SnapShot: Microbial Hydrocarbon Bioremediation.

Hydrocarbon-degrading bacteria are phylogenetically and physiologically diverse and employ layered strategies to sense hydrocarbons, respond transcriptionally, and then move toward an oil source. They then produce biopolymers that increase hydrocarbon bioavailability. This SnapShot highlights how these bacteria respond to and then remove hydrocarbon contaminants from the environment. To view this SnapShot, open or download the PDF.

VOC Profiles of Saliva in Assessment of Halitosis and Submandibular Abscesses Using HS-SPME-GC/MS Technique.

Halitosis and submandibular abscesses are examples of mouth-related diseases with the possible bacterial origin. Salivary volatile organic compounds (VOCs) are potential biomarkers of them, once they can be addressed as metabolites of bacterial activity. Healthy patients (n = 15), subjects with submandibular abscesses located in fascial deep space (n = 10), and subjects with halitosis (n = 5) were enrolled in the study. Saliva samples were subjected to headspace solid-phase microextraction (HS-SPME) and gas chromatography coupled to mass spectrometry (GC/MS) analysis. A total number of 164 VOCs was detected by the developed methodology, 23 specific for halitosis and 41 for abscess. Halitosis' profiles were characterized by a larger number of sulfur compounds, while for abscess they had a higher variety of alcohols, aldehydes, and hydrocarbons-biomarkers of inflammatory processes. Principal components analysis allowed visualization of clusters formed according to the evaluated conditions. Kruskal-Wallis test indicated that 39 VOCs presented differentiated responses between the studied groups, with statistical relevance (p < 0.05). Random forest was applied, and a prediction model based on eight VOCs (2-butanone, methyl thioacetate, 2-methylbutanoic acid, S-methyl pentanethioate, dimethyl tetrasulfide, indolizine, pentadecane, and octadecanal) provided 100% of sensitivity, 82% of specificity, and 91% of balanced accuracy, indicating the specific presence of submandibular abscess.

Characterization of the toxicological hazards of hydrocarbon solvents.

Hydrocarbon solvents are liquid hydrocarbon fractions derived from petroleum processing streams, containing only carbon and hydrogen atoms, with carbon numbers ranging from approximately C5-C20 and boiling between approximately 35-370°C. Many of the hydrocarbon solvents have complex and variable compositions with constituents of 4 types, alkanes (normal paraffins, isoparaffins, and cycloparaffins) and aromatics (primarily alkylated one- and two-ring species). Because of the compositional complexity, hydrocarbon solvents are now identified by a nomenclature ("the naming convention") that describes them in terms of physical/chemical properties and compositional elements. Despite the compositional complexity, most hydrocarbon solvent constituents have similar toxicological properties, and the overall toxicological hazards can be characterized in generic terms. To facilitate hazard characterization, the solvents were divided into 9 groups (categories) of substances with similar physical and chemical properties. Hydrocarbon solvents can cause chemical pneumonitis if aspirated into the lung, and those that are volatile can cause acute CNS effects and/or ocular and respiratory irritation at exposure levels exceeding occupational recommendations. Otherwise, there are few toxicologically important effects. The exceptions, n-hexane and naphthalene, have unique toxicological properties, and those solvents containing constituents for which classification is required under the Globally Harmonized System (GHS) are differentiated by the substance names. Toxicological information from studies of representative substances was used to fulfill REACH registration requirements and to satisfy the needs of the OECD High Production Volume (HPV) initiative. As shown in the examples provided, the hazard characterization data can be used for hazard classification and for occupational exposure limit recommendations.

Recurrent oil sheens at the deepwater horizon disaster site fingerprinted with synthetic hydrocarbon drilling fluids.

We used alkenes commonly found in synthetic drilling-fluids to identify sources of oil sheens that were first observed in September 2012 close to the Deepwater Horizon (DWH) disaster site, more than two years after the Macondo well (MW) was sealed. While explorations of the sea floor by BP confirmed that the well was sound, they identified the likely source as leakage from an 80-ton cofferdam, abandoned during the operation to control the MW in May 2010. We acquired sheen samples and cofferdam oil and analyzed them using comprehensive two-dimensional gas chromatography. This allowed for the identification of drilling-fluid C16- to C18-alkenes in sheen samples that were absent in cofferdam oil. Furthermore, the spatial pattern of evaporative losses of sheen oil alkanes indicated that oil surfaced closer to the DWH wreckage than the cofferdam site. Last, ratios of alkenes and oil hydrocarbons pointed to a common source of oil found in sheen samples and recovered from oil-covered DWH debris collected shortly after the explosion. These lines of evidence suggest that the observed sheens do not originate from the MW, cofferdam, or from natural seeps. Rather, the likely source is oil in tanks and pits on the DWH wreckage, representing a finite oil volume for leakage.

Cuticular hydrocarbon phenotypes do not indicate cryptic species in fungus-growing termites (Isoptera: Macrotermitinae).

In several termite species, distinct differences in the composition of cuticular hydrocarbons among colonies correspond to high genetic divergence of mitochondrial DNA sequences. These observations suggest that hydrocarbon phenotypes represent cryptic species. Different cuticular hydrocarbon phenotypes also are found among colonies of fungus-growing termites of the genus Macrotermes. To determine if these hydrocarbon differences in Macrotermes also indicate cryptic species, we sequenced the mitochondrial CO I gene from species in West and East Africa. Among individuals of a supposed species but belonging to different cuticular hydrocarbon phenotypes, the genetic distances are much smaller than distances between species. Unlike what has been observed in other termites, Macrotermes hydrocarbon phenotypes do not represent cryptic species. Our findings suggest fundamental differences in the evolution and/or function of cuticular hydrocarbons among different termite lineages.

An efficient method to simultaneously analyze multi-class organic pollutants in human serum.

The degree of population exposure to various organic pollutants (OPs), including polycyclic aromatic hydrocarbons, organochlorinated pesticides, polychlorinated biphenyls, and polybrominated diphenyl ethers, can be determined by measuring their concentrations in human serum. However, performing large-scale measurements with such a variety of compounds in serum is challenging in terms of efficiency and cost. We describe herein the development of a high-efficiency extraction and sample cleanup protocol for simultaneous and quantitative analyses of OPs using gas chromatography-mass spectrometry. OPs, together with crude lipid impurities, were extracted from human serum with a mixture of n-hexane and methyl tert-butyl ether. A disperse sorbent composed of primary secondary amine and C18 (PSA/C18) was used to roughly remove co-extracted impurities. A combined column of neutral silica gel and neutral alumina oxide (AlO/SiG) was then used for deep cleanup. For the removal of impurities, the overall performance of our protocol for the analysis of OPs in serum was comparable to that of traditional gel permeation chromatography (GPC) and dramatically better than that of PSA/C18, which is a frequently used QuEChERS (quick, easy, cheap, effective, rugged, safe) based method. While both the proposed protocol and GPC yielded recoveries of 80%-110% for four classes of OPs, our protocol consumed about 10 times less solvent, resulting in lower experimental expenses and a lower risk of contamination from residual OPs in the solvent and other supplies. In contrast to GPC, our protocol also permits efficient batch processing of serum samples, allowing for large sample sizes such as those encountered in epidemiological studies.

Foraging populations and distances of the desert subterranean termite, Heterotermes aureus (Isoptera: Rhinotermitidae), associated with structures in southern Arizona.

Mark-release-recapture studies were conducted on foraging populations of Heterotermes aureus (Snyder) (Isoptera: Rhinotermitidae) associated with three structures in Tucson, AZ. Foraging population estimates ranged from 64,913 to 307,284 termites by using the Lincoln Index and from 75,501 to 313,251 termites using the weighted mean model. The maximum distance between monitors ranged from 26 to 65 m, with minimum total foraging distance ranging between 297 and 2,427 m. Characterizations of the cuticular hydrocarbons of foraging groups were qualitatively identical. Quantitative similarities within sites and differences among sites suggested that each site was occupied by a single colony during the sampling period. The colony at each site had a proportion of soldiers (0.135, 0.069, and 0.040) that was significantly different from the colonies at each of the other sites. From this study, we question the assumption of equal mixing of marked H. aureus foragers throughout the occupied collars around structures.

Characteristics and sources of anthropogenic and biogenic hydrocarbons in sediments from the coast of Qatar.

Surface sediment samples from the coastal zone of Qatar were collected and analyzed to determine the characteristics, and sources of anthropogenic and biogenic hydrocarbons. The main compounds in these surface sediments included n-alkanes, methyl n-alkanoates, diterpenoids, hopanes, steranes, phthalate esters, polycyclic aromatic hydrocarbons (PAHs) and unresolved complex mixture (UCM). Their total concentrations ranged from 18.7±3.7-81.1±7.5ng/g (3.7±0.6-10.4±4.8%) for n-alkanes, 8.3±2.3-51±3.4ng/g (3.0±2.0-5.6±2.0%) for methyl n-alkanoates, 1.8±0.1-10.5±1.0ng/g (1.0±0.5-0.4±0.1%) for diterpenoids, 0.0-79.3±7.4ng/g (0.0-7.9±0.6%) for hopanes, 0.0-32.9±7.9ng/g (0.0-6.5±1.0%) for steranes, 0.7±0.1-36.3±3.4ng/g (0.1±0.1-1.9±3.4%) for phthalates, 0.30±0.2-7.8±0.7ng/g (0.02±0.04-0.42±0.72%) for PAHs, and 38±9-609±57ng/g (38.5±13.4-56.5±13.4%) for UCM. The major sources of these lipids were anthropogenic petroleum residues and plasticizers (80-89%), with lesser amounts from natural higher plants and microbial residues (11-20%). Petroleum residues and plasticizer inputs to the coastal sediments of Qatar likely affect the marine ecosystems and associated species groups as well as shallow coastal nursery and spawning areas.

Solid-phase microextraction-based cuticular hydrocarbon profiling for intraspecific delimitation in Acyrthosiphon pisum.

Insect cuticular hydrocarbons (CHCs) play critical roles in reducing water loss and chemical communication. Species-specific CHC profiles have been used increasingly as an excellent character for species classification. However, considerably less is known about their potential for population delimitation within species. The aims of this study were to develop a solid-phase microextraction (SPME)-based CHC collection method and to investigate whether CHC profiles could serve as potential chemotaxonomic tools for intraspecific delimitation in Acyrthosiphon pisum. Optimization of fibers for SPME sampling revealed that 7 µm polydimethylsiloxane (PDMS) demonstrated the most efficient adsorption of CHCs among five different tested fibers. SPME sampling showed good reproducibility with repeated collections of CHCs from a single aphid. Validation of SPME was performed by comparing CHC profiles with those from conventional hexane extractions. The two methods showed no qualitative differences in CHCs, although SPME appeared to extract relatively fewer short-chained CHCs. While CHC profiles of a given population differed among developmental stages, wing dimorphism types, and host plants, wingless adult aphids showed very low variance in relative proportions of individual CHC components. Reproducibility of CHC profiles was explored further to classify wingless adult morphs of A. pisum from five different geographic regions that showed no variation in mitochondrial COI gene sequences. Our results demonstrate that CHC profiles are useful in intraspecific delimitation in the field of insect chemotaxonomy.

Prediction of source rock origin by chemometric analysis of fourier transform infrared-attenuated total reflectance spectra of oil petroleum: evaluation of aliphatic and aromatic fractions by self-modeling mixture analysis.

This study describes a new methodology for the interpretation of Fourier transform infrared (FT-IR) attenuated total reflectance (ATR) spectra of Algerian, Brazilian, and Venezuelan crude oils. It is based on a comparative study between a chemometric treatment and the classical one, which refers to indices calculation. In fact, the combined use of FT-IR indices and principal component analysis (PCA) has led to the classification of the studied samples in terms of geographic distribution. Quantitative analysis has been successfully realized by the supervised method partial least squares (PLS), which has permitted the prediction of the locations of oils. We have also applied another mathematical processing method, simple-to-use interactive self-modeling mixture analysis (SIMPLISMA), to evaluate the aromatic and aliphatic composition of the oils by extracting pure spectra representative of the different fractions.

[Petroleum substances--human health hazards. I. Classification of petroleum substances on the list of dangerous substances and assessment of existing hazards]. / Pochodne ropy naftowej--zagrozenia dla zdrowia czlowieka. I. Klasyfikacja substancji ropopochodnych w wykazie substancji niebezpiecznych a ocena rzeczywistych zagrozen.

Complex products derived from petroleum are widely used as fuels, greases, solvents, and intermediates in many branches of industry. Petroleum exposure-related human health hazards, observed in occupationally exposed people and in the general population, are a serious sanitary problem. Complex and variable composition of individual petroleum products makes the actual assessment of human health hazards difficult. Potential hazards, and resulting classification of individual petroleum substance groups, are discussed in the presented work. This should prove to be helpful to work safety and hygiene services as well as to supervising institutions, mainly the sanitary inspection, in a proper assessment of the hazards, and consequently in taking appropriate preventive actions. In Part I., general issues concerning the hazard assessment and legal aspects of petroleum substances classification are presented. In Part. II., individual groups of petroleum substances are discussed with respect to health hazards, resulting from both physicochemical properties and toxicity, and their classification based on this analysis is suggested.

Odor diversity decreases with inbreeding in the ant Hypoponera opacior.

Reduction in heterozygosity can lead to inbreeding depression. This loss of genetic variability especially affects diverse loci, such as immune genes or those encoding recognition cues. In social insects, nestmates are recognized by their odor, that is their cuticular hydrocarbon profile. Genes underlying hydrocarbon production are thought to be under balancing selection. If so, inbreeding should result in a loss of chemical diversity. We show here that cuticular hydrocarbon diversity decreases with inbreeding. Studying an ant with a facultative inbreeding lifestyle, we found inbred workers to exhibit both a lower number of hydrocarbons and less diverse, that is less evenly proportioned profiles. The association with inbreeding was strong for methyl-branched alkanes, which play a major role in nestmate recognition, and for n-alkanes, whereas unsaturated compounds were unaffected. Shifts in allocation strategies with inbreeding in our focal species indicate that these ants can detect their inbreeding level and use this information to adjust their reproductive strategy. Our study is the first to demonstrate that odor profiles can encode information on inbreeding, with broad implications not only for social insects, but for sexual selection and mate choice in general. Odor profiles may constitute an honest signal of inbreeding, a fitness-relevant trait in many species.

Chemical fingerprinting of hydrocarbon-contamination in soil.

Chemical fingerprinting analyses of 29 hydrocarbon-contaminated soils were performed to assess the soil quality and determine the main contaminant sources. The results were compared to an assessment based on concentrations of the 16 priority polycyclic aromatic hydrocarbons pointed out by the U.S. Environmental Protection Agency (EPAPAH16) and total petroleum hydrocarbon (TPH). The chemical fingerprinting strategy proposed in this study included four tiers: (i) qualitative analysis of GC-FID chromatograms, (ii) comparison of the chemical composition of both un-substituted and alkyl-substituted polycyclic aromatic compounds (PACs), (iii) diagnostic ratios of selected PACs, and (iv) multivariate data analysis of sum-normalized PAC concentrations. The assessment criteria included quantitative analysis of 19 PACs and C1-C4 alkyl-substituted homologues of naphthalene, fluorene, dibenzothiophene, phenanthrene, pyrene, and chrysene; and 13 oxygenated polycyclic aromatic compounds (O-PACs). The chemical composition of un-substituted and alkyl-substituted PACs and visual interpretation of GC-FID chromatograms were in combination successful in differentiating pyrogenic and petrogenic hydrocarbon sources and in assessing weathering trends of hydrocarbon contamination in the soils. Multivariate data analysis of sum-normalized concentrations could as a stand-alone tool distinguish between hydrocarbon sources of petrogenic and pyrogenic origin, differentiate within petrogenic sources, and detect weathering trends. Diagnostic ratios of PACs were not successful for source identification of the heavily weathered hydrocarbon sources in the soils. The fingerprinting of contaminated soils revealed an underestimation of PACs in petrogenic contaminated soils when the assessment was based solely on EPAPAH16. As alkyl-substituted PACs are dominant in petrogenic sources, the evaluation of the total load of PACs based on EPAPAH16 was not representative. Likewise, the O-PACs are not represented in soil quality assessments based on EPAPAH16 and TPH. The ∑O-PACs ranged between

Patterns of cuticular hydrocarbon variation and genetic similarity between natural populations of Amblyomma cajennense (Acari: Ixodidae).

Gas chromatography has been used to analyze the variation in cuticular hydrocarbon patterns between several populations of Amblyomma cajennense. 88 compounds were detected and these could be divided into 17 groups of hydrocarbons. Heterozygosis in the populations ranges from 0% to 25.84%. Isomers for pentacosane, heptacosane and nonatriacontane are the most variable, with 13, 10 and 11 variants, respectively. Nei's genetic identity and genetic distance show that populations may be considered as regional variants of only one species: the results do not indicate the presence of sibling species. However, a relatively high genetic distance has been observed between several Cuban and continental populations, suggesting a long reproductive isolation. Gas chromatography of cuticular hydrocarbons is a good alternative to isozyme analysis for population studies, when collecting conditions do not allow the use of live ticks and only alcohol-preserved collections are available. The high number of compounds available for genetic studies will provide excellent markers for evaluating the extent of gene flow and migration of tick species.

Classification of ion mobility spectra by functional groups using neural networks.

Neural networks were trained using whole ion mobility spectra from a standardized database of 3137 spectra for 204 chemicals at various concentrations. Performance of the network was measured by the success of classification into ten chemical classes. Eleven stages for evaluation of spectra and of spectral pre-processing were employed and minimums established for response thresholds and spectral purity. After optimization of the database, network, and pre-processing routines, the fraction of successful classifications by functional group was 0.91 throughout a range of concentrations. Network classification relied on a combination of features, including drift times, number of peaks, relative intensities, and other factors apparently including peak shape. The network was opportunistic, exploiting different features within different chemical classes. Application of neural networks in a two-tier design where chemicals were first identified by class and then individually eliminated all but one false positive out of 161 test spectra. These findings establish that ion mobility spectra, even with low resolution instrumentation, contain sufficient detail to permit the development of automated identification systems.

Organic geochemistry of sediments from the continental margin off southern New England, U.S.A.--Part II. Lipids.

Organic geochemical measurements of the lipid fraction, comparing saturated and aromatic hydrocarbons, fatty acids, alcohols and sterols, have been carried out on six sediments cores collected from the Atlantic shelf, slope and the rise areas to evaluate the cross-shelf transport of the organic carbon. The concentration of most of the organic compound classes studied is correlated with the total organic carbon, which decreases from the shelf through slope to the rise. Terrigenous carbon is recognizable even in the slope and rise sediments, but terrestrial influx decreases relative to marine generated lipids in the slope and rise organic matter. We estimate that approximately 50% of the shelf organic matter is exported to the slope. Data of sediment trap material collected at 1200 m from 1250 m water depth are discussed and compared with that of surface sediment from 1280 m water depth (slope). Fluxes for specific organic compound classes have been computed. The fluxes are of the same magnitude as for equatorial North Atlantic trap particulates at comparable water depth, studied by other investigations.

Hydrocarbons in the surface wax of eggs and adults of the Colorado potato beetle, Leptinotarsa decemlineata.

The major components of the egg hydrocarbons were dimethylalkanes (40%) and trimethylalkanes (24%) in which the first methyl branch was on carbon 2. The major dimethylalkanes were an approximately 2:1 mixture of 2,10- and 2,6-dimethyloctacosanes in females and eggs. The major trimethylalkanes were a mixture of 2,10,16- and 2,10,18-trimethyloctacosanes. 2,x- and 2,x,y-methyl-branched alkanes with an odd-numbered carbon backbone were proposed to have an even number of carbon atoms between the first and second methyl branch points indicating that their biosynthesis started with a primer derived from leucine. 13,17,21,25-Tetramethylheptatriacontane was the only tetramethylalkane identified. Females and eggs had more hydrocarbons with a 2-methyl branch point than did the males. The eggs had the lowest amount of internally-branched dimethylalkanes but the largest amount of 2,x-dimethylalkanes in their surface hydrocarbons. Only trace amounts of n-alkanes and alkenes were detected in the surface hydrocarbons of adult males and females, larvae and eggs, of the Colorado potato beetle.

Testing and classification methods for the biodegradabilities of organic compounds under anaerobic conditions.

Biodegradability is one of the most important characteristics of an organic compound for predicting its fate and life in the environment and its application in biological wastewater treatment. But there is no general testing method for biodegradability under anaerobic conditions. The biodegradabilities of thirteen principal organic compounds was investigated in a batch test using vials under various conditions, such as the concentration of an organic compound, the cultivation method and the concentration of anaerobic bacteria for seeding. Two test methods in the standard concentration and the low concentration were developed. A new method to classify the biodegradabilities of organic compounds into thirteen ranks was proposed by considering inhibition, complete biodegradation and first step biodegradation.

Biodegradation ranks of priority organic compounds under anaerobic conditions.

The biodegradations of 52 priority organic compounds were evaluated under anaerobic conditions by two tests developed in a preceding paper (Urano et al., 1995). Namely, the biodegradabilities of the compounds were classified into 13 ranks by the method proposed by Urano et al. (1995). Most of the aliphatic alcohols and carboxylic acids were not inhibitory and were biodegraded, but the compounds having ether bonds or branched hydrocarbon groups were biodegraded slowly. Aliphatic aldehyde and amines were not so much inhibitory but were hardly biodegraded. The benzene substitutes having groups of -CH2OH, -CHO, -CH2CH(NH2)COOH, -COOH and -OH were easily biodegraded, but the compounds having groups of -NO2, -NH2 and -SO3H were hardly biodegraded. Most of the nitro compounds were inhibitory in the higher concentration test though they were reduced into amino compounds. Since the biodegradation characteristics of many organic compounds could be classified and discussed appropriately, the suitability of the proposed method is substantiated.

Accumulation and effect of volatile organic compounds in closed life support systems.

Bioregenerative life support systems (BLSS) being considered for long duration space missions will operate with limited resupply and utilize biological systems to revitalize the atmosphere, purify water, and produce food. The presence of man-made materials, plant and microbial communities, and human activities will result in the production of volatile organic compounds (VOCs). A database of VOC production from potential BLSS crops is being developed by the Breadboard Project at Kennedy Space Center. Most research to date has focused on the development of air revitalization systems that minimize the concentration of atmospheric contaminants in a closed environment. Similar approaches are being pursued in the design of atmospheric revitalization systems in bioregenerative life support systems. in a BLSS one must consider the effect of VOC concentration on the performance of plants being used for water and atmospheric purification processes. In addition to phytotoxic responses, the impact of removing biogenic compounds from the atmosphere on BLSS function needs to be assessed. This paper provides a synopsis of criteria for setting exposure limits, gives an overview of existing information, and discusses production of biogenic compounds from plants grown in the Biomass Production Chamber at Kennedy Space Center.