Hydrocarbon uptake in hydrocarbon fermentations

Gutierrez, J. R.; Erickson, Larry E.

doi:10.1002/bit.260190907

Cited by 54 publications

(16 citation statements)

References 20 publications

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“…Studies focused on the kinetics of growth of yeasts on n-alkanes were conducted in the seventies and models were proposed to account for the complex kinetic patterns observed (Blanch & Einsele, 1973 ;Erickson et al, , 1970Gutierrez & Erickson, 1977 ;Moo-Young & Shimizu, 1971 ;Verkooyen & Rietma, 1980a, b ;Yoshida & Yamane, 1974). However, with other alkane-degrading micro-organisms, the interest was essentially oriented towards the production of biosurfactants and kinetic studies are scarce.…”

Section: Whatever the Mechanisms Involved A Point Which Ismentioning

confidence: 99%

Evidence for interfacial uptake in hexadecane degradation by Rhodococcus equi: the importance of cell flocculation

et al. 2001

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The kinetics of hexadecane degradation were studied in four strains of Rhodococcus equi that did not produce biosurfactants. The aim was to analyse the characteristics of alkane uptake and their relevance to a mechanism of interfacial uptake. The kinetic studies involved continuous determination of degradation by electrolytic respirometry in a diphasic system where the hydrophobic phase was hexadecane or a solution of hexadecane in a non-toxic, non-biodegradable solvent, either 2,2,4,4,6,8,8-heptamethylnonane or silicone oil. The technique allowed large variations in interfacial area between the aqueous and hydrophobic phases. For the four strains, the kinetics obtained were reproducible and showed, in almost all cases, an initial short phase of exponential growth, followed by a long phase of linear growth. Specific growth rates during exponential growth varied amongst the strains from 011 to 020 h N1 and were independent of interfacial area, in accordance with the very strong adsorption of bacterial cells at the interface of solvent and aqueous media. The degradation rates during linear growth did not increase with interfacial area but increased with efficiency of stirring. These characteristics can be explained by the formation of cellular flocs due to the hydrophobicity of the strains. These flocs were observed during growth on hexadecane in almost all conditions. In one case, with a non-flocculating culture, a kinetic pattern with a longer exponential phase, closer to that expected for simple interfacial uptake, was observed. The results show that strictly interfacial uptake, limited by floc formation (occurring at moderate and higher cell densities, and controlled by stirring efficiency) is a common pattern for growth on long-chain alkanes of micro-organisms that do not produce biosurfactants.

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Section: Whatever the Mechanisms Involved A Point Which Ismentioning

confidence: 99%

Evidence for interfacial uptake in hexadecane degradation by Rhodococcus equi: the importance of cell flocculation

et al. 2001

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“…Specifically, in the presence of casein and/or olive oil, Nacetylglucosamine and serum Y. lipolytica transitions from yeast to mycelial forms (Ota et al, 1984;Guevara-Olvera et al, 1993;Zinjarde et al, 1998;Kim et al, 2000;Pérez-Campo & Domínguez, 2001;Ruiz-Herrera & Sentandreu, 2002;Szabo & Štofaníková, 2002;Kawasse et al, 2003). The opposite phenomenon has been observed when glucose or alkanes are used as carbon source or when cultivated at low pH (Gutierrez & Erickson, 1977;Rodríguez & Domínguez, 1984;Guevara-Olvera et al, 1993;Zinjarde et al, 1997Zinjarde et al, , 1998Szabo & Štofaníková, 2002). Significant progress has recently been made in identifying genes that play a crucial role in the dimorphism of Y. lipolytica (genes involved in the mitogen-activated protein kinase and protein kinase A pathways, Rho family, etc.)…”

Section: Introductionmentioning

confidence: 99%

Morphological and metabolic shifts of Yarrowia lipolytica induced by alteration of the dissolved oxygen concentration in the growth environment

et al. 2014

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Yarrowia lipolytica, an ascomycete with biotechnological potential, is able to form either yeast cells or hyphae and pseudohyphae in response to environmental conditions. This study shows that the morphology of Y. lipolytica, cultivated in batch cultures on hydrophilic (glucose and glycerol) and hydrophobic (olive oil) media, was not affected by the nature of the carbon source, nor by the nature or the concentration of the nitrogen source. By contrast, dissolved oxygen concentration (DOC) should be considered as the major factor affecting yeast morphology. Specifically, when growth occurred at low or zero DOC the mycelial and/or pseudomycelial forms predominated over the yeast form independently of the carbon and nitrogen sources used. Experimental data obtained from a continuous culture of Y. lipolytica on glycerol, being used as carbon and energy source, demonstrated that the mycelium-to-yeast form transition occurs when DOC increases from 0.1 to 1.5 mg l "1 . DOC also affected the yeast physiology, as the activity of enzymes implicated in lipid biosynthesis (i.e. ATP-citrate lyase, malic enzyme) was upregulated at high DOC whereas the activity of enzymes implicated in glycerol assimilation (such as glycerol dehydrogenase and kinase) remained fundamentally unaffected in the cell-free extract.

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“…Emulsification which increases the surface area between two immiscible phases, results in small oil drops in water. It is generally concluded that microorganisms growing on water-insoluble hydrocarbons benefit from the presence of a surfactant (6,8,13). Biosurfactants are usually complex lipids, with more chemically complicated structures than synthetic surfactants.…”

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confidence: 99%

A new lipopeptide biosurfactant produced by Arthrobacter sp. strain MIS38

et al. 1993

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A biosurfactant termed arthrofactin produced by Arthrobacter species strain MIS38 was purified and chemically characterized as 3-hydroxydecanoyl-D-leucyl-D-asparagyl-D-threonyl-D-leucyl-D-leucyl-D-seryl-Lleucyl-D-seryl-L-isoleucyl-L-isoleucyl-L-asparagyl lactone. Surface activity of arthrofactin was examined, with surfactin as a control. Critical micelle concentration values of arthrofactin and surfactin were around 1.0 X 10 -5 M and 7.0 x 10-5 M at 25°C, respectively. Arthrofactin was found to be five to seven times more effective than surfactin. The minimum surface tension value of arthrofactin was 24 mN/m at a concentration higher than the critical micelle concentration. According to the oil displacement assay, arthrofactin was a better oil remover than synthetic surfactants, such as Triton X-100 and sodium dodecyl sulfate. Arthrofactin is one of the most effective lipopeptide biosurfactants.Biosurfactants are surface active substances derived from living organisms, mainly from microorganisms (2, 5). The biological function of biosurfactants is thought to be participation in the solubilization of hydrophobic substances (hydrocarbons, lipids, and sterols, etc.), promoting enhanced cell assimilation. Emulsification which increases the surface area between two immiscible phases, results in small oil drops in water. It is generally concluded that microorganisms growing on water-insoluble hydrocarbons benefit from the presence of a surfactant (6,8,13). Biosurfactants are usually complex lipids, with more chemically complicated structures than synthetic surfactants. Lipopeptide biosurfactants are structurally more heterogeneous than glycolipid types.The minimum surface tension and critical micelle concentration are parameters used to measure the efficiency of surfactant systems. The best-known lipopeptide biosurfactant is surfactin, which lowers the surface tension of 0.1 M NaHCO3 from 71.6 to 27.0 mN/m (1). Recently, some strains of Bacillus licheniformis were shown to produce quite similar biosurfactant to surfactin (9,15). Arthrobacter species have been reported to produce extracellular glycolipids (12,20), none of which lowers the surface tension of water to 30 mN/m. We describe the chemical structure of a new lipopeptide-type biosurfactant. MATERIALS AND METHODSScreening of biosurfactant-producing bacteria. Biosurfactant-producing strains were selected as described previously (16), except that the cultivation temperature was 30°C. A slimy colony (strain MIS38) surrounded by a large halo on an oil-agar plate was obtained and used for further experiments.Production and purification of biosurfactant. Strain MIS38 was cultivated in 3 liters of L broth (1% Bacto tryptone, 0.5% yeast extract, 0.5% NaCl [pH 7.2]) at 30°C for 48 h. The culture was centrifuged (10,000 x g for 10 min), and the supernatant fluid was concentrated by ultrafiltration (exclusion molecular size, 10 kDa).The concentrated biosurfactant was extracted three times * Corresponding author.with an equal volume of hexane. After evaporation, the biosur...

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Hydrocarbon uptake in hydrocarbon fermentations

Cited by 54 publications

References 20 publications

Evidence for interfacial uptake in hexadecane degradation by Rhodococcus equi: the importance of cell flocculation

Evidence for interfacial uptake in hexadecane degradation by Rhodococcus equi: the importance of cell flocculation

Morphological and metabolic shifts of Yarrowia lipolytica induced by alteration of the dissolved oxygen concentration in the growth environment

A new lipopeptide biosurfactant produced by Arthrobacter sp. strain MIS38

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