Marine Sediment Samples Research Articles

Lorneic Acids, Trialkyl-Substituted Aromatic Acids from a Marine-Derived Actinomycete

A marine-derived actinomyces strain (NPS554) isolated from a marine sediment sample collected from Miyazaki Harbor, Japan, at a depth of 38 m yielded two trialkyl-substituted aromatic acids, lorneic acid A (1) and lorneic acid B (2). The structures of the lorneic acids, which were elucidated by spectroscopic analysis, differed only in the side-chain, which contained either a conjugated double bond or a benzylic alcohol. Their structural differences affected inhibition activities against phosphodiesterase 5.

Characteristics and Dynamics of Salmonella Contamination along the Coast of Agadir, Morocco

The occurrence of Salmonella enterica in the environment of tropical and desert regions has remained largely uninvestigated in many areas of the world, including Africa. In the present study, we investigated the presence of Salmonella spp. along 122 km of the coastline of Agadir (southern Morocco) in relation to environmental parameters. A total of 801 samples of seawater (243), marine sediment (279), and mussels (279) were collected from six sites between July 2004 and May 2008. The overall prevalence of Salmonella spp. was 7.1%, with the highest occurrence in mussels (10%), followed by sediment (6.8%) and seawater (4.1%). Only three serotypes were identified among the 57 Salmonella sp. strains isolated. S. enterica serotype Blockley represented 43.8% of all Salmonella strains and was identified in mussel and sediment samples. S. enterica serotype Kentucky (29.8%) was found almost exclusively in mussels, whereas S. enterica serotype Senftenberg (26.3%) was detected in sediment and seawater. Statistical analysis using generalized additive models identified seawater temperature, environmental temperature, rainfall, and solar radiation as significant factors associated with the presence of Salmonella. Rainfall was the only variable showing a linear positive effect on the presence of Salmonella in the sea, whereas the remaining variables showed more complex nonlinear effects. Twenty-eight (49.1%) Salmonella isolates displayed resistance to ampicillin (22 isolates), nalidixic acid (9 isolates), sulfonamide compounds (2 isolates), and tetracycline (1 isolate), with six of these isolates displaying multiple resistance to two of these antimicrobial agents. Pulsed-field gel electrophoresis analysis revealed homogenous restriction patterns within each serotype that were uncorrelated with the resistance pattern profiles.

Pressurized liquid extraction of organophosphate triesters from sediment samples using aqueous solutions

A novel procedure for the extraction of seven organophosphate triesters (OPs), used as flame retardants and plasticizers, from sediment samples has been developed. It is based on the pressurized liquid extraction of the analytes with aqueous solutions, combined with a further concentration step using solid-phase extraction (SPE) and followed by gas chromatography coupled to mass spectrometry (GC-MS) determination. The effects of different variables on the yield and selectivity of the sample preparation process are systematically evaluated. The optimal responses were observed extracting 2 g of sediment with a water:acetonitrile (75:25) solution at 90 °C and 1500 psi for 5 min. The obtained extract was made up to 200 mL with ultrapure water and passed through an OASIS HLB, 60 mg cartridge. Analytes were recovered with 2 mL of ethyl acetate and this extract concentrated to a lower volume, ca. 0.2 mL. Recoveries of the proposed extraction method ranged from 77 to 111%, with relative standard deviations below 10%, for spiked river and marine sediment samples with total carbon contents (TC) up to 4.0%. The limits of quantification (LOQs) of the method varied between 0.5 and 5 ng g −1. Analysis of non-spiked sediment samples revealed the presence of low levels for some of the investigated species, with the highest concentration (47 ng g −1) corresponding to tris(2-chloroethyl) phosphate (TCEP).

Bacterial Diversity and Bioprospecting for Cold-Active Lipases, Amylases and Proteases, from Culturable Bacteria of Kongsfjorden and Ny-Ålesund, Svalbard, Arctic

Culturable bacterial diversity of seven marine sediment samples of Kongsfjorden and a sediment and a soil sample from Ny-Alesund, Svalbard, Arctic was studied. The bacterial abundance in the marine sediments of Kongsfjorden varied marginally (0.5 x 10(3)-1.3 x 10(4) cfu/g sediment) and the bacterial number in the two samples collected from the shore of Ny-Alesund also was very similar (0.6 x 10(4) and 3.4 x 10(4), respectively). From the nine samples a total of 103 bacterial isolates were obtained and these isolates could be grouped in to 47 phylotypes based on the 16S rRNA gene sequence belonging to 4 phyla namely Actinobacteria, Bacilli, Bacteroidetes and Proteobacteria. Representatives of the 47 phylotypes varied in their growth temperature range (4-37 degrees C), in their tolerance to NaCl (0.3-2 M NaCl) and growth pH range (2-11). Representatives of 26 phylotypes exhibited amylase and lipase activity either at 5 or 20 degrees C or at both the temperatures. A few of the representatives exhibited amylase and/or lipase activity only at 5 degrees C. None of the phylotypes exhibited protease activity. Most of the phylotypes (38) were pigmented. Fatty acid profile studies indicated that short chain fatty acids, unsaturated fatty acids, branched fatty acids, the cyclic and the cis fatty acids are predominant in the psychrophilic bacteria.

Distribution of polycyclic aromatic hydrocarbons in marine sediments and their potential toxic effects

The presence of polycyclic aromatic hydrocarbons (PAHs) in samples of marine sediments from Paranagua Bay on the southern coast of Brazil was investigated. Paranagua Bay is the location of a major port, one of the busiest in Brazil. The region has a great potential for tourism and port-related industries and activities. Due to its characteristics as a venue for tourism, two major campaigns were planned: one 3 months before the summer (between December and February) and a second after the vacation season. Total concentration of PAHs in sediments ranged from 26.33 to 406.76 ng/g (in both campaigns). The highest values were found in sediments with higher organic carbon content. We found no substantial differences between the two campaigns, and the values are quite similar. Ternary diagrams show that points P5 and P6 were considered polluted, while others were classified as non-polluted. Molecular ratios indicate that the main sources of PAHs are petrogenic and the burning of fossil fuels. Sediment toxicity was assessed by the presence of PAHs in terms of benzo(a)pyrene (BaP) concentration. The toxicity of PAHs mixtures can be characterized more accurately by developing and establishing toxic equivalency factors (TEFs) for PAHs. Considering TEFs, the BaP(eq) concentrations vary between 0.264 and 5.922 ng/g (considering both campaigns). Thus, two points are above the maximum level recommended (3 ng/g) by the Netherlands sediment quality guidelines. In fact, sites P5 and P6 apparently are exposed to a greater number of pollution sources, thus reflecting the higher concentration of PAHs compounds in sediments.

Molecular ecology of marine sediments: determination of Real-Time PCR efficiency for quantifying microbial cells

Polymerase chain reaction (PCR) efficiency is the rate at which a PCR amplicon is generated. More efficient amplification of the DNA fragment (amplicon) will generate more products in fewer cycles, thus improving accuracy and sensitivity of quantitative PCR. The efficiency of Real-Time PCR to detect and quantify microbial cells was compared in marine sediment samples of different origin and chemical composition, and in standard samples. Real-Time PCR efficiencies of marine sediment samples ranged from 1.48±0.1 to 1.83±0.1 and were significantly different from those of standard samples, most probably due to different concentrations of PCR inhibitors. The Real-Time PCR efficiency was higher using species-specific primers (>1.7), and lower using universal primers (<1.7). Generally, when the PCR efficiency was higher, its detection limit was lower. In addition, the sensitivity of the Real-Time capillary assay over the traditional assay was generally greater. We suggest that for quantifying microbial cells in marine sediment samples using Real-Time PCR, standard curves should be constructed for both the standard and sediment samples, and a correction factor should be applied. For qualitative PCR a real-time capillary assay should be used for the detection of small quantities of DNA.

Streptomyces xinghaiensis sp. nov., isolated from marine sediment

A novel actinomycete, strain S187(T), was isolated from a marine sediment sample collected from Xinghai Bay, Dalian, China. Growth occurred on ISP medium 2 containing 0-9 % NaCl and at pH 6.0-9.0 and 10-45 degrees C. The cell wall of strain S187(T) contained the isomer ll-diaminopimelic acid as the diagnostic diamino acid. The predominant menaquinones were MK-9(H(6)) (40.8 %), MK-9(H(8)) (38.2 %) and MK-9(H(2)) (8.8 %). The major fatty acids were iso-C(16 : 0) (29.6 %), anteiso-C(15 : 0) (14.0 %) and anteiso-C(17 : 0) (11.6 %). Cells contained phosphatidylethanolamine, phosphatidylinositol, phosphatidylglycerol, phosphatidylinositol mannosides and one unknown phospholipid. The G+C content of the genomic DNA was 72.01 mol%. The 16S rRNA gene sequence of the isolate had similarities of 98.1 and 97.5 % with those of Streptomyces flavofuscus NRRL B-8036(T) (=DSM 41426(T)) and Streptomyces albiaxialis DSM 41799(T), respectively, showing that the novel strain should be assigned to the genus Streptomyces. DNA-DNA hybridizations with the two above-mentioned Streptomyces species showed 31.4 and 46.9 % relatedness, respectively. Moreover, the three strains differed in some physiological and biochemical properties. Thus, on the basis of phenotypic and genotypic analyses, it is proposed that strain S187(T) represents a novel species of the genus Streptomyces, for which the name Streptomyces xinghaiensis sp. nov. is proposed; the type strain is S187(T) (=NRRL B-24674(T)=CCTCC AA 208049(T)=KCTC 19546(T)).

Paraoerskovia marina gen. nov., sp. nov., an actinobacterium isolated from marine sediment

A Gram-positive-staining, facultatively anaerobic bacterial strain, CTT-37T, was isolated from a marine sediment sample collected from Tottori city, located on the shore of the Sea of Japan. A 16S rRNA gene sequence comparison indicated that the isolate represents a novel clade that clusters with members of the families Cellulomonadaceae and Sanguibacteraceae. Strain CTT-37T shared maximum 16S rRNA gene sequence similarity of 96.4% with Oerskovia paurometabola DSM 14281T and 96.2% with Oerskovia enterophila DSM 43852T. The DNA-DNA hybridization value between strain CTT-37T and O. enterophila JCM 7350T was 10-12%. The following chemotaxonomic characteristics of strain CTT-37T were markedly different from those of strains in the genus Oerskovia. The cell wall contained L-serine in the peptidoglycan interpeptide bridge. The predominant menaquinone was MK-9 (H4); other quinones detected were MK-9 and MK-9(H2). The only polar lipid was phosphatidylglycerol and the G+C content of the DNA was 70 mol%. Differences in phenotypic characteristics and large phylogenetic distances between strain CTT-37T and all members of the genus Oerskovia supported the classification of CTT-37T within a new genus and species, for which the name Paraoerskovia marina gen. nov., sp. nov. is proposed. The type strain of Paraoerskovia marina is CTT-37T (=NBRC 104352T=DSM 21750T).

Development of a focused ultrasonic-assisted extraction of polycyclic aromatic hydrocarbons in marine sediment and mussel samples

Focused ultrasonic-assisted extraction (FUSE) is a new and particular technique based on the cavitation effect. In this work, the focused ultrasound assisted extraction was studied and developed for the extraction of polycyclic aromatic hydrocarbons from marine sediments and mussel tissues. The variables influencing the extraction (amplitude of the ultrasound pulse, the extraction time and the solvent) were studied by a full factorial design and a central composite design. As a result, flat response surfaces were obtained and the most convenient conditions were 45% of ultrasound amplitude, 120 s of extraction time and 5 mL of acetone. Both accuracy and precision of the method were evaluated by means of two certified reference materials (marine sediment and mussel tissue) and the results were also compared to those obtained by microwave assisted extraction.

Optically stimulated luminescence dating of young (

The reliability of single-grain optically stimulated luminescence (OSL) dating of young (<500 years old) samples is assessed by examining the results of 166 single-grain OSL analyses of Australian alluvial, lacustrine, estuarine, coastal and marine sediment samples. All samples have been analysed using the modified SAR protocol of Olley et al. [2004b. Optical dating of Holocene sediments from a variety of geomorphic settings using single grains of quartz. Geomorphology 60, 337–358], with burial doses ( D b) calculated by fitting a single Gaussian curve to the peak of a multi-Gaussian summed probability distribution (PDF Gaussian). The near-equivalence of this approach to currently accepted methods of palaeodose estimation – namely the minimum age and central age models of Galbraith et al. [1999. Optical dating of single and multiple grains of quartz from Jinmium rock shelter, northern Australia: part I, experimental design and statistical models. Archaeometry 41, 339–364] – is demonstrated. Considered as a whole, OSL ages calculated using the PDF Gaussian D b determination method are consistent with other chronometric, geomorphological, botanical and historical indicators of depositional age, while four alternative (previously published) methods are generally less reliable when applied to the samples analysed here. The single-grain data from 12 samples of known age (reported by Olley et al. [2004b. Optical dating of Holocene sediments from a variety of geomorphic settings using single grains of quartz. Geomorphology 60, 337–358]) are re-analysed using the PDF Gaussian approach, with all but one yielding a D b consistent with the independently known age. Examples of luminescence data (dose recovery tests, preheat plateaux, continuous-wave and linear-modulated OSL, growth curves, single-grain dose distributions) are provided that together indicate the suitability of Australian quartz for dating young sediments.

Winogradskyella arenosi sp. nov., a member of the family Flavobacteriaceae isolated from marine sediments from the Sea of Japan

An aerobic, Gram-negative, yellow-pigmented, gliding bacterial strain, designated R60(T), was isolated from a marine sediment sample obtained from the Sea of Japan and was characterized by using a polyphasic approach. 16S rRNA gene sequence analysis showed that strain R60(T) belonged to the genus Winogradskyella, sharing <97 % sequence similarity with the type strains of recognized Winogradskyella species. The main fatty acids of strain R60(T) were iso-C(15 : 0) 3-OH, iso-C(16 : 0) 3-OH, iso-C(17 : 0) 3-OH, anteiso-C(17 : 0) 3-OH and iso-C(15 : 0), consistent with its assignment to the genus Winogradskyella. On the basis of phenotypic distinctiveness and phylogenetic divergence, strain R60(T) is considered to represent a novel species of the genus Winogradskyella, for which the name Winogradskyella arenosi sp. nov. is proposed. The type strain is R60(T) (=KMM 3968(T) =NRIC 0748(T)= JCM 15527(T)).

Autotrophic denitrification and its effect on metal speciation during marine sediment remediation

Denitrification-based remediation has been proved as a cost-effective approach for organic removal in sediment. However, little attention has been drawn on the concomitant autotrophic denitrification process and its impacts during such treatment. In this study, a contaminated marine sediment sample was treated with nitrate in a series of experiments to characterize the autotrophic denitrification and its impacts on metal speciation. Through treatment, as the consequence of autotrophic denitrification which accounts for 73.9% of nitrate reduction, ∼98.8% acid volatile sulfide (AVS) was oxidized to sulfate, causing changes of Zn, Cu and Pb speciation in the sediment. Their oxidizable fractions decreased by 71.7%, 13% and 71% respectively while the bound-to-carbonate fractions increased by 52.0%, >700% and >40%, and the reducible fractions also increased by 276%, >280% and 140%. Thus, the relatively stable oxidizable phase of Zn, Cu and Pb was generally transferred to the more mobile bound-to-carbonate and reducible phases. According to SEM (simultaneously extracted metal) analysis, most of extractable Zn and Pb were no longer present in the form of metal sulfides after denitrification. The (Zn + Pb)/AVS ratio increased from 0.030 to 3.1. Both sequential extraction and AVS–SEM suggested a possible increase of heavy metal mobility and, thus, toxicity. Two major species responsible for autotrophic denitrification were identified to be phylogenetically related with Sulfurimonas paralvinellae and Thiohalophilus thiocyanoxidans.

Streptomyces nanshensis sp. nov., isolated from the Nansha Islands in the South China Sea

A novel actinomycete strain, designated SCSIO 01066(T), was isolated from a marine sediment sample collected from the Nansha Islands in the South China Sea and was subjected to a polyphasic taxonomic study. A phylogenetic tree based on 16S rRNA gene sequences showed that strain SCSIO 01066(T) had the highest similarity (96.5 %) to members of the genus Streptomyces and was loosely associated with Streptomyces armeniacus JCM 3070(T), Streptomyces cacaoi subsp. cacaoi NBRC 12748(T) and Streptomyces sodiiphilus YIM 80305(T). Predominant menaquinones, major fatty acids and morphological properties were also consistent with typical characteristics of the genus Streptomyces; however, the presence of phosphatidylglycerol in the phospholipid pattern differs greatly from those of members of the genus Streptomyces. Additionally, strain SCSIO 01066(T) showed some physiological differences from its most closely related neighbours. Based on the polyphasic data, a novel species, Streptomyces nanshensis sp. nov., is proposed, with the type strain SCSIO 01066(T) (=KCTC 19400(T)=CCTCC AA 208005(T)).

Determination of Trace Element Contents in Solid Environmental Matrices using Collision/Reaction Cell ICP-MS

Objectives of this study were to: a) optimize EPA-3052 microwave digestion method using a c/r ICP-MS method by adjusting combinations of acids, digestion temperature and duration; b) validate the c/r ICP-MS method for multi-element analyses to determine their total concentration in solid matrices; and c) set up a robust single-step partial extraction method by using the c/r ICP-MS method. Here, special emphasis has been given to total trace element analyses of marine sediment samples from the Back Biloxi Bay, MS to monitor the effects of Hurricane Katrina on the region. This study confirmed that the amount of acid extraction not only depends on the applied digestion method including different types and combinations of acids, but also the type of element, its origin (natural or anthropogenic) and its chemical form. Optimized conditions for total digestion have been selected as-Acid: HNO3+ HF + HCl (10:3:2); Temperature: 180°C; Power: 1600 W; and Duration: 15 minutes. The dilute acid (single-step) microwave digestion methods extract a significant amount of trace elements from sediment solid matrices, therefore these methods can lead to overestimation of the amount of trace elements that might be released into the environment. The dilute acid (0.5 M HCl) (single-step) “cold” extraction method can provide valuable information for evaluating the amount of trace metal that might become remobilized and/or bioavailable. Total trace element contents of marine sediments from Back Biloxi Bay, collected monthly following Hurricane Katrina, revealed a wide range of variation, but no apparent temporal trends. Acknowledgement: This study was supported by NOAA-NIUST-NA05NOS4261163.

Cytotoxic and Antimicrobial Potential of Actinomycete Species Saccharopolyspora salina VITSDK4 Isolated from the Bay of Bengal Coast of India

Problem statement: Although the diversity of marine Actinobacteria have been studied and biotechnologically exploited throughout the world, the studies on marine actinobacteria in Indian peninsula are largely unexplored. Of 9 maritime states in India, only 4 states have been extensively studied for the diversity of actinobacteria. Further, the studies on bioactive actinomycetes from saline soil are very scanty. In the present study, we had taken an initiative to isolate culturable halophilic actinomycetes and to screen the bioactive potential. Approach: The marine sediment sample was collected at a depth of 400 cm at Marakkanam. The strain was isolated using ISP No. 2 medium supplemented with 25% sea water. The polyphasic taxonomy of the strain was evaluated by phenotypic, chemotaxonomic and phylogenetic analysis. The 16S rRNA was sequenced and phylogenetic relationship with the closest related species were studied. The growth conditions and the medium had been optimized under shake-flask conditions by measuring the dry weight of the mycelium. The isolate was subjected to fermentation and the crude extract was screened for cytotoxic, hemolytic and antimicrobial activity. The cytotoxicity was evaluated on HeLa cells by MTT assay, hemolytic assay on mouse erythrocytes and the antimicrobial activity was determined by agar diffusion assay. Results: Based on polyphasic taxonomy the species was identified as Saccharopolyspora salina and belongs to the genus Saccharopolyspora. The 16S rRNA sequence of the isolate showed 100% similarity with Saccharopolyspora salina. Based on the phylogenetic and phenotypic evaluation the isolate was designated as Saccharopolyspora salina VITSDK4. The growth was maximal in the designed production medium with the incubation temperature of 28°C and pH of 7.4. It is a moderately halophilic species requires 9% NaCl concentration for optimal growth. The cytotoxicity on HeLa cells showed the IC50 value of 26.2 μg mL-1 by MTT assay. The hemolytic activity on mouse erythrocytes showed the EC50 value of 266 μg mL-1. The crude extract also exhibited significant antagonistic activity against fungal pathogens Aspergillus niger, Aspergillus fumigatus, Candida albicans and the Gram negative bacteria Escherichia coli and Klebsiella pneumoniae. Only moderate activity was seen against Gram positive bacteria Staphylococcus aureus and Bacillus subtilis. Conclusion/Recommendations: Based on the results of our investigation, the isolated strain was identified as Saccharopolyspora salina VITSDK4, which was moderately halophilic, produces an extracellular bioactive metabolite, which inhibits the proliferation of HeLa cells as well as antagonistic to fungal and bacterial pathogens. Further studies on purification and characterization of the pure compound from the strain were ongoing. The results of this study suggested that the marine actinomycetes from the unexplored Indian coast could provide lead compounds of therapeutic value.

Validation of an analytical methodology for the quantitative analysis of petroleum hydrocarbons in marine sediment samples

This work describes a validation of an analytical procedure for the analysis of petroleum hydrocarbons in marine sediment samples. The proposed protocol is able to measure n-alkanes and polycyclic aromatic hydrocarbons (PAH) in samples at concentrations as low as 30 ng/g, with a precision better than 15% for most of analytes. The extraction efficiency of fortified sediments varied from 65.1 to 105.6% and 59.7 to 97.8%, for n-alkanes and PAH in the ranges: C16 - C32 and fluoranthene - benzo(a)pyrene, respectively. The analytical protocol was applied to determine petroleum hydrocarbons in sediments collected from a marine coastal zone.

Evaluation of contribution sources for the sediments of the La Paz Lagoon, based on statistical treatment of the mineralogy of their heavy fraction and surrounding rock and drainage basin characteristics

To identify the main sources of terrigenous sediments of the La Paz Lagoon, a description of the hydrology of the drainage basins and the mineralogy of the heavy fraction of the lagoon sediments is needed. In this work, 14 terrigenous sediment samples from the arroyos (dry streams) and 55 superficial marine sediment samples were collected from the study area. The drainage basins of the principal arroyos discharging into the lagoon were defined using geomorphologic analyses on Geographic Information Systems (GIS). The sediment samples’ grain size fraction of 3.25 – 3.00 phi was obtained by sieving. The heavy minerals were separated using bromoform and the mineralogical composition was determined using a petrographic polarization microscope. Three main sedimentary provinces in the lagoon were distinguished based on principal component analysis of the heavy mineral data and the study of the surrounding regional streams. The eastern sedimentary province is characterized by the predominance of orthopyroxene, especially hypersthene, as well as a high hornblende presence. This is due to the erosion of volcanoclastic sequences of the Comondu Formation and intrusive granitic complexes of Sierra de Las Cruces. The southeastern province displays a high abundance of hornblendes (up to 81% in some stations), micas, apatite, sphene, anatase, tourmaline, chlorite, clinopyroxene and orthopyroxene. Lower contents of amphibole (up to 27.2% in some stations) and resistant garnet and zircon minerals were found, as were some soft-pink piedmontite and pale-green hypersthene. These minerals were supplied by the El Cajoncito, Los Bledales, La Palma, Cardonal and El Novillo arroyos eroding the intrusive rocks of “Granito Sierra de Las Cruces”, “Tonalita La Buena Mujer” and in a smaller extent the extrusive and non-marine rocks (tuffs, riodacites, conglomerates and sandstones) of the Comondu Formation. The predominant minerals of the northwestern province are clinopyroxene, orthopyroxene and phosphatic ooids. Relatively high abundance of olivine, hornblende, zircon, epidote and garnet were also found. These minerals are presumably supplied by the arroyos La Ardilla and other streams to the north of the El Centenario and El Comitan villages, as well as by eolian and littoral transport of the El Mogote sandbar dunes, which accumulates eroded sediments from the marine sedimentary rocks of El Cien Formation.

Determination of Total Chromium in the Marine Sediment Certified Reference Material by Inductively Coupled Plasma Optical Emission Spectrometry after Pressurized Acid Decomposition

(1) The marine sediment (NMIJ CRM 7302a) was directly decomposed with a mixture of 1 mL of hydrofluoric acid, 1 mL of nitric acid and 8 mL of (1 + 1)sulfuric acid in a Teflon sealed vessel at 230°C for 16 h. The total chromium was determined. (2) An indirect acid method after the decomposition of organic materials by H2SO4-HNO3 was compared to a direct acid decomposition method (1). The analytical results of the total-chromium (t-Cr) by methods (1) and (2) coincided with the certified value of the NMIJ CRM 7302a. The direct method of (1) was recommended for a pre-treatment of a marine sediment sample. On the other hand, an electron probe micro-analyzer (EPMA) was applied to an element analysis of the trace precipitation in a direct acid decomposition process in a Teflon-sealed vessel. The white trace precipitation was a crystal of AlF, and the black trace precipitation was carbon. Trace chromium was not detected by the precipitations. How to obtain accurate data from the pre-treatments was discussed regarding the data of this method and other data : that is EPA 3050B, ISO 11466, EPA 3052B, or NAA found from the Union Internationale des Laboratories Indepentants, Inter-Laboratoriy Practice report. The importance of deciding the assigned value was discussed for a statistical evaluation of the data of participants in a proficiency testing. The certified reference materials (CRM) should be furnished by both the sheet decomposition methods of CRM in addition to methods (sheet) for accurate quantitative analyses of the analytes in the CRM.

Production and purification of agarase from a marine agarolytic bacteriumAgarivoranssp. HZ105

Isolation and characterization of an agarase-producing bacterium Agarivorans sp. HZ105. An agarase-producing bacterium strain HZ105 had been isolated from marine sediment sample. Based on phylogenetic analysis of the 16S rRNA gene sequence and phenotypic analysis, as well as biochemical analyses, this strain was named Agarivorans sp. HZ105. Effect of pH, NaCl on the growth and agarase production of strain HZ105 was studied. Strain HZ105 produced three extracellular agarases which were purified to homogeneity from bands in the PAGE gel. Two agarases of these three had a molecular mass of 54, 58 kDa, respectively. And the MS and MS/MS spectra were used to identify the agarases. The MS spectra result showed that the agarases of strain HZ105 should be beta-agarase and belong to the family 50 of glycosyl hydrolases. The agarases could keep stable activity at room temperature. The strain HZ105 was useful to produce stable agarases. The solution produced by agar's degradation in the agar plates was first reported to be used for purification of agarase. Agarases were purified to homogeneity directly from the PAGE gel without stained by Coomassie brilliant blue.

Actinobacterial diversity from marine sediments collected in Mexico

Seventeen different media known to support the growth and isolation of members of the class Actinobacteria were evaluated as selective isolation media for the recovery of this microbial group from marine sediments samples collected in the Gulf of California and the Gulf of Mexico. A general selective isolation procedure was employed for six sediments and nearly 300 actinomycetes were recovered from the selective isolation plates. Full 16S rRNA gene sequencing revealed that the isolates belonged to several actinobacterial taxa, notably to the genera Actinomadura, Dietzia, Gordonia, Micromonospora, Nonomuraea, Rhodococcus, Saccharomonospora, Saccharopolyspora, Salinispora, Streptomyces, "Solwaraspora" and Verrucosispora. Previous works on marine sediments have been restricted to the isolation of members of the genera Micromonospora, Rhodococcus and Streptomyces. This study provides further evidence that Actinobacteria present in marine habitats are not restricted to the Micromonospora-Rhodococcus-Streptomyces grouping. Indeed, this first systematic study shows the extent of actinobacterial diversity that can be found in marine sediments collected in Mexico and probably, worldwide.