A Comparative Analysis of the Ultrastructure of Hydrocarbon-oxidizing Micro-organisms

Scott, C C; Finnerty, W. R.

doi:10.1099/00221287-94-2-342

Cited by 41 publications

(19 citation statements)

References 15 publications

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“…Inclusions were similar in a Rhodococcus genus grown on phenyldecane39. Scott and Finnerty40 also reported accumulation of hydrocarbons were in inclusion bodies of n -alkane degrading bacteria when grown in the presence of n -hexadecane. Besides, the intracellular hexadecanol dehydrogenase activity increased along with incubation period before day 4 and decreased in other days.…”

Section: Resultsmentioning

confidence: 78%

Metabolic pathway for a new strain Pseudomonas synxantha LSH-7′: from chemotaxis to uptake of n-hexadecane

Long

Bao

et al. 2017

Sci Rep

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Bacteria can use n-hexadecane as a carbon source, but it remains incompletely understood whether n-hexadecane is transformed into metabolic intermediates prior to cellular uptake or not. We newly isolated a strain identified as Pseudomonas synxantha LSH-7′ and conducted chemotaxis experiment of this bacterial strain towards n-hexadecane, hexadecanol and hexadecanoic acid with qualitative assays respectively. Furthermore, we described the identification of extracellular alkane hydroxylase and alcohol dehydrogenase activity; acidification of the culture medium; identification of hexadecanoic acid in the culture medium by the GC-MS analysis; and variation concentration of intracellular n-hexadecane and hexadecanoic acid. A detailed analysis of the experimental data revealed the chemotaxis of this bacterial strain towards n-hexadecane instead of its metabolic intermediates. Our results further suggested that only a fraction of total n-hexadecane followed this path, and alkane hydrolase and hexadecanol dehydrogenase were constitutively expressed when grown in the medium of n-hexadecane. Most strikingly, we quantitatively investigated the concentration of n-hexadecane adsorbed by bacterial chemotaxis. Our findings provided an original insight n-hexadecane might be converted to hexadecanoic acid extracellularly before it was taken up across the cell membrane.Alkanes are found highly abundant constituents of petroleum hydrocarbons are major environmental pollutants as a result of terrestrial and freshwater runoff, refuse from coastal oil refineries, off shore oil production, shipping activities and accidental spills 1,2 . Among the alkanes, n-hexadecane is a major component. The solubility of n-hexadecane in water is 5.21 × 10 −5 mg L −1 at 15 °C and has high partitioning co-efficient 9.1 logKow 3 . Biodegradation of n-hexadecane is believed to be a friendly way to environment as well as human beings. For this, it is necessary to know the metabolic mechanisms of n-hexadecane.Singer and Finnerty 4 observed terminal n-hexadecane degradation by Acinetobacter HO1-N and Pseudomonas putida, and identified five intermediates as n-hexadecylhydroperoxide, n-hexadecanol, n-hexadecyldehyde, n-hexadecanoic acid and n-hexadecylhexadecanoate in degradation process. However, Whyte et al. 5 reported both terminal and sub-terminal oxidation of n-C16 by Rhodococcus strain Q15 producing 1-hexadecanol and 2-hexadecanol. Recently, a new insights into alkane metabolism pathways from alkane sensing, chemotaxis, signal transduction, uptake to degradation was put forward by Wang and shao 6 from the aspect of genes. The underlying mechanisms that control the early responses of bacterial cells to n-hexadecane, such as chemotaxis and uptake, remain largely unexplored.Chemotaxis is defined as the capacity of certain organisms to sense substance concentration gradients and in turn moved towards or away from this gradient 7-9 . Most importantly, alkane chemotaxis had been observed in bacterial isolates of Flavimonas oryzihabitans genus 10 , and even ...

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Section: Resultsmentioning

confidence: 78%

Metabolic pathway for a new strain Pseudomonas synxantha LSH-7′: from chemotaxis to uptake of n-hexadecane

Long

Bao

et al. 2017

Sci Rep

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“…Studies on the environmental isolate Rhodococcus opacus strain PD630 have demonstrated the accumulation and mobilization of TAGs (which coincided with the presence of ILIs) under different growth conditions (Alvarez et al, 1996(Alvarez et al, , 2000Wa$ ltermann et al, 2000). The accumulation of TAGs has also been described for species of Actinomyces (Koval'chuk, 1973) and Acinetobacter (Scott & Finnerty, 1976).…”

Section: Discussionmentioning

confidence: 99%

“…With the exception of a study on Mycobacterium album grown on hexadecane vapours (Scott & Finnerty, 1976), mycobacteria have not previously been reported to contain PHB. However, M. album has subsequently been reclassified as Tsukamurella (Goodfellow et al, 1991).…”

Section: Em-tsmentioning

confidence: 99%

Intracellular lipophilic inclusions of mycobacteria in vitro and in sputum

et al. 2002

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Although most mycobacterial lipids are thought to be associated with the cell envelope, the authors previously observed substantial deposits of intracellular lipophilic material. A Nile-red-based cytological assay was used to determine factors which affect the presence and natural history of intracellular lipophilic inclusions (ILIs) in Mycobacterium smegmatis. Development of ILIs was associated with stationary-phase cultures in broth and with aged (6 days) colonies on agar. Using variants of Youmans' defined medium, the frequency and size of ILIs was observed to be minimal in carbon-poor medium. ILIs were observed to form within 15 min after provision of fatty acids to the medium and after a period of several days in nitrogen-poor medium. Analysis of the non-polar lipid extracts of ILI-rich and -poor preparations indicated that the triacylglycerols (TAGs) were a major component of the inclusions. The acyl substituents of the TAGs varied according to whether they were formed in Middlebrook 7H9 broth, in low-nitrogen Youmans' broth or rapidly after oleic acid supplementation of Youmans' broth. These studies support a storage function for TAGs in mycobacteria in addition to their previously suggested occurrence as components of the cell envelope. To assess a possible role for ILIs in Mycobacterium tuberculosis, a combined acid-fast (Auramine)/Nile red assay was applied to heavily positive sputum samples from patients with tuberculosis. Strong intracellular Nile red signals were obtained from acid-fast cells, indicating that ILI occur in M. tuberculosis in vivo. This may reflect a distinct physiological state of these cells, which it has not been possible to reproduce in vitro. These findings indicate that the uptake of long-chain fatty acids and TAG biosynthetic and degradative pathways are important aspects of mycobacterial lipid metabolism, meriting further investigation.

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“…Alkanes, particularly n-alkanes, are important components of crude oils and its derivatives, such as heating oil, jet fuel, gasoline and kerosene (Marin et al 1995; Berekaa and Steinbüchel 2000). In nature, some microorganisms oxidize aerobically (Berekaa and Steinbüchel 2000; Solano-Serena et al2000; Dutta and Harayama 2001) and anaerobically (Chayabutra and Ju 2000; Kniemeyer et al 2003), co-metabolize (Whyte et al 1997; Garnier et al 2000) and detoxify most of the C4-C20 compounds from linear, branched and cyclic alkanes (Scott and Finnerty 1976; Leahy and Colwell 1990), including low-carbon hydrocarbons, which may affect cell membrane integrity (Marin et al 1995). Particularly, alkanes that are metabolized via oxidation are used as a carbon source for cell growth.…”

Section: Introductionmentioning

confidence: 99%

Biosurfactant-mediated biodegradation of straight and methyl-branched alkanes by Pseudomonas aeruginosa ATCC 55925

2011

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Accidental oil spills and waste disposal are important sources for environmental pollution. We investigated the biodegradation of alkanes by Pseudomonas aeruginosa ATCC 55925 in relation to a rhamnolipid surfactant produced by the same bacterial strain. Results showed that the linear C11-C21 compounds in a heating oil sample degraded from 6% to 100%, whereas the iso-alkanes tended to be recalcitrant unless they were exposed to the biosurfactant; under such condition total biodegradation was achieved. Only the biodegradation of the commercial C12-C19 alkanes could be demonstrated, ranging from 23% to 100%, depending on the experimental conditions. Pristane (a C19 branched alkane) only biodegraded when present alone with the biosurfactant and when included in an artificial mixture even without the biosurfactant. In all cases the biosurfactant significantly enhanced biodegradation. The electron scanning microscopy showed that cells depicted several adaptations to growth on hydrocarbons, such as biopolymeric spheres with embedded cells distributed over different layers on the spherical surfaces and cells linked to each other by extracellular appendages. Electron transmission microscopy revealed transparent inclusions, which were associated with hydrocarbon based-culture cells. These patterns of hydrocarbon biodegradation and cell adaptations depended on the substrate bioavailability, type and length of hydrocarbon.

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A Comparative Analysis of the Ultrastructure of Hydrocarbon-oxidizing Micro-organisms

Cited by 41 publications

References 15 publications

Metabolic pathway for a new strain Pseudomonas synxantha LSH-7′: from chemotaxis to uptake of n-hexadecane

Metabolic pathway for a new strain Pseudomonas synxantha LSH-7′: from chemotaxis to uptake of n-hexadecane

Intracellular lipophilic inclusions of mycobacteria in vitro and in sputum

Biosurfactant-mediated biodegradation of straight and methyl-branched alkanes by Pseudomonas aeruginosa ATCC 55925

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