[Analysis of DMD gene variants in a single center]

Objective: To investigate the DMD genetic variants of the Chinese population with Duchenne (DMD) and Becker muscular dystrophies (BMD). Methods: A cross-sectional study was conducted on 2 690 unrelated patients with DMD and BMD aged 0-18 who visited the Genetic and Prenatal Diagnosis Center of the First Affiliated Hospital of Zhengzhou University from January 2005 to February 2022. The clinical data, such as gender, age, clinical manifestations, and address, were collected. Multiplex ligation-dependent probe amplification, next generation sequencing panel, Sanger sequencing, and PCR amplification were used to detect the variants of the DMD gene in the patients, whose clinical information and gene detection results were descriptively analyzed. Results: The 2 690 patients included 2 648 males and 42 females, with an age of 6.0 (4.0, 9.0) years. The serum creatine kinase increased in all patients. Pathogenic DMD gene variants were detected in the 2 618 patients, including 1 875 cases (71.6%) large deletions, 231 cases (8.8%) duplications, and 512 cases (19.6%) small variants. Among the deletion variants, the deletion of 3 exons was the most common, accounting for 15.4% (288/1 875); and hotspot deletion involved exons 45 to 50, accounting for 6.3% (119/1 875). Exon 2 was the most common type duplication region, accounting for 13.0% (30/231). Small variants were distributed in all 79 exons of the DMD gene, with no hotspots. In addition, the 46 small variants were previously unreported. Conclusion: Exon deletion is the most common type of DMD gene variant, followed by small variants and exon duplication.

Safety and benefit of modified mesohepatectomy in the treatment of bilobar involvement congenital biliary dilatation

BACKGROUND

The diseased bile duct in bilobar congenital biliary dilatation is extensive and often requires major hepatectomy or liver transplantation associated with a higher risk. We aimed to evaluate the safety and benefit of modified mesohepatectomy, in comparison with trisectionectomy, to treat bilobar congenital biliary dilatation.

METHODS

This study included 28 patients with type IV and V bilobar congenital biliary dilatation. An innovative mesohepatectomy comprising the hepatectomy technique beyond the P/U point and bile duct shaping was applied to 14 patients to address the extensively diseased bile duct and difficulty in hepaticojejunostomy. Another 14 patients received trisectionectomy. The perioperative and long-term outcomes of these patients were compared.

RESULTS

The ratio of residual liver volume to standard liver volume in the mesohepatectomy group was higher (78.68% vs. 40.90%, p = 0.005), while the resection rate of the liver parenchyma was lower (28.25% vs. 63.97%, p = 0.000), than that in trisectionectomy group. The mesohepatectomy group had a lower severe complication (>Clavein III, 0% vs. 57.70%, p = 0.019) and incidence of posthepatectomy liver failure (7.14% vs. 42.86%, p = 0.038). No significant difference was observed in blood loss and bile leakage (p > 0.05). All the patients in the mesohepatectomy group achieved optimal results in the long-term follow-up.

CONCLUSIONS

mesohepatectomy provides an efficient treatment option for bilobar congenital biliary dilatation and can achieve radical resection, retain more liver parenchyma, and reduce the difficulty of hepaticojejunostomy, especially for patients that are not eligible for major hepatectomy and liver transplantation.

Structural and compositional diversity of biosurfactants produced by a novel strain of Sporosarcina luteola ME44 from oil reservoir

The urealytically active microorganism Sporosarcina luteola induces the precipitation of metals, which has attracted attention in biomineralization, bioremediation, and industrial waste recycling. Herein, we report a novel biosurfactant-producing strain of S. luteola ME44 isolated from Chinese Oilfield. The structure, composition, and surface activity of the biosurfactants produced by S. luteola ME44 were investigated by using a combination of the high-performance liquid chromatography, time-of-flight mass spectrometry, and surface tensiometer. The biosurfactant extracted by strain ME44 was identified as surfactin with five variants and the yield was 1010 ± 60 mg⋅L-1 . This is the first report on the structural composition and surface activity of biosurfactants isolated from the S. luteola. It extended our knowledge about the role of the species S. luteola in the ecosystem of extreme natural environments such as oil reservoir. In addition, S. luteola ME44 showed bioprecipitation properties for metal ions Cd(II), Cu(II), Zn(II), and Ag(I), which indicated the application potential of S. luteola in the field of bioremediation.

Structural diversity and applications of lipopeptide biosurfactants as biocontrol agents against phytopathogens: A review

Amphipathic compounds known as biosurfactants are able to reduce surface and interfacial tensions. These substances produced by microbial organisms perform the same functions as chemical surfactants with several enhancements, the most significant of which is biocontrol activity. Lipopeptide is one of the five biosurfactants from natural resources and is identified as the best alternative for chemical surfactants and the major topic of interest for both scientific and industrial communities due to their increasingly growing potential applications in biological and commercial fields. These are the biological compounds with very less toxicity level that increase their importance in the pesticide industry. In this article we summarize the structural diversity of the microbial lipopeptide biosurfactants and focus on their applications as biocontrol agents in plants, covering (1) an intensive study of the structural diversity of lipopeptide biosurfactants originated primarily by the Bacillus, Pseudomonas, Cyanobacteria, and Actinomycetes species is presented, (2) the comparative study of advantages and disadvantages of characterization techniques and physicochemical properties which have a major role in biocontrol activity of microbial lipopeptides, and (3) their wide range biocontrol applications as systemic resistance inducers against different plant diseases, resistance against phytopathogens by alteration of wettability of plant surfaces and antimicrobial activities of important bioactive lipopeptides produced from Bacillus strains.

Quantitative determination of rhamnolipid using HPLC-UV through carboxyl labeling

Rhamnolipid, as a low-toxic, biodegradable and environmentally friendly biosurfactant, has broad application prospects in many industries. However, the quantitative determination of rhamnolipid is still a challenging task. Here, a new sensitive method for the quantitative analysis of rhamnolipid based on a simple derivatization reaction was developed. In this study, 3-[3'-(l-rhamnopyranosyloxy) decanoyloxy] decanoic acid (Rha-C10-C10) and 3-[3'-(2'-O-α-l-rhamnopyranosyloxy) decanoyloxy] decanoic acid (Rha-Rha-C10-C10) were utilized as the representative rhamnolipids. Liquid chromatography-mass spectrometry and high-performance liquid chromatography-ultra violet results showed that these two compounds were successfully labeled with 1 N1-(4-nitrophenyl)-1,2-ethylenediamine. There was an excellent linear relationship between rhamnolipid concentration and peak area of labeled rhamnolipid. The detection limits of the Rha-C10-C10 and Rha-Rha-C10-C10 were 0.018 mg/L (36 nmol/L) and 0.014 mg/L (22 nmol/L), respectively. The established amidation method was suitable for the accurate analysis of rhamnolipids in the biotechnological process. The method had good reproducibility with the relative standard deviation of 0.96% and 0.79%, respectively, and sufficient accuracy with a recovery of 96%-100%. This method was applied to quantitative analysis of 10 rhamnolipid homologs metabolized by Pseudomonas aeruginosa LJ-8. The single labeling method was used for the quantitative analysis of multiple components, which provided an effective method for the quality evaluation of other glycolipids with carboxyl groups.

A new biosurfactant-producing strain, Fictibacillus nanhaiensis ME46, isolated from an oil field in China

The genus Fictibacillus contains twelve species significant in the synthesis of cellulose-degrading enzymes and phenylalanine dehydrogenase, isolated mainly from marine sedimentary environments. Here, we report a new biosurfactant-producing strain, Fictibacillus nanhaiensis ME46, isolated from Daqing oil field in China. The biosurfactant extracted from Strain ME46 was determined as surfactin, one of the representative families of lipopeptide biosurfactants. The yield of the surfactin produced by strain ME46 was 0.62 g·L-1 as determined by high-performance liquid chromatography, and the critical micelle concentration (CMC) of the surfactin was estimated to be about 68 mg·L-1 and the surface tension at CMC was 35.1 mN·m-1. This study extended our knowledge about the role of the species Fictibacillus nanhaiensis in the ecosystem of natural environments such as the oil field.

Significance of the plasma membrane H+-ATPase and V-ATPase for growth and pathogenicity in pathogenic fungi

Pathogenic fungi are widespread and cause a variety of diseases in human beings and other organisms. At present, limited classes of antifungal agents are available to treat invasive fungal diseases. With the wide use of the commercial antifungal agents, drug resistance of pathogenic fungi are continuously increasing. Therefore, exploring effective antifungal agents with novel drug targets is urgently needed to cope with the challenges that the antifungal area faces. pH homeostasis is vital for multiple cellular processes, revealing the potential for defining novel drug targets. Fungi have evolved a number of strategies to maintain a stable pH internal environment in response to rapid metabolism and a dramatically changing extracellular environment. Among them, plasma membrane H+-ATPase (PMA) and vacuolar H+-ATPase (V-ATPase) play a central role in the regulation of pH homeostasis system. In this chapter, we will summarize the current knowledge about pH homeostasis and its regulation mechanisms in pathogenic fungi, especially for the recent advances in PMA and V-ATPase, which would help in revealing the regulating mechanism of pH on cell growth and pathogenicity, and further designing effective drugs and identify new targets for combating fungal diseases.

Structural Diversity of the Lipopeptide Biosurfactant Produced by a Newly Isolated Strain, Geobacillus thermodenitrifcans ME63

The genus Geobacillus is active in degradation of hydrocarbons in thermophilic and facultative environments since it was first reported in 1920. Here, we report a new strain, Geobacillus thermodenitrificans ME63, isolated from an oilfield with the ability of producing the biosurfactant. The composition, chemical structure, and surface activity of the biosurfactant produced by G. thermodenitrificans ME63 were investigated by using a combination of the high-performance liquid chromatography, time-of-flight ion mass spectrometry, and surface tensiometer. The biosurfactant produced by strain ME63 was identified as surfactin with six variants, which is one of the representative family of lipopeptide biosurfactants. The amino acid residue sequence in the peptide of this surfactin is N-Glu → Leu → Leu → Val → Leu → Asp → Leu-C. The critical micelle concentration (CMC) of the surfactin is 55 mg L^-1, and the surface tension at CMC is 35.9 mN m^-1, which is promising in bioremediation and oil recovery industries. The surface activity and emulsification properties of biosurfactants produced by G. thermodenitrificans ME63 showed excellent resistance to temperature changes, salinity changes, and pH changes.

Adsorption Kinetics of Biosurfactant Surfactin at the n-Hexadecane/Aqueous Solution Interface

Surfactin is a typical kind of biosurfactant with a large diversity of structure, and its molecular structure is expected to play a crucial role in its adsorption dynamics. Adsorption kinetics of surfactin homologues at the n-hexadecane/aqueous solution interface is studied using a droplet-based microfluidic method. Molecular dynamics simulations are performed to illustrate the dependence of adsorption energy on the surfactin structure. Rapid reduction of dynamic interfacial tensions is obtained. The best fit to experimental results reveals that surfactin with shorter aliphatic chains, C13-surfactin and C14-surfactin, has larger rate constants of adsorption and desorption. Interfacial tensions are rapidly reduced in the case of the oil/water interface which is freshly formed, and the equilibrium adsorption is rapidly established approximately in 100-350 ms at concentrations above the critical micelle concentration. C15-surfactin that has a longer aliphatic chain adsorbs and desorbs slower, and the equilibration time of adsorption is slightly longer. Moreover, C15-surfactin has a strong tendency for adsorbing at the interface, which is in accordance with the larger adsorption energy obtained by molecular dynamics simulation, and aggregating behavior in solution. The present study provides insights on the surfactin structure and the dynamics of adsorption at the liquid/liquid interface.

Characteristics of microbiota, core sulfate-reducing taxa and corrosion rates in production water from five petroleum reservoirs in China

Microbial diversity and activities in petroleum reservoir systems can be altered by water-flooding operation, but the current understanding of the mechanism for such changes in microbial composition characteristics and community is inadequate. In this study, microbial communities especially functional groups in production water from five petroleum reservoirs in China were investigated by chemical and molecular biological analyses. The dominant and core phyla in the five oil reservoirs were Proteobacteria, Deferribacterota, Firmicutes, Desulfobacterota, Euryarchaeota and Thermoplasmatota. At the genus level, the dominant taxa in each petroleum reservoir were different, and not all of the dominant genera were the core members across the five oil reservoirs. The microbiologically influenced corrosion (MIC) were investigated for the functional groups in each production water. The corrosion rates in production water were higher than controls with a positive correlation to the abundances of sulfate-reducing prokaryotes (SRP). The SRP diversity based on the aprA and dsrA gene analysis showed that obvious differences were evident between onshore (JS, SL, DQ and XJ) and offshore (BS) oilfields. The core SRP taxa in onshore oilfields were Desulfomicrobium and Desulfovibrio, also with Desulfotomaculum in medium/low-temperature oil reservoirs (DQ and XJ), but in high-temperature petroleum reservoirs (JS, BS and SL), Archaeoglobus, Thermodesulfobacterium and Thermodesulfovibrio were the core groups. Statistical analysis indicated that temperature, electron acceptors and donors showed significant influence on the SRP community. This research reveals the characteristics of microbial and functional community as well as their interaction mechanism on corrosion in petroleum reservoir environments, and will improve industrial bio-control and management of MIC in oilfields.

Genetic engineering of the branched-chain fatty acid biosynthesis pathway to enhance surfactin production from Bacillus subtilis

Surfactin, which is composed of a β-hydroxy fatty acid chain and a peptide ring, has drawn considerable attention due to its potential applications in the biomedicine, bioremediation, and petroleum industries. However, the low yield of surfactin from wild strains still restricts its industrial applications. In this study, eight genes relevant to the fatty acid biosynthesis pathway were targeted to enhance surfactin production, and high surfactin-yielding strains with potential industrial applications were obtained. When ldeHA and acc were co-overexpressed, the surfactin yield of recombinant strains TDS8 and TPS8 increased to 1.55- and 1.19-fold of their parental strains, respectively, again proving that the conversion of acetyl-coenzyme A (CoA) to malonyl-CoA is the rate-limiting step in fatty acid biosynthesis. Furthermore, changes in surfactin isoforms of recombinant strain TPS8 suggest that the fatty acid precursor synthesis pathway can be modified to improve the proportion of different isoforms. In addition, the deletion of lpdV, which is responsible for the conversion of α-ketoacyl-CoA precursors, resulted in a sharp decrease in surfactin production, further demonstrating the importance of branched-chain fatty acid biosynthesis in surfactin production. This work will facilitate the design and construction of more efficiently engineered strains for surfactin production and further extend industrial applications.

A new surfactin-C17 produced by Bacillus subtilis TD7 with a low critical micelle concentration and high biological activities

A new member of the surfactin family of microbial lipopeptide has been isolated from the cell broth of Bacillus subtilis TD7 by a combination of organic solvent extraction and RP-HPLC,...

Highly Ca2+-Ion-Tolerant Biobased Zwitterionic Surfactant with High Interfacial Activity

The wide application of surfactants has a harmful effect on the environment, drawing more attention to the development and application of low-toxicity surfactants. A salt-tolerant and low-toxicity biobased zwitterionic surfactant, N,N-dimethyl-N-[2-hydroxy-3-sulfo-propyl]-N-benzyloxyoctadecanoyl-1,3-propanediamine (SPBOPA), was prepared from the oleic acid extracted from waste oils and anise ether extracted from the tarragon. The final surfactant structure was confirmed using gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), and ¹H nuclear magnetic resonance (NMR) spectroscopy. The SPBOPA surfactant could reduce the interfacial tension between crude oil and formation brine to ultralow (5.2 × 10^-4 mN/m) at a low dosage without extra alkali. It still had good interfacial properties in NaCl up to 60 g/L, Ca²⁺ up to 2000 mg/L, and temperature up to 100 °C. Furthermore, SPBOPA had strong antidilution and antiadsorption properties with low toxicity as demonstrated by the high LD₅₀ value of >5000 mg/kg·BW. It could also enhance the wetting ability of crude oil surfaces. Meanwhile, it showed a high biodegradability in the environment. All of the results achieved in this work confirmed that the SPBOPA surfactant is a more robust and promising biobased surfactant candidate than traditional surfactants as an eco-friendly surfactant for enhanced oil recovery (EOR).

[Preliminary experience of surgical treatment for torus tubarius hypertrophy in children]

Objective: To assess the incidence of symptomatic torus tubarius hypertrophy (TTH) in recurred OSA in children, and to explore the preliminary experience of partial resection of TTH assisted with radiofrequency ablation. Methods: From January 2004 to February 2020, 4 922 children, who diagnosed as OSA and received adenotonsillectomy at the Department of Otolaryngology, The 4th Medical Center of the PLA General Hospital, were retrospectively reviewed. There were 3 266 males and 1 656 females, the age ranged from 1 to 14 years old(median age of 5.0 years). Twenty-two cases were identified with recurrence of OSA syndrome, and the clinical data, including sex, age of primary operation, age of recurrence and presentation, and opertation methods were analyzed. Follow-up was carried out by outpatient visit or telephone. Graphpad prism 5.0 software was used for statistical analysis. Results: Twenty-two cases were identified as recurred OSA and received revised surgery in 4 922 cases. Among these 22 cases, 11 cases were diagnosed as TTH resulting in an incidence of 2.23‰(11/4 922), 1 case was cicatricial adhesion on tubal torus (0.20‰, 1/4 922), 10 cases were residual adenoid combined with tubal tonsil hypertrophy (2.03‰, 10/4 922). Median age of primary operation was 3.0 years (range:2.4 to 6.0 years) in 11 TTH cases. Recurrent interval varied from 2 months to 5.5 years (2.4±1.9 years) after first operation. Age of revised partial resection of TTH was 7.0±2.7 years (range: 4.0 to 12.0 years). Average time interval between primary operation and revised operation was 3.5±2.1 years (range: 0.5 to 6.0 years). Individualized treatments were carried out based on partial resection of TTH assisted with radiofrequency ablation. All of 11 cases received satisfied therapeutic results without nasopharyngeal stenosis occured. Twenty-two cases were followed up for 1.6 to 13 years (median follow-up time was 6.2 years). Conclusions: TTH contributed to recurred OSA in child. TTH might be misdiagnosed as tubal tonsil hypertrophy. Partial resection of TTH assisted with radiofrequency ablation was a safty and effective treatment.

Discovery of the non-cosmopolitan lineages in Candidatus Thermoprofundales

The recently proposed order Candidatus Thermoprofundales, currently containing only one family-level lineage Marine Benthic Group-D (MBG-D), is distributed in global subsurface ecosystems and ecologically important, but its diversity, evolution and metabolism remain largely unknown. Here we described two novel family-level specialized lineages in Ca. Thermoprofundales, JdFR-43 and HyVt, which are restricted to specific biotopes (primarily in marine hydrothermal vents and occasionally in oil reservoirs and hot springs) in contrast to the cosmopolitan lineage MBG-D. The comparative genomics revealed that the specialized lineages have streamlined genomes, higher GC contents, enriched genes associated with nucleotide biosynthesis, ribosome biogenesis and DNA repair and additional thermostable aminopeptidases, enabling them to adapt to high-temperature habitats such as marine hydrothermal vents, deep subsurface oil reservoirs and hot springs. On the contrary, the unique metabolic traits of the cosmopolitan MBG-D, motility, glycolysis, butanoate metabolism, secondary metabolites production and additional genes for specific peptides and carbohydrates degradation potentially enhance its response to environmental change. Substrate preference is found for most MAGs across all lineages with the ability to utilize both polysaccharides (chitin and starch) and proteinaceous substances, whereas JdFR-43 members from oil reservoirs can only utilize proteins. These results expand the diversity of Ca. Thermoprofundales significantly and further improve our understandings of the adaptations of Ca. Thermoprofundales to various environments. This article is protected by copyright. All rights reserved.

New evidence for a hydroxylation pathway for anaerobic alkane degradation supported by analyses of functional genes and signature metabolites in oil reservoirs

Microbial degradation of recalcitrant alkanes under anaerobic conditions results in the accumulation of heavy oil fraction in oil reservoirs. Hydroxylation of alkanes is an important activation mechanism under anaerobic conditions, but the diversity and distribution of the responsible microorganisms in the subsurface environment are still unclear. The lack of functional gene polymerase chain reaction (PCR) primers and commercially available intermediate degradation chemical compounds are the major obstacles for this research. In this investigation, PCR primers for the ahyA gene (encoding alkane hydroxylase) were designed, evaluated, and improved based on the nucleotide sequences available. Using microbial genomic DNA extracted from oil-contaminated soil and production water samples of oil reservoirs, ahyA gene nucleotide sequences were amplified and retrieved successfully from production water sample Z3-25 of Shengli oilfield. Additionally, the signature biomarker of 2-acetylalkanoic acid was detected in both Shengli and Jiangsu oilfields. These results demonstrate that anaerobic hydroxylation is an active mechanism used by microorganisms to degrade alkanes in oxygen-depleted oil reservoirs. This finding expands the current knowledge of biochemical reactions about alkane degradation in subsurface ecosystems. In addition, the PCR primers designed and tested in this study serve as an effective molecular tool for detecting the microorganisms responsible for anaerobic hydroxylation of alkanes in this and other ecosystems.

Simultaneous detection of transcribed functional assA gene and the corresponding metabolites of linear alkanes (C4, C5, and C7) in production water of a low-temperature oil reservoir

Methanogenic hydrocarbon degradation is an important biogeochemical process in oil reservoirs; however, genomic DNA-based analysis of microorganisms and metabolite detection are not conclusive for identification of the ongoing nature of this bioprocess. In this study, a suite of analyses, involving the study of microbial community and selective gene quantification of both genomic DNA and RNA together with signature metabolites, were performed to comprehensively advance the understanding of the methanogenic biodegradation of hydrocarbons in a low-temperature oilfield. The fumarate addition products for alkanes-C₄, C₅, and C₇-alkylsuccinates-and transcribed assA and mcrA genes were simultaneously detected in the production water sample, providing robust and convincing evidence for both the initial activation of n-alkanes and methane metabolism in this oilfield. The clone library of assA gene transcripts showed that Smithella was active and most likely responsible for the addition of fumarate to n-alkanes, whereas Methanoculleus and Methanothrix were the dominant and active methane-producers via CO₂ reduction and acetoclastic pathways, respectively. Additionally, qPCR results of assA and mcrA genes and their transcribed gene copy numbers revealed a roughly similar transcriptional activity in both n-alkanes-degraders and methane producers, implying that they were the major participants in the methanogenic degradation of n-alkanes in this oilfield. To the best of our knowledge, this is the first report presenting sufficient speculation, through detection of signature intermediates, corresponding gene quantification at transcriptional levels, and microbial community analysis, of methanogenic degradation of n-alkanes in production water of an oil reservoir.

Anaerobic Degradation of Paraffins by Thermophilic Actinobacteria under Methanogenic Conditions

Microbial anaerobic alkane degradation is a key process in subsurface oil reservoirs and anoxic environments contaminated with petroleum, with a major impact on global carbon cycling. However, the thermophiles capable of water-insoluble paraffins (>C₁₇) degradation under methanogenic conditions has remained understudied. Here, we established thermophilic (55 °C) n-paraffins-degrading (C₂₁-C₃₀) cultures from an oil reservoir. After over 900 days of incubation, the even-numbered n-paraffins were biodegraded to methane. The bacterial communities are dominated by a novel class-level lineage of actinobacteria, 'Candidatus Syntraliphaticia'. These 'Ca. Syntraliphaticia'-like metagenome-assembled genomes (MAGs) encode a complete alkylsuccinate synthases (ASS) gene operon, as well as hydrogenases and formate dehydrogenase, and several enzymes potentially involved in alkyl-CoA oxidation and the Wood-Ljungdahl pathway. Metatranscriptomic analysis suggests that n-paraffins are activated via fumarate addition reaction, and oxidized into carbon dioxide, hydrogen/formate and acetate by 'Ca. Syntraliphaticia', that could be further converted to methane by the abundant hydrogenotrophic and acetoclastic methanogens. We also found a divergent methyl-CoM reductase-like complex (MCR) and a canonical MCR in two MAGs representing 'Ca. Methanosuratus' (within candidate phylum Verstraetearchaeota), indicating the capability of methane and short-chain alkane metabolism in the oil reservoir. Ultimately, this result offers new insights into the degradability and the mechanisms of n-paraffins under methanogenic conditions at high temperatures.

The optimization of heterogeneous catalytic conditions in the direct alkylation of waste vegetable oil

Alkylated waste vegetable oil is a versatile intermediate product in the synthesis of bio-based materials. Heterogeneous catalytic condition with high conversion rate in the direct alkylation of waste vegetable oil was reported and the deactivation mechanism of catalyst was revealed. The total exchange capacity, elemental composition and pyrolysis product of catalyst before and after the alkylation reaction were analysed by back titration, elemental analysis, electrospray ionization mass spectrometry, gas chromatography mass spectrometry and pyrolysis-gas chromatography/mass spectrometry, respectively. The results indicated that the metallic and non-metallic (C, H) elements contents of the catalyst have very much increased with great changes in pyrolysis product and a slight decrease in the total exchange capacity. The formation of insoluble polymers through Diels-Alder cycloaddition between triglycerides was proved to be the major factor causing the dysfunction of the catalytic centre. The metal ions from corrosion of the reactor were the minor factor causing about 2.56% loss of the catalytic centre. Moreover, the catalyst was able to maintain high catalytic efficiency when replacing the raw materials with other waste vegetable oil having low concentration of polyunsaturated fatty acids, which is significant for producing not only the aryl fatty acids derivatives but also the bio-based surfactants.

Long-chain n-alkane biodegradation coupling to methane production in an enriched culture from production water of a high-temperature oil reservoir

Paraffinic n-alkanes (C22–C30), crucial portions of residual oil, are generally considered to be difficult to be biodegraded owing to their general solidity at ambient temperatures and low water solubility, rendering relatively little known about metabolic processes in different methanogenic hydrocarbon-contaminated environments. Here, we established a methanogenic C22–C30 n-alkane-degrading enrichment culture derived from a high-temperature oil reservoir production water. During two-year incubation (736 days), unexpectedly significant methane production was observed. The measured maximum methane yield rate (164.40 μmol L⁻¹ d⁻¹) occurred during the incubation period from day 351 to 513. The nearly complete consumption (> 97%) of paraffinic n-alkanes and the detection of dicarboxylic acids in n-alkane-amended cultures indicated the biotransformation of paraffin to methane under anoxic condition. 16S rRNA gene analysis suggested that the dominant methanogen in n-alkane-degrading cultures shifted from Methanothermobacter on day 322 to Thermoplasmatales on day 736. Bacterial community analysis based on high-throughput sequencing revealed that members of Proteobacteria and Firmicutes exhibiting predominant in control cultures, while microorganisms affiliated with Actinobacteria turned into the most dominant phylum in n-alkane-dependent cultures. Additionally, the relative abundance of mcrA gene based on genomic DNA significantly increased over the incubation time, suggesting an important role of methanogens in these consortia. This work extends our understanding of methanogenic paraffinic n-alkanes conversion and has biotechnological implications for microbial enhanced recovery of residual hydrocarbons and effective bioremediation of hydrocarbon-containing biospheres.

Methanogenic biodegradation of C9 to C12n-alkanes initiated by Smithella via fumarate addition mechanism

In the present study, a methanogenic alkane-degrading (a mixture of C₉ to C₁₂n-alkanes) culture enriched from production water of a low-temperature oil reservoir was established and assessed. Significant methane production was detected in the alkane-amended enrichment cultures compared with alkane-free controls over an incubation period of 1 year. At the end of the incubation, fumarate addition metabolites (C₉ to C₁₂ alkylsuccinates) and assA genes (encoding the alpha subunit of alkylsuccinate synthase) were detected only in the alkane-amended enrichment cultures. Microbial community analysis showed that putative syntrophic n-alkane degraders (Smithella) capable of initiating n-alkanes by fumarate addition mechanism were enriched in the alkane-amended enrichment cultures. In addition, both hydrogenotrophic (Methanocalculus) and acetoclastic (Methanothrix) methanogens were also observed. Our results provide further evidence that alkanes can be activated by addition to fumarate under methanogenic conditions.

Direct microbial transformation of carbon dioxide to value-added chemicals: A comprehensive analysis and application potentials

Carbon dioxide storage in petroleum and other geological reservoirs is an economical option for long-term separation of this gas from the atmosphere. Other options include applications through conversion to valuable chemicals. Microalgae and plants perform direct fixation of carbon dioxide to biomass, which is then used as raw material for further microbial transformation (MT). The approach by microbial transformation can achieve reduction of carbon dioxide and production of biofuels. This review addresses the research and technological processes related to direct MT of carbon dioxide, factors affecting their efficiency in operation and the review of economic feasibility. Additionally, some commercial plants making utilization of CO₂ around the globe are also summarized along with different value-added chemicals (methane, acetate, fatty acids and alcohols) as reported in literature. Further information is also provided for a better understanding of direct CO₂ MT and its future prospects leading to a sustainable and clean environment.

Anaerobic hydrocarbon degradation in candidate phylum 'Atribacteria' (JS1) inferred from genomics

The hydrocarbon-enriched environments, such as oil reservoirs and oil sands tailings ponds, contain a broad diversity of uncultured microorganisms. Despite being one of the few prokaryotic lineages that is consistently detected in both production water from oil reservoirs and stable hydrocarbon-degrading enrichment cultures originated from oil reservoirs, the physiological and ecological roles of candidate phylum “Atribacteria” (OP9/JS1) are not known in deep subsurface environments. Here, we report the expanded metabolic capabilities of Atribacteria as inferred from genomic reconstructions. Seventeen newly assembled medium-to-high-quality metagenomic assembly genomes (MAGs) were obtained either from co-assembly of two metagenomes from an Alaska North Slope oil reservoir or from previous studies of metagenomes coming from different environments. These MAGs comprise three currently known genus-level lineages and four novel genus-level groups of OP9 and JS1, which expands the genomic coverage of the major lineages within the candidate phylum Atribacteria. Genes involved in anaerobic hydrocarbon degradation were found in seven MAGs associated with hydrocarbon-enriched environments, and suggest that some Atribacteria could ferment short-chain n-alkanes into fatty acid while conserving energy. This study expands predicted metabolic capabilities of Atribacteria (JS1) and suggests that they are mediating a key role in subsurface carbon cycling.

Characterization of biosurfactant lipopeptide and its performance evaluation for oil-spill remediation

Biosurfactant lipopeptide is a promising dispersant over varieties of chemical ones in oil-spill remediation. The toxicity, biodegradability and performance of the biosurfactant lipopeptide are studied in this paper.

Biosurfactant lipopeptide is a promising dispersant over varieties of chemical ones in oil-spill remediation.

Different Diversity and Distribution of Archaeal Community in the Aqueous and Oil Phases of Production Fluid From High-Temperature Petroleum Reservoirs

To get a better knowledge on how archaeal communities differ between the oil and aqueous phases and whether environmental factors promote substantial differences on microbial distributions among production wells, we analyzed archaeal communities in oil and aqueous phases from four high-temperature petroleum reservoirs (55–65°C) by using 16S rRNA gene based 454 pyrosequencing. Obvious dissimilarity of the archaeal composition between aqueous and oil phases in each independent production wells was observed, especially in production wells with higher water cut, and diversity in the oil phase was much higher than that in the corresponding aqueous phase. Statistical analysis further showed that archaeal communities in oil phases from different petroleum reservoirs tended to be more similar, but those in aqueous phases were the opposite. In the high-temperature ecosystems, temperature as an environmental factor could have significantly affected archaeal distribution, and archaeal diversity raised with the increase of temperature (p < 0.05). Our results suggest that to get a comprehensive understanding of petroleum reservoirs microbial information both in aqueous and oil phases should be taken into consideration. The microscopic habitats of oil phase, technically the dispersed minuscule water droplets in the oil could be a better habitat that containing the indigenous microorganisms.

Insight into the Selectivity and Mechanism of Surfactin Containing Multiple Dissociated Carboxyls with 1-Bromoacetylpyrene in Fluorescent Derivatization

Fluorescent derivatization of the carboxyls in surfactin peptide rings is an effective way to improve the sensitivity of trace detection of surfactin, but very little is known about the reaction selectivity of surfactin containing multiple carboxyls in derivatization. In this paper, the reaction selectivity in fluorescent derivatization of a surfactin containing two carboxyls in its peptide ring with 1-bromoacetylpyrene and the catalysis role in the reactions were investigated using electrospray ionization mass spectrometry and tandem mass spectrometry. It showed that only one carboxyl was labeled with 1-bromoacetylpyrene in derivatization reactions, and the connection of the Asp residue with 1-bromoacetylpyrene was confirmed. It also showed that triethylamine as a catalyst was connected with surfactin to liberate more nucleophilic groups beneficial to promote the derivatization rate. This would contribute to better understanding the mechanism of derivatization of surfactin and its analogues with 1-bromoacetylpyrene, and with other fluorescent labeling reagents.

Anaerobic biodegradation of partially hydrolyzed polyacrylamide in long-term methanogenic enrichment cultures from production water of oil reservoirs

The increasing usage of partially hydrolyzed polyacrylamide (HPAM) in oilfields as a flooding agent to enhance oil recovery at so large quantities is an ecological hazard to the subsurface ecosystem due to persistence and inertness. Biodegradation of HPAM is a potentially promising strategy for dealing with this problem among many other methods available. To understand the responsible microorganisms and mechanism of HPAM biodegradation under anaerobic conditions, an enrichment culture from production waters of oil reservoirs were established with HPAM as the sole source of carbon and nitrogen incubated for over 328 days, and analyzed using both molecular microbiology and chemical characterization methods. Gel permeation chromatography, High-pressure liquid chromatography and Fourier-transformed infrared spectroscopy results indicated that, after 328 days of anaerobic incubation, some of the amide groups on HPAM were removed and released as ammonia/ammonium and carboxylic groups, while the carbon backbone of HPAM was converted to smaller polymeric fragments, including oligomers and various fatty acids. Based on these results, the biochemical process of anaerobic biodegradation of HPAM was proposed. The phylogenetic analysis of 16S rRNA gene sequences retrieved from the enrichments showed that Proteobacteria and Planctomycetes were the dominant bacteria in the culture with HPAM as the source of carbon and nitrogen, respectively. For archaea, Methanofollis was more abundant in the anaerobic enrichment. These results are helpful for understanding the process of HPAM biodegradation and provide significant insights to the fate of HPAM in subsurface environment and for possible bioremediation.

[Analysis of curative effect of transoral radiofrequency ablation microsurgery on glottic carcinoma with anterior commissure involvement at the early stage]

Objective: To explore the key technique and outcome of transoral radiofrequency ablation microsurgery for early stage of glottic carcinoma with anterior commissure involvement (ACI). Methods: A retrospective analysis was conducted on 31 patients, who were diagnosed as early stage glottic carcinoma during January 2010 to March 2016 in ENT Department. According to whether the anterior commissure was involved or not, two groups were divided. There were eleven cases with ACI (stages T1a, T1b, and T2). Twenty cases without ACI (stages Tis, T1a, and T2). All the patients received transoral radiofrequency ablation microsurgery and followed up closely.Only one case received radiotheraphy after surgery. SPSS19.0 software was used to analyze data. Results: The follow-up time was 12-67 months, and the median follow-up time was 30 months. Nine among 11 cases with ACI obtained good oncologic outcomes, initial local recurrence was identified in 2/11 cases, including 2 cases of T2. Two cases ultimately required salvage total laryngectomy. Meanwhile, initial local recurrence was identified in 2/20 cases without ACI, including 1 case of T1a and 1 case of T2. One case underwent elective neck dissection, and another one received salvage total laryngectomy.Compared to the patients without ACI, it seemed that the cases with ACI always accomponied with a little higher initial local recurrence and lower overall laryngealpreservation, but the difference had no significance (P>0.05). Conclusions: Transoral radiofrequency ablation microsurgery is an effective treatment for glottic carcinoma with ACI. Its advantages, such as more flexibility and deformability, make it more feasible to operate at the narrow space of anterior commissure assisted with laryngeal endoscopy.Good oncologic outcomes can be obtained by this technique with lower initial local recurrence as well as higher overall laryngeal preservation rate.

A novel binary flooding system of a biobased surfactant and hydrophobically associating polymer with ultralow interfacial tensions

A novel alkali free binary flooding system of a biobased zwitterionic surfactant and hydrophobically associating polymer with ultralow interfacial tension at a low surfactant dosage was studied in this paper.

Responses of Microbial Community Composition to Temperature Gradient and Carbon Steel Corrosion in Production Water of Petroleum Reservoir

Oil reservoir production systems are usually associated with a temperature gradient and oil production facilities frequently suffer from pipeline corrosion failures. Both bacteria and archaea potentially contribute to biocorrosion of the oil production equipment. Here the response of microbial populations from the petroleum reservoir to temperature gradient and corrosion of carbon steel coupons were investigated under laboratory condition. Carbon steel coupons were exposed to production water from a depth of 1809 m of Jiangsu petroleum reservoir (China) and incubated for periods of 160 and 300 days. The incubation temperatures were set at 37, 55, and 65°C to monitoring mesophilic, thermophilic and hyperthermophilic microorganisms associated with anaerobic carbon steel corrosion. The results showed that corrosion rate at 55°C (0.162 ± 0.013 mm year^-1) and 37°C (0.138 ± 0.008 mm year^-1) were higher than that at 65°C (0.105 ± 0.007 mm year^-1), and a dense biofilm was observed on the surface of coupons under all biotic incubations. The microbial community analysis suggests a high frequency of bacterial taxa associated with families Porphyromonadaceae, Enterobacteriaceae, and Spirochaetaceae at all three temperatures. While the majority of known sulfate-reducing bacteria, in particular Desulfotignum, Desulfobulbus and Desulfovibrio spp., were predominantly observed at 37°C; Desulfotomaculum spp., Thermotoga spp. and Thermanaeromonas spp. as well as archaeal members closely related to Thermococcus and Archaeoglobus spp. were substantially enriched at 65°C. Hydrogenotrophic methanogens of the family Methanobacteriaceae were dominant at both 37 and 55°C; acetoclastic Methanosaeta spp. and methyltrophic Methanolobus spp. were enriched at 37°C. These observations show that temperature changes significantly alter the microbial community structure in production fluids and also affected the biocorrosion of carbon steel under anaerobic conditions.

[Complications analysis of adenoidectomy and tonsillectomy assisted with ablation on children]

Objective:To analyze the complications of adenotonsilectomy assisted with coblation in children. Method:Complications of 2 089 cases of children with adenoid and tonsil surgery assisted with coblation, in our hospital nearly 10 years, were analyzed by epidemiological methods through the method of retrospective analysis. Result:①the sex ratio of male to female was 2.08：1, average age (5.87±3.12) years old, and most of 2 089 cases 76.35% (1 595/2 089) were 3-7 years old; ②all cases underwent adenoidectomy. Different surgery methods of tonsil consisted of three groups as partial resection associated with ablation was 69.17% (1 445/2 089), ablation (channeling) alone was 22.26% (465/2 089) and total resection was 8.57% (179/208). The amount of bleeding in operation was (8.52±3.18)ml, average operation time was (30.15±8.26) minutes, the postoperative pain score was (3.77±1.61); ③The incidence of postoperative complications: postoperative bleeding (all were secondary bleeding cases) rate was 0.24% (5/2 089), recurrence rate was 0.14% (3/2 089), prevertebral lymphadenitis was 0.96% (20/2 089), the other was 0.29% (torus hyperplasia in 2 cases, dyspnea in 2 cases, 1 cases of angle of mouth burned, nasopharyngeal adhesion in 1 cases). Postoperative fever rate was 9.81% (205/2 089). Conclusion:coblation technique is a good method for the treatment of children's adenoids and tonsil diseases with high efficiency and low complications. But improving the operation procedure proficiency level and skills of operation is an important link to reduce complications.

Diversity and Composition of Sulfate-Reducing Microbial Communities Based on Genomic DNA and RNA Transcription in Production Water of High Temperature and Corrosive Oil Reservoir

Deep subsurface petroleum reservoir ecosystems harbor a high diversity of microorganisms, and microbial influenced corrosion is a major problem for the petroleum industry. Here, we used high-throughput sequencing to explore the microbial communities based on genomic 16S rDNA and metabolically active 16S rRNA analyses of production water samples with different extents of corrosion from a high-temperature oil reservoir. Results showed that Desulfotignum and Roseovarius were the most abundant genera in both genomic and active bacterial communities of all the samples. Both genomic and active archaeal communities were mainly composed of Archaeoglobus and Methanolobus. Within both bacteria and archaea, the active and genomic communities were compositionally distinct from one another across the different oil wells (bacteria p = 0.002; archaea p = 0.01). In addition, the sulfate-reducing microorganisms (SRMs) were specifically assessed by Sanger sequencing of functional genes aprA and dsrA encoding the enzymes adenosine-5'-phosphosulfate reductase and dissimilatory sulfite reductase, respectively. Functional gene analysis indicated that potentially active Archaeoglobus, Desulfotignum, Desulfovibrio, and Thermodesulforhabdus were frequently detected, with Archaeoglobus as the most abundant and active sulfate-reducing group. Canonical correspondence analysis revealed that the SRM communities in petroleum reservoir system were closely related to pH of the production water and sulfate concentration. This study highlights the importance of distinguishing the metabolically active microorganisms from the genomic community and extends our knowledge on the active SRM communities in corrosive petroleum reservoirs.

Distribution Coefficients of Lipopeptide Biosurfactant in Different Solvents and its Separation from a Surfactant/Polymer Mixture in Aqueous Solutions

The distribution coefficients of lipopeptide biosurfactant in four different commercially available organic solvents and water were determined by HPLC. A method with a high recovery of 92.1% for isolation of the lipopeptide in a surfactant/polymer mixture in aqueous solutions was established by using the combined means of acid extraction, alkaline conversion and acid re-extraction. The results showed that the lipopeptide distribution coefficients range from 0.010 to 61 at different pH values in different organic solvents, which is an indicator for optimizing the process of separation of lipopeptide biosurfactant in surfactant/polymer mixtures in aqueous solutions. The proposed separation method was used to determine the lipopeptide biosurfactant concentration in production fluids of the Daqing oil field. The concentrations were 6.57 μg/L and 4.56 μg/L.

Effect of Shuanghu Qinggan Granule () and Yigan Yiqi Jieyu Granule () plus lamivudine on chronic hepatitis B patients: A randomized double-blind placebo-controlled trial

OBJECTIVE

To observe the clinical efficacy and safety of Shuanghu Qinggan Granule ( , SQG) plus Yigan Yiqi Jieyu Granule (, YYJG) combined with lamivudine (LAM) on chronic hepatitis B (CHB) patients.

METHODS

The study was a multicenter, randomized, double-blinded and parallel controlled trial. A total of 320 patients were randomly allocated into 2 groups equally: 160 patients (treatment group) were given SQG and YYJG combined with LAM; and 160 patients (control group) were given LAM plus Chinese herb placebo, respectively. Liver functions, hepatitis B envelop antigen (HBeAg) titer levels, and hepatitis B virus DNA (HBV-DNA) load were monitored.

RESULTS

(1) In the 48th week, the treatment group showed superior HBeAg seroconversion rate than that in the control group (38.0% vs. 24.0%, P<0.05). (2) In the 48th week, the treatment group demonstrated lower HBeAg titer than that in the control group (P<0.05). (3) In the 12th, 24th, 48th week, there was no statistical significance in HBV-DNA response rate between the two groups. (4) In the 12th week, the level of glutamyl transpeptidase (GGT) was significantly decreased in the treatment group compared with the control group (P<0.05); in the 36th week, the levels of alanine aminotransferase and aspartate transaminase were significantly lower in the treatment group than those in the control group (P<0.05).

CONCLUSION

The protocol of SQG and YYJG combined with LAM to treat CHB showed superior efficacy than LAM monotherapy.

[Photodynamic therapy by topical drup for the treatment of juvenile onset laryngeal papillomatosis]

Objective:To observe the therapeutic effect of photodynamic therapy(PDT) on the treatment of juvenile onset laryngeal papillomatosis. Method:Twenty-eight cases of children with laryngeal papilloma were treated,only 2 cases for the first time, and the rest were repeatedly treated outside our hospital, the average hospital surgery were more than 4 times. Under self retaining laryngoscope and microscope and endoscope assisted by semiconductor laser and plasma and cold instrument method，visible tumor resection and local affixed deposited 20% 5-aminolevulinic acid(photosensitizer) 3 hours later, with 635 nm semiconductor laser photodynamic,200-280 mW and can volume density of 80 to 120 J/cm², 20 min irradiation. PDT should be repeated after 25 days until no visible tumor.Then,2 times PDT must be done. Result:In 28 cases, 24 cases were followed up for more than 1 years(12 cases were followed up for 3 years),19 had no recurrence, the cure rate was 79.2%(19/24)；5 cases recurrence, and the recurrence rate was 20.8%(5/24)，among them,2 cases were abandoned because of the relapse，the other 3 cases were cure after 3 times of PDT.The main complications were adhesion of larynx. Conclusion:The preliminary effect of PDT by topical drug for the treatment of juvenile onset laryngeal papillomatosis is encouraging. The principle of PDT and the principle of the recurrence of laryngeal papilloma in children were also introduced in this paper.

High Frequency of Thermodesulfovibrio spp. and Anaerolineaceae in Association with Methanoculleus spp. in a Long-Term Incubation of n-Alkanes-Degrading Methanogenic Enrichment Culture

In the present study, the microbial community and functional gene composition of a long-term active alkane-degrading methanogenic culture was established after two successive enrichment culture transfers and incubated for a total period of 1750 days. Molecular analysis was conducted after the second transfer (incubated for 750 days) for both the active alkanes-degrading methanogenic enrichment cultures (T2-AE) and the background control (T2-BC). A net increase of methane as the end product was detected in the headspace of the enrichment cultures amended with long-chain n-alkanes and intermediate metabolites, including octadecanoate, hexadecanoate, isocaprylate, butyrate, isobutyrate, propionate, acetate, and formate were measured in the liquid cultures. The composition of microbial community shifted through the successive transfers over time of incubation. Sequences of bacterial and archaeal 16S rRNA gene (16S rDNA) and mcrA functional gene indicated that bacterial sequences affiliated to Thermodesulfovibrio spp. and Anaerolineaceae and archaeal sequences falling within the genus Methanoculleus were the most frequently encountered and thus represented the dominant members performing the anaerobic degradation of long-chain n-alkanes and methanogenesis. In addition, the presence of assA functional genes encoding the alkylsuccinate synthase α subunit indicated that fumarate addition mechanism could be considered as a possible initial activation step of n-alkanes in the present study. The succession pattern of microbial communities indicates that Thermodesulfovibrio spp. could be a generalist participating in the metabolism of intermediates, while Anaerolineaceae plays a key role in the initial activation of long-chain n-alkane biodegradation.

[Clinical effect analysis of adenoidectomy and tonsillectomy assisted with ablation on children]

Objective:This study aims to explore the clinical effect of adenoidectomy and tonsillectomy assisted with ablation on children.Method:The investigation took the form of retrospective review of 2 089 cases of children applied with adenoidectomy and tonsillectomy assisted with ablation in our hospital in recent 10 years. We obtained data of these children with epidemiological methods based on analyzing the status of general information and operation selections, and then analyzing the scores of snoring and breath preoperation and postoperation.Result:①General information of 2 089 cases followed with: the ratio of male and female was 2.08∶1，the average onset age was（5.87±3.12）years old, mostly ranged from 3 to 7 years old, which consists of 76.35%（1595/2089）of the group.②Different surgery methods of tonsil consisted of three groups as: partial resection associate with ablation was 69.17%(1445/2089), ablation alone was 22.26%(465/2089) and partial resection alone was 8.57%(179/2089) of the group.③A high level scores of snoring and breath more frequently found in preoperative cases than in postoperative cases(P <0.01).There are no differentiation among the scores of above three groups(P >0.05).The postoperative effect evaluation were related to allergic rhinitis, recurrent of tonsillitis, obesity, circular occipital hyperplasia and nasopharyngeal adhesion.Conclusion:The results suggested that surgery assisted with ablation has its advantage in adenoidectomy and tonsillectomy. Individual therapy for different children will improve the curative effect and relieve the pain of operation, thus is worth a wide application.

Formate-Dependent Microbial Conversion of CO2 and the Dominant Pathways of Methanogenesis in Production Water of High-temperature Oil Reservoirs Amended with Bicarbonate

CO2 sequestration in deep-subsurface formations including oil reservoirs is a potential measure to reduce the CO2 concentration in the atmosphere. However, the fate of the CO2 and the ecological influences in carbon dioxide capture and storage (CDCS) facilities is not understood clearly. In the current study, the fate of CO2 (in bicarbonate form; 0∼90 mM) with 10 mM of formate as electron donor and carbon source was investigated with high-temperature production water from oilfield in China. The isotope data showed that bicarbonate could be reduced to methane by methanogens and major pathway of methanogenesis could be syntrophic formate oxidation coupled with CO2 reduction and formate methanogenesis under the anaerobic conditions. The bicarbonate addition induced the shift of microbial community. Addition of bicarbonate and formate was associated with a decrease of Methanosarcinales, but promotion of Methanobacteriales in all treatments. Thermodesulfovibrio was the major group in all the samples and Thermacetogenium dominated in the high bicarbonate treatments. The results indicated that CO2 from CDCS could be transformed to methane and the possibility of microbial CO2 conversion for enhanced microbial energy recovery in oil reservoirs.

Structural Analysis of the Lipopeptide Produced by the Bacillus subtilis Mutant R2-104 with Mutagenesis

The lipopeptide and its homologues are a kind of the five major biosurfactants with prominent interfacial and biological activities. A suite of mutagenesis method was adopted to expose a wild lipopeptide-producing strain Bacillus subtilis HSO121 to improve lipopeptide yield, and a stable mutant named R2-104 with a 2.0-fold production of lipopeptide was obtained. Compared to that of the wild strain HSO121, the lipopeptide produced by R2-104 showed a similar surface activity, but the course profiles of lipopeptide production during cultivation were different, with the peak yield of 500 mg at about 9 h by R2-104, and 400 mg at about 5 h by HSO121. The constituent abundance of the lipopeptide homologues produced by R2-104 was also different from that by HSO121. Combined methods of ESI-MS, GC-MS and MS-MS were applied for structural characterization of lipopeptide homologues, and it showed that the lipopeptides produced by R2-104 and HSO121 were attributed to a surfactin family with different constituents. The dominant constituent of the surfactin family produced by R2-104 was anteiso C15-surfactin with a relative content of 43.8 %, while the dominant one produced by HSO121was iso C14-surfactin with a relative content of 33.1 %.

The biofilm property and its correlationship with high-molecular-weight polyacrylamide degradation in a water injection pipeline of Daqing oilfield

Biofilms increase dragging force for liquid transportation, cause power consumption, and result in equipment corrosion in polymer-flooding oilfields. To reveal the responsible microorganisms for biofilm formation and stability of high-molecular-weight polyacrylamide (PAM), a biofilm, developed on the sieve of a piston plunger pump in a water transport and injection pipeline with partial hydrolyzed polyacrylamide (HPAM) in Daqing Oilfield, was collected and analyzed by molecular microbiology, chemical and physical methods. Diverse bacterial groups (11 families) were detected in the biofilm, including Pseudomonadaceae, Rhodocyclaceae, Desulfobulbaceae, Alcaligenaceae, Comamonadaceae, Oxalobacteraceae, Bacteriovoracaceae, Campylobacteraceae, Flavobacteriaceae, Clostridiales Incertae Sedis XIII and Moraxellaceae. Three archaeal orders of methanogens including Methanomicrobiales, Methanosarcinales and Thermoplasmatales were also detected separately. HPAM was degraded into lower molecular weight polymers and organic fragments with its amide groups hydrolyzed into carboxylic groups by the microorganisms. The microenvironment of the biofilm contained diverse bacterial and archaeal communities, correlating with the extracellular polymeric substance (EPS) and HPAM biodegradation. The results are helpful to provide information for biofilm control in oil fields.

Synthesis and characterization of anaerobic degradation biomarkers of n-alkanes via hydroxylation/carboxylation pathways

Metabolite profiling is a powerful method in research on anaerobic biodegradation of hydrocarbons. Hydroxylation and carboxylation are proposed pathways in anaerobic degradation but very little direct evidence is available about metabolites and signature biomarkers. 2-Acetylalkanoic acid is a potential signature metabolite because of its unique and specific structure among possible intermediates. A procedure for the synthesis of four homologues with various carbon chain lengths was proposed and the characteristics of 2-acetyl- alkanoic acid esters were investigated using four derivatization processes, namely methyl, ethyl, n-butyl and trimethylsilyl esterification. Four intermediate fragments observed were at m/z 73 + 14n, 87 + 14n, 102 + 14n (n = 1, 2 and 4 for methyl, ethyl and n-butyl ester, respectively) and [M - 42]+ for three of the derivatization methods. For silylation, characteristic ions were observed at m/z 73, 117, [M - 42](+) and [M - 55](+). These are basic and significant data for the future identification of potential intermediates of the hydroxylation and carboxylation pathways in hydrocarbon degradation.

Anaerolineaceae and Methanosaeta turned to be the dominant microorganisms in alkanes-dependent methanogenic culture after long-term of incubation

The methanogenic alkanes-degrading enrichment culture which had been incubated for over 1,300 days amended with n-alkanes (C₁₅–C₂₀) was investigated through clone libraries of bacteria, archaea and assA, mcrA functional genes. These enrichment cultures were obtained from oily sludge after an initial incubation of the oily sludge without any carbon source and then an enrichment transfer with n-alkanes (C₁₅–C₂₀) for acclimation. Activation of alkanes, methane precursor generation and methanogenic pathways are considered as three pivotal stages for the continuous methanogenesis from degradation of alkanes. The presence of functional genes encoding the alkylsuccinate synthase α-subunit indicated that fumarate addition is most likely the one of initial activation step for degradation of n-alkanes. Degradation intermediates of n-alkanes were octadecanoate, hexadecanoate, butyrate, isobutyrate, acetate and propionate, which could provide the appropriate substrates for acetate formation. Both methyl coenzyme M reductase gene and 16S rRNA gene analysis showed that microorganisms of Methanoseata were the most dominant methanogens, capable of using acetate as the electron donor to produce methane. Bacterial clone libraries showed organisms of Anaerolineaceae (within the phylum of Chloroflexi) were predominant (45.5%), indicating syntrophically cooperation with Methanosaeta archaea was likely involved in the process of methanogenic degradation of alkanes. Alkanes may initially be activated via fumarate addition and degraded to fatty acids, then converted to acetate, which was further converted to methane and carbon dioxide by methanogens.

Effect of sevoflurane preconditioning on the digestive system of patients with primary liver cancer undergoing surgery

AIM: To explore the effect of sevoflurane preconditioning on the digestive system of patients with primary liver cancer undergoing surgery.

METHODS: Eighty patients who underwent right liver resection for primary liver cancer from January 2012 to January 2015 at Zhejiang Armed Police Hospital were randomly divided into an observation group and a control group, with 40 cases in each group. The observation group was given sevoflurane pretreatment. Serum levels of tumor necrosis factor-α (TNF-α), intestinal fatty acid binding protein (I-FABP), and D-lactate at different time points were compared between the two groups, and adverse reactions of the digestive system were recorded.

RESULTS: Serum TNF-α and D-lactate concentrations in both groups rose from before induction of anesthesia, peaked at 6 h after the release of the porta hepatis, and then declined. Serum TNF-α and D-lactate concentrations from the occlusion of the porta hepatis to 24 h after the release of the porta hepatis were significantly lower in the observation group than in the control group (P < 0.05). Serum I-FABP concentrations in both groups increased from the occlusion of the porta hepatis, peaked at 36 h after the release of the porta hepatis, and declined from 6 h. Serum I-FABP concentrations from the occlusion of the porta hepatis to 24 h after the release of the porta hepatis were significantly lower in the observation group than in the control group (P < 0.05).The incidence of adverse reactions of the digestive system was significantly lower in the observation group than in the control group (12.5% vs 27.5%, P < 0.05).

CONCLUSION: Sevoflurane preconditioning can suppress the body's inflammatory response, reduce the incidence of postoperative digestive system adverse reactions, and mitigate digestive system damage in patients with primary liver cancer undergoing surgery.

Comparison of high-intensity focused ultrasound therapy under nasal endoscopy guidance versus first-line drug treatment in patients with persistent allergic rhinitis

The aim of this study was to determine whether high-intensity focused ultrasound (HIFU) therapy under nasal endoscopy guidance could provide better efficacy and safety in patients with persistent allergic rhinitis (PAR) than the first-line drugs recommended by the World Health Organization. A total of 120 adult patients with PAR were randomly divided into 2 groups (N = 60 each). One group underwent HIFU therapy under nasal endoscopy guidance using an ultrasound rhinitis therapeutic machine. The other group served as the control group and was treated with corticosteroid nasal spray and oral cetirizine hydrochloride. All patients underwent follow-up treatment for 1 year, after which the efficacy and safety were evaluated. There was no significant difference between the two groups (P > 0.05) in the total effective rate. Moreover, no complications such as nasal adhesion, septal perforation, mucosal atrophy, and hyposmia were observed, indicating that HIFU was as effective as the first-line drug treatments recommended by the World Health Organization for symptom relief in PAR patients. The treatment efficacy, repeatability, safety, economical aspects, ease of performance, and few complications of HIFU therapy strongly suggest that HIFU should be routinely incorporated into clinical practice.