Association between gut microbial change and acute gastrointestinal toxicity in patients with prostate cancer receiving definitive radiation therapy.

BACKGROUND: This prospective study investigated the association between gut microbial changes and acute gastrointestinal toxicities in prostate cancer patients receiving definitive radiation therapy (RT). METHODS: Seventy-nine fecal samples were analyzed. Stool samples were collected at the following timepoints: pre-RT (prRT), 2 weeks after the start of RT (RT-2w), 5 weeks after the start of RT (RT-5w), 1 month after completion of RT (poRT-1 m), and 3 months after completion of RT (poRT-3 m). We computed the microbial community polarization index (MCPI) as an indicator of RT-induced dysbiosis. RESULTS: Patients experiencing toxicity had lower alpha diversity, especially at RT-2w (p = 0.037) and RT-5w (p = 0.003). Compared to patients without toxicity, the MCPI in those experiencing toxicities was significantly elevated (p = 0.019). In terms of predicted metabolic pathways, we found linearly decreasing pathways, including carbon fixation pathways in prokaryotes (p = 0.035) and the bacterial secretion system (p = 0.005), in patients who experienced toxicities. CONCLUSIONS: We showed RT-induced dysbiosis among patients who experienced toxicities. Reduced diversity and elevated RT-related MCPI could be helpfully used for developing individualized RT approaches.

Overexpression of the (R)-specific enoyl-CoA hydratase gene from Pseudomonas chlororaphis HS21 in Pseudomonas strains for the biosynthesis of polyhydroxyalkanoates of altered monomer composition.

The (R)-specific enoyl-CoA hydratase gene (phaJ(HS21)) from Pseudomonas chlororaphis HS21 was overexpressed in various Pseudomonas strains, alone and in combination with the polyhydroxyalkanoate synthase gene (phaC(HS21)), for the biosynthesis of polyhydroxyalkanoates (PHAs) of altered monomer composition. Recombinant Pseudomonas strains harboring phaC(HS21) and phaJ(HS21) generated saturated and unsaturated monomers of C12-C14 in their PHAs. In particular, the level of the 3-hydroxytetradecenoate monomer in recombinant P. chlororaphis HS21 increased by approximately 260%. PhaJ(HS21) is expected to be useful in the biosynthesis of PHAs consisting of unusual monomer units.

Biocompatibility and antimicrobial activity of poly(3-hydroxyoctanoate) grafted with vinylimidazole.

Vinylimidazole-grafted poly(3-hydroxyoctanoate) (VI-g-PHO) copolymers were prepared by heating homogeneous solutions of PHO, VI monomer, and benzoylperoxide initiator. The Fourier transform infrared spectroscopy attenuated total reflection and electron spectroscopy for chemical analyses showed that VI was successfully grafted onto the PHO chains. The surfaces and the bulk of VI-g-PHO copolymers became more hydrophilic as the VI grafting density in the copolymer increased. Measurements of the growth of Chinese hamster ovary cells and the adsorption of blood proteins and platelets in vitro showed that biocompatibility was also enhanced by grafting of VI groups. Antimicrobial activity of the VI-g-PHO copolymers was studied against Escherichia coli, Staphylococcus aureus, and Candida albicans. Treatment of each culture suspension with 2.0% (w/v) copolymers for 12h resulted in >90% reduction in viable cell counts against all test microorganisms. These results indicate that the VI-g-PHO copolymers are promising materials for biomedical applications, as they exhibited both biocompatibility and broad spectrum antimicrobial activity.

Biosynthesis of medium-chain-length poly(3-hydroxyalkanoates) by volatile aromatic hydrocarbons-degrading Pseudomonas fulva TY16.

Pseudomonas fulva TY16 biosynthesized medium-chain-length poly(3-hydroxyalkanoates) (MCL-PHAs) containing unsaturated 3-hydroxydodecenoate unit (approximately 8-9%) when grown with volatile aromatic compounds including benzene, toluene, and ethylbenzene as sole carbon substrate. In particular, when cultivated using a continuous feeding system designed to supply toluene at a flow rate of 0.42gL(-1)h(-1) into a 7-L jar fermentor, the growth of the organism reached up to approximately 3.87gL(-1) after the 48h fed-batch fermentation, representing an accumulated cellular MCL-PHA of 58.9% by weight. The obtained MCL-PHA was a copolyester primarily consisting of 3-hydroxydecanoate (55.2%) and 3-hydroxyoctanoate (26.8%) with minor constituents being 3-hydroxyhexanoate (3.7%), 3-hydroxydodecenoate (8.2%), and 3-hydroxydodecanoate (6.1%). The present results suggest that P. fulva TY16 is a promising candidate for the biotechnological conversion of toxic petrochemical wastes to valuable biopolymers.

Biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolyesters with a high molar fraction of 3-hydroxyvalerate by an insect-symbiotic Burkholderia sp. IS-01.

Burkholderia sp. IS-01 capable of biosynthesizing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [poly(3HB-co-3HV)] copolyesters with a high molar fraction of 3HV was isolated from the gut of the adult longicorn beetle, Moechotypa diphysis. The strain IS-01 was relatively tolerant to high concentrations of levulinic acid and accumulated a poly(13.5 mol% 3HB-co-86.5 mol% 3HV) copolyester when cultivated on a mixture of gluconate (20 g/L) and levulinic acid (12.5 g/L). In this case, the content of the copolyester in the cells was approximately 60.0%. The compositions of the copolyesters were easily regulated by altering the molar ratio of gluconate and levulinic acid in the medium. The organism was found to possess a class I PHA synthase (PhaC) gene (1,881 bp) that encodes a protein with a deduced molecular mass of 68,538 Da that consists of 626 amino acids. The PhaC of this organism was most similar to that of B. cenocepacia PC184 (92% similarity).

Stable expression and secretion of polyhydroxybutyrate depolymerase of Paucimonas lemoignei in Escherichia coli.

An efficient strategy for the expression and secretion of extracellular polyhydroxybutyrate depolymerase (PhaZ1) of Paucimonas lemoignei in Escherichia coli was developed by employing the signal peptide of PhaZ1 and a truncated ice nucleation protein anchoring motif (INPNC). Directly synthesized mature form of Phaz1 was present in the cytoplasm of host cells as inclusion bodies, while a construct containing Phaz1 and its own N-terminal signal peptide (PrePhaz1) enabled the secretion of active Phaz1 into the extracellular medium. However, the PrePhaz1 construct was harmful to the host cell and resulted in atypical growth and instability of the plasmid during the cultivation. In contrast, INPNC-Phaz1 and INPNC-PrePhaz1 fusion constructs did not affect growth of host cells. INPNC-Phaz1 was successfully displayed on the cell surface with its fusion form, but did not retain Phaz1 activity. In the case of INPNC-PrePhaz1, the initially synthesized fusion form was separated by precise cleavage of the signal peptide, and active Phaz1 was consequently released into the culture medium. The amount of Phaz1 derived from E. coli (INPNC-PrePhaz1) was almost twice as great as that directly expressed from E. coli (PrePhaz1), and was predominantly (approximately 85%) located in the periplasm when cultivated at 22 degrees C but was efficiently secreted into the extracellular medium when cultivated at 37 degrees C.

Graft copolymerization of glycerol 1,3-diglycerolate diacrylate onto poly(3-hydroxyoctanoate) to improve physical properties and biocompatibility.

Glycerol 1,3-diglycerol diacrylate-grafted poly(3-hydroxyoctanoate) (GDD-g-PHO) copolymers were prepared by heating homogeneous solutions of PHO, GDD monomer and benzoylperoxide initiator. Experiments showed that GDD was successfully grafted onto the PHO chains and that the resulting copolymers had enhanced thermal properties and mechanical strengths. The surfaces and the bulk of GDD-g-PHO copolymers became more hydrophilic as the GDD grafting density in the copolymer increased. Measurements of the growth of Chinese hamster ovary cells and the adsorption of blood proteins and platelets in vitro showed that biocompatibility was also enhanced by grafting of GDD groups. These results indicate that the GDD-g-PHO copolymers are promising materials for biocompatible biomedical applications.

Biosynthesis, modification, and biodegradation of bacterial medium-chain-length polyhydroxyalkanoates.

Medium-chain-length polyhydroxyalkanoates (MCL-PHAs), which have constituents with a typical chain length of C6-C14, are polyesters that are synthesized and accumulated in a wide variety of Gram-negative bacteria, mainly pseudomonads. These biopolyesters are promising materials for various applications because they have useful mechanical properties and are biodegradable and biocompatible. The versatile metabolic capacity of some Pseudomonas spp. enables them to synthesize MCL-PHAs that contain various functional substituents; these MCL-PHAs are of great interest because these functional groups can improve the physical properties of the polymers, allowing the creation of tailor-made products. Moreover, some functional substituents can be modified by chemical reactions to obtain more useful groups that can extend the potential applications of MCL-PHAs as environmentally friendly polymers and functional biomaterials for use in biomedical fields. Although MCL-PHAs are water-insoluble, hydrophobic polymers, they can be degraded by microorganisms that produce extracellular MCL-PHA depolymerase. MCL-PHA-degraders are relatively uncommon in natural environments and, to date, only a limited number of MCL-PHA depolymerases have been investigated at the molecular level. All known MCL-PHA depolymerases share a highly significant similarity in amino acid sequences, as well as several enzymatic characteristics. This paper reviews recent advances in our knowledge of MCL-PHAs, with particular emphasis on the findings by our research group.