Identification of an arsenic resistance mechanism in rhizobial strains

Arsenic (As) is a very toxic metalloid to a great number of organisms. It is one of the most important global environmental pollutants. To resist the arsenate invasion, some microorganisms have developed or acquired genes that permit the cell to neutralize the toxic effects of arsenic through the exclusion of arsenic from the cells. In this work, two arsenic resistance genes, arsA and arsC, were identified in three strains of Rhizobium isolated from nodules of legumes that grew in contaminated soils with effluents from the chemical and fertilizer industry containing heavy-metals, in the industrial area of Estarreja, Portugal. The arsC gene was identified in strains of Sinorhizobium loti [DQ398936], Rhizobium leguminosarum [DQ398938] and Mesorhizobium loti [DQ398939]. This is the first time that arsenic resistance genes, namely arsC, have been identified in Rhizobium leguminosarum strains. The search for the arsA gene revealed that not all the strains with the arsenate reductase gene had a positive result for ArsA, the ATPase for the arsenite-translocating system. Only in Mesorhizobium loti was the arsA gene amplified [DQ398940]. The presence of an arsenate reductase in these strains and the identification of the arsA gene in Mesorhizobium loti, confirm the presence of an ars operon and consequently arsenate resistance.     

DNA sequence homology analysis of<Emphasis Type="Italic">ars</Emphasis> genes in arsenic-resistant bacteria

Homology ofars (arsenic-resistance system) genes was examined among the indigenous bacteria isolated from the soils and sediments of two abandened Au mines, which are highly contaminated with arsenic. The DNA and amino acid sequence homology of thears determinants were investigated using anars genotype. The isolated showed As(III)-oxidation ability containedarsAB genes encoding the efflux pump as well asarsR andarsD regulator genes. ThearsR andarsD leader gene are required for an arsenic resistance system when the high-homology genes (arsR; pl258 52.09% andarsD;Shewanell sp. 42.33%) are controlled by thears inducer-independent regulatory amino acid sequence. These leader gene were observed under weak acidic conditions in the Myoung-bong (pH; 5.0 to 6.0) and Duck-um (pH; 4.0 to 7.0) mines In addition, the strains with the ability of As (V)-reduction involved thearsC gene homologues, as in the strain CW-16 (Pseudomonas putida). The arsenic-resistance genes in the isolated indigenous bacteria showed varying degrees of amino acid similarity to the homologous genes found in the database (GenBank) such asP. putida KT2440: 39–53% forarsR, 22–42% forarsD, 16–84% forarsA, 26–45% forarsB, 17–44% forarsAB, 37–41% forarsC, and 14–47% forarsH. These findings suggested that the function of the variousars gene in indigenous bacteria existing in weakly oxidative conditions may be the key factor for redox mechanisms and biogeochemical systems in arsenic contaminated soils.     

Heavy metal and arsenic accumulating fern species as potential ecological indicators in As-contaminated abandoned mines

Ferns are good ecological indicators of arsenic accumulation in contaminated abandoned mines. The rhizomes of ferns were analyzed for arsenic and other heavy metals using inductively coupled plasma-mass spectrometry. In addition, we examined the ribulose-bisphosphate carboxylase (rbcL) gene isolated from the indigenous species of ferns at the pithead, tailings and soil sites in the vicinity of the Myoungbong abandoned mine, Republic of Korea. A search of the GenBank database revealed that the predicted amino acid sequence of this gene was homologous with 99% of Pteridium aquilinum As-2 (EU476184), 99% of Deparia petersenii As-6 (EU476188), 97% of Deparia lobatocrenata As-8 (EU476190), and 98% of Deparia conilii As-7 (EU476189). High concentrations of heavy metals (arsenic, 17.6 mg/kg in rhizomes and 2690 mg/kg in soil; copper, 17.1 mg/kg in rhizomes and 40.7 mg/kg in soil; cadmium, 2.9 mg/kg in rhizomes and 12.2 mg/kg in soil; lead, 41.9 mg/kg in rhizomes and 135 mg/kg in soil; zinc, 27.0 mg/kg in rhizomes and 172 mg/kg in soil) were found in P. aquilinum As-2 (EU476184) from the Myoungbong mine area, which may play an important role as ecological indicators of the contaminated areas.     

The first investigation of the diversity of bacteria associated with <Emphasis Type="Italic">Leptinotarsa decemlineata</Emphasis> (Coleoptera: Chrysomelidae)

Colorado potato beetle, Leptinotarsa decemlineata (Say), is a devastating pest of potatoes in North America and Europe. L. decemlineata has developed resistance to insecticides used for its control. In this study, in order to find a more effective potential biological control agent against L. decemlineata, we investigated its microbiota and tested their insecticidal effects. According to morphological, physiological and biochemical tests as well as 16S rDNA sequences, microbiota was identified as Leclercia adecarboxylata (Ld1), Acinetobacter sp. (Ld2), Acinetobacter sp. (Ld3), Pseudomonas putida (Ld4), Acinetobacter sp. (Ld5) and Acinetobacter haemolyticus (Ld6). The insecticidal activities of isolates at 1.8×10⁹ bacteria/mL dose within five days were 100%, 100%, 35%, 100%, 47% and 100%, respectively, against the L. decemlineata larvae. The results indicate that Leclercia adecarboxylata (Ld1) and Pseudomonas putida (Ld4) isolates may be valuable potential biological control agents for biological control of L. decemlineata.     

Intergeneric protoplast fusion between Acinetobacter sp. A3 and Pseudomonas putida DP99 for enchanced hydrocarbon degradation

Summary Polyethylene glycol 6000 mediated protoplast fusion between an alkane degrader Acinetobacter sp. A3, and a naphthalene degrader, Pseudomonas putida DP99 , resulted in fusants capable of degrading both hydrocarbons and were morphologically similar to Acinetobacter sp. A3. While fusant F4/13 and Pseudomonas putida DP99 degraded over 98% of naphthalene provided by the end of five days, tetradecane degradation by fusant F4/13 was 82% compared to 77% by Acinetobacter sp. A3 in the same time period. Also, while from naphthalene +tetradecane mixture, fusant F4/13 could degrade 99% and 53% of naphthalene and tetradecane respectively, both the parent strains together could degrade over 99% naphthalene but only about 16% tetradecane.     

Bacterial Communities in Bangladesh Aquifers Differing in Aqueous Arsenic Concentration

At Titas, Bangladesh, two aquifers of different arsenic concentrations and redox conditions were investigated to link variations in geochemistry to in situ bacterial diversity characterized by T-RFLP (terminal restriction fragment length polymorphism) and clone library analysis. While the shallow aquifer was characterized by reduced gray sediments with a higher share of easily mobilized sedimentary arsenic (2.6% was easily mobilized from 18 mg/kg of total arsenic available in sediments) and higher aqueous arsenic concentrations of 120 ± 6 μg/L (45% arsenite), the deeper aquifer consisted of brown oxidized sediments with lower aqueous arsenic concentrations, predominantly as arsenate (60 ± 6 μg/L; 3% arsenite) and a higher share of tightly bound arsenic (only 0.6% of 53 mg/kg total sorbed arsenic was easily mobilized). The bacterial communities of both aquifers were dominated by putative aerobic or denitrifying populations of Pseudomonas, Elizabethkingia and Pantoea. The shallow aquifer was more diverse in bacterial populations of aerobic, facultative and anaerobic bacteria, an observation which may be correlated to more variable geochemical conditions resulting in arsenic mobilization and re-sorption. The deeper aquifer showed higher abundance of aerobic bacterial populations including the presence of iron-oxidizing Sideroxydans possibly of importance for the sorption of arsenic on oxidized iron hydroxides. From the arsenic-affected shallow aquifer, As(III) oxidizing isolates of Comamonas and Microbacterium were obtained, which may provide information on suitable conditions for arsenic immobilization useful for future bioremediation efforts. Supplemental materials are available for this article. Go to the publisher’s online edition of Geomicrobiology Journal to view the free supplemental file.     

Arsenic exposure levels of petrochemical workers in three workplace settings in Rayong Province,Thailand

Background: Crude oil and natural gas are often contaminated with arsenic. As a carcinogen, arsenic contamination in the workplace is of concern, particularly when urinary arsenic levels are higher than the standard. The aim of this study was to identify exposure sources of arsenic among petrochemical workers. Methods: A total of 188 operators and 30 office workers participated in the study. Ninety-three workplace air samples, three main meals in five consecutive days, and drinking water were collected from each participant. Urine was collected at the end of the day after the last food sample was collected from each subject. Urine samples where arsenic concentration exceeded 100 mg/L were further analyzed to identify species. Results: The average arsenic concentrations in operators' and office workers' food and urine were 0.55 ± 1.00 and 0.49 ± 0.67 mg/kg; and 76.43 ± 107.36 and 149.92 ± 200.28 mg/L, respectively. The arsenic concentrations in air and water were well below their standards. The urinary arsenic correlated well with arsenic in the food but not in the air and water. Conclusion: Occupational exposure to arsenic among operators and office workers was lower than 1% TLV (Threshold limit value) and did not differ significantly. The major source of arsenic exposure Q2 was food.     

Characterization of Copper-Resistant Rhizosphere Bacteria from <Emphasis Type="Italic">Avena sativa</Emphasis> and <Emphasis Type="Italic">Plantago lanceolata</Emphasis> for Copper Bioreduction and Biosorption

Copper is a toxic heavy metal widely used to microbial control especially in agriculture. Consequently, high concentrations of copper residues remain in soils selecting copper-resistant organisms. In vineyards, copper is routinely used for fungi control. This work was undertaken to study copper resistance by rhizosphere microorganisms from two plants (Avena sativa L. and Plantago lanceolata L.) common in vineyard soils. Eleven rhizosphere microorganisms were isolated, and four displayed high resistance to copper. The isolates were identified by 16S rRNA gene sequence analysis as Pseudomonas putida (A1), Stenotrophomonas maltophilia (A2) and Acinetobacter sp. (A6), isolated from Avena sativa rhizosphere, and Acinetobacter sp. (T5), isolated from Plantago lanceolata rhizosphere. The isolates displayed high copper resistance in the temperature range from 25°C to 35°C and pH in the range from 5.0 to 9.0. Pseudomonas putida A1 resisted as much as 1,000 mg L⁻¹ of copper. The isolates showed similar behavior on copper removal from liquid medium, with a bioremoval rate of 30% at 500 mg L⁻¹ after 24 h of growth. Speciation of copper revealed high copper biotransformation, reducing Cu(II) to Cu(I), capacity. Results indicate that our isolates are potential agents for copper bioremoval and bacterial stimulation of copper biosorption by Avena sativa and Plantago lanceolata.     

Isolation and characterization ofAcinetobacter sp. mutants defective in exopolysaccharide biosynthesis

Nitrosoguanidine-induced mutants ofAcinetobacter sp. defective in exopolysaccharide biosynthesis did not differ from the parent strain in distinguishing physiological and biochemical properties, such as requirements for growth factors, utilization of mono- and disaccharides, and resistance to antibiotics. The genetic relation of parent and mutant strains was shown by 16S rRNA PCR analysis. The comparative study of parent and mutant strains with respect to resistance to unfavorable environmental factors confirmed our hypothesis thatAcinetobacter sp. exopolysaccharides perform protective functions. Hybridization experiments revealed the conjugal transfer of plasmid R68.45 fromPseudomonas putida BS228 (R68.45) to mutant but not to the parentAcinetobacter sp. strains. The role of theAcinetobacter sp. exopolysaccharides in providing the genetic stability of this bacterium is discussed.     

Binding of ArsR, the repressor of the Staphylococcus xylosus (pSX267) arsenic resistance operon to a sequence with dyad symmetry within the ars promoter

arsR, the first gene of the Staphylococcus xylosus (pSX267) arsenic/antimonite resistance (rs) operon encodes a negative regulatory protein, ArsR, which mediates inducibility of the resistances by arsenic and antimony compounds. ArsR, which has no obvious DNA-binding motif in its primary structure, was purified from an ArsR-overproducing Escherichia coli strain and identified as a DNA-binding protein by its behaviour in gel mobility shift assays. ArsR had a specific affinity for a 312 by DNA restriction fragment carrying the ars promoter; the minimum sequence complexed by ArsR was a 75 by polymerase chain reaction (PCR) fragment, which mainly comprised the –35 and –10 regions of the promoter. The effect of inducers on the DNA-binding activity of ArsR was examined by in vitro induction assays; only arsenite inhibited DNA-binding of the repressor. DNase I footprinting revealed two protected regions within the promoter region, spanning 23 and 9 nucleotides, respectively. Furthermore, a new cleavage site for DNase I between the protected regions was made accessible by binding of the repressor. The footprints cover a region of three inverted repeats located between the –35 and –10 motifs of the ars promoter. By high resolution footprinting with the hydroxy radical, five sites of close contact between the protein and DNA were identified.     

Removal of Chlorpyrifos by Water Hyacinth (Eichhornia crassipes) and the Role of a Plant-Associated Bacterium

The objective of this research was to study the efficiency of water hyacinth (Eichhornia crassipes) and the role of any plant-associated bacteria in removing chlorpyrifos from water. The relative growth rate (RGR) of E. crassipes in the presence of 0.1 mg/L chlorpyrifos was not significantly different from that in its absence and only slightly decreased at concentrations of 0.5 and 1.0 mg/L by ～1.1- and ～1.2-fold, respectively, with an observed dry weight based RGR_DW for E. crassipes of 0.036–0.041 mg/g/d. The removal rate constants of chlorpyrifos in the absence of plants were low at 3.52, 2.29 and 1.84 h^?1 for concentrations of 0.1, 0.5 and 1.0 mg/L, respectively, but were some 3.89- to 4.87-fold higher in the presence of E. crassipes. Chlorpyrifos removal was markedly facilitated by the presence of a root-associated bacterium, preliminarily identified as Acinetobacter sp. strain WHA. The interaction of E. crassipes and Acinetobacter sp. strain WHA provide an efficient and ecological alternative to accelerate the removal and degradation of chlorpyrifos pollution from aquatic systems including wastewater.     

ArsH is an organoarsenical oxidase that confers resistance to trivalent forms of the herbicide monosodium methylarsenate and the poultry growth promoter roxarsone

Environmental organoarsenicals are produced by microorganisms and are introduced anthropogenically as herbicides and antimicrobial growth promoters for poultry and swine. Nearly every prokaryote has an ars (arsenic resistance) operon, and some have an arsH gene encoding an atypical flavodoxin. The role of ArsH in arsenic resistance has been unclear. Here we demonstrate that ArsH is an organoarsenical oxidase that detoxifies trivalent methylated and aromatic arsenicals by oxidation to pentavalent species. Escherichia coli, which does not have an arsH gene, is very sensitive to the trivalent forms of the herbicide monosodium methylarsenate [MSMA or MAs(V)] and antimicrobial growth promoter roxarsone [Rox(V)], as well as to phenylarsenite [PhAs(III), also called phenylarsine oxide or PAO]. Pseudomonas putida has two chromosomally encoded arsH genes and is highly resistant to the trivalent forms of these organoarsenicals. A derivative of P. putida with both arsH genes deleted is sensitive to MAs(III), PhAs(III) or Rox(III). P. putida arsH expressed in E. coli conferred resistance to each trivalent organoarsenical. Cells expressing PpArsH oxidized the trivalent organoarsenicals. PpArsH was purified, and the enzyme in vitro similarly oxidized the trivalent organoarsenicals. These results suggest that ArsH catalyzes a novel biotransformation that confers resistance to environmental methylated and aromatic arsenicals.     

Mineral and trace element composition of the roe and muscle tissue of farmed rainbow trout (Oncorhynchus mykiss) with respect to nutrient requirements: Elements in rainbow trout products

BackgroundDue to excellent nutritional properties of fish and fish products, dietitians recommend their larger share in the diet, for both the prevention and treatment of diet-related diseases. In this context particular attention should be given to fish eggs (roe). The aim of the study was to compare the content of selected minerals and trace elements in the roe and muscle tissue of aquaculture-reared rainbow trout. Moreover, the extent to which an edible portion of 100 g of fish product (roe or fillet) satisfies the requirements for these elements in adult consumers (women and men) and children was determined.MethodsThe research material was represented by 20 farmed rainbow trout females (Oncorhynchus mykiss). In muscle tissue and roe the proximate composition, energy value, and nutritional quality index were examined. Concentrations of K, Na, Ca, Mg, Zn, Fe, Mn and Cu were determined by flame atomic absorption spectrometry analysis. The levels of minerals and trace elements in fish products were used to calculate the percentages of the recommended dietary reference values for adults and children in portion of 100 g.ResultsThe roe had higher content of 7 elements including, Zn (29.40 ± 1.38, 27.74–30.91 mg/kg), Mn (1.66 ± 0.08, 1.55–1.73 mg/kg), Fe (11.17 ± 0.35, 10.75–11.60 mg/kg), Cu (1.24 ± 0.04, 1.21–1.30 mg/kg), Ca (546.90 ± 23.68, 522.02–578.96 mg/kg), Mg (546.97 ± 23.68, 522.02–578.96 mg/kg), Na (403.61 ± 5.53, 397.29–407.57 mg/kg) compared to muscle tissue, respectively, Zn (2.73 ± 0.97, 0.94–3.77 mg/kg, Mn (0.22 ± 0.10, 0.14–0.46 mg/kg), Fe (2.19 ± 1.44, 1.02–5.50 mg/kg), Cu (0.24 ± 0.06, 0.17–0.36 mg/kg), Ca (164.07 ± 71.72, 93.24–306.32 mg/kg), Mg (240.00 ± 73.37, 127.92–316.41 mg/kg), Na (273.37 ± 99.65, 183.93–524.41 mg/kg). In turn, the muscle tissue contained 3 times as much K (5159.87 ± 974.70, 4004.63–6343.91 mg/kg) as the roe (1713.65 ± 58.68, 1643.97–1764.14 mg/kg). The roe covered the recommended nutrition standards (population reference intake, PRI and adequate intake, AI) to a greater extent than the fillet for all analysed trace elements and minerals except K. For children, the contribution of roe to the reference intake of such elements as Mg, Zn, Fe, Mn and Cu was particularly high. Therefore the roe should be considered as a source of Mg for all consumer groups, and as high in Zn for women and children. The suggested portion of fillet and roe provided only 2–3 % of the daily requirement for Na.ConclusionsDespite the differences found, both roe and fillet from rainbow trout are a good source of analysed elements. The results indicate the need to continue research in order to determine the influence of other factors on the content of minerals and trace elements in roe and the possibility of using gonads to enrich other food products with elements.     

Effect of Wild and Genetically Modified Rhizosphere Bacteria Pseudomonas aureofaciens on the Accumulation of Arsenic by Plants

Gene constructions rendering recombinant bacteria resistant to arsenic and increasing their ability to dissolve soil phosphates and/or arsenates were created by cloning the ars operon and the gene of citrate synthase from a chromosome of the strain Pseudomonas aeruginosa PA01. Genetically modified variants of the strain Pseudomonas aureofaciens BS1393 have been constructed that are resistant to high concentrations of arsenic and dissolve poorly soluble phosphates and/or arsenates. The recombinant strains P. aureofaciens BS1393(pUCP22::arsRBC) and P. aureofaciens BS1393(pUCP22::gltA) exerted positive effects on the survival of sorgo (Sorghum saccharatum L.) and its ability to accumulate arsenic.     

Microbial production of 3-hydroxydodecanoic acid by pha operon and fadBA knockout mutant of Pseudomonas putida KT2442 harboring tesB gene

To produce extracellular chiral 3-hydroxyacyl acids (3HA) by fermentation, a novel pathway was constructed by expressing tesB gene encoding thioesterase II into Pseudomonas putida KTOY01, which was a polyhydroxyalkanoate (PHA) synthesis operon knockout mutant. 3HA mixtures of 0.35 g/l consisting of 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and 3-hydroxydodecanoate (3HDD) were produced in shake-flask study using dodecanoate as a sole carbon source. Additional knockout of fadB and fadA genes encoding 3-ketoacyl-CoA thiolase and 3-hydroxyacyl-CoA dehydrogenase in P. putida KTOY01 led to the weakening of the β-oxidation pathway. The fadBA and PHA synthesis operon knockout mutant P. putida KTOY07 expressing tesB gene produced 2.44 g/l 3HA, significantly more than that of the β-oxidation intact mutant. The 3HA mixture contained 90 mol% 3HDD as a dominant component. A fed-batch fermentation process carried out in a 6-l automatic fermentor produced 7.27 g/l extracellular 3HA containing 96 mol% fraction of 3HDD after 28 h of growth. For the first time, it became possible to produce 3HDD-dominant 3HA monomers. Ahleum Chung and Qian Liu contributed equally to this paper.     

Development of Spatial Distribution Patterns by Biofilm Cells

Confined spatial patterns of microbial distribution are prevalent in nature, such as in microbial mats, soil communities, and water stream biofilms. The symbiotic two-species consortium of Pseudomonas putida and Acinetobacter sp. strain C6, originally isolated from a creosote-polluted aquifer, has evolved a distinct spatial organization in the laboratory that is characterized by an increased fitness and productivity. In this consortium, P. putida is reliant on microcolonies formed by Acinetobacter sp. C6, to which it attaches. Here we describe the processes that lead to the microcolony pattern by Acinetobacter sp. C6. Ecological spatial pattern analyses revealed that the microcolonies were not entirely randomly distributed and instead were arranged in a uniform pattern. Detailed time-lapse confocal microscopy at the single-cell level demonstrated that the spatial pattern was the result of an intriguing self-organization: small multicellular clusters moved along the surface to fuse with one another to form microcolonies. This active distribution capability was dependent on environmental factors (carbon source and oxygen) and historical contingency (formation of phenotypic variants). The findings of this study are discussed in the context of species distribution patterns observed in macroecology, and we summarize observations about the processes involved in coadaptation between P. putida and Acinetobacter sp. C6. Our results contribute to an understanding of spatial species distribution patterns as they are observed in nature, as well as the ecology of engineered communities that have the potential for enhanced and sustainable bioprocessing capacity.     

北桑寄生产黄酮内生菌的分离鉴定及其抗氧化和抑菌活性评价

【背景】北桑寄生(Loranthus tanakae)植物中黄酮类化合物成分含量较高,生物活性较好。由于植物资源短缺,导致其生物活性成分的研究受限。【目的】从北桑寄生中分离、筛选和鉴定产黄酮类化合物的内生菌,并评估其体外抗氧化和抑菌活性。【方法】以北桑寄生枝条为研究对象分离内生菌,通过显色反应和薄层色谱法(thin-layer chromatography,TLC)筛选产黄酮类化合物的内生菌,并采用NaNO₂-Al (NO₃)₃比色法测定其总黄酮含量。利用清除自由基和抑菌的体外实验来初步评估产黄酮内生菌的生物活性。【结果】共筛选出4株产黄酮内生菌,其中3株为内生真菌,1株为内生细菌,通过形态学和分子生物学方法将其分别鉴定为Botryosphaeria sp.(ZC020)、Phoma sp.(ZZ105)、Nemania sp.(ZS042)和Pseudomonas sp.(ZC026)。4株菌中ZC020和ZS042的总黄酮含量较高,分别为(44.58±0.72) mg/L和(31.98±0.18) mg/L (P<0.05,n=3),并且ZS042可产生与北桑寄生植物相同类型的黄酮类化合物。ZC026和ZS042表现出优异的抗氧化活性,其1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)和2,2''-联氮-二(3-乙基苯并噻唑啉-6-磺酸)二铵盐[2,2''-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt,ABTS]自由基清除率分别为72.85%±0.66%(ZC026)、57.01%±0.89%(ZS042)和85.36%±0.75%(ZC026)、88.17%±0.15%(ZS042)(P<0.05,n=3)。ZZ105对革兰氏阳性菌和革兰氏阴性菌均有抑制作用。【结论】从北桑寄生枝条中分离出4株产黄酮类化合物的内生菌,其中有一株为内生细菌。这项工作为北桑寄生黄酮类化合物的生产提供了新的资源,也为其他珍稀药用植物和材料的开发和保护提供了参考。     

Utilization of complex phenolic compounds by Acinetobacter sp.

Summary Acinetobacter sp. utilized the [ring-¹⁴C]dehydropolymer of coniferyl alcohol (DHP) (sp. act. 1.4 × 10⁴ dpm/mg), ¹⁴C-labelled teakwood lignin (sp. act. 2.5 × 10⁴ dpm/mg), guaiacolglyceryl ether, 2-methoxy-4-formylphenoxyacetic acid, p-benzyloxyphenol, dehydrodivanillyl alcohol, dehydrodiisoeugenol, veratrylglycerol--guaiacyl ether, conidendrin, black liquor lignin and indulin as sole carbon sources. The bacterium produced p-coumaric acid, p-hydroxybenzoic acid, vanillic acid, protocatechuic acid and catechol as intermediates from lignins. Acinetobacter sp. produced catechol 1,2-dioxygenase and protocatechuate 3,4-dioxygenase during the degradation of lignins. Correspondence to: A. Mahadevan     

Basal Endothelial Nitric Oxide Release Is Preserved in Overweight and Obese Adults

Objective: Impaired basal nitric oxide release is associated with a number of cardiovascular disorders including hypertension, arterial spasm, and myocardial infarction. We determined whether basal endothelial nitric oxide release is reduced in otherwise healthy overweight and obese adult humans. Research Methods and Procedures: Seventy sedentary adults were studied: 32 normal weight (BMI <25 kg/m²), 24 overweight (BMI ≥ 25 < 30 kg/m²), and 14 obese (BMI ≥ 30 kg/m²). Forearm blood flow (FBF) responses to intra‐arterial infusions of N^g‐monomethyl‐l ‐arginine (5 mg/min), a nitric oxide synthase inhibitor, were used as an index of basal nitric oxide release. Results: N^g‐monomethyl‐l ‐arginine elicited significant reductions in FBF in the normal weight (from 4.1 ± 0.2 to 2.7 ± 0.2 mL/100 mL tissue/min), overweight (4.1 ± 0.1 to 2.8 ± 0.2 mL/100 mL tissue/min), and obese (3.9 ± 0.3 to 2.7 ± 0.2 mL/100 mL tissue/min) subjects. Importantly, the magnitude of reduction in FBF (～30%) was similar among the groups. Discussion: These results indicate that the capacity of the endothelium to release nitric oxide under basal conditions is not compromised in overweight and obese adults.