Characterization of three rapidly growing novel Mycobacterium species with significant polycyclic aromatic hydrocarbon bioremediation potential.

Mycobacterium species exhibit high bioremediation potential for the degradation of polycyclic aromatic hydrocarbons (PAHs) that are significant environmental pollutants. In this study, three Gram-positive, rapidly growing strains (YC-RL4T, MB418T, and HX176T) were isolated from petroleum-contaminated soils and were classified as Mycobacterium within the family Mycobacteriaceae. Genomic average nucleotide identity (ANI; < 95%) and digital DNA-DNA hybridization (dDDH; < 70%) values relative to other Mycobacterium spp. indicated that the strains represented novel species. The morphological, physiological, and chemotaxonomic characteristics of the isolates also supported their affiliation with Mycobacterium and their delineation as novel species. The strains were identified as Mycobacterium adipatum sp. nov. (type strain YC-RL4T = CPCC 205684T = CGMCC 1.62027T), Mycobacterium deserti sp. nov. (type strain MB418T = CPCC 205710T = KCTC 49782T), and Mycobacterium hippophais sp. nov. (type strain HX176T = CPCC 205372T = KCTC 49413T). Genes encoding enzymes involved in PAH degradation and metal resistance were present in the genomes of all three strains. Specifically, genes encoding alpha subunits of aromatic ring-hydroxylating dioxygenases were encoded by the genomes. The genes were also identified as core genes in a pangenomic analysis of the three strains along with 70 phylogenetically related mycobacterial strains that were previously classified as Mycolicibacterium. Notably, strain YC-RL4T could not only utilize phthalates as their sole carbon source for growth, but also convert di-(2-ethylhexyl) phthalate into phthalic acid. These results indicated that strains YC-RL4T, MB418T, and HX176T were important resources with significant bioremediation potential in soils contaminated by PAHs and heavy metals.

A New Method for Ecological Risk Assessment of Combined Contaminated Soil.

Ecological risk assessment of combined polluted soil has been conducted mostly on the basis of the risk screening value (RSV) of a single pollutant. However, due to its defects, this method is not accurate enough. Not only were the effects of soil properties neglected, but the interactions among different pollutants were also overlooked. In this study, the ecological risks of 22 soils collected from four smelting sites were assessed by toxicity tests using soil invertebrates (Eisenia fetida, Folsomia candida, Caenorhabditis elegans) as subjects. Besides a risk assessment based on RSVs, a new method was developed and applied. A toxicity effect index (EI) was introduced to normalize the toxicity effects of different toxicity endpoints, rendering assessments comparable based on different toxicity endpoints. Additionally, an assessment method of ecological risk probability (RP), based on the cumulative probability distribution of EI, was established. Significant correlation was found between EI-based RP and the RSV-based Nemerow ecological risk index (NRI) (p < 0.05). In addition, the new method can visually present the probability distribution of different toxicity endpoints, which is conducive to aiding risk managers in establishing more reasonable risk management plans to protect key species. The new method is expected to be combined with a complex dose-effect relationship prediction model constructed by machine learning algorithm, providing a new method and idea for the ecological risk assessment of combined contaminated soil.

Simultaneous adsorption of Cd and As by a novel coal gasification slag based composite: Characterization and application in soil remediation.

Cadmium (Cd) and arsenic (As) co-contamination has become increasingly serious in China agricultural soil due to rapid industrialization and urbanization. The opposite geochemical behaviors of Cd and As pose huge challenges for developing a material for their simultaneous immobilization in soils. Coal gasification slag (CGS) as a by-product of coal gasification process, is always dumped into a local landfill, which has a negative impact on environment. Few reports have been available on applying CGS as a material to immobilize simultaneously multiple soil heavy metals. A series of iron-modified coal gasification slag (IGS) composites IGS3/5/7/9/11 (with different pH values) were synthesized by alkali fusion and iron impregnation. After modification, carboxyl groups were activated, and Fe was successfully loaded onto the surface of IGS in the form of FeO and Fe2O3. The IGS7 exhibited the best adsorption capacity with the maximum Cd and As adsorption capacity of 42.72 mg/g and 35.29 mg/g, respectively. The Cd was mainly adsorbed through electrostatic attraction and precipitation, while the As through complexation with iron (hydr)oxides. IGS7 significantly reduced the bioavailability of Cd and As in soil with Cd bioavailability reduced from 1.17 mg/kg to 0.69 mg/kg and As bioavailability reduced from 10.59 mg/kg to 6.86 mg/kg at 1 % IGS7 addition. The Cd and As were all transformed to more stable fractions after IGS7 addition. The acid soluble and reducible Cd fractions were transformed into oxidizable and residual Cd fractions, and the non-specifically and specifically adsorbed As fractions were transformed to amorphous iron oxide-bound As fraction. This study provides valuable references for the application of CGS to the remediation of Cd and As co-contaminated soil.

Transcriptome analysis and cytochrome P450 monooxygenase reveal the molecular mechanism of Bisphenol A degradation by Pseudomonas putida strain YC-AE1.

BACKGROUND: Bisphenol A (BPA) is a rapid spreading organic pollutant that widely used in many industries especially as a plasticizer in polycarbonate plastic and epoxy resins. BPA reported as a prominent endocrine disruptor compound that possesses estrogenic activity and fulminant toxicity. Pseudomonas putida YC-AE1 was isolated in our previous study and exerted a strong degradation capacity toward BPA at high concentrations; however, the molecular degradation mechanism is still enigmatic. RESULTS: We employed RNA sequencing to analyze the differentially expressed genes (DEGs) in the YC-AE1 strain upon BPA induction. Out of 1229 differentially expressed genes, 725 genes were positively regulated, and 504 genes were down-regulated. The pathways of microbial metabolism in diverse environments were significantly enriched among DEGs based on KEGG enrichment analysis. qRT-PCR confirm the involvement of BPA degradation relevant genes in accordance with RNA Seq data. The degradation pathway of BPA in YC-AE1 was proposed with specific enzymes and encoded genes. The role of cytochrome P450 (CYP450) in BPA degradation was further verified. Sever decrease in BPA degradation was recorded by YC-AE1 in the presence of CYP450 inhibitor. Subsequently, CYP450bisdB deficient YC-AE1 strain △ bisdB lost its ability toward BPA transformation comparing with the wild type. Furthermore, Transformation of E. coli with pET-32a-bisdAB empowers it to degrade 66 mg l-1 of BPA after 24 h. Altogether, the results showed the role of CYP450 in biodegradation of BPA by YC-AE1. CONCLUSION: In this study we propose the molecular basis and the potential role of YC-AE1cytochrome P450 monooxygenase in BPA catabolism.

Characterization of the phosphotriesterase capable of hydrolyzing aryl-organophosphate flame retardants.

A related group of phosphotriesters known as organophosphate flame retardants (OPFRs) has become emerging contaminants due to its worldwide use. The lack of an easily hydrolysable bond renders OPFRs inert to the well-known phosphotriesterases capable of hydrolyzing the neurotoxic organophosphates. An OPFRs phosphotriesterase gene stpte was cloned from plasmid pStJH of strain Sphingopyxis terrae subsp. terrae YC-JH3 and was heterologously expressed in Escherichia coli. The recombinant protein St-PTE was purified and analyzed. St-PTE showed the highest catalytic activity at pH 8.5 and 35 °C. The optimal substrate for St-PTE is triphenyl phosphate, with kcat/Km of 5.03 × 106 M-1 s-1, two orders of magnitude higher than those of tricresyl phosphate (4.17 × 104 M-1 s-1), 2-ethylhexyl diphenyl phosphate (2.03 × 104 M-1 s-1) and resorcinol bis(diphenyl phosphate) (6.30 × 104 M-1 s-1). St-PTE could break the P-O bond of tri-esters and convert aryl-OPFRs into their corresponding di-ester metabolites, including polymers of resorcinol bis(diphenyl phosphate). Mediated by transposase, the gene of OPFRs phosphotriesterase could be transferred horizontally among closely related strains of Sphingomonas, Sphingobium and Sphingopyxis. KEY POINTS: • St-PTE from Sphingopyxis terrae subsp. terrae YC-JH3 could hydrolyze aryl-OPFRs. • Metabolites of RBDPP hydrolyzed by phosphotriesterase were identified. • St-PTE could hydrolyze the P-O cleavage of dimer and trimer of RBDPP. • Phosphotriesterase genes transfer among Sphingomonadaceae mediated by transposase.

First Report of Postharvest Blue Mold decay caused by Penicillium expansum on Lemon (Citrus limon) fruit in China.

Lemon (Citrus limon) is one of the most important commercial (both dried and fresh) citrus fruits in China. In the spring of 2019, postharvest blue mold decay was observed at an incidence of 3-5% on lemon fruit at the local markets in Beijing, China. Fruit lesions were circular, brown, soft, and watery, and rapidly expanded at 25°C. To isolate the causal organism, small pieces (2 mm3) were cut from the lesions, surface-sterilized for 1 min in 1.5% NaOCl, rinsed three times with sterilized water, dried with sterile filter paper, placed onto potato dextrose agar (PDA) medium, and incubated at 25°C for 6 days. Eight morphologically similar single-colony fungal isolates were recovered from six lemon fruit. Colony surfaces were bluish-green on the upper surface and cream to yellow-brown one the reverse. Hyphae on colony margins were entirely subsurface and cream in color. Mycelium was highly branched, septate, and colorless, and conidiophores were 250 to 450 × 3.0 to 4.0 µm in size. Stipe of conidiophores were smooth-walled, bearing terminal penicilli, typically terverticillate or less commonly birverticillate, rami occurring singly, 16 to 23 × 3.0 to 4.0 µm, metulae in 3 to 6, measuring 12 to 15 × 3.0 to 4.0 µm. Phialides were ampulliform to almost cylindrical, in verticils of 5 to 8, measuring 8 to 11 × 2.5 to 3.2 µm with collula. Conidia were smooth-walled, ellipsoidal, measuring 3.0 to 3.5 × 2.5 to 3.0 µm. According to morphological characteristics, the fungus was identified as Penicillium expansum (Visagie et al. 2014). For molecular identification, genomic DNA of eight fungal isolates was extracted, regions of the beta-tubulin (TUB), and calmodulin (CAL) genes and ITS region, were amplified using Bt2a/Bt2b, CAL-228F/ CAL-737, and ITS1/ITS4 primers respectively. Obtained sequences of all isolates were identical to sequences of the representative isolate YC-IK12, which was submitted in the GenBank. BLAST results of YC-IK12 sequences (ITS; MT856700: TUB; MT856958: CAL; MT856959) showed 98 to 100% similarity with P. expansum accessions (NR-077154, LN896428, JX141581). For pathogenicity tests, 10 µl of conidial suspension (10 × 105 conidia/ml) from seven-day-old YC-IK12 culture was inoculated using a sterilized needle into the surface of each five asymptomatic disinfected lemons. As a control, three lemons were inoculated using sterile distilled water. All inoculated lemons were placed in plastic containers and incubated at 25°C for 7 days. Decay lesions, identical to the original observations, developed on all inoculated lemons, while control lemons remained asymptomatic. Fungus re-isolated from the inoculated lemon was identified as P. expansum on the basis morphology and Bt2a/Bt2b, CAL-228F/ CAL-737, and ITS1/ITS4 sequences. Previously, Penicillium spp. including P. expansum have been reported as post-harvest pathogens on various Citrus spp. (Louw & Korsten 2015). However, P. digitatum has been reported on lemons and P. expansum has been reported on stored Kiwifruit (Actinidia arguta), Malus, and Pyrus species in China (Tai, 1979; Wang et al. 2015). To our knowledge, this is the first report of blue mold caused by P. expansum on lemons in China. References Louw, J. P., Korsten, L. 2015. Plant Dis. 99:21-30. Tai, F.L. 1979. Sylloge Fungorum Sinicorum. Sci. Press, Acad. Sin., Peking, 1527 pages. 8097 Visagie, C.M. et al. 2014. Studies. Mycol.78: 343. Wang, C. W. et al. 2015. Plant Dis. 99:1037.

The Analgesic Effect of Transcutaneous Electrical Acupoint Stimulation on Labor: A Randomized Control Study.

OBJECTIVE: This study aimed to investigate the analgesic effect of transcutaneous electrical acupoint stimulation (TEAS) on labor. METHODS: Primiparas with single birth and head presentation were enrolled in this study and randomly divided into three groups: TEAS group (n = 76), patient-controlled epidural analgesia (PCEA) group (n = 75), and control group without any analgesic measures (n = 78). RESULTS: Compared with the control group, the visual analog scores of the TEAS group and the PCEA group at each time point decreased (P < 0.01). The decrease was greater in the PCEA group than that in the TEAS group (P < 0.01). At 120 minutes after analgesia, there were significant differences in plasma ß-endorphin content between the TEAS group, PCEA group, and control group (P < 0.01). The difference between the PCEA group and the control group was statistically significant (P < 0.01). Among the parturients having a vaginal delivery, the duration of the first stage of labor was significantly shorter in the TEAS group and control group than in the PCEA group (P < 0.01). The duration of the second stage of labor was significantly shorter in the TEAS group than in the PCEA group (P < 0.01). Oxytocin usage rate during labor was significantly lower in the TEAS group and control group than in the PCEA group (P < 0.01), and adverse reactions were significantly fewer in the TEAS group and control group than in the PCEA group (P < 0.01). CONCLUSION: The duration of the first and second stage of labor is significantly shorter in the TEAS group than in the PCEA group. TEAS does not increase the use rate of oxytocin or the rate of cesarean section and will not bring about obvious maternal or fetal adverse reactions.

Primary biodegradation and mineralization of aryl organophosphate flame retardants by Rhodococcus-Sphingopyxis consortium.

In this study, the biodegradation towards aryl organophosphate flame retardants (aryl-OPFRs) was investigated by the Rhodococcus-Sphingopyxis consortium, mixture of strain Rhodococcus sp. YC-JH2 and Sphingopyxis sp. YC-JH3. The optimal ratio between the two composition strains was determined as 1:1. Under the optimum condition (pH 8, 35 °C and 0% salinity), the consortium could utilize aryl-OPFRs as sole carbon source and degrade them rapidly with half-life of 4.53, 21.11 and 23.0 h for triphenyl phosphate (TPhP), tricresyl phosphate (TCrP) and 2-ethylhexyl diphenyl phosphate (EHDPP) respectively. The consortium maintained high degrading efficiency under a wide of range of pH (6-10), temperature (20-40 °C) and salinity (0-6%). Besides, the consortium could rapidly degrade high concentration of TPhP and no inhibitory effect towards degradation speed was observed up to 500 mg/L. The effect of metal ions and surfactants was estimated. Most metal ions exhibited significant inhibition, except Zn2+ and Pb2+, which showed no effect or slight promotion. Ionic surfactants could severely reduce the degrading capacity, while nonionic surfactants showed no effect. With abundant inoculation of the consortium, mineralization higher than 75% could be achieved within a week. This study provides efficient microorganisms for bioremediation of aryl-OPFRs contamination.

Biodegradation of Di (2-Ethylhexyl) Phthalate by a novel Enterobacter spp. Strain YC-IL1 Isolated from Polluted Soil, Mila, Algeria.

Di-(2-ethylhexyl) phthalate (DEHP) is one of the phthalic acid ester representatives and is mainly used as a plasticizer to endow polyvinyl chloride plastics with desirable physical properties. It is synthesized in massive amounts worldwide. Many studies have proved the adverse effects of DEHP on human health and wildlife. DEHP is labeled as an endocrine disruptor which causes human reproductive problems. Enterobacter spp. YC-IL1, a novel isolated strain from contaminated soil, was identified by 16S rRNA gene analysis and electronic microscope. It is capable of efficiently degrading DEHP (100%) and a wide range of phthalic acid ester PAEs, particularly those containing side chains with branches, or ring structures such as dutylbenzyl phthalate and dicyclohexyl phthalate, which are hard to degrade, with, respectively, 81.15% and 50.69% degradation after 7 days incubation. YC-IL1 is an acido-tolerant strain which remained in pH values lower than pH 5.0 with the optimum pH 7.0 and temperature 30 °C. The DEHP metabolites were detected using HPLC-QQQ and then the degradation pathway was tentatively proposed. Strain YC-IL1 showed high DEHP degradation rate in artificially contaminated soil with 86% removed in 6 days. These results indicate the application potential of YC-IL1 in bioremediation of PAE-polluted sites, even the acidic ones.

Cometabolic biodegradation of quizalofop-p-ethyl by Methylobacterium populi YC-XJ1 and identification of QPEH1 esterase

BACKGROUND: Quizalofop-p-ethyl (QPE), a unitary R configuration aromatic oxyphenoxypropionic acid ester (AOPP) herbicide, was widely used and had led to detrimental environmental effects. For finding the QPEdegrading bacteria and promoting the biodegradation of QPE, a series of studies were carried out. RESULTS: A QPE-degrading bacterial strain YC-XJ1 was isolated from desert soil and identified as Methylobacterium populi, which could degrade QPE with methanol by cometabolism. Ninety-seven percent of QPE (50 mg/L) could be degraded within 72 h under optimum biodegradation condition of 35°C and pH 8.0. The maximum degradation rate of QPE was 1.4 mg/L/h, and the strain YC-XJ1 exhibited some certain salinity tolerance. Two novel metabolites, 2-hydroxy-6-chloroquinoxaline and quinoxaline, were found by high-performance liquid chromatography/mass spectroscopy analysis. The metabolic pathway of QPE was predicted. The catalytic efficiency of strain YC-XJ1 toward different AOPPs herbicides in descending order was as follows: haloxyfop-pmethyl ≈ diclofop-methyl ≈ fluazifop-p-butyl N clodinafop-propargyl N cyhalofop-butyl N quizalofop-p-ethyl N fenoxaprop-p-ethyl N propaquizafop N quizalofop-p-tefuryl. The genome of strain YC-XJ1 was sequenced using a combination of PacBio RS II and Illumina platforms. According to the annotation result, one α/ß hydrolase gene was selected and named qpeh1, for which QPE-degrading function has obtained validation. Based on the phylogenetic analysis and multiple sequence alignment with other QPE-degrading esterases reported previously, the QPEH1 was clustered with esterase family V. CONCLUSION: M. populi YC-XJ1 could degrade QPE with a novel pathway, and the qpeh1 gene was identified as one of QPE-degrading esterase gene.

The Genome Analysis of Methylobacterium populi YC-XJ1 with Diverse Xenobiotics Biodegrading Capacity and Degradation Characteristics of Related Hydrolase.

Methylobacterium populi YC-XJ1 isolated from desert soil exhibited a diverse degrading ability towards aromatic oxyphenoxypropionic acid esters (AOPPs) herbicide, phthalate esters (PAEs), organophosphorus flame retardants (OPFRs), chlorpyrifos and phoxim. The genome of YC-XJ1 was sequenced and analyzed systematically. YC-XJ1 contained a large number of exogenous compounds degradation pathways and hydrolase resources. The quizalofop-p-ethyl (QPE) degrading gene qpeh2 and diethyl phthalate (DEP) degrading gene deph1 were cloned and expressed. The characteristics of corresponding hydrolases were investigated. The specific activity of recombinant QPEH2 was 0.1 ± 0.02 U mg-1 for QPE with kcat/Km values of 1.8 ± 0.016 (mM-1·s-1). The specific activity of recombinant DEPH1 was 0.1 ± 0.02 U mg-1 for DEP with kcat/Km values of 0.8 ± 0.02 (mM-1·s-1). This work systematically illuminated the metabolic versatility of strain YC-XJ1 via the combination of genomics analysis and laboratory experiments. These results suggested that strain YC-XJ1 with diverse xenobiotics biodegrading capacity was a promising candidate for the bioremediation of polluted sites.

Biodegradation of Bisphenol A by Sphingobium sp. YC-JY1 and the Essential Role of Cytochrome P450 Monooxygenase.

Bisphenol A (BPA) is a widespread pollutant threatening the ecosystem and human health. An effective BPA degrader YC-JY1 was isolated and identified as Sphingobium sp. The optimal temperature and pH for the degradation of BPA by strain YC-JY1 were 30 °C and 6.5, respectively. The biodegradation pathway was proposed based on the identification of the metabolites. The addition of cytochrome P450 (CYP) inhibitor 1-aminobenzotriazole significantly decreased the degradation of BPA by Sphingobium sp. YC-JY1. Escherichia coli BL21 (DE3) cells harboring pET28a-bisdAB achieved the ability to degrade BPA. The bisdB gene knockout strain YC-JY1ΔbisdB was unable to degrade BPA indicating that P450bisdB was an essential initiator of BPA metabolism in strain YC-JY1. For BPA polluted soil remediation, strain YC-JY1 considerably stimulated biodegradation of BPA associated with the soil microbial community. These results point out that strain YC-JY1 is a promising microbe for BPA removal and possesses great application potential.

Biodegradation of endocrine disruptor Bisphenol A by Pseudomonas putida strain YC-AE1 isolated from polluted soil, Guangdong, China.

BACKGROUND: Bisphenol A is an important organic chemical as an intermediate, final and inert ingredient in manufacturing of many important products like polycarbonate plastics, epoxy resins, flame retardants, food-drink packaging coating, and other. BPA is an endocrine disruptor compound that mimics the function of estrogen causing damage to reproductive organs. Bacterial degradation has been consider as a cost effective and eco-friendly method for BPA degradation compared with physical and chemical methods. This study aimed to isolate and identify bacterial strain capable to degrade and tolerate high concentrations of this pollutant, studying the factors affecting the degradation process and study the degradation mechanism of this strain. RESULTS: YC-AE1 is a Gram negative bacterial strain isolated from soil and identified as Pseudomonas putida by 16S rRNA gene sequence and BIOLOG identification system. This strain found to have a high capacity to degrade the endocrine disruptor Bisphenol A (BPA). Response surface methodology using central composite design was used to statistically optimize the environmental factors during BPA degradation and the results obtained by significant model were 7.2, 30 °C and 2.5% for optimum initial pH, temperature and inoculum size, respectively. Prolonged incubation period with low NaCl concentration improve the biodegradation of BPA. Analysis of variance (ANOVA) showed high coefficient of determination, R2 and Adj-R2 which were 0.9979 and 0.9935, respectively. Substrate analysis found that, strain YC-AE1 could degrade a wide variety of bisphenol A-related pollutants such as bisphenol B, bisphenol F, bisphenol S, Dibutyl phthalate, Diethylhexyl phthalate and Diethyl phthalate in varying proportion. Pseudomonas putida YC-AE1 showed high ability to degrade a wide range of BPA concentrations (0.5-1000 mg l- 1) with completely degradation for 500 mg l- 1 within 72 h. Metabolic intermediates detected in this study by HPLC-MS were identified as 4,4-dihydroxy-alpha-methylstilbene, p-hydroxybenzaldeyde, p-hydroxyacetophenone, 4-hydroxyphenylacetate, 4-hydroxyphenacyl alcohol, 2,2-bis(4-hydroxyphenyl)-1-propanol, 1,2-bis(4-hydroxyphenyl)-2-propanol and 2,2-bis(4-hydroxyphenyl) propanoate. CONCLUSIONS: This study reports Pseudomonas putida YC-AE1 as BPA biodegrader with high performance in degradation and tolerance to high BPA concentration. It exhibited strong degradation capacity and prominent adaptability towards a wide range of environmental conditions. Moreover, it degrades BPA in a short time via two different degradation pathways.

[Characterization and 16S rRNA gene-based metagenomic analysis of the organophosphorous flame retardants degrading consortium YC-BJ1].

As flame retardants, organophosphate is recognized as a global environmental contaminant because of its wide application. This contaminant is hardly degradable by hydrolysis in the environment due to its special physicochemical properties. Therefore, it is of urgent needs to study the microbial degradation of organophosphate. Through continuous enrichment, we isolated one bacterial consortium, named YC-BJ1, from leachate of waste treatment plant in Beijing. The bacterial consortium YC-BJ1 could efficiently degrade 99.8% of triphenyl phosphate (TPhP) and 91.9% of tricresyl phosphate (TCrP) with the concentration of 100 mg/L within 4 days. Besides aryl phosphates, it could degrade chloro-phosphates, tris(1,3-dichloroisopropyl) phosphate (TDCPP) and tris(2-chloroethyl) phosphate (TCEP) by 16.5% and 22.0% respectively. The degradation of the consortium on TPhP was optimized through a broad range of temperature (15-40 ℃), pH (5.0-12.0) and salinity (0%-4%). 16S rRNA gene-based metagenomic analysis revealed that Hyphomicrobium (38.80%), Chryseobacterium (17.57%) and Sphingopyxis (17.46%) were the dominant genera of the consortium YC-BJ1. Compared with the reported organophosphorus flame retardants (OPFRs) degrading bacteria and microflora, the mixed microflora YC-BJ1 exhibited great advantages in degradation efficiency and environmental adaptability, demonstrating its wide application potential. The enrichment and isolation of highly efficient degrading flora can provide abundant microbial resources for the degradation of OPFRs and the bioremediation towards OPFRs-contaminated environments, and also lay a solid foundation for the exploration of its degradation mechanism.

Characterization and 16S metagenomic analysis of organophosphorus flame retardants degrading consortia.

Three bacterial consortia, named YC-SY1, YC-BJ1 and YC-GZ1, were enriched from different areas of China. Bacterial consortia YC-SY1, YC-BJ1 and YC-GZ1 could efficiently degrade triphenyl phosphate (TPhP) (100 mg/L) by approximately 79.4%, 99.8% and 99.6%, tricresyl phosphate (TCrP) by 90.6%, 91.9% and 96.3%, respectively, within 4 days. And they could retain high degrading efficiency under a broad range of temperature (15-40 ℃), pH (6.0-10.0) and salinity (0-4%). A total of 10 bacterial isolates were selected and investigated their degradation capacity. Among these isolates, two were significantly superior to the others. Strain Rhodococcus sp. YC-JH2 could utilize TPhP (50 mg/L) as sole carbon source for growth with 37.36% degradation within 7 days. Strain Sphingopyxis sp. YC-JH3 could efficiently degrade 96.2% of TPhP (50 mg/L) within 7 days, except that no cell growth was observed. Combined with 16S diversity analysis, our results suggest that the effective components of three bacterial consortia responsible for TPhP and TCrP degradation were almost the same, that is, bacteria capable of degrading TPhP and TCrP are limited, in this study, the most efficient component is Sphingopyxis. This study provides abundant microorganism sources for research on organophosphorus flame retardants (OPFRs) metabolism and bioremediation towards OPFRs-contaminated environments.

Identification and characterization of a meta-cleavage product hydrolase involved in biphenyl degradation from Arthrobacter sp. YC-RL1.

Polychlorinated biphenyls (PCBs) are a group of persistent organic pollutants (POPs) widely existing in the environment. Arthrobacter sp. YC-RL1 is a biphenyl-degrading bacterium that shows metabolic versatility towards aromatic compounds. A 2-hydroxy-6-oxo-6-phenylhexa-2, 4-dienoate (HOPDA) hydrolase (BphD) gene involved in the biodegradation of biphenyl was cloned from strain YC-RL1 and heterologously expressed in Escherichia coli BL21 (DE3). The recombinant BphDYC-RL1 was purified and characterized. BphDYC-RL1 showed the highest activity at 45 °C and pH 7. It was stable under a wide range of temperature (20-50 °C). The enzyme had a Km value of 0.14 mM, Kcat of 11.61 s-1, and Vmax of 0.027 U/mg. Temperature dependence catalysis exhibited a biphasic Arrhenius Plot with a transition at 20 °C. BphDYC-RL1 was inactivated by SDS, Tween 20, Tween 80, Trition X-100, DTT, CHAPS, NBS, PMSF, and DEPC, but insensitive to EDTA. Site-directed mutagenesis of the active-site residues revealed that the catalytic triad residues (Ser115, His275, and Asp247) of BphDYC-RL1 were necessary for its activity. The investigation of BphDYC-RL1 not only provides new potential enzyme resource for the biodegradation of biphenyl but also helps deepen our understanding on the catalytic process and mechanism.

In silico genome analysis reveals the metabolic versatility and biotechnology potential of a halotorelant phthalic acid esters degrading Gordonia alkanivorans strain YC-RL2.

Members of genus Gordonia are known to degrade various xenobitics and produce secondary metabolites. The genome of a halotorelant phthalic acid ester (PAEs) degrading actinobacterium Gordonia alkanivorans strain YC-RL2 was sequenced using Biosciences RS II platform and Single Molecular Real-Time (SMRT) technology. The reads were assembled de novo by hierarchical genome assembly process (HGAP) algorithm version 2. Genes were annotated by NCBI Prokaryotic Genome Annotation Pipeline. The generated genome sequence was 4,979,656 bp with an average G+C content of 67.45%. Calculation of ANI confirmed previous classification that strain YC-RL2 is G. alkanivorans. The sequences were searched against KEGG and COG databases; 3132 CDSs were assigned to COG families and 1808 CDSs were predicted to be involved in 111 pathways. 95 of the KEGG annotated genes were predicted to be involved in the degradation of xenobiotics. A phthalate degradation operon could not be identified in the genome indicating that strain YC-RL2 possesses a novel way of phthalate degradation. A total of 203 and 22 CDSs were annotated as esterase/hydrolase and dioxygenase genes respectively. A total of 53 biosynthetic gene clusters (BGCs) were predicted by antiSMASH (antibiotics & Secondary Metabolite Analysis Shell) bacterial version 4.0. The genome also contained putative genes for heavy metal metabolism. The strain could tolerate 1 mM of Cd2+, Co2+, Cu2+, Ni2+, Zn2+, Mn2+ and Pb2+ ions. These results show that strain YC-RL2 has a great potential to degrade various xenobiotics in different environments and will provide a rich genetic resource for further biotechnological and remediation studies.

Excellent Degradation Performance of a Versatile Phthalic Acid Esters-Degrading Bacterium and Catalytic Mechanism of Monoalkyl Phthalate Hydrolase.

Despites lots of characterized microorganisms that are capable of degrading phthalic acid esters (PAEs), there are few isolated strains with high activity towards PAEs under a broad range of environmental conditions. In this study, Gordonia sp. YC-JH1 had advantages over its counterparts in terms of di(2-ethylhexyl) phthalate (DEHP) degradation performance. It possessed an excellent degradation ability in the range of 20⁻50 °C, pH 5.0⁻12.0, or 0⁻8% NaCl with the optimal degradation condition 40 °C and pH 10.0. Therefore, strain YC-JH1 appeared suitable for bioremediation application at various conditions. Metabolites analysis revealed that DEHP was sequentially hydrolyzed by strain YC-JH1 to mono(2-ethylhexyl) phthalate (MEHP) and phthalic acid (PA). The hydrolase MphG1 from strain YC-JH1 hydrolyzed monoethyl phthalate (MEP), mono-n-butyl phthalate (MBP), mono-n-hexyl phthalate (MHP), and MEHP to PA. According to molecular docking and molecular dynamics simulation between MphG1 and monoalkyl phthalates (MAPs), some key residues were detected, including the catalytic triad (S125-H291-D259) and the residues R126 and F54 potentially binding substrates. The mutation of these residues accounted for the reduced activity. Together, the mechanism of MphG1 catalyzing MAPs was elucidated, and would shed insights into catalytic mechanism of more hydrolases.

Effects of forkhead box protein M1 on trophoblast invasion and its role in preeclampsia development.

The present study aimed to investigate the expression of the forkhead box protein M1 (FOXM1) in the placenta of patients with preeclampsia, and its effect on trophoblasts. A total of 28 patients with preeclampsia and 30 patients without preeclampsia (controls) who underwent cesarean section and were admitted to the Affiliated Hospital of Qingdao University between June 2013 and September 2016 were enrolled in the present study. The expression of FOXM1 in placental tissues was examined by reverse transcription-quantitative polymerase chain reaction, western blotting and immunohistochemistry. HTR8/SVneo cells were used to measure the in vitro expression of the vascular endothelial growth factor (VEGF). The results demonstrated that FOXM1 expression was downregulated in the placental tissues of patient with preeclampsia (P<0.05). Following the silencing of FOXM1 expression, the proliferation of HTR8/SVneo cells was suppressed. The results of flow cytometry demonstrated that proportion of HTR8/SVneo cells in the G0/G1 phase and the proportion of apoptotic cells increased. The expression of the apoptosis regulator BCL-2, as well as the expression of VEGF mRNA and protein expression were also downregulated following FOXM1 silencing. FOXM1 may therefore promote the development of preeclampsia via the VEGF signaling pathway.

Complete genome sequence of Gordonia sp. YC-JH1, a bacterium efficiently degrading a wide range of phthalic acid esters.

Phthalic acid esters (PAEs) are a family of recalcitrant pollutants mainly used as plasticizer. The strain Gordonia sp.YC-JH1, isolated from petroleum-contaminated soil, is capable of efficiently degrading a wide range of PAEs. In order to pertinently investigate the genetic mechanism of PAEs catabolism by strain YC-JH1, its complete genome sequencing has been performed by SMRT sequencing technology. The genome comprises a circular chromosome and a plasmid with a size of 4,101,557 bp and 91,767 bp respectively. Based on the genome sequence, 3563 protein-coding genes are predicted, of which the genes responsible for PAEs degradation are identified, including the two genes of PAEs hydrolase and the gene clusters for phthalic acid and protocatechuic acid degradation. The genome information provides genomic basis of PAEs degradation to allow the complete metabolism of PAEs. The wide substrate spectrum and its genetic basis of this strain should expand its application potential for environments bioremediation, provide novel gene resources involved in PAEs degradation for biotechnology and gene engineering, and contribute to shed light on the mechanism of PAEs metabolism.