Bacterial degradation of acrylic oligomers and polymers

Three bacterial strains that assimilate acrylic trimer as a carbon and energy source were isolated from activated sludge and soil samples and were tentatively identified as Microbacterium sp. II-7-12, Xanthomonas maltophilia W1 and Acinetobacter genospecies 11 W2. They could assimilate acrylic monomer, dimer and trimer, but not polymers. Trimer, 0.2%, was completely consumed in 3 days. The culture filtrate became alkaline during bacterial growth. From the values of biological O₂ consumption versus theoretical O₂ consumption towards oligomers and polymers, biodegradation of acrylic polymers by trimer-utilizing bacteria was suggested. The resting cells of three bacteria grown on trimer degraded acrylic polymers (average relative molecular mass of 1000–4500) at a concentration of 100 ppm (0.01%). The biodegradation rate of acrylic polymer by resting cells was calculated to be approximately 1/120 of that of acrylic trimer. Acyl-CoA synthetase activities towards oligomeric or polymeric acrylates were found with cell-free extracts of the three bacteria.     

Development of microbodies in Candida tropicalis during incubation in a n-alkane medium

Development of microbodies in Candida tropicalis pK 233 was studied mainly by electron microscopical observation. The yeast cells, precultured on malt extract, scarcely contained microbodies and showed very low catalase activity. When the precultured cells were transferred to a n-alkane medium and incubated with shaking, the number of microbodies increased and concomitantly the activity of catalase was enhanced. That is, both the area ratio of microbodies in the cell and the ratio of microbodies to cytoplasm in area increased significantly during the utilization of n-alkanes for 8 hrs. Localization of catalase in the microbodies was demonstrated cytochemically by use of 3,3'-diaminobenzidine, but other organella in the cell, except for vacuoles appearing in the early growth phase and mitochondria, were not stained with this reagent. Microbodies seemed to grow by division. Biogenesis of microbodies in the yeast cells is also discussed.     

Microbial Formation of D-Pantothenic Acid-α-glucoside

The formation of D-pantothenic acid-α-glucoside (PaA-α-G) was found from D-pantothenic acid (PaA) and maltose in incubation mixtures of microorganisms, especially Saccharomyces yeasts and Sporobolomyces coralliformis IFO 1032. The reaction conditions were investigated for formation of PaA-α-G by resting cells of Spor. coralliformis. The formation of the compound increased with PaA concentration (3~20 mg/ml). The yield was maximum at 5~10 mg/ml of PaA. Cetyl trimethyl ammonium bromide (0.1 %) promoted the formation of PaA-α-G. Sucrose was the optimal α-glucosyl donor. When 30 mg/ml of sucrose was fed to the reaction mixture (initial sucrose, 100 mg/ml; and PaA, 10 mg/ml) at 12-hr intervals, 5.74 mg/ml (3.30 mg/ml as PaA) of PaA-α-G was formed in 48-hr incubation at 28°C with shaking. PaA-α-G was also formed by yeast α-glucosidase, mold maltase and the cell-free extract of Spor. coralliformis. The compound showed approximately 9~10% and 0.1~0.3% (molar ratio) of activity of PaA for Saccharomyces carlsbergensis ATCC 9080 and Lactobacillus plantarum ATCC 8014, respectively. The compound had the same microbiological activity as authentic 4′-O-(α-D-glucopyranosyl)-D-pantothenic acid.     

Studies on Transglycosidation to Vitamin B6 by Microorganisms

Some properties of pyridoxine glucoside-synthesizing enzyme were studied using the partially and highly purified enzyme preparations from Micrococcus sp. No. 431.

The enzyme was stable at pH 7.0 and between 0°C and 30°C. The maximal activity was obtained at pH 8.0 and 37°C. Besides sucrose, phenyl-α-d-glucoside and maltose served as glucosyl donor. Of vitamin B₆ compounds tested, only pyridoxine served as glucosyl acceptor. The enzyme activity was inhibited by PCMB and heavy metal ions, and the inhibition was prevented by 2-mercaptoethanol, indicating the enzyme would be a sulfhydryl enzyme. The activity was not affected by chelating agents and not activated by metal ions.     

Maximization of hydrogen production ability in high-density suspension of Rhodovulum sulfidophilum cells using intracellular poly(3-hydroxybutyrate) as sole substrate

Growth of and hydrogen production by wild-type (WT) Rhodovulum sulfidophilum were compared with those by one of its mutants lacking the poly(3-hydroxybutyrate) (PHB) biosynthesis ability (PNM2). During phototrophic growth under aerobic conditions with fixed illumination, changes in the extinction coefficient and PHB content of WT and PNM2 cells revealed interference of light penetration by PHB. WT cells synthesized PHB at an early stage of the cultivation. PHB degradation after exhaustion of acetate during the cultivation of WT resulted in a decrease of the extinction coefficient. The hydrogen production rate under anaerobic conditions with fixed illumination was examined in WT and PNM2 cell suspensions at different densities. The hydrogen production rate was determined not by the light penetration but by the kinds of hydrogen donors and the density of suspension. The highest value of the rate of hydrogen production from PHB, 33.0 ml/l/h, was improved compared with 26.6 ml/l/h, which was the highest value in hydrogen production from succinate. Under the same illumination, conversion to hydrogen from PHB is more efficient than that from succinate, which is one of the best substrates for hydrogen production. These results suggest that the hydrogen production rate can be maximized in the hydrogen production system based on PHB degradation, which is achieved in high-density suspension under external-substrate-depleted conditions after aerobic cultivation in the presence of an excess amount of acetate.     

Mitogen-activated protein kinase kinase 1/2 inhibition and angiotensin II converting inhibition in mice with cardiomyopathy caused by lamin A/C gene mutation

Background

Mutations in the LMNA gene encoding A-type nuclear lamins can cause dilated cardiomyopathy with or without skeletal muscular dystrophy. Previous studies have shown abnormally increased extracellular signal-regulated kinase 1/2 activity in hearts of Lmna^H222P/H222P mice, a small animal model. Inhibition of this abnormal signaling activity with a mitogen-activated protein kinase kinase 1/2 (MEK1/2) inhibitor has beneficial effects on heart function and survival in these mice. However, such treatment has not been examined relative to any standard of care intervention for dilated cardiomyopathy or heart failure. We therefore examined the effects of an angiotensin II converting enzyme (ACE) inhibitor on left ventricular function in Lmna^H222P/H222P mice and assessed if adding a MEK1/2 inhibitor would provide added benefit.

Methods

Male Lmna^H222P/H222P mice were treated with the ACE inhibitor benazepril, the MEK1/2 inhibitor selumetinib or both. Transthoracic echocardiography was used to measure left ventricular diameters and fractional shortening was calculated.

Results

Treatment of Lmna^H222P/H222P mice with either benazepril or selumetinib started at 8 weeks of age, before the onset of detectable left ventricular dysfunction, lead to statistically significantly increased fractional shortening compared to placebo at 16 weeks of age. There was a trend towards a great value for fractional shortening in the selumetinib-treated mice. When treatment was started at 16 weeks of age, after the onset of left ventricular dysfunction, the addition of selumetinib treatment to benazepril lead to a statistically significant increase in left ventricular fractional shortening at 20 weeks of age.

Conclusions

Both ACE inhibition and MEK1/2 inhibition have beneficial effects on left ventricular function in Lmna^H222P/H222P mice and both drugs together have a synergistic benefit when initiated after the onset of left ventricular dysfunction. These results provide further preclinical rationale for a clinical trial of a MEK1/2 inhibitor in addition to standard of care in patients with dilated cardiomyopathy caused by LMNA mutations.     

Xenoestrogenic short ethoxy chain nonylphenol is oxidized by a flavoprotein alcohol dehydrogenase from <Emphasis Type="Italic">Ensifer</Emphasis> sp. strain AS08

The ethoxy chains of short ethoxy chain nonylphenol (NPEO_av2.0, containing average 2.0 ethoxy units) were dehydrogenated by cell-free extracts from Ensifer sp. strain AS08 grown on a basal medium supplemented with NPEO_av2.0. The reaction was coupled with the reduction in 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide and phenazine methosulfate. The enzyme (NPEO_av2.0 dehydrogenase; NPEO-DH) was purified to homogeneity with a yield of 20% and a 56-fold increase in specific activity. The molecular mass of the native enzyme was 120 kDa, consisting of two identical monomer units (60 kDa). The gene encoding NPEO-DH was cloned, which consisted of 1,659 bp, corresponding to a protein of 553 amino acid residues. The deduced amino acid sequence agreed with the N-terminal amino acid sequence of the purified NPEO-DH. The presence of a flavin adenine dinucleotide (FAD)-binding motif and glucose–methanol–choline (GMC) oxidoreductase signature motifs strongly suggested that the enzyme belongs to the GMC oxidoreductase family. The protein exhibited homology (40–45% identity) with several polyethylene glycol dehydrogenases (PEG-DHs) of this family, but the identity was lower than those (approximately 58%) among known PEG-DHs. The substrate-binding domain was more hydrophobic compared with those of glucose oxidase and PEG-DHs. The recombinant protein had the same molecular mass as the purified NPEO-DH and dehydrogenated PEG400-2000, NPEO_av2.0 and its components, and NPEOav10, but only slight or no activity was found using diethylene glycol, triethylene glycol, and PEG200. English edition: The paper was edited by a native speaker through American Journal Experts ().     

Isolation of bacteria able to grow on both polyethylene glycol (PEG) and polypropylene glycol (PPG) and their PEG/PPG dehydrogenases

Two bacterial consortia growing on a random copolymer of ethylene glycol and propylene glycol units were obtained by enrichment cultures from various microbial samples. Six major strains included in both consortia were purified and identified as Sphingomonads, Pseudomonas sp. and Stenotrophomonas maltophilia. Three of them (Sphingobium sp. strain EK-1, Sphingopyxis macrogoltabida strain EY-1, and Pseudomonas sp. strain PE-2) utilized both PEG and polypropylene glycol (PPG) as a sole carbon source. Four PEG-utilizing bacteria had PEG dehydrogenase (PEG-DH) activity, which was induced by PEG. PCR products from DNA of these bacteria generated with primers designed from a PEG-DH gene (AB196775 for S. macrogoltabida strain 103) indicated the presence of a sequence that is the homologous to the PEG-DH gene (99% identity). On the other hand, five PPG-utilizing bacteria had PPG dehydrogenase (PPG-DH) activity, but the activity was constitutive. PCR of a PPG-DH gene was performed using primers designed from a polyvinyl alcohol dehydrogenase (PVA-DH) gene (AB190288 for Sphingomonas sp. strain 113P3) because a PPG-DH gene has not been cloned yet, but both PPG-DH and PVA-DH were active toward PPG and PVA (Mamoto et al. 2006). PCR products of the five strains did not have similarity to each other or to oxidoreductases including PVA-DH. The paper was edited by a native speaker through American Journal Experts (http://www.journalexperts.com).     

Unusual Accumulation of Demethylspheroidene in Anaerobic-Phototrophic Growth of crtA-Deleted Mutants of Rhodovulum sulfidophilum

Rhodovulum sulfidophilum produces carotenoids in the spheroidene pathway. Spheroidene monooxygenase, CrtA, catalyzes the conversion of spheroidene to spheroidenone. crtA-deleted mutants of R. sulfidophilum did not produce spheroidenone and demethylspheroidenone. In these mutants, the ratio of demethylspheroidene to spheroidene increased with exposure to light. One mutant exhibiting a spheroidene-predominant phenotype did not grow under anaerobic-light conditions and was devoid of bacteriochlorophyll a, even under semiaerobic-light conditions There was no difference in the growth of the mutants under aerobic-dark conditions. These data suggest that demethylspheroidene is important for photosynthesis in R. sulfidophilum.