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Applied and Environmental Microbiology Sep 2021The lipid production potentials of 8 microalgal species were investigated. Among these 8 species, the best strain was a dominant bloom-causing dinoflagellate,...
The lipid production potentials of 8 microalgal species were investigated. Among these 8 species, the best strain was a dominant bloom-causing dinoflagellate, Prorocentrum donghaiense; this species had a lipid content of 49.32% ± 1.99% and exhibited a lipid productivity of 95.47 ± 0.99 mg liter day, which was 2-fold higher than the corresponding values obtained for the oleaginous microalgae Nannochloropsis gaditana and Phaeodactylum tricornutum. which is enriched in C and C, is appropriate for commercial docosahexaenoic acid (DHA) production. Nitrogen or phosphorus stress markedly induced lipid accumulation to levels surpassing 75% of the dry weight, increased the C and C contents, and decreased the C and C contents, and these effects resulted in decreases in the unsaturated fatty acid levels and changes in the lipid properties of such that the species met the biodiesel specification standards. Compared with the results obtained under N-deficient conditions, the enhancement in the activity of alkaline phosphatase of observed under P-deficient conditions partly alleviated the adverse effects on the photosynthetic system exerted by P deficiency to induce the production of more carbohydrates for lipogenesis. The supernatant of the algicidal bacterium sp. strain Y42 culture lysed without decreasing its lipid content, which resulted in facilitation of the downstream oil extraction process and energy savings through the lysis of algal cells. The Y42 supernatant treatment improved the lipid profiles of algal cells by increasing their C, C, and C contents and decreasing their C and C contents, which is favorable for biodiesel production. This study demonstrates the high potential of Prorocentrum donghaiense, a dominant bloom-causing dinoflagellate, for lipid production. Compared with previously studied oleaginous microalgae, exhibit greater potential for practical application due to its higher biomass and lipid contents. Nutrient deficiency and the algicidal bacterium sp. strain Y42 improved the suitability of the lipid profile of for biodiesel production. Furthermore, sp. Y42 effectively lysed algal cells, which facilitates the downstream oil extraction process for biodiesel production and results in energy savings through the lysing of algal cells. This study provides a more promising candidate for the production of docosahexaenoic acid (DHA) for human nutritional products and of microalgal biofuel as well as a more cost-effective method for breaking algal cells. The high lipid productivity of and algal cell lysis by algicidal bacteria contribute to reductions in the production cost of microalgal oil.
Topics: Biofuels; Dinoflagellida; Lipid Metabolism; Lipids; Nutrients; Paracoccus
PubMed: 34319787
DOI: 10.1128/AEM.01159-21 -
Applied and Environmental Microbiology Oct 2018blooms occur frequently in the Yangtze River estuary and the adjacent East China Sea. These blooms have damaged marine ecosystems and caused enormous economic losses...
blooms occur frequently in the Yangtze River estuary and the adjacent East China Sea. These blooms have damaged marine ecosystems and caused enormous economic losses over the past 2 decades. Thus, highly efficient, low-cost, ecofriendly approaches must be developed to control blooms. In this study, a bacterial strain (strain Y42) was identified as sp. and was used to lyse The supernatant of the strain Y42 culture was able to lyse , and the algicidal activity of this Y42 supernatant was stable with different temperatures and durations of light exposure and over a wide pH range. In addition to , Y42 showed high algicidal activity against , , and , suggesting that it targets primarily Pyrrophyta. To clarify the algicidal effects of Y42, we assessed algal lysis and determined the chlorophyll contents, photosynthetic activity, and malondialdehyde contents of after exposure to the Y42 supernatant. Scanning electron microscopy and transmission electron microscopy analyses showed that the Y42 supernatant disrupted membrane integrity and caused algal cell breakage at the megacytic zone. Photosynthetic pigment loss and significant declines in both photosynthetic efficiency and the electron transport rate indicated that the Y42 supernatant damaged the photosynthetic system of Malondialdehyde overproduction indicated that the Y42 supernatant caused lipid peroxidation and oxidative damage to membrane systems in the algal cell, ultimately leading to death. The findings of this study reveal the potential of Y42 to remove algal cells from blooms. is one of the most common dinoflagellate species that form harmful algal blooms, which frequently cause serious ecological pollution and pose health hazards to humans and other animals. Screening for bacteria with high algicidal activity against and studying their algicidal processes and characteristics will contribute to an understanding of their algicidal effects and provide a theoretical basis for preventing algal blooms and reducing their harm to the environment. This study reports the algicidal activity and characteristics of against The stability of the algicidal activity of in different environments (including different temperature, pH, and sunlight conditions) indicates its potential for use in the control of blooms.
Topics: Antibiosis; China; Chlorophyll A; Dinoflagellida; Harmful Algal Bloom; Paracoccus; Photosynthesis; Seawater
PubMed: 30054369
DOI: 10.1128/AEM.01015-18 -
Microbial Cell Factories Jul 2020Carotenoids are natural tetraterpene pigments widely utilized in the food, pharmaceutical and cosmetic industries. Currently, chemical synthesis of these compounds...
BACKGROUND
Carotenoids are natural tetraterpene pigments widely utilized in the food, pharmaceutical and cosmetic industries. Currently, chemical synthesis of these compounds outperforms their production in Escherichia coli or yeast due to the limited efficiency of the latter. The use of natural microbial carotenoid producers, such as bacteria of the genus Paracoccus (Alphaproteobacteria), may help to optimize this process. In order to couple the ability to synthesize these pigments with the metabolic versatility of this genus, we explored the possibility of introducing carotenoid synthesis genes into strains capable of efficient growth on simple low-cost media.
RESULTS
We constructed two carotenoid-producing strains of Paracoccus carrying a new plasmid, pCRT01, which contains the carotenoid synthesis gene locus crt from Paracoccus marcusii OS22. The plasmid was created in vivo via illegitimate recombination between crt-carrying vector pABW1 and a natural "paracoccal" plasmid pAMI2. Consequently, the obtained fusion replicon is stably maintained in the bacterial population without the need for antibiotic selection. The introduction of pCRT01 into fast-growing "colorless" strains of Paracoccus aminophilus and Paracoccus kondratievae converted them into efficient producers of a range of both carotenes and xanthophylls. The exact profile of the produced pigments was dependent on the strain genetic background. To reduce the cost of carotenoid production in this system, we tested the growth and pigment synthesis efficiency of the two strains on various simple media, including raw industrial effluent (coal-fired power plant flue gas desulfurization wastewater) supplemented with molasses, an industrial by-product rich in sucrose.
CONCLUSIONS
We demonstrated a new approach for the construction of carotenoid-producing bacterial strains which relies on a single plasmid-mediated transfer of a pigment synthesis gene locus between Paracoccus strains. This strategy facilitates screening for producer strains in terms of synthesis efficiency, pigment profile and ability to grow on low-cost industrial waste-based media, which should increase the cost-effectiveness of microbial production of carotenoids.
Topics: Carotenoids; DNA, Bacterial; Industrial Microbiology; Industrial Waste; Metabolic Networks and Pathways; Multigene Family; Paracoccus; Plasmids; Xanthophylls
PubMed: 32660485
DOI: 10.1186/s12934-020-01396-z -
Microbiology (Reading, England) Apr 2004Growth of the alpha-proteobacterium Paracoccus denitrificans NKNIS with taurine or isethionate as sole source of carbon involves sulfoacetaldehyde acetyltransferase...
Growth of the alpha-proteobacterium Paracoccus denitrificans NKNIS with taurine or isethionate as sole source of carbon involves sulfoacetaldehyde acetyltransferase (Xsc), which is presumably encoded by an xsc gene in subgroup 3, none of whose gene products has been characterized. The genome of the alpha-proteobacterium Rhodobacter sphaeroides 2.4.1 was interpreted to contain a nine-gene cluster encoding the inducible dissimilation of taurine, and this deduced pathway included a regulator, a tripartite ATP-independent transporter, taurine dehydrogenase (TDH; presumably TauXY) as well as Xsc (subgroup 3), a hypothetical protein and phosphate acetyltransferase (Pta). A similar cluster was found in P. denitrificans NKNIS, in contrast to an analogous cluster encoding an ATP-binding cassette transporter in Paracoccus pantotrophus. Inducible TDH, Xsc and Pta were found in extracts of taurine-grown cells of strain NKNIS. TDH oxidized taurine to sulfoacetaldehyde and ammonium ion with cytochrome c as electron acceptor. Whereas Xsc and Pta were soluble enzymes, TDH was located in the particulate fraction, where inducible proteins with the expected masses of TauXY (14 and 50 kDa, respectively) were detected by SDS-PAGE. Xsc and Pta were separated by anion-exchange chromatography. Xsc was effectively pure; the molecular mass of the subunit (64 kDa) and the N-terminal amino acid sequence confirmed the identification of the xsc gene. Inducible isethionate dehydrogenase (IDH), Xsc and Pta were assayed in extracts of isethionate-grown cells of strain NKNIS. IDH was located in the particulate fraction, oxidized isethionate to sulfoacetaldehyde with cytochrome c as electron acceptor and correlated with the expression of a 62 kDa protein. Strain NKNIS excreted sulfite and sulfate during growth with a sulfonate and no sulfite dehydrogenase was detected. There is considerable biochemical, genetic and regulatory complexity in the degradation of these simple molecules.
Topics: Acetaldehyde; Acetyltransferases; Bacterial Proteins; Isethionic Acid; Molecular Sequence Data; Multigene Family; Oxidoreductases; Oxidoreductases Acting on CH-NH Group Donors; Paracoccus denitrificans; Phosphate Acetyltransferase; Rhodobacteraceae; Sequence Analysis, DNA; Taurine
PubMed: 15073291
DOI: 10.1099/mic.0.26795-0 -
Scientific Reports May 2021Mitochondrial complex I (NADH:ubiquinone oxidoreductase) is a crucial metabolic enzyme that couples the free energy released from NADH oxidation and ubiquinone reduction...
Mitochondrial complex I (NADH:ubiquinone oxidoreductase) is a crucial metabolic enzyme that couples the free energy released from NADH oxidation and ubiquinone reduction to the translocation of four protons across the inner mitochondrial membrane, creating the proton motive force for ATP synthesis. The mechanism by which the energy is captured, and the mechanism and pathways of proton pumping, remain elusive despite recent advances in structural knowledge. Progress has been limited by a lack of model systems able to combine functional and structural analyses with targeted mutagenic interrogation throughout the entire complex. Here, we develop and present the α-proteobacterium Paracoccus denitrificans as a suitable bacterial model system for mitochondrial complex I. First, we develop a robust purification protocol to isolate highly active complex I by introducing a His-tag on the Nqo5 subunit. Then, we optimize the reconstitution of the enzyme into liposomes, demonstrating its proton pumping activity. Finally, we develop a strain of P. denitrificans that is amenable to complex I mutagenesis and create a catalytically inactive variant of the enzyme. Our model provides new opportunities to disentangle the mechanism of complex I by combining mutagenesis in every subunit with established interrogative biophysical measurements on both the soluble and membrane bound enzymes.
Topics: Catalysis; Cell Respiration; Electron Transport; Electron Transport Complex I; Operon; Paracoccus denitrificans; Recombinant Fusion Proteins; Substrate Specificity
PubMed: 33980947
DOI: 10.1038/s41598-021-89575-9 -
Biochemistry Jan 2019Bacteria must acquire the essential element zinc from extremely limited environments, and this function is performed largely by ATP binding cassette (ABC) transporters....
Bacteria must acquire the essential element zinc from extremely limited environments, and this function is performed largely by ATP binding cassette (ABC) transporters. These systems rely on a periplasmic or extracellular solute binding protein (SBP) to bind zinc specifically with a high affinity and deliver it to the membrane permease for import into the cytoplasm. However, zinc acquisition systems in bacteria may be more complex, involving multiple transporters and other periplasmic or extracellular zinc binding proteins. Here we describe the zinc acquisition functions of two zinc SBPs (ZnuA and AztC) and a novel periplasmic metallochaperone (AztD) in Paracoccus denitrificans. ZnuA was characterized in vitro and demonstrated to bind as many as 5 zinc ions with a high affinity. It does not interact with AztD, in contrast to what has been demonstrated for AztC, which is able to acquire a single zinc ion through associative transfer from AztD. Deletions of the corresponding genes singly and in combination show that either AztC or ZnuA is sufficient and essential for robust growth in zinc-limited media. Although AztD cannot support transport of zinc into the cytoplasm, it likely functions to store zinc in the periplasm for transfer through the AztABCD system.
Topics: ATP-Binding Cassette Transporters; Bacterial Proteins; Calorimetry; Cytoplasm; Metallochaperones; Mutation; Paracoccus denitrificans; Periplasm; Zinc
PubMed: 30353723
DOI: 10.1021/acs.biochem.8b00854 -
Applied and Environmental Microbiology Jul 2023Metabolic degeneracy describes the phenomenon that cells can use one substrate through different metabolic routes, while metabolic plasticity, refers to the ability of...
Functional Degeneracy in Paracoccus denitrificans Pd1222 Is Coordinated via RamB, Which Links Expression of the Glyoxylate Cycle to Activity of the Ethylmalonyl-CoA Pathway.
Metabolic degeneracy describes the phenomenon that cells can use one substrate through different metabolic routes, while metabolic plasticity, refers to the ability of an organism to dynamically rewire its metabolism in response to changing physiological needs. A prime example for both phenomena is the dynamic switch between two alternative and seemingly degenerate acetyl-CoA assimilation routes in the alphaproteobacterium Paracoccus denitrificans Pd1222: the ethylmalonyl-CoA pathway (EMCP) and the glyoxylate cycle (GC). The EMCP and the GC each tightly control the balance between catabolism and anabolism by shifting flux away from the oxidation of acetyl-CoA in the tricarboxylic acid (TCA) cycle toward biomass formation. However, the simultaneous presence of both the EMCP and GC in P. denitrificans Pd1222 raises the question of how this apparent functional degeneracy is globally coordinated during growth. Here, we show that RamB, a transcription factor of the ScfR family, controls expression of the GC in P. denitrificans Pd1222. Combining genetic, molecular biological and biochemical approaches, we identify the binding motif of RamB and demonstrate that CoA-thioester intermediates of the EMCP directly bind to the protein. Overall, our study shows that the EMCP and the GC are metabolically and genetically linked with each other, demonstrating a thus far undescribed bacterial strategy to achieve metabolic plasticity, in which one seemingly degenerate metabolic pathway directly drives expression of the other. Carbon metabolism provides organisms with energy and building blocks for cellular functions and growth. The tight regulation between degradation and assimilation of carbon substrates is central for optimal growth. Understanding the underlying mechanisms of metabolic control in bacteria is of importance for applications in health (e.g., targeting of metabolic pathways with new antibiotics, development of resistances) and biotechnology (e.g., metabolic engineering, introduction of new-to-nature pathways). In this study, we use the alphaproteobacterium P. denitrificans as model organism to study functional degeneracy, a well-known phenomenon of bacteria to use the same carbon source through two different (competing) metabolic routes. We demonstrate that two seemingly degenerate central carbon metabolic pathways are metabolically and genetically linked with each other, which allows the organism to control the switch between them in a coordinated manner during growth. Our study elucidates the molecular basis of metabolic plasticity in central carbon metabolism, which improves our understanding of how bacterial metabolism is able to partition fluxes between anabolism and catabolism.
Topics: Acetyl Coenzyme A; Paracoccus denitrificans; Bacterial Proteins; Carbon; Glyoxylates
PubMed: 37318336
DOI: 10.1128/aem.00238-23 -
PLoS Computational Biology Jan 2016Denitrifying bacteria accumulate [Formula: see text], NO, and N2O, the amounts depending on transcriptional regulation of core denitrification genes in response to...
Denitrifying bacteria accumulate [Formula: see text], NO, and N2O, the amounts depending on transcriptional regulation of core denitrification genes in response to O2-limiting conditions. The genes include nar, nir, nor and nosZ, encoding [Formula: see text]-, [Formula: see text]-, NO- and N2O reductase, respectively. We previously constructed a dynamic model to simulate growth and respiration in batch cultures of Paracoccus denitrificans. The observed denitrification kinetics were adequately simulated by assuming a stochastic initiation of nir-transcription in each cell with an extremely low probability (0.5% h-1), leading to product- and substrate-induced transcription of nir and nor, respectively, via NO. Thus, the model predicted cell diversification: after O2 depletion, only a small fraction was able to grow by reducing [Formula: see text]. Here we have extended the model to simulate batch cultivation with [Formula: see text], i.e., [Formula: see text], NO, N2O, and N2 kinetics, measured in a novel experiment including frequent measurements of [Formula: see text]. Pa. denitrificans reduced practically all [Formula: see text] to [Formula: see text] before initiating gas production. The [Formula: see text] production is adequately simulated by assuming stochastic nar-transcription, as that for nirS, but with a higher probability (0.035 h-1) and initiating at a higher O2 concentration. Our model assumes that all cells express nosZ, thus predicting that a majority of cells have only N2O-reductase (A), while a minority (B) has [Formula: see text]-, NO- and N2O-reductase. Population B has a higher cell-specific respiration rate than A because the latter can only use N2O produced by B. Thus, the ratio [Formula: see text] is low immediately after O2 depletion, but increases throughout the anoxic phase because B grows faster than A. As a result, the model predicts initially low but gradually increasing N2O concentration throughout the anoxic phase, as observed. The modelled cell diversification neatly explains the observed denitrification kinetics and transient intermediate accumulations. The result has major implications for understanding the relationship between genotype and phenotype in denitrification research.
Topics: Bacterial Proteins; Cell Hypoxia; Computational Biology; Denitrification; Metabolic Networks and Pathways; Models, Biological; Nitrogen Dioxide; Nitrous Oxide; Oxidoreductases; Paracoccus denitrificans; Phenotype
PubMed: 26731685
DOI: 10.1371/journal.pcbi.1004621 -
Journal of Microbiology and... Jul 2020Mealybugs (Hemiptera: Coccomorpha: Pseudococcidae) harbour diverse microbial symbionts that play essential roles in host physiology, ecology, and evolution. In this...
Mealybugs (Hemiptera: Coccomorpha: Pseudococcidae) harbour diverse microbial symbionts that play essential roles in host physiology, ecology, and evolution. In this study we aimed to reveal microbial communities associated with two different mealybugs, papaya mealybug () and two-tailed mealybug () collected from the same host plant. Comparative analysis of microbial communities associated with these mealybugs revealed differences that appear to stem from phylogenetic associations and different nutritional requirements. This first report on both bacterial and fungal communities associated with these mealybugs provides a preliminary insight on factors affecting the endomicrobial communities. .
Topics: Animals; Bacteria; Biodiversity; Carica; Ecology; Fungi; Hemiptera; Microbiota; Paracoccus; Phylogeny
PubMed: 32238776
DOI: 10.4014/jmb.2001.01016 -
Biochimica Et Biophysica Acta Apr 2012The paper presents a survey of time-resolved studies of charge translocation by cytochrome c oxidase coupled to transfer of the 1st, 2nd 3rd and 4th electrons in the... (Review)
Review
The paper presents a survey of time-resolved studies of charge translocation by cytochrome c oxidase coupled to transfer of the 1st, 2nd 3rd and 4th electrons in the catalytic cycle. Single-electron photoreduction experiments carried out with the A-class cytochrome c oxidases of aa(3) type from mitochondria, Rhodobacter sphaeroides and Paracoccus denitrificans as well as with the ba(3)-type oxidase from Thermus thermophilus indicate that the protonmotive mechanisms, although similar, may not be identical for different partial steps in the same enzyme species, as well as for the same single-electron transition in different oxidases. The pattern of charge translocation coupled to transfer of a single electron in the A-class oxidases confirms major predictions of the original model of proton pumping by cytochrome oxidase [Artzatbanov, V. Y., Konstantinov, A. A. and Skulachev, V.P. "Involvement of Intramitochondrial Protons in Redox Reactions of Cytochrome a." FEBS Lett. 87: 180-185]. The intermediates and partial electrogenic steps observed in the single-electron photoreduction experiments may be very different from those observed during oxidation of the fully reduced oxidase by O(2) in the "flow-flash" studies. .
Topics: Bacterial Proteins; Electron Transport; Electron Transport Complex IV; Heme; Kinetics; Models, Biological; Oxidation-Reduction; Paracoccus denitrificans; Rhodobacter sphaeroides; Thermus thermophilus
PubMed: 21871433
DOI: 10.1016/j.bbabio.2011.08.003