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1.
A method is described for the isolation of photosynthetically active chloroplasts from four species of brown algae: Fucus vesiculosis, Nereocystis luetkeana, Laminaria saccharina, and Macrocystis integrifolia. When compared to lettuce and spinach chloroplasts, the algal chloroplasts all showed lower activities for both photosystems II and I. Chloroplasts from all the plants produced H2O2, with photosystem I functioning as the O2 reductant in the light. In contrast to the green plants, however, brown algal chloroplasts strongly reduced O2 under conditions where both photosystems II and I remain active. Relative variable fluorescence values were lower both in intact plants and chloroplasts of the brown algae than for either spinach or lettuce. It is suggested that although light harvesting activities appear similar in all the plants, details of electron transport in brown algae may differ from those of green plants. 相似文献
2.
Background and Aims In photosynthetic organisms exposure to high light induces the production of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), which in part is prevented by non-photochemical quenching (NPQ). As one of the most stable and longest-lived ROS, H2O2 is involved in key signalling pathways in development and stress responses, although in excess it can induce damage. A ubiquitous response to high light is the induction of the xanthophyll cycle, but its role in algae is unclear as it is not always associated with NPQ induction. The aim of this study was to reveal how diurnal changes in the level of H2O2 are regulated in a freshwater algal community.Methods A natural freshwater community of algae in a temporary rainwater pool was studied, comprising photosynthetic Euglena species, benthic Navicula diatoms, Chlamydomonas and Chlorella species. Diurnal measurements were made of photosynthetic performance, concentrations of photosynthetic pigments and H2O2. The frequently studied model organisms Chlamydomonas and Chlorella species were isolated to study photosynthesis-related H2O2 responses to high light.Key Results NPQ was shown to prevent H2O2 release in Chlamydomonas and Chlorella species under high light; in addition, dissolved organic carbon excited by UV-B radiation was probably responsible for a part of the H2O2 produced in the water column. Concentrations of H2O2 peaked at 2 µm at midday and algae rapidly scavenged H2O2 rather than releasing it. A vertical H2O2 gradient was observed that was lowest next to diatom-rich benthic algal mats. The diurnal changes in photosynthetic pigments included the violaxanthin and diadinoxanthin cycles; the former was induced prior to the latter, but neither was strictly correlated with NPQ.Conclusions The diurnal cycling of H2O2 was apparently modulated by the organisms in this freshwater algal community. Although the community showed flexibility in its levels of NPQ, the diurnal changes in xanthophylls correlated with H2O2 concentrations. Alternative NPQ mechanisms in algae involving proteins of the light-harvesting complex type and antioxidant protection of the thylakoid membrane by de-epoxidized carotenoids are discussed. 相似文献
3.
Sang-Myung Jung Jun Sang Park Hyun Jung Shim Yeo Seon Kwon Hyung Geun Kim Hwa Sung Shin 《Biotechnology and Bioprocess Engineering》2016,21(5):676-682
Astrocytes, which support neuronal tissue and activity in the brain, are receiving attention as a possible target for treating neurological damage. Phycoerythrin extract, a pigment protein of red algae, is known to have anti-inflammatory, anti-cancer, and anti-viral effects. In this study, Phycoerythrin extract from Grateloupia filicina (GfPE) was used to treat astrocytes and then assessed for its ability to protect against physiological changes under oxidative stress via H2O2. GfPE had a good effect on viability and proliferation of astrocytes that were downregulated under oxidative stress. Accordingly, GfPE alleviated the increasing effect of H2O2 on ROS of astrocytes. 相似文献
4.
Florian Weinberger Patricia Leonardi Alicia Miravalles Juan A. Correa Ulrich Lion Bernard Kloareg Philippe Potin 《Journal of phycology》2005,41(4):863-873
The two agar‐producing red algae, Gracilaria chilensis C. J. Bird, McLachlan & E. C. Oliveira and Gracilaria conferta (Schousboe ex Montagne) Montagne, responded with hydrogen peroxide (H2O2) release when agar oligosaccharides were added to the medium. In G. conferta, a transient release was observed, followed by a refractory state of 6 h. This response was sensitive to chemical inhibitors of NADPH oxidase, protein kinases, protein phosphatases, and calcium translocation in the cell, whereas it was insensitive to inhibitors of metalloenzymes. Transmission electron microscopic observations of the H2O2‐dependent formation of cerium peroxide from cerium chloride indicated oxygen activation at the plasma membrane of G. conferta. A putative system, consisting of a receptor specific to agar oligosaccharides and a plasma membrane‐located NADPH oxidase, appears to be responsible for the release of H2O2 in G. conferta. Subcellular examination of G. chilensis showed that the H2O2 release was located in the cell wall. It was sensitive to inhibitors of metalloenzymes and flavoenzymes, and no refractory state was observed. The release was correlated with accumulation of an aldehyde in the algal medium, suggesting that an agar oligosaccharide oxidase is present in the apoplast of G. chilensis. The presence of this enzyme could also be demonstrated by polyacrylamide electrophoresis under nondenaturating conditions and proven to be variable. Cultivation of G. chilensis at 16 to 17°C resulted in significantly stronger expression of agar oligosaccharide oxidase than cultivation at 12°C, which indicates that the enzyme is used under conditions that generally favor microbial agar macerating activity. 相似文献
5.
《Microbes and infection / Institut Pasteur》2009,11(5):537-544
Duox proteins are members of the NADPH oxidase (Nox) family and are responsible for hydrogen peroxide (H2O2) production by various tissue types including bronchial and intestinal mucosae. The antimicrobial killing role of H2O2 in leukocytes and macrophages is generally considered as the paradigm of its function. We investigated here the positive role of H2O2 in the prevention of cellular invasion by Salmonella. We show that H2O2, under conditions that preserved bacterial growth, has a repellent effect on Salmonella motility on agar plates. In addition, H2O2 produced by PCCl3, a rat thyroid cell line, reduces bacterial invasion of the cells by around 40%. To test whether the observed phenotype is attributable to H2O2 production, we constructed a CHO stable cell line expressing Duox2 protein at the cell surface (CHO-D2). The transfected cells produce a high amount of H2O2. Upon infection with Salmonella, the invasion of CHO-D2 cells was reduced by up to 60%. In both PCCl3 and CHO expressing Duox2 cells, normal invasion was restored upon incubation with catalase. Our data suggest that H2O2 at reduced concentrations acts as a repellent for bacteria, keeping them away from cells, a situation that could naturally prevent mucosal cells infection in vivo. 相似文献
6.
Objectives
To improve H2 production, the green algae Chlamydomonas reinhardtii cc849 was co-cultured with Azotobacter chroococcum.Results
The maximum H2 production of the co-culture was 350% greater than that of the pure algal cultures under optimal H2 production conditions. The maximum growth and the respiratory rate of the co-cultures were about 320 and 300% of the controls, and the dissolved O2 of co-cultures was decreased 74%. Furthermore, the in vitro maximum hydrogenase activity of the co-culture was 250% greater than that of the control, and the in vivo maximum hydrogenase activity of the co-culture was 1.4-fold greater than that of the control. In addition, the maximum starch content of co-culture was 1400% that of the control.Conclusions
Azotobacter chroococcum improved the H2 production of the co-cultures by decreasing the O2 content and increasing the growth and starch content of the algae and the hydrogenase activity of the co-cultures relative to those of pure algal cultures.7.
Joseph M. Gennity Nestor R. Bottino Ralph A. Zingaro Andrew E. Wheeler Kurt J. Irgolic 《Phytochemistry》1985,24(12):2817-2821
Two unicellular marine algae cultured in media containing sodium selenite were examined for glutathione peroxidase activity. The 400 g supernatant from disrupted cells of both the green alga Dunaliella primolecta and the red alga Porphyridium cruentum were able to enhance both the H2O2 and the tert-butyl hydroperoxide dependent oxidation of glutathione. The glutathione peroxidation activity of D. primolecta was reduced only slightly by heating the 400 g supernatant, a 30% decrease in the rate with H2O2 and 10% decrease in the rate with t-BuOOH being observed. Heating caused the H2O2 dependent activity in P. cruentum to be reduced by only 30%, but the activity with t-BuOOH was reduced by 90%. Freezing decreased the t-BuOOH dependent activity of P. cruentum by 90%, but did not lower the t-BuOOH dependent activity of D. primolecta or the H2O2 dependent activity of either alga. It was concluded that the heat and cold stable, glutathione peroxidation was non-enzymatic in nature. A variety of small molecules (ascorbate, Cu(NO3)2, selenocystine, dimethyldiselenide and selenomethionine) were shown to be able to enhance the hydroperoxide dependent oxidation of glutathione in the assay system employed in this study. Such compounds could be responsible for the activity observed in algae. The heat and cold labile t-BuOOH reductase activity of P. cruentumwas possibly enzymatic, but was not attributable to the presence of glutathione-S-transferase. Both algae, when cultured in the presence of added selenite, displayed an approximate doubling of the non-enzymatic H2O2 and t-BuOOH dependent glutathione oxidase activities. The heat and cold labile t-BuOOH reductase activity of P. cruentum was unaltered when the alga was grown in the presence of added selenite. These observations are consistent with the hypothesis that selenium compounds present in the algae are responsible for the selenium induced glutathione peroxidation. 相似文献
8.
In this study, the antioxidant activities of 21 species of marine algae were assessed via an ABTS free radical scavenging assay. The Ishige okamurae extract tested herein evidenced profound free radical scavenging activity, compared to that exhibited by other marine algae extracts. Thus, I. okamurae was selected for use in further experiments, and was partitioned with different organic solvents. Profound radical scavenging activity was detected in the ethyl acetate fraction, and the active compound was identified as the carmalol derivative, diphlorethohydroxycarmalol, which evidenced higher levels of activity than that of commercial antioxidants. Moreover, the protective effects of diphlorethohydroxycarmalol against H2O2-induced cell damage were evaluated. Intracellular reactive oxygen species (ROS) were overproduced as the result of the addition of H2O2, but this ROS generation was reduced significantly after diphlorethohydroxycarmalol treatment; this corresponds to a significant enhancement of cell viability against H2O2-induced oxidative damage. The inhibitory effects of diphlorethohydroxycarmalol against cell damage were determined via comet assay and Hoechst staining assay, and diphlorethohydroxycarmalol was found to exert a positive dose-dependent effect. These results clearly indicate that the diphlorethohydroxycarmalol isolated from I. okamurae exerts profound antioxidant effects against H2O2-mediated cell damage, and treatment with this compound may be a potential therapeutic modality for the treatment or prevention of several diseases associated with oxidative stress. 相似文献
9.
Mei Jing Piao Yu Jae Hyun Tae-Heon Oh Hee Kyoung Kang Eun Sook Yoo Young Sang Koh Nam Ho Lee In Soo Suh Jin Won Hyun 《In vitro cellular & developmental biology. Animal》2012,48(10):666-674
The aim of this study was to investigate the protective effects of the ethanol extract of the red algae Chondracanthus tenellus (Harvey) Hommersand (CTE) on cultured human keratinocyte cell line. The cellular protection conferred by CTE was evidenced by the ability of the extract to absorb ultraviolet B (UVB; 280?C320 nm) and to scavenge the radical 1,1-diphenyl-2-picrylhydrazyl, as well as intracellular reactive oxygen species (ROS), induced by either hydrogen peroxide (H2O2) or UVB radiation. In addition, both superoxide anion generated by the xanthine/xanthine oxidase system and hydroxyl radical generated by the Fenton reaction (FeSO4?+?H2O2) were scavenged by CTE, as confirmed using electron spin resonance spectrometry. In the human keratinocyte cell line, CTE decreased the degree of injury resulting from UVB-induced oxidative stress to lipids, proteins, and DNA. CTE-treated cells also showed a reduction in UVB-induced apoptosis, as exemplified by fewer apoptotic bodies and less DNA fragmentation. Taken together, these results suggest that CTE confers protection on the human keratinocyte cell line against UVB-induced oxidative stress by absorbing UVB ray and scavenging ROS, thereby reducing injury to cellular constituents. 相似文献
10.
Hans W. Paerl 《Microbial ecology》1977,4(3):215-231
Anabaena species are commonly colonized by bacteria, especially during N2-fixing blooms. Generally these associations do not represent bacterial attack on algal hosts. Instead, the algal N2-fixing capabilities are increased in the presence of the bacteria. Possible mechanisms promoting the mutual growth of algae and attached bacteria were investigated by observing specific sites of bacterial attachment, by noting reduced microzones created by the bacteria, and by locating sites of bacterial uptake of organics representative of algal excretion products.Attached bacteria show preference for typical algal excretion products and their growth is enhanced by such products. In return, enhancement of algal nitrogenase activity occurs when bacteria create O2-consuming microzones around the nitrogenase-bearing heterocysts. 相似文献
11.
《农业工程》2022,42(5):461-466
This work reports for the first time the anticandidal activity of the dichloromethane (DCM) extract from the Algerian invasive red marine algae A. armata Harvey. In a preliminary assessment, the DCM extract was screened for its antifungal activity against two strains of Candida albicans, namely (IP 444) and (ATCC 10231). As a well-established approach, the anticandidal activity was expressed as zone of inhibition by agar well and disk diffusion methods. The minimum inhibitory concentration (MIC) was also determined for the two fungal strains. Within this framework, the DCM extract of the red algae A. armata has a strong inhibition effect against the considered Candida albicans strains. In addition, Candida albicans IP444 (MIC = 0.58 mg/mL) was more sensitive to DCM algal extract when compared to Candida albicans ATCC 10231 (MIC = 2.34 mg/mL). GC–MS analysis suggested that brominated compounds and fatty acids are responsible for anticandidal activity of dichloromethane extract of A. armata. These preliminary results may constitute a future applied of lipophilic extract of the red algae A. armata as a promising source of natural compounds with antifungal properties. 相似文献
12.
H(2) metabolism in photosynthetic organisms: I. Dark h(2) evolution and uptake by algae and mosses
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Dark H2 metabolism was studied in marine and fresh water red algae, the green alga, Chlamydomonas, and mosses. A time variable and temperature-sensitive anaerobic incubation was required prior to H2 evolution. H2 evolution was sensitive to disalicylidenepropanediamine. An immediate H2 uptake was observed in these algae. Immediate dark H2 uptake but no evolution was observed in the mosses. 相似文献
13.
b-Type Dihydroorotate Dehydrogenase Is Purified as a H2O2-Forming NADH Oxidase from Bifidobacterium bifidum
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Shinji Kawasaki Takumi Satoh Mitsunori Todoroki Youichi Niimura 《Applied microbiology》2009,75(3):629-636
Our previous report showed the existence of microaerophilic Bifidobacterium species that can grow well under aerobic conditions rather than anoxic conditions in a liquid shaking culture. The difference in the aerobic growth properties between the O2-sensitive and microaerophilic species is due to the existence of a system to produce H2O2 in the growth medium. In this study, we purified and characterized the NADH oxidase that is considered to be a key enzyme in the production of H2O2. Bifidobacterium bifidum, an O2-sensitive bacterium and the type species of the genus Bifidobacterium, possessed one dominant active fraction of NADH oxidase and a minor active fraction of NAD(P)H oxidase activity detected in the first step of column chromatography for purification of the enzyme. The dominant active fraction was further purified and determined from its N-terminal sequence to be a homologue of b-type dihydroorotate dehydrogenase (DHOD), composed of PyrK (31 kDa) and PyrDb (34 kDa) subunits. The genes that encode PyrK and PryDb are tandemly located within an operon structure. The purified enzyme was found to be a heterotetramer showing the typical spectrum of a flavoprotein, and flavin mononucleotide and flavin adenine dinucleotide were identified as cofactors. The purified enzyme was characterized as the enzyme that catalyzes the DHOD reaction and also catalyzes a H2O2-forming NADH oxidase reaction in the presence of O2. The kinetic parameters suggested that the enzyme could be involved in H2O2 production in highly aerated environments. 相似文献
14.
Dual oxidases (DUOX) are enzymes that contain an NADPH oxidase domain that produces hydrogen peroxide (H2O2) and a peroxidase domain that can utilize H2O2 to carry out a variety of reactions. The model organism Caenorhabditis elegans produces the DUOX, BLI-3, which has roles in both cuticle development and in protection against infection. In previous work, we demonstrated that while certain peroxidases were protective against the human bacterial pathogen Enterococcus faecalis, the peroxidase domain of BLI-3 was not, leading to the postulate that the NADPH oxidase domain is the basis for BLI-3’s protective effects. In this work, we show that a strain carrying a mutation in the NADPH oxidase domain of BLI-3, bli-3(im10), is more susceptible to E. faecalis and the human fungal pathogen Candida albicans. Additionally, less H2O2 is produced in response to pathogen using both an established Amplex Red assay and a strain of C. albicans, WT-OXYellow, which acts as a biosensor of reactive oxygen species (ROS). Finally, a C. elegans line containing a BLI-3::mCherry transgene was generated. Previous work suggested that BLI-3 is produced in the hypodermis and the intestine. Expression of the transgene was observed in both these tissues, and additionally in the pharynx. The amount and pattern of localization of BLI-3 did not change in response to pathogen exposure. 相似文献
15.
Brown tide algal blooms, caused by the excessive growth of Aureococcus anophagefferens, recur in several northeastern US coastal bays. Direct bloom control could alleviate the ecological and economic damage associated with bloom outbreak. This paper explored the effectiveness and safety of natural chemical biocide hydrogen peroxide (H2O2) for brown tide bloom control. Culture studies showed that H2O2 at 1.6 mg L−1 effectively eradicated high density A. anophagefferens within 24-hr, but caused no significant growth inhibition in the diatoms, prymnesiophytes, green algae and dinoflagellates of >2–3 μm cell sizes among 12 phytoplankton species tested over 1-week observation. When applied to brown tide bloom prone natural seawater in a microcosm study, this treatment effectively removed the developing brown tide bloom, while the rest of phytoplankton assemblage (quantified via HPLC based marker pigment analyses), particularly the diatoms and green algae, experienced only transient suppression then recovered with total chlorophyll a exceeding that in the controls within 72-hr; cyanobacteria was not eradicated but was still reduced about 50% at 72-hr, as compared to the controls. The action of H2O2 against phytoplankton as a function of cell size and cell wall structure, and a realistic scenario of H2O2 application were discussed. 相似文献
16.
As a sustainable biofuel feedstock, marine algae have superior aspects to terrestrial biomass such as less energy and water requirement for cultivation, higher CO2 capture capacity, and negligible lignin content. In this study, various marine algae were tested for fermentative hydrogen production (FHP). Among them, Laminaria japonica exhibited the best performance, showing the highest H2 yield of 69.1 mL H2/g CODadded. It was attributed to its high carbohydrate content and main constituents of polysaccharides, laminarin and alginate, which were found to posses higher H2 production potential than agar and carrageenan. To enhance the H2 production from L. japonica, thermal pretreatment was applied at various conditions. At 170 °C and 20 min, H2 yield was maximized to 109.6 mL H2/g CODadded. The experimental results suggested that marine algae, especially L. japonica, could be used for FHP, and future works would be focused on gaining more energy from the H2 fermentation effluent. 相似文献
17.
Nature and Role of Bacterial Contaminants in Mass Cultures of Thermophilic Chlorella pyrenoidosa 总被引:2,自引:1,他引:1
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Richard J. Blasco 《Applied microbiology》1965,13(3):473-477
A study was made of bacterial contaminants isolated from an algal mass-culture unit. The study was performed specifically to determine the dependence of the size of bacterial population on algal density and the nature of any association of the contaminants with the algal cell. Growth of the bacterial contaminants on standard medium was also investigated. An estimate was made of the O2 uptake of the bacterial population under normal operating conditions of the algal massculture system. Viable numbers of bacteria tended to increase with increased algal density. Bacteria were found imbedded in the surface of algal cells when the cultures of algae were characterized by subnormal rates of growth and photosynthetic gas exchange. Bacterial isolates failed to grow in standard medium alone, thus implying a dependency of bacterial growth on material(s) produced by the algae. A slight inhibitory effect on algal growth was noted in the case of two of three of the bacterial isolates. Manometric studies demonstrated that the bacterial population normally found in the algal cultures did not appreciably effect total gas exchange. 相似文献
18.
Growth Pattern and Yield of a Chemoautotrophic Beggiatoa sp. in Oxygen-Sulfide Microgradients 总被引:4,自引:3,他引:1
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Recently developed techniques involving opposed, gel-stabilized gradients of O2 and H2S permit cultivation of a marine Beggiatoa strain as a chemolithoautotroph which uses gliding motility to precisely track the interface between H2S and O2. In the current study with microelectrodes, vertical profiles of H2, O2, and pH were measured in replicate cultures grown for various intervals. After an initial period of exponential biomass increase (doubling time, 11 h), linear growth prevailed throughout much of the time course. This H2S-limited growth was followed by a transition to stationary phase when the declining H2S flux was sufficient only to supply maintenance energy. During late-exponential and linear growth phases, the Beggiatoa sp. consumed a constant 0.6 mol of H2S for each 1.0 mol of O2, the ratio anticipated for balanced lithoautotrophic growth at the expense of complete oxidation of H2S to SO42−. Over the entire range of conditions studied, this consumption ratio varied by approximately twofold. By measuring the extent to which the presence of the bacterial plate diminished the overlap of O2 and H2S, we demonstrated that oxidation of H2S by Beggiatoa sp. is approximately 3 orders of magnitude faster than spontaneous chemical oxidation. By integrating sulfide profiles and comparing sulfide consumed with biomass produced, a growth yield of 8.4 g (dry weight) mol−1 of H2S was computed. This is higher than that found for sulfide-grown thiobacilli, indicating very efficient growth of Beggiatoa sp. as a chemoautotroph. The methods used here offer a unique opportunity to determine the yield of H2S-oxidizing chemolithoautotrophs while avoiding several problems inherent in the use of homogeneous liquid culture. Finally, by monitoring time-dependent formation of H2S profiles under anoxic conditions, we demonstrate a method for calculating the molecular diffusion coefficient of soluble substrates in gel-stabilized media. 相似文献
19.
Rosanne Hertzberger Jos Arents Henk L. Dekker R. David Pridmore Christof Gysler Michiel Kleerebezem M. Joost Teixeira de Mattos 《Applied and environmental microbiology》2014,80(7):2229-2239
Hydrogen peroxide production is a well-known trait of many bacterial species associated with the human body. In the presence of oxygen, the probiotic lactic acid bacterium
Lactobacillus johnsonii NCC 533 excretes up to 1 mM H2O2, inducing growth stagnation and cell death. Disruption of genes commonly assumed to be involved in H2O2 production (e.g., pyruvate oxidase, NADH oxidase, and lactate oxidase) did not affect this. Here we describe the purification of a novel NADH-dependent flavin reductase encoded by two highly similar genes (LJ_0548 and LJ_0549) that are conserved in lactobacilli belonging to the Lactobacillus acidophilus group. The genes are predicted to encode two 20-kDa proteins containing flavin mononucleotide (FMN) reductase conserved domains. Reductase activity requires FMN, flavin adenine dinucleotide (FAD), or riboflavin and is specific for NADH and not NADPH. The Km for FMN is 30 ± 8 μM, in accordance with its proposed in vivo role in H2O2 production. Deletion of the encoding genes in L. johnsonii led to a 40-fold reduction of hydrogen peroxide formation. H2O2 production in this mutant could only be restored by in trans complementation of both genes. Our work identifies a novel, conserved NADH-dependent flavin reductase that is prominently involved in H2O2 production in L. johnsonii. 相似文献
20.
Extracellular DNA (eDNA) is an important component of the biofilm matrix produced by many bacteria. In general, the release of eDNA is associated with the activity of muralytic enzymes leading to obvious cell lysis. In the Gram-positive oral commensal Streptococcus gordonii, eDNA release is dependent on pyruvate oxidase generated hydrogen peroxide (H2O2). Addition of H2O2 to cells grown under conditions non-permissive for H2O2 production causes eDNA release. Furthermore, eDNA release is maximal under aerobic growth conditions known to induce pyruvate oxidase gene expression and H2O2 production. Obvious cell lysis, however, does not occur. Two enzymes have been recently associated with eDNA release in S. gordonii. The autolysin AtlS and the competence regulated murein hydrolase LytF. In the present report, we investigated the role of both proteins in the H2O2 dependent eDNA release process. Single and double mutants in the respective genes for LytF and AtlS released less eDNA under normal growth conditions, but the AtlS mutant was still inducible for eDNA release by external H2O2. Moreover, we showed that the AtlS mutation interfered with the ability of S. gordonii to produce eDNA release inducing amounts of H2O2. Our data support a role of LytF in the H2O2 eDNA dependent release of S. gordonii as part of the competence stress pathway responding to oxidative stress. 相似文献