of rhizosphere soil effectively, simultaneously increase the diversity of microbial communities structure and the abundance of PAH-RHDα genes. Therefore, Suaeda was beneficial to promote halophilic PAHs degrading microorganisms play a role in bioremediation of PAHs-contaminated saline-alkali soil.

Abstract:[Objective] To examine the stable maintenance and conjugative transfer of the dioxin-catabolic plasmids pDF01 (170 kb) and pDF02 (242 kb) harbored by Rhodococcus sp. strain p52. [Methods] We monitored the presence of pDF01 and pDF02 in strain p52 during continuous transfer in LB medium. We also performed mating experiments using strain p52 as a donor and bacterial strains belonging to different genera as recipients, and confirmed the transconjugant by colony hybridization and Southern hybridization. Further, we examined the function of catabolic genes in a transconjugant by degrading test. [Results] Both pDF01 and pDF02 could maintain in strain p52 after continuous transfer in LB medium less than 47 times, but pDF01 was lost after 65 times transfer in LB medium. Plasmid pDF01 and pDF02 could transfer concomitantly from strain p52 to the recipient strains, such as Rhodococcus rhodochrous, Rhodococcus erythropolis, Janibacter terrae and Arthrobacter sp., while Arthrobacter sp. showed the highest transconjugation frequency of 3.5×10?6 colonies per recipient. The results of Southern hybridization confirmed that Arthrobacter sp. transconjugant obtained pDF01 and pDF02. Furthermore, the catabolic plasmids could function in Arthrobacter sp. transconjugant, which could use dibenzofuran for growth comparing with the donor strain p52. [Conclusion] The dioxin-degrader Rhodococcus sp. strain p52 has potential for genetic bioaugmentation in contaminated environments.

Abstract:[Objective] To clone and express an esterase gene e22 from marine bacterium Altererythrobacter epoxidivorans CGMCC 1.7731T and characterize the enzyme. [Methods] Screening of the genome of strain CGMCC 1.7731T obtained an esterase-encoding gene, e22. The gene was amplified by PCR and cloned into the expression vector pET-28a. Then, the recombinant plasmid was transformed into Escherichia coli BL21(DE3) for heterogenetic expression. After purified by affinity chromatography, the enzyme was characterized. [Results] The amino acids sequence analysis indicated E22 belongs to Family II of lipolytic enzyme. The enzymatic property assay revealed that E22 had maximum activity using p-nitrophenyl butyrate as substrate. It was an alkaline esterase that had highest activity at pH 10.5. The optimal reaction temperature was 55 °C. After incubated at 60 °C for 2 h, E22 still remained over 50% activity, which showed its moderate thermal stability. The activity of E22 was not significantly affected by the presence of 1% methanol, 1% Triton X-100 or 0.1% SDS. On the contrary, the addition of 10 mmol/L Ba2+ and Ca2+ would apparently inhibit the catalytic capacity of E22. [Conclusion] E22 is a novel marine esterase with excellent properties such as thermostability, and alkaline, organic solvent and detergent tolerance. These characteristics suggest its application prospects in the industrial production.

Abstract:[Objective] Water-soluble hexavalent chromium (Cr(VI)) environment and human hazards are the social problems to be solved urgently. Thus, the purpose of this study was to provide a scientific basis and a new method for Cr(VI) contaminated water bioremediation by the purification of Cr(VI) reduction strains and the application of the reduction properties in microbial fuel cells. [Methods] The samples were collected from the outfall of Lanzhou section of Yellow River. Then screened strains with Cr(VI) reduction ability by plate method and applied LZU-26 strain with the strongest Cr(VI) reducing ability to microbial fuel cells, measured the electricity generation capacity and Cr(VI) reduction characteristics. [Results] Strain LZU-26 can reduce 95.89% of Cr(VI) after 24 h and 99.97% after 48 h at initial Cr(VI) concentration of 0.4 mmol/L respectively. Furthermore, applying LZU-26 to microbial fuel cell biological cathode, we obtained the maximum voltage is 68 mV and the maximum power density is 6.8 W/cm2. And the Cr(VI) reduction rate of biological cathode (68.9%) was higher than that of chemical cathode (14.7%) and control group (2.7%). [Conclusion] Strain LZU-26 as a bio-cathode of MFCs will be an efficient, economical and environmentally friendly technology of chromium-containing wastewater treatment.

Abstract:[Objective] This study aims to isolate and identify chitin-degradation bacteria from the hindgut of a fungus-growing termite Macrotermes barneyi. [Methods] Using an oligotrophic medium containing chitin as the only carbon source, chitin-degradation bacteria were screened and identified based on the transparent zone around the clone and morphological, physiological and biochemical properties as well as 16S rRNA gene sequence analysis. [Results] Eight chitin-degradation strains, which belong to Bacillus, Brevibacillus, Cellulomonas, Dactylosporangium, Flavobacterium, Paenibacillus, Sphingomonas and Stenotrophomonas, were isolated from the gut of M. barneyi. In addition to chitinase activity, the strains also exhibit β-glucosidase and endoglucanase activities. [Conclusion] Eight chitin-degradation strains, which also have other carbohydrate-active degradation activities, were obtained from the hindgut of M. barneyi. The study can help us understanding how gut symbionts facilitate termite in its food digest.

Abstract:[Objective] To uncover the diversity of cultivable lipase-producing bacterial isolated from the sediments of Bohai Sea and expand our knowledge on lipase-producing bacteria. Through screening efficient lipase production strains to expanding the marine lipase-producing microorganism resources. [Methods] The lipase-producing bacteria were isolated by using tween -80 plate and tributyrin plate from 8 sediment samples of the Bohai Sea. The diversity of these bacteria was evaluated through phylogenetic analyses based on 16S rRNA gene sequences. Using the p-nitrophenol method to detect extracellular lipase activity and select high lipase producing strains. [Results] A total of 51 lipase-producing strains were isolated from 8 sediment samples. The isolates were classified into 8 genera of three phyla including Bacteroidetes, Proteobacteria, and Firmicutes, with Pseudoalteromonas (35.2%), Marinobacter (23.5%) and Sulfitobacter (17.6%) as the dominant. Enzyme activity test showed that all the strains were able to secrete lipase, and a lipase-producing strain Marinobacter sp. 70623 possesses the highest lipase activity of 42.4 U/mL. [Conclusion] The cultivable lipase-producing bacteria isolated from the sediment of Bohai Sea are abundant with Pseudoalteromonas, Marinobacter and Sulfitobacter bacteria as the dominant groups, all the tested strains possess lipase activity, and the highest lipase activity producing strain Marinobacter sp. 70623 was obtained in this study.

Abstract:Chromium is a transitional metal mainly existing as hexavalent [CrO42?, Cr2O72?, Cr(VI)] and trivalent [Cr(OH)3, Cr(III)] forms in the natural environment. Several microorganisms have evolved various transformation and resistant mechanisms for chromium detoxification to resist the poisonous chromium. Microbial chromium-transformation contain Cr(VI) reduction and Cr(III) oxidation. Chromate-reducing microbes can transform high toxic Cr(VI) to low or non-toxic Cr(III). These microbes show a big potential to bioremediate chromium-contaminated soil and water. In addition, various microbes have been reported to participate in Cr(III) oxidation. These microorganisms play a key role in the chromium transformation and biogeochemical cycle. So far, four microbial chromium-resistant mechanisms have been found including: (1) reducing the uptake of Cr(VI); (2) Cr(VI) efflux; (3) removing intracellular oxidative stress; and (4) DNA repair. This review mainly focuses on summarizing the molecular mechanisms and new research progress in chromate transformation and bioremediation of chromium contamination by microorganisms.

Abstract:Carbon cycle is among the most important biogeochemical cycles in ecosystems, and microorganisms play critical roles in lots of its primary processes, such as carbon fixation, methane metabolism and carbon degradation. With the deep insight into functions of microbes in carbon cycle, we could better understand how they response and regulate the global climate change, which is a hot spot in the studies of microbial ecology. Previous studies focused on microbial isolations and cultivations, however, only little of the microorganisms in nature are cultivable while a majority of microorganisms are uncultured. With rapid development of the metagenomics technology, in-situ and comprehensive investigation of microbial functions and structures became feasible. In this article, we briefly introduced several widely-applied metagenomics technology such as quantitative PCR, DNA fingerprinting, microarray, clone library and high-throughput sequencing. Furthermore, we reviewed the advanced studies by using metagenomic methods to investigate the key functional genes involving in carbon cycle, including carbon fixation, methanogenesis, methane oxidation and carbon degradation. Finally, we prospected the future studies of the microbial metagenomics in carbon cycle.

Abstract:Bathyarchaeota, formerly known as Miscellaneous Crenarchaeotal Group (MCG), are a newly named uncultured archaeal phylum with widespread occurrence in marine and freshwater sediments at relatively high abundance. Recently, 23 subgroups were found in Bathyarchaeota with diverse distinct physiological and biochemical functions, such as degradation ability on proteins, polymeric carbohydrates, fatty acids, aromatics and methyl compounds, acetate production, dissimilatory nitrite and sulfate reduction, participating in methane cycling, indicating that they are one of the most important drivers in carbon cycling on the Earth. In this review, we give a brief summary of recent studies on Bathyarchaeota, including their taxonomy, distribution and physiological characteristics. In addition, we also highlight the current study on Bathyarchaeota in coastal ecosystems, and indicate the future research directions of Bathyarchaeota in coastal ecosystems.

Abstract:In different environments, different microorganisms can attach on materials and cause materials corrosion, which is termed as microbiologically influenced corrosion or biocorrosion. According to their types and functions, microorganisms involved in corrosion are divided into sulfate-reducing bacteria, sulfur-oxidizing bacteria, acid-producing bacteria, iron-oxidizing bacteria, iron-reducing bacteria, nitrate-reducing bacteria and slime-forming bacteria. Corrosive microorganisms can affect almost all existing materials, so as to change and destroy the structures and performances of the materials. Microbiologically influenced corrosion can cause huge security risks and property damage on the construction, transportation pipelines, industrial environment (e. g. petrochemical) and marine environment. Here, we summarize corrosive microorganisms and their properties, as well as the corrosion mechanisms, to provide a theoretical basis to protect and control microbiologically influenced corrosions.

Abstract:Nitrous oxide (N2O) is a powerful greenhouse gas which can destroy the ozone layer. Nitrous oxide reductase coded by nosZ gene in microorganisms, can reduce N2O to harmless N2, thus the study on nosZ gene in the environments becomes a research hotspot. A recent study of genome sequence comparative analysis revealed that a new class of nosZ gene (atypical nosZ II gene) is present in diverse nitrogen metabolism microbes. This type of nosZ gene encodes a functional nitrous oxide reductase and is found in variety of natural environments. However, the research on microbes containing atypical nosZ II genes is still incomplete, and the environmental conditions in which these microorganisms act and characteristics of N2O reduction process is still unknown. This paper reviews the differences between atypical nosZ II and typical nosZ I, and their distribution in environment. We also propose the direction of future research on the nosZ II gene.

Abstract:Fungal laccases are capable of transforming many organic pollutants, thus are promising in environmental detoxification. Over the last two decades, the characteristics and mechanisms of polycyclic aromatic hydrocarbons (PAHs) transformation by laccase were extensively studied, meanwhile fungal ligninolytic enzymes-based remediation technologies targeting PAHs-contaminated soil were rapidly developed. In this article, we begin with a review of the redox mechanisms and PAHs oxidation characteristics of fungal laccase. A fate model of PAHs transformed by laccase in soil is put forward based on our recent studies. The remediation potentials of fungal laccase and remediation efforts using agricultural wastes like spent mushroom substrates are summarized. Lastly, a few key issues associated with research frontiers and practical application of fungi and their laccase systems are discussed.

Abstract:Selenium is an essential trace element for life, incorporates into selenoproteins (seleno-enzymes) in the form of selenocysteine (Sec, also referred to as the 21st protein amino acid) and selenomethionine (Se-Met). Either selenium over-intake or deficiency will lead to the occurrence of many diseases. Microorganisms are involved in the transformation of different selenium speciation including Se(?II), Se(0), Se(IV) and Se(VI). Here we mainly reviewed the reduction of selenium in microorganisms. The reduction of selenium by microbes include assimilation reduction and dissimilation reduction. Selenoproteins could be produced via the pathway of the selenium assimilation reduction, which is benefit for the selenium enrichment through food chain. Higher concentration of selenate and selenite would promote the process of selenium dissimilation reduction and the formation of selenium nanoparticles in some microbes. Both selenium methylation and the formation of selenium nanoparticles were mechanisms of detoxification, and would provide an economical and “green” solution to the bioremediation of environmental selenium contamination. Finally, the potential applications of biogenic selenium nanoparticles (bio-SeNPs) in medicine, biosensor and heavy metal contamination bioremediation were discussed. The biosynthesis of CdSe quantum dots by microbes and its biological applications were also introduced.

Abstract:Inorganic polyphosphate (polyP) is a linear polymer consisting of dozens to hundreds of orthophosphate residues (Pi) linked by high-energy phosphoanhydride bond. The studies have demonstrated that polyP is accumulated in bacteria under the unsuitable life conditions and endows bacteria with strong tolerance against environmental stresses, which trigger the stringent response along with the related enzymes of PPK, PPX and pppGpp. In oligotrophic environment, polyP acts as energy and Pi reservoir. More importantly, it participates in a series of starvation stress response together with RpoS, protease Lon, σ factor, etc. Such survival mechanism is similar to the life style of oligotrophic bacteria. All of these benefits from the flexibility and electron-density of polyP polymer, but its specific regulation mechanisms are still unclear. This review states the DAPI-based method to observe (fluorescent or electron microscope) and determine (fluorospectrophotometer) polyP in bacterial bodies, and mainly summarizes and analyzes the “core polyP” mechanistic alternatives in tuning microbial fitness for the adaptation under harsh living conditions.

Abstract:Carbofuran, 2,3-Dihydro-2,2-dimethyl-7-benzofuranol N-methylcarbamate, is a carbamate pesticide which has been used widely in agricultural production. Although the use of carbofuran is restricted now in China, its residues are still destroying the ecological environment and threatening the human health. Microbial degradation is an effective measure to eliminate the environment pollution of carbofuran, but the molecular mechanism of microbial degradation of carbofuran has not been clarified. The latest research progress on the degradation of carbofuran at home and abroad are reviewed from the aspects of microorganism resource, degradation pathway, key enzymes and genes, to provide reference for bioremediation of carbofuran-contaminated environments.