Prospects of microbial polysaccharides-based hybrid constructs for biomimicking applications.

Polysaccharides are biobased polymers obtained from renewable sources. They exhibit various interesting features including biocompatibility, biodegradability, and nontoxicity. Microbial polysaccharides are produced by several microorganisms including yeast, fungi, algae, and bacteria. Microbial polysaccharides have gained high importance in biotechnology due to their novel physiochemical characteristics and composition. Among microbial polysaccharides, xanthan, alginate, gellan, and dextran are the most commonly reported polysaccharides for the development of biomimetic materials for biomedical applications including targeted drug delivery, wound healing, and tissue engineering. Several chemical and physical cross-linking reactions are performed to increase their technological and functional properties. Owning to the broad-scale applications of microbial polysaccharides, this review aims to summarize the characteristics with different ways of physical/chemical crosslinking for polysaccharide regulation. Recently, several biopolymers have gained high importance due to their biologically active properties. This will help in the formation of bioactive nutraceuticals and functional foods. This review provides a perspective on microbial polysaccharides, with special emphasis given to applications in promising biosectors and the subsequent advancement on the discovery and development of new polysaccharides for adding new products.

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.

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.

Quercetin liposome sensitizes colon carcinoma to thermotherapy and thermochemotherapy in mice models.

Thermotherapy and thermochemotherapy have been used in clinics to treat patients with malignant diseases, including colon cancer, and their efficacy has been well proved. Heat shock proteins (HSPs), especially Hsp70, play important roles in neutralizing their efficacy. It has been reported that quercetin can suppress cancer by inhibiting the intratumoral expression of Hsp70. This study was designed to investigate whether quercetin could enhance sensitivity to thermotherapy and thermochemotherapy. Soluble quercetin liposome was used in this study. The effects of quercetin were investigated in vitro and in mouse colon cancer models of subcutaneous tumor and peritoneal carcinomatosis. The results showed that quercetin liposome inhibited the upregulation of Hsp70 and enhanced apoptosis induced by hyperthermia and thermochemotherapy. Systemic administration of quercetin liposome can sensitize CT26 cells to thermotherapy and chemothermotherapy. This study suggests that quercetin liposome might be potentially applied for clinical cancer therapy.

Inhibition of lymphatic metastases by a survivin dominant-negative mutant.

Metastasis is the most lethal attribute of human malignancy. High-level expression of survivin is involved in both carcinogenesis and angiogenesis in cancer. Previous studies indicate that a mutation of the threonine residue at position 34 (Thr34Ala) of survivin generates a dominant-negative mutant that induces apoptosis, inhibits angiogenesis, and suppresses highly metastatic breast carcinoma in mouse models. We investigated the efficacy of gene therapy with a survivin dominant-negative mutant and possible factors related to lymph node metastasis. The metastasis rate was compared between each group in order to find a survivin-targeted therapy against lymphangiogenesis in its earliest stages. We established lymph node metastasis models and treated animals with H22 tumors with Lip-mSurvivinT34A (Lip-mS), Lip-plasmid (Lip-P), or normal saline (NS). Eight days after the last dose, five randomly chosen mice from each group were sacrificed. We detected the apoptotic index, microvessel density (MVD), lymphatic microvessel density (LMVD), and the expression of VEGF-D with immunohistochemistry. After the remaining animals were sacrificed, we compared the tumor-infiltrated lymph nodes in each group. Administration of mSurvivinT34A plasmid complexed with cationic liposome (DOTAP/chol) resulted in the efficacious inhibition of tumor growth and lymph node metastasis within the mouse H22 tumor model. These responses were associated with tumor cell apoptosis, and angiogenesis and lymphangiogenesis inhibition. Our results suggested that Lip-mSurvivinT34A induced apoptosis and inhibited tumor angiogenesis and lymphangiogenesis, thus suppressing tumor growth and lymphatic metastasis. The mSurvivinT34A survivin mutant is a promising strategy of gene therapy to inhibit lymphatic metastasis.

The pigment epithelial-derived factor gene loaded in PLGA nanoparticles for therapy of colon carcinoma.

Colon carcinoma is one of the common malignant tumors and has high morbidity and mortality in the world. Pigment epithelial-derived factor (PEDF) has been found to be the most potent natural inhibitor of angiogenesis and PEDF gene has been extensively used for the therapy of tumors, which suggests a potential approach to the therapy of colon carcinoma. However, the transfer of PEDF gene largely depends on the effective gene delivery systems. Poly (lactic-co-glycolic acid) nanoparticles (PLGANPs) have been extensively used for gene therapy due to its low-toxicity, biocompatibility and biodegradability, due to its potential to be an excellent carrier of the PEDF gene. We investigated the effect of PEDF gene loaded in PLGA nanoparticles (PEDF-PLGANPs) on the mouse colon carcinoma cells (CT26s) in vitro and in vivo. Blank PLGANPs (bPLGANPs) showed lower cytotoxicity than PEI to the CT26s. In vitro, PEDF-PLGANPs directly induced CT26 apoptosis and inhibit human umbilical vein endothelial cell (HUVEC) proliferation. In vivo, PEDF-PLGANPs inhibited CT26 tumors growth by inducing CT26 apoptosis, decreasing MVD and inhibiting angiogenesis. Our present study demonstrates the inhibitory effect of PEDF-PLGANPs on the growth of CT26s in vitro and in vivo for the first time. PLGANP-mediated PEDF gene could provide an innovative strategy for the therapy of colon carcinoma.

Fe3O4/SiO2-g-PSStNa polymer nanocomposite microspheres (PNCMs) from a surface-initiated atom transfer radical polymerization (SI-ATRP) approach for pectinase immobilization.

Polymer nanocomposite microspheres (PNCMs) as solid supports can improve the efficiency of immobilized enzymes by reducing diffusional limitation as well as by increasing the surface area per mass unit. In this work, pectinase was immobilized on Fe(3)O(4)/SiO2-g-poly(PSStNa) nanocomposite microspheres by covalent attachment. Biochemical studies showed an improved storage stability of the immobilized pectinase as well as enhanced performance at higher temperatures and over a wider pH range. The immobilized enzyme retained >50% of its initial activity over 30 days, and the optimum temperature and pH also increased to the ranges of 50-60 degrees C and 3.0-4.7, respectively. The kinetics of a model reaction catalyzed by the immobilized pectinase was finally investigated by the Michaelis-Menten equation. The PSStNa support presents a very simple, mild, and time-saving process for enzyme immobilization, and this strategy of immobilizing pectinase also makes use of expensive enzymes economically viable, strengthening repeated use of them as catalysts following their rapid and easy separation with a magnet.