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 bacterial and archaeal communities along a high-molecular-weight polyacrylamide transportation pipeline system in an oil field.

Viscosity loss of high-molecular-weight partially hydrolyzed polyacrylamide (HPAM) solution was observed in a water injection pipeline before being injected into subterranean oil wells. In order to investigate the possible involvement of microorganisms in HPAM viscosity loss, both bacterial and archaeal community compositions of four samples collected from different points of the transportation pipeline were analyzed using PCR-amplification of the 16S rRNA gene and clone library construction method together with the analysis of physicochemical properties of HPAM solution and environmental factors. Further, the relationship between environmental factors and HPAM properties with microorganisms were delineated by canonical correspondence analysis (CCA). Diverse bacterial and archaeal groups were detected in the four samples. The microbial community of initial solution S1 gathered from the make-up tank is similar to solution S2 gathered from the first filter, and that of solution S3 obtained between the first and the second filter is similar to that of solution S4 obtained between the second filter and the injection well. Members of the genus Acinetobacter sp. were detected with high abundance in S3 and S4 in which HPAM viscosity was considerably reduced, suggesting that they likely played a considerable role in HPAM viscosity loss. This study presents information on microbial community diversity in the HPAM transportation pipeline and the possible involvement of microorganisms in HPAM viscosity loss and biodegradation. The results will help to understand the microbial community contribution made to viscosity change and are beneficial for providing information for microbial control in oil fields.

Transcriptional Analysis of Tea Plants (Camellia sinensis) in Response to Salicylic Acid Treatment.

Salicylic acid (SA) is an important plant hormone and signal required for establishing resistance to diverse pathogens and plant diseases. The abundant polyphenols in tea plants also defend plants from biotic and abiotic stresses. However, whether exogenous SA would increase the resistance of tea plants to adversity and the relationship between SA and polyphenols are still poorly understood. Here, we carried out SA treatment on tea seedlings and performed transcriptome sequencing. SA treatment inhibited the phenylpropanoid and flavonoid metabolic pathways but promoted the lignin metabolic pathways. The increased accumulation of lignin in tea leaves after treating with SA indicated that lignin might coordinate SA, enhance, and improve plant defense and disease resistance. Simultaneously, an SA-inducible flavonoid glucosyltransferase (CsUGT0554) specifically involved in 7-OH site glycosylation was characterized in vitro. These results provided valuable information about the effects of SA on tea seedlings and the molecular basis for SA-mediated immune responses.

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.

Novel galactosylated biodegradable nanoparticles for hepatocyte-delivery of oridonin.

Nanoparticles based on the newly synthesized copolymers of linear PLGA blocked with two TPGS ends and galactosylated TPGS were successfully constructed as carriers of oridonin for liver-targeting. The novel copolymers were characterized by (1)H-NMR and TGA. The drug-loaded nanoparticles were prepared by a nanoprecipitation technique and characterized in terms of physicochemical properties, such as particle size, zeta potential, morphology, encapsulation efficiency, in vitro drug release behavior and physical state of the entrapped drug. The ORI-Gal-PT NPs were found to have the highest antitumor efficacy in comparison with the oridonin solution and non-galactosylated nanoparticles and induced a higher apoptotic rate of tumor cells. The targeting nanoparticles could enhance the therapeutic effect of oridonin by increasing uptake of the nanoparticles through asialoglycoprotein receptor-mediated endocytosis. The ORI-Gal-PT NPs system could be a highly promising drug delivery system to be used in liver cancer therapy.

Synthesis, characterization, in vitro and in vivo evaluation of PEGylated oridonin conjugates.

Oridonin (ORI), a diterpenoid compound with promising antitumor activity, was proved to possess potent antileukemia efficacies in vitro and in vivo recently. However, the development and application of ORI was limited by its poor solubility and rapid plasma clearance. The purpose of this study was to solve these problems. PEGylated oridonin linked with succinic acid (SA) as spacer moiety (PEG-SA-ORI conjugate) was synthesized. mPEG amines with four specifications of molecular weight (MW) were utilized. All polymeric conjugates showed satisfactory aqueous solubility and in vitro studies implied that the drug solubility and release features of conjugates were relevant to PEGs. The drug solubility increased more when the MW of PEG was lower, while more significant sustained-release effect was shown with higher PEG MW. Moreover, the release behaviors of conjugates showed a pH-sensitive property. In vivo pharmacokinetic studies demonstrated that the elimination half-life was prolonged in comparison with ORI solution. PEGylation could be a promising method to obtain better efficacy in the field of drug delivery system.

Self-assembled nanoparticles based on galactosylated O-carboxymethyl chitosan-graft-stearic acid conjugates for delivery of doxorubicin.

A novel polymer, i.e. galactosylated O-carboxymethyl chitosan-graft-stearic acid (Gal-OCMC-g-SA) was synthesized for liver targeting delivery of doxorubicin. The chemical structure was characterized by FT-IR, (1)H NMR and elemental analysis. Gal-OCMC-g-SA could self-assemble into nanoparticles with diameter of 160 nm by probe sonication in aqueous medium and exhibited a low critical aggregation concentration of 0.047 mg/mL. The DOX-loaded Gal-OCMC-g-SA (Gal-OCMC-g-SA/DOX) self-assembled nanoparticles were almost spherical in shape with an average diameter of less than 200 nm and zeta potential of around -10 mV. In vitro release revealed that the Gal-OCMC-g-SA/DOX nanoparticles exhibited a sustained and pH-dependent drug release manner. Furthermore, the hemolysis test demonstrated the good safety of Gal-OCMC-g-SA in blood-contacting applications. These results indicated that Gal-OCMC-g-SA/DOX nanoparticles were highly potential to be applied in cancer therapy.