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Journal of Biotechnology Dec 2022Polyhydroxyalkanoates (PHA) represent an environmentally friendly alternative to petroleum based plastics for a broad range of applications from packaging to biomedical...
Polyhydroxyalkanoates (PHA) represent an environmentally friendly alternative to petroleum based plastics for a broad range of applications from packaging to biomedical devices. In the prospect of an industrial PHA production, it is highly valuable to accurately control the incorporation of different repeating units into the polymer, to produce a polyester with specific material characteristics. In this study, we develop macroscopic dynamic models predicting the polymer production and composition when mixtures containing up to four volatile fatty acids (VFA) are used as substrates. These models successfully reproduce the sequential (and preferential) substrate consumption and polymer production/reconsumption patterns, experimentally observed during biomass growth, thanks to simple kinetic structures based on Monod and inhibition factors. These models can serve as a basis for numerical simulation and process analysis, as well as process intensification through model-based optimization and control.
Topics: Rhodospirillum rubrum; Polyhydroxyalkanoates; Fatty Acids, Volatile
PubMed: 36273668
DOI: 10.1016/j.jbiotec.2022.10.014 -
Biochemical and Biophysical Research... Oct 2017Rhodospirillum rubruml-asparaginase mutant RrA E149R, V150P, F151T (RrA) was previously identified to down-regulate telomerase activity along with catalyzing the...
Rhodospirillum rubruml-asparaginase mutant RrA E149R, V150P, F151T (RrA) was previously identified to down-regulate telomerase activity along with catalyzing the hydrolysis of l-asparagine. The aim of this study was to define the effect of prolonged RrA exposure on telomerase activity, maintenance of telomeres and proliferation of cancer cells in vitro and in vivo. RrA could inhibit telomerase activity in SCOV-3, SkBr-3 and A549 human cancer cell lines due to its ability to down-regulate the expression of telomerase catalytic subunit hTERT. Telomerase activity in treated cells did not exceeded 29.63 ± 12.3% of control cells. Continuous RrA exposure of these cells resulted in shortening of telomeres followed by cell death in vitro. Using real time PCR we showed that length of telomeres in SCOV-3 cells has been gradually decreasing from 10105 ± 2530 b.p. to 1233 ± 636 b.p. after 35 days of cultivation. RrA treatment of xenograft models in vivo showed slight inhibition of tumor growth accompanied with 49.5-53.3% of decrease in hTERT expression in the all tumors. However down-regulation of hTERT expression, inhibition of telomerase activity and the loss of telomeres was significant in response to RrA administration in xenograft models. These results should facilitate further investigations of RrA as a potent therapeutic protein.
Topics: Animals; Antineoplastic Agents; Asparaginase; Cell Line, Tumor; Down-Regulation; Enzyme Inhibitors; Female; Humans; Mice, Inbred BALB C; Mice, Nude; Neoplasms; Point Mutation; Rhodospirillum; Telomerase; Telomere Shortening
PubMed: 28837806
DOI: 10.1016/j.bbrc.2017.08.078 -
Nature Feb 1952
Topics: Biological Products; Chromatophores; Pigments, Biological; Rhodospirillum rubrum
PubMed: 14910754
DOI: 10.1038/169282a0 -
Archives of Microbiology May 2003The cytoplasmic pyrophosphatase of the photosynthetic bacterium Rhodospirillum rubrum was purified to electrophoretic homogeneity. The enzyme is a homohexamer of 20-kDa...
The cytoplasmic pyrophosphatase of the photosynthetic bacterium Rhodospirillum rubrum was purified to electrophoretic homogeneity. The enzyme is a homohexamer of 20-kDa monomers. The gene was cloned and sequenced. Alignment of the deduced 179-amino-acid protein with known bacterial pyrophosphatases revealed conservation of all residues in the active site. Attempts to obtain an insertion mutant of the cytoplasmic pyrophosphatase gene did not yield any cell completely devoid of cytoplasmic pyrophosphatase activity. The mutants obtained showed 50% of the enzymatic activity and grew in twice the generation time of wild-type cells. This suggests that the membrane-bound pyrophosphatase of Rsp. rubrum is not sufficient for a normal growth rate, whereas the cytoplasmic enzyme is essential for growth. The characteristics of the gene and the encoded protein fit those of prokaryotic family I pyrophosphatases.
Topics: Amino Acid Sequence; Base Sequence; Cloning, Molecular; Mutation; Pyrophosphatases; Rhodospirillum rubrum; Sequence Alignment
PubMed: 12658333
DOI: 10.1007/s00203-003-0537-4 -
International Journal of Systematic and... Aug 2013A reddish-brown bacterium, designated strain JA318(T), was purified from a photoheterotrophic enrichment culture obtained from the rhizosphere soil of paddy. Cells of...
A reddish-brown bacterium, designated strain JA318(T), was purified from a photoheterotrophic enrichment culture obtained from the rhizosphere soil of paddy. Cells of strain JA318(T) are spiral shaped, Gram-stain-negative and motile by means of amphitrichous flagella. Strain JA318(T) has no NaCl requirement for growth but can tolerate up to 1.5 % (w/v) NaCl. Internal photosynthetic membranes are present as lamellar stacks. Photoorganoheterotrophy is the only growth mode observed. Strain JA318(T) contains bacteriochlorophyll a, lycopene and rhodopin as major carotenoids. Thiamine, niacin and para-aminobenzoic acid (PABA) are required as growth factors. Major fatty acids are C18 : 1ω7c and C16 : 0. Ubiquinone-8 and rhodoquinone-8 are the observed quinones. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified aminolipid are the major polar lipids in strain JA318(T). Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain JA318(T) clustered with species of the genus Rhodospirillum which belongs to the class Alphaproteobacteria. The highest sequence similarity of strain JA318(T) was found with Rhodospirillum sulfurexigens JA143(T) (99.9 %). The DNA-DNA reassociation values of strain JA318(T) with Rsp. sulfurexigens JA143(T) and Rhodospirillum photometricum DSM 122(T) were 52 ± 2 % and 45 ± 1 %, respectively. The genomic DNA G+C content of strain JA318(T) was 60.2 mol%. Based on the morphological, physiological, chemotaxonomical and molecular evidence, strain JA318(T) is significantly different from the type strains of species of the genus Rhodospirillum, of the family Rhodospirillaceae, and it is proposed that the strain be classified as a representative of a novel species for which the name Rhodospirillum oryzae sp. nov. is proposed. The type strain is JA318(T) (= KCTC 5960(T) = NBRC 107573(T)).
Topics: Bacterial Typing Techniques; Bacteriochlorophyll A; Base Composition; Carotenoids; DNA, Bacterial; Fatty Acids; India; Lycopene; Molecular Sequence Data; Nucleic Acid Hybridization; Oryza; Phylogeny; RNA, Ribosomal, 16S; Rhizosphere; Rhodospirillum; Sequence Analysis, DNA; Soil Microbiology; Ubiquinone
PubMed: 23416569
DOI: 10.1099/ijs.0.049023-0 -
Journal of Bacteriology Aug 1969Rhodospirillum tenue sp. n. differs from the rhodospirilla described so far by its small size, ultrastructure, and physiological and biochemical characteristics.
Rhodospirillum tenue sp. n. differs from the rhodospirilla described so far by its small size, ultrastructure, and physiological and biochemical characteristics.
Topics: Microscopy, Electron; Rhodospirillum
PubMed: 5808083
DOI: 10.1128/jb.99.2.619-620.1969 -
Biophysical Journal Jun 2014Purple photosynthetic bacteria harvest light using pigment-protein complexes which are often arranged in pseudo-organelles called chromatophores. A model of a...
Purple photosynthetic bacteria harvest light using pigment-protein complexes which are often arranged in pseudo-organelles called chromatophores. A model of a chromatophore from Rhodospirillum photometricum was constructed based on atomic force microscopy data. Molecular-dynamics simulations and quantum-dynamics calculations were performed to characterize the intercomplex excitation transfer network and explore the interplay between close-packing and light-harvesting efficiency.
Topics: Absorption, Physicochemical; Amino Acid Sequence; Bacterial Chromatophores; Bacterial Proteins; Light-Harvesting Protein Complexes; Molecular Dynamics Simulation; Molecular Sequence Data; Protein Structure, Tertiary; Rhodospirillum
PubMed: 24896130
DOI: 10.1016/j.bpj.2014.04.030 -
The Journal of Biophysical and... Oct 1959Cells from serial cultures of R. rubrum, grown anaerobically in the light, were harvested at intervals from (1/2) to 15 days and sectioned for electron microscopy by...
Cells from serial cultures of R. rubrum, grown anaerobically in the light, were harvested at intervals from (1/2) to 15 days and sectioned for electron microscopy by conventional methods. Cells of this species possess a multilayered outer envelope, and the external cell surface is differentiated into ridges extending parallel or obliquely to the long axis of the cell. Cells from very young cultures resemble non-photosynthetic bacteria and contain only a granular cytoplasm, scattered high-density particles, and low-density areas corresponding to the chromatin areas observed by light microscopy. They contain neither the chromatophores nor the lamellar systems assumed by previous investigators to be characteristic of this species when grown anaerobically in the light. Chromatophores appear in cells from cultures older than about 12 hours, while systems of paired lamellae appear along with the chromatophores in cells from cultures older than about 8 days. Divergent opinions concerning the occurrence of chromatophores or lamellae in this species can be resolved on the basis of the age of cultures used in previous studies. Other changes occurring in cells from cultures of increasing age include the appearance of granular and reticulate cytoplasmic bodies and vacuoles, extension of the chromatin areas, and the appearance of a single membrane enclosing several chromatophores.
Topics: Cell Membrane; Chromatophores; Light; Microscopy, Electron; Rhodospirillum; Rhodospirillum rubrum
PubMed: 14401694
DOI: 10.1083/jcb.6.2.277 -
International Journal of Systematic and... Dec 2008A Gram-negative, spiral-shaped, phototrophic, purple non-sulfur bacterial strain, JA143(T), was isolated from a freshwater habitat. Strain JA143(T) was motile by means...
A Gram-negative, spiral-shaped, phototrophic, purple non-sulfur bacterial strain, JA143(T), was isolated from a freshwater habitat. Strain JA143(T) was motile by means of bipolar tufts of flagella. Intracellular photosynthetic membranes are of the lamellar stacked type. Bacteriochlorophyll a and carotenoids of the spirilloxanthin series with rhodovibrin are present as photosynthetic pigments. Thiamine and a reduced sulfur source are required for growth. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain JA143(T) clusters with species of the genus Rhodospirillum, belonging to the class Alphaproteobacteria. The highest sequence similarities of strain JA143(T) were found with the type strains of Rhodospirillum rubrum (95.6 %) and Rhodospirillum photometricum (95.7 %). Based on 16S rRNA gene sequence analysis and morphological and physiological characteristics, strain JA143(T) was significantly different from the other two recognized species of the genus Rhodospirillum and represents a novel species, for which the name Rhodospirillum sulfurexigens sp. nov. is proposed. The type strain is JA143(T) (=DSM 19785(T) =NBRC 104433(T)).
Topics: Molecular Sequence Data; Phototrophic Processes; Phylogeny; RNA, Ribosomal, 16S; Rhodospirillum; Species Specificity; Sulfur
PubMed: 19060082
DOI: 10.1099/ijs.0.65689-0 -
The Journal of Cell Biology Feb 1963The fine structure of Rhodospirillum rubrum grown under a series of defined conditions has been examined in thin sections prepared by the methods of Ryter and...
The fine structure of Rhodospirillum rubrum grown under a series of defined conditions has been examined in thin sections prepared by the methods of Ryter and Kellenberger. In cells grown anaerobically at different light intensities, the abundance of 500 A membrane-bounded vesicles in the cytoplasm is inversely related to light intensity, and directly related to cellular chlorophyll content. When the chlorophyll content of the cell is low, the vesicles are exclusively peripheral in location; they extend more deeply into the cytoplasm when the chlorophyll content is high. Typical vesicles also occur, though rarely, in cells grown aerobically in the dark, which have a negligible chlorophyll content. When synthesis of the photosynthetic pigment system is induced in a population of aerobically grown cells by incubation under semianaerobic conditions in the dark, the vesicles become increasingly abundant with increasing cellular chlorophyll content, and the cells eventually acquire the cytoplasmic structure that is characteristic of cells growing anaerobically at a high light intensity. Poststaining with lead hydroxide reveals that the membranes surrounding the 500 A vesicles are indistinguishable in structure from the cytoplasmic membrane, and continuous with it in some areas of the sections. The bearing of these observations on current notions concerning the organization of the bacterial photosynthetic apparatus is discussed.
Topics: Cell Membrane; Chlorophyll; Cytoplasm; Light; Membranes; Photosynthesis; Rhodospirillum; Rhodospirillum rubrum
PubMed: 14022119
DOI: 10.1083/jcb.16.2.401