Heterotrophic Potentials and Hydrocarbon Biodegradation Potentials of Sediment Microorganisms Within the Athabasca Oil Sands Deposit

Techniques for the enumeration and the determination of the potential activity of disturbed sediment mixed populations at control sites and sites within the Athabasca oil sands formation were applied to August and December samples. These techniques included the determination of general heterotrophic potential for the assimilation and respiration of glutamate, which indicated no oil sand-related changes in the sediments but which indicated a significant seasonal change. Enumeration by epifluorescence direct counts, oil sand hydrocarbon plate counts, and most-probable-number determinations of [¹⁴C]hexadecane and [¹⁴C]-naphthalene degraders indicated that only the plate count was sensitive to increased numbers of oil sand-related hydrocarbon-oxidizing microorganisms within the oil sands deposit. Unlike the most probable number determinations of [¹⁴C]hexadecane and [¹⁴C]naphthalene degraders, however, the biodegradation potential results of these substrates indicated a significant increase in activity at oil sands sites. These biodegradation potentials also showed a marked seasonal fluctuation. Although the biodegradation potentials and the endogenous hydrocarbon plate counts indicated an oil sand-adapted mixed sediment population, the results of these techniques did not correlate well with the concentrations of bituminous hydrocarbons in the sediments. The results suggest that a general capability for hydrocarbon oxidation exists in the Athabasca River system and that this capability is enhanced within the natural bounds of the Athabasca oil sands.     

Denitrification and Nitrogen Fixation in Alaskan Continental Shelf Sediments

Rates of nitrogen fixation and denitrification were measured in Alaskan continental shelf sediments. In some regions, rates of nitrogen fixation and denitrification appeared to be equal; in other areas, rates were significantly different. Potential rates of denitrification were found to be limited primarily by the available nitrate substrate. Major regional differences in rates of denitrification were not statistically significant, but significant differences were found for nitrogen fixation rates in different regions of the Alaskan continental shelf. Estimated net losses of nitrogen from Bering Sea sediments were calculated as 1.8 × 10¹² g of N/yr. Experimental exposure of continental shelf sediments to petroleum hydrocarbons reduced rates of nitrogen fixation and denitrification in some cases but not others. Long-term exposure was necessary before a reduction in nitrogen fixation rates was observed; unamended rates of denitrification but not potential denitrification rates (NO₃⁻ added) were depressed after exposure to hydrocarbons.     

泉古菌醇与绿素在东海陆架区的分布及关系研究

【目的】研究东海陆架地区的沉积物中的泉古菌醇、绿素的分布及其相关关系。【方法】通过有机化学的方法将泉古菌醇和绿素从沉积物中萃取出来之后,利用高效液相色谱质谱连用对泉古菌醇进行定量检测,利用高效液相色谱对绿素进行定量检测。【结果】泉古菌醇和绿素在长江河口绝对量的分布在空间上呈现类似关系,并且受到陆源输入的影响较小。【结论】东海陆架区的泉古菌醇和绿素均为海洋产生,而非陆源输入,且两者呈现明显的相关关系,提示泉古菌醇具有指示历史时期东海表层初级生产力变化的潜在应用。     

Drug-resistant bacteria in Continental Shelf sediments

Fecal indicator bacteria were isolated from water and sediment samples obtained from a sewage sludge disposal site in the Middle Atlantic. Some were found to be resistant to several antimicrobial agents. Isolation of these microbes 30 months after cessation of sludge dumping indicates their survivability in the environment.     

Measurement of rRNA Variations in Natural Communities of Microorganisms on the Southeastern U.S. Continental Shelf

The development of a clear understanding of the physiology of marine prokaryotes is complicated by the difficulties inherent in resolving the activity of various components of natural microbial communities. Application of appropriate molecular biological techniques offers a means of overcoming some of these problems. In this regard, we have used direct probing of bulk RNA purified from selective size fractions to examine variations in the rRNA content of heterotrophic communities and Synechococcus populations on the southeastern U.S. continental shelf. Heterotrophic communities in natural seawater cultures amended with selected substrates were examined. Synechococcus populations were isolated from the water column by differential filtration. The total cellular rRNA content of the target populations was assayed by probing RNA purified from these samples with an oligonucleotide complementing a universally conserved region in the eubacterial 16S rRNA (heterotrophs) or with a 1.5-kbp fragment encoding the Synechococcus sp. strain WH 7803 16S rRNA (cyanobacteria). The analyses revealed that heterotrophic bacteria responded to the addition of glucose and trace nutrients after a 6-h lag period. However, no response was detected after amino acids were added. The cellular rRNA content increased 48-fold before dropping to a value 20 times that detected before nutrients were added. Variations in the rRNA content from Synechococcus spp. followed a distinct diel pattern imposed by the phasing of cell division within the irradiance cycle. The results indicate that careful application of these appropriate molecular biological techniques can be of great use in discerning basic physiological characteristics of selected natural populations and the mechanisms which regulate growth at the subcellular level.     

Drug-resistant bacteria in Continental Shelf sediments.

Fecal indicator bacteria were isolated from water and sediment samples obtained from a sewage sludge disposal site in the Middle Atlantic. Some were found to be resistant to several antimicrobial agents. Isolation of these microbes 30 months after cessation of sludge dumping indicates their survivability in the environment.     

Viability of Selected Microorganisms in Hydrocarbon Fuels

A laboratory study of the viability of selected microorganisms in a hydrocarbon fuel medium was carried out on 19 species of microorganisms, representative of the types found as natural contaminants in aircraft fuels. More species remained viable when inoculated in pure cultures than when inoculated in mixed (composite) cultures. Of the 19 species selected, 10 were still viable after 3 months and 5 were viable after 4 months in the pure culture inoculants. In the complete composite culture inoculant, the bacterial species which were viable at the end of 4 months were the same as those found in the pure culture inoculant. No fungi remained viable in the complete composite cultures after a 3-week period. The microorganisms which remain viable in a hydrocarbon fuel medium are considered indicative of a satisfactory inoculum to be used as a test culture in laboratory analysis of mechanical control techniques.     

基因工程菌在生物降解中的应用及其发展

在简要阐述基因工程菌构建方法的基础上,系统综述和评价了基因工程构建方法的研究进展及其在生物降解中存在的问题。     

Ecological Distribution of Polychaetous Annelids from the New England Outer Continental Shelf,Georges Bank

Four hundred and eight quantitative grab samples collected during the winter and spring of 1977 from the New England Continental Shelf (Georges Bank) yielded 333 species of polychaetes. Polychaetes comprised 53.8% of the number of all infaunal species, 53% of the density, and 60.5% of the wet weight biomass for all soft-bodied organisms, at least for the winter. Mean number of species and mean density was significantly higher in the spring than in the winter. Mean values of number of species, H', SDN, density, and biomass were associated with various environmental factors. Based on numerical classification (normal and inverse) five polychaete site groups were identified. To a great extent these site groups were molded by major physical, geologic and biologic processes which influence the productivity of this ecologically and economically important area.     

Biological Communities of the South Texas Continental Shelf

A multi-disciplinary study of the south Texas continental shelfin 1975–1977 investigated physical, chemical, geological,and biological characteristics over spatial and temporal scales,and the results are briefly summarized here. Chlorophyll a concentrationsand zooplankton density and biomass showed reductions relatedto distance from shore. These factors also displayed north-southgradients and correlations with surface salinities. Bottom sedimentsgraded seaward from fine sands nearshore to silts and clayson the outer shelf. Coarser sediments were associated with geologicand physical features such as ancestral deltas and wave action.Benthic populations were distributed in relation to sedimenttype, but other features such as depth, bottom water variability/stability,and primary production in the overlying waters were also importantin determining benthic community structure. The study providesa baseline for future process-oriented investigations and environmentalassessments.     

Canada and Arctic Politics: The Continental Shelf Extension

This article challenges the validity of the commonly held assumption that Canada and other Arctic countries are engaged in a highly competitive scramble to stake claims for extensions to their continental shelves beyond 200 nautical miles, and that Canada may lose out because it is lagging behind in this race to claim as many seabed resources as possible. It argues that the process is orderly; that, under international law, Canada already has sovereign rights over the continental shelf beyond 200 nautical miles; that the process is generally characterized by cooperation; and that the timing of various countries’ submissions to the Commission on the Limits of the Continental Shelf will not be a key determinant of success.     

Prokaryotic Metabolic Activity and Community Structure in Antarctic Continental Shelf Sediments

The prokaryote community activity and structural characteristics within marine sediment sampled across a continental shelf area located off eastern Antarctica (66°S, 143°E; depth range, 709 to 964 m) were studied. Correlations were found between microbial biomass and aminopeptidase and chitinase rates, which were used as proxies for microbial activity. Biomass and activity were maximal within the 0- to 3-cm depth range and declined rapidly with sediment depths below 5 cm. Most-probable-number counting using a dilute carbohydrate-containing medium recovered 1.7 to 3.8% of the sediment total bacterial count, with mostly facultatively anaerobic psychrophiles cultured. The median optimal growth temperature for the sediment isolates was 15°C. Many of the isolates identified belonged to genera characteristic of deep-sea habitats, although most appear to be novel species. Phospholipid fatty acid (PLFA) and isoprenoid glycerol dialkyl glycerol tetraether analyses indicated that the samples contained lipid components typical of marine sediments, with profiles varying little between samples at the same depth; however, significant differences in PLFA profiles were found between depths of 0 to 1 cm and 13 to 15 cm, reflecting the presence of a different microbial community. Denaturing gradient gel electrophoresis (DGGE) analysis of amplified bacterial 16S rRNA genes revealed that between samples and across sediment core depths of 1 to 4 cm, the community structure appeared homogenous; however, principal-component analysis of DGGE patterns revealed that at greater sediment depths, successional shifts in community structure were evident. Sequencing of DGGE bands and rRNA probe hybridization analysis revealed that the major community members belonged to delta proteobacteria, putative sulfide oxidizers of the gamma proteobacteria, Flavobacteria, Planctomycetales, and Archaea. rRNA hybridization analyses also indicated that these groups were present at similar levels in the top layer across the shelf region.     

Mapping of the Biological Resources of the Continental Shelf

Distribution patterns of the penaeid shrimp and demersal fishspecies are discussed based upon collections totaling in excessof 330,000 shrimp and 2,245,000 fishes. Depth related zonationreveals nearshore, mid-shelf, outer shelf, and trans-shelf assemblages.Estuary related species are particularly prominent on the northwesternGulf shelf, while rock and reef related species are most importantin the fauna of the eastern Gulf shelf. Recognizable elementsin the shelf fauna also include species of tropical affinity;open ocean and upper slope species; inhabitants of seagrassbeds, mangrove swamps, and carbonate rubble and shell hash;burrowers in soft bottoms; and inhabitants of the upper watercolumn. The eastern Gulf shelf is inhabited by twice as manyfish species and eight times as many unique species as the northwesternshelf, reflecting the great diversity of habitat types in theeastern Gulf. A few key species numerically dominate the ichthyofaunaof the northwestern shelf, but dominance is spread through manyspecies in the east. Seasonal shifts in species density primarilyreflect inshore/offshore seasonal migrations of estuary relatedspecies, but seasonal inshore/offshore density shifts are alsoobserved among the true shelf residents. Trophically the shelfsystems are supported by precipitated plankton and organic detritusderived from rivers, bays and estuaries, seagrass beds, andmangrove swamps, although attached algae are also importantproducers in the east. Mollusks, polychaetes, and small crustaceanswhich feed upon this material, in turn, support the demersalfish communities whose species are generally short-lived. Largerlonglived predators are mostly seasonal migrants which appearin the northern Gulf during the warmer months. Bottom-feedinggeneralists are prominent in the northwest, while specialistsare in great evidence in the east. These distributional studieslay the foundation for understanding the shelf ecological systems,and they also provide a basis for informed management decisions.     

Diversity,Distribution and Hydrocarbon Biodegradation Capabilities of Microbial Communities in Oil-Contaminated Cyanobacterial Mats from a Constructed Wetland

Various types of cyanobacterial mats were predominant in a wetland, constructed for the remediation of oil-polluted residual waters from an oil field in the desert of the south-eastern Arabian Peninsula, although such mats were rarely found in other wetland systems. There is scarce information on the bacterial diversity, spatial distribution and oil-biodegradation capabilities of freshwater wetland oil-polluted mats. Microbial community analysis by Automated Ribosomal Spacer Analysis (ARISA) showed that the different mats hosted distinct microbial communities. Average numbers of operational taxonomic units (OTUs_ARISA) were relatively lower in the mats with higher oil levels and the number of shared OTUs_ARISA between the mats was <60% in most cases. Multivariate analyses of fingerprinting profiles indicated that the bacterial communities in the wetland mats were influenced by oil and ammonia levels, but to a lesser extent by plant density. In addition to oil and ammonia, redundancy analysis (RDA) showed also a significant contribution of temperature, dissolved oxygen and sulfate concentration to the variations of the mats’ microbial communities. Pyrosequencing yielded 282,706 reads with >90% of the sequences affiliated to Proteobacteria (41% of total sequences), Cyanobacteria (31%), Bacteriodetes (11.5%), Planctomycetes (7%) and Chloroflexi (3%). Known autotrophic (e.g. Rivularia) and heterotrophic (e.g. Azospira) nitrogen-fixing bacteria as well as purple sulfur and non-sulfur bacteria were frequently encountered in all mats. On the other hand, sequences of known sulfate-reducing bacteria (SRBs) were rarely found, indicating that SRBs in the wetland mats probably belong to yet-undescribed novel species. The wetland mats were able to degrade 53–100% of C₁₂–C₃₀ alkanes after 6 weeks of incubation under aerobic conditions. We conclude that oil and ammonia concentrations are the major key players in determining the spatial distribution of the wetland mats’ microbial communities and that these mats contribute directly to the removal of hydrocarbons from oil field wastewaters.     

Relation between Candida maltosa Hydrophobicity and Hydrocarbon Biodegradation

Summary The growth of Candida maltosa on hydrocarbons (dodecane and hexadecane) was influenced by adding various natural and synthetic surfactants. Microbial adhesion to the hydrocarbon was used to measure the surface cell hydrophobicity of the yeast, which in the presence of a synthetic surfactant correlated with the degree of hydrocarbon biodegradation. Non-ionic surfactants caused the highest degree of hydrocarbon biodegradation corresponding the lowest hydrophobicity. A different correlation was observed with natural surfactants, of which saponin was the most effective for hydrocarbon biodegradation, though the concentration of this surfactant had no influence on surface cell hydrophobicity.     

Protocols To Enhance Biodegradation of Hydrocarbon Contaminants in Soil

Protocols were developed to determine whether microbial metabolism limits the ultimate removal of contaminants from soil. Two soils were used: a creosote contaminated soil and a soil contaminated with crude oil. A laboratory-scale slurry-phase bioreactor was used to maximize the rate of desorption of components from the soil to the aqueous phase. The protocols to enhance the ultimate removal of hydrocarbons were as follows: stimulation of the bacterial cultures with either naphthalene or a mixture of anthracene and phenanthrene, the use of static conditions to enhance bacterial attachment to the nonaqueous phase liquids in the soil, and increased incubation temperature. Addition of the polycyclic aromatic hydrocarbon (PAH) compounds did not stimulate removal of individual target compounds, classes of compounds or total thermally extractable organics. A comparison of well-mixed and static culture conditions showed equivalent removal, except for the lightest PAH and petroleum fractions that were removed more under well-mixed conditions. Increasing the temperature to 30°C from 21°C gave more rapid initial removal of petroleum components, but the ultimate removal was unaffected. Removal of components from the creosote-contaminated soil was unaffected by temperature. These results suggest that desorption of contaminants from the soils limited the ultimate removal of contaminants, not the biological activity.     

Studies on the Utilization of Hydrocarbon by Microorganisms

An uracil-requiring mutant (KY7122) of Arthrobacter paraffineus KY4303 (ATCC15591) was found to accumulate orotic acid and orotidine on n-paraffine as a sole carbon source.

Both substances were definitely indentified as orotic acid and orotidine, from the results on column and paper chromatography, UV and IR absorption spectra, elementary analysis and analyses of hydrolysate.

Cultural conditions for orotic acid and orotidine fermentation were then investigated. As the carbon source n-paraffines from C₁₄ to C₁₆ were the most suitable for the fermentation, and sorbitol, fructose and mannitol were best utilized for the growth, and orotidine produced from them were twice as much as those from hydrocarbon. The addition of 200 mg of uracil and 2 g of C. S. L to 1 liter of medium was most optimal for orotic acid and orotidine fermentation.

Orotic acid and orotidine accumulations were enhanced by the addition of either l-tyrosine, l-leusine, l-threonine, gluconate or meat extract.     

Aerobic and Anaerobic Biodegradation of Aged Pentachlorophenol by Indigenous Microorganisms

Pentachlorophenol (PCP) use as a general biocide, particularly for treating wood, has led to widespread environmental contamination. Biodegradation has emerged as the main mechanism for PCP degradation in soil and groundwater and a key strategy for remediation. Examining the microbial biodegrading potential for PCP at a contaminated site is crucial in determining its fate. Hundreds of studies have been published on PCP microbial degradation, but few have described the biodegradation of PCP that has been in contact with soils for many years. The bioavailability of “aged” hydrophobic organics is a significant concern. PCP- and 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP)-contaminated soil samples from several depths at a former wood treatment site were placed under varying conditions in the laboratory to determine the anaerobic and aerobic potential for biodegradation of chlorophenols at the site. PCP biodegradation occurred in both anaerobic and aerobic soil samples. Rapid aerobic degradation occurred in samples spiked with 2- and 4-chlorophenol, but not with 3-chlorophenol. Reductive dechlorination of PCP in anaerobic samples resulted in the accumulation of 3-chlorophenol. In most anaerobic replicates, 3-chlorophenol was degraded with the appearance of detectable, but not quantifiable amounts of phenol. These results indicate excellent potential for remediation at the site using the indigenous microorganisms under both aerobic and anaerobic conditions. However, a fraction of the PCP was unavailable for degradation.