Temperature-independent and -dependent expression of desaturase genes in filamentous cyanobacterium Spirulina platensis strain C1 (Arthrospira sp. PCC 9438)

The alteration of the degree of unsaturated fatty acids in membrane lipids has been shown to be a key mechanism in the tolerance to temperature stress of living organisms. The step that most influences the physiology of membranes has been proposed to be the amount of di-unsaturated fatty acids in membrane lipids. In this study, we found that the desaturation of fatty acid to yield the di-unsaturated fatty acid 18:2(9,12), in Spirulina platensis strain C1, was not regulated by temperature. As shown by the fatty acid composition and gene expression patterns, the levels of 18:1(9) and 18:2(9,12) remained almost constant either when the cells were grown at 35 degrees C (normal growth temperature) or 22 and 40 degrees C. The expression of desC (Delta9) and desA (Delta12) genes, which are responsible for the introduction of first and second double bonds into fatty acids, respectively, was not affected by the temperature shift from 35 to 22 degrees C or to 40 degrees C. Only the expression and mRNA stability of the desD gene (Delta6) that is responsible for the introduction of a third double bond into fatty acids were enhanced by a temperature shift from 35 to 22 degrees C, but not the shift from 35 to 40 degrees C. The increase in the level of desD mRNA elevated the desaturation of fatty acid from 18:2(9,12) to 18:3(6,9,12) at 22 degrees C. However, the increased level of 18:3(6,9,12) was observed after 36 h of incubation at 22 degrees C, indicating a slow response to temperature of fatty acid desaturation in this cyanobacterium. These findings suggest that the desaturation of fatty acids might not be a key mechanism in the response to the temperature change of S. platensis strain C1.     

A Temperature Dependence of the Intra- and Extracellular Fatty-Acid Composition of Green Algae and Cyanobacterium

The effect of ambient temperature on the composition of intracellular fatty acids and the release of free fatty acids (FFA) into a medium by cyanobacterium Spirulina platensis and eukaryotic microalgae, Chlorella vulgaris and Botryococcus braunii, was studied using their batch cultures. It was found that all the species studied, regardless of their taxonomic status, responded to the temperature regime by similar changes in their intracellular fatty acid composition: the relative content of more unsaturated fatty acids decreased with the elevation of temperature. At the same time, in the prokaryote, this temperature shift blocked, first of all, the elongation of 16:0 to 18:0 and then their further desaturation. In eukaryotes, the change in the desaturation of dienoic to trienoic fatty acids was the most pronounced process. The ratio of dienoic to trienoic fatty acids remained almost unchanged in S. platensis. The relative content of extracellular unsaturated FFA increased in the prokaryotic organism S. platensis at a higher temperature. But no significant changes in the composition of extracellular unsaturated FFA were detected in eukaryotic algae upon temperature elevation.     

Composition of fat acids in three Mexican populations of Artemia franciscana from epicontinental waters

In this paper is presented the percentage of fatty acids composition of three Artemia franciscana Mexican populations of epicontinentals waters; two are from natural environments (Coahuila and San Luis Potosf) and one (Texcoco) is a culture fed with Spirulina. Determination of fatty acids composition in each population, was performed by extraction of total lipid by the soxhlet method and the fatty acids methyl esters were determined by gas chromatography. The results show that Artemia of Texcoco contains the six fatty acids recommended for the culture of fish and crustaceans (16:0; 16:1; 18:1; 18:2w6; 18:3w3 and 20:5w3); Artemia from San Luis Potosi showed the poorest content in these acids and Artemia from Coahuila, although it showed a wide profile, it lacks the linolenic acid. When comparing results among the three populations with ecological data that have been published, it can be pointed out that the environment is decisive for this crustacean; Artemia from Texcoco fed with Spirulina showed the largest variety of fatty acids; the other two populations are wild, and lives in different habitats, Artemia of Coahuila is found in waters that are rich in sulfates and Artemia of San Luis Potosf lives in evaporation saltern ponds, built with stone blocks and therefore with scarce phytoplankton growth. Both Artemia populations showed deficiencies in essential fatty acids, mainly the last one.     

INFLUENCE OF TEMPERATURE ON THE FATTY ACID PROFILE OF LISTERIA MONOCYTOGENES

Variation in the fatty acid profile of two Listeria monocytogenes strains grown at varying temperatures was determined. The fatty acid profiles varied greatly at different temperatures. General decreases in relative percentages of branched and medium chain (up to C16:0) fatty acids and variable changes in long chain fatty acids were found with increasing growth temperature. Individual fatty acid percentages between strains were variable. The relative percentages of unknown long chain fatty acids, detected in both strains at various temperatures, were greatest in Scott A (7.07%) and ATCC 19114 (13.15%) at 35C. Results demonstrated that L. monocytogenes had altered fatty acid profile in response to changes in growth temperature.     

Impact of UV-B Radiation on Thylakoid Membrane and Fatty Acid Profile of <Emphasis Type="Italic">Spirulina platensis</Emphasis>

Ultraviolet-B (UV-B) radiation to thylakoid membrane and fatty acid profile has been investigated in cyanobacterium, Spirulina platensis. The thylakoid membrane was isolated by mechanical disruption of the freeze-dried and lysozyme-treated cells followed by differential density gradient centrifugation and morphological variations were examined. UV radiation distorted the membrane on the outer side with reduced chlorophyll a (chl a) content compared to its untreated counterpart. Liquid chromatography-mass spectrometry (LC-MS) was used for characterization of chl a of the thylakoid membrane. UV-B exposure resulted in alterations in the pigment-protein complexes 47 kDa and 43 kDa. Furthermore, 94 kDa and 20 kDa protein appeared in UV-B-exposed thylakoid membrane of S. platensis. The composition of fatty acid in response to UV-B radiation was detected by gas chromatography–mass spectrometry having 23.5% saturated fatty acid (SFA), 76.4% monounsaturated fatty acid (MUFA), and polyunsaturated fatty acid (PUFA). In contrast to its UV-B-untreated counterpart, SFA was 46.6%, and MUFA and PUFA were 53.3%. Our findings suggest that UV-B radiation not only affects membrane morphology and its protein profile but also reduces saturated fatty acid and increases unsaturated fatty acids in S. platensis.     

Exogenous isoleucine and fatty acid shortening ensure the high content of anteiso-C15:0 fatty acid required for low-temperature growth of Listeria monocytogenes

Previous studies have demonstrated that the branched-chain fatty acid anteiso-C15:0 plays a critical role in the growth of Listeria monocytogenes at low temperatures by ensuring sufficient membrane fluidity. Studies utilizing a chemically defined minimal medium revealed that the anteiso fatty acid precursor isoleucine largely determined the fatty acid profile and fatty acid response of the organism to lowered growth temperature. When isoleucine was sufficient, the fatty acid profile was very uniform, with anteiso fatty acids comprising up to 95% of total fatty acid, and the major fatty acid adjustment to low temperature was fatty acid chain shortening, which resulted in an increase of anteiso-C15:0 solely at the expense of anteiso-C17:0. When isoleucine was not supplied, the fatty acid profile became more complex and was readily modified by leucine, which resulted in a significant increase of corresponding iso fatty acids and an inability to grow at 10 degrees C. Under this condition, the increase of anteiso-C15:0 at low temperature resulted from the combined effect of increasing the anteiso:iso ratio and chain shortening. A branched-chain alpha-keto acid dehydrogenase-defective strain largely lost the ability to increase the anteiso:iso ratio. Cerulenin, an inhibitor of beta-ketoacyl-acyl carrier protein synthase (FabF), induced a similar fatty acid chain shortening as low temperature did. We propose that the anteiso precursor preferences of enzymes in the branched-chain fatty acid biosynthesis pathway ensure a high production of anteiso fatty acids, and cold-regulated chain shortening results in a further increase of anteiso-C15:0 at the expense of anteiso-C17:0.     

Comparison of the phospholipid and triacylglycerol fatty acid profile of rat serum, skeletal muscle and heart

Although several studies have analyzed the fatty acid profile of phospholipids (PL) and, to a lesser degree, triacylglycerols (TG) in one or more tissues concurrently, a systematic comparison of the fatty acid composition of different tissues and/or lipid classes is lacking. The purpose of the present study was to compare the fatty acid composition of major lipid classes (PL and TG) in the rat serum, soleus muscle, extensor digitorum longus muscle and the heart. Lipids were extracted from these tissues and analyzed by a combination of thin-layer chromatography and gas chromatography. We found many significant differences in various tissues and lipid classes. Serum had the most distinct fatty acid profile in PL but this "uniqueness" was less apparent in TG, where differences among tissues were in general less frequent than in PL. These two skeletal muscles exhibited similar fatty acid composition in both lipid classes despite their different muscle fiber type composition, denoting that fiber type is not a major determinant of the fatty acid composition of rat skeletal muscle. The fatty acid profile of heart PL was the most different from that of the other tissues examined. PL were rich in polyunsaturated fatty acids, whereas TG were rich in monounsaturated fatty acids. Although the reasons for the differences in fatty acid profile among the tissues examined are largely unknown, it is likely that these differences have an impact upon numerous biological functions.     

Lipid profile: a useful chemotaxonomic marker for classification of a new cyanobacterium in Spirulina genus

The morphological, physiological and genetic characteristics of an isolate cyanobacterium from hard sand of the lake Venere in the Pantelleria island (Italy) were described. The isolate with a small-size coiled helix shape, growing optimally at pH 9.2-9.5 at 30 degrees C under continuous illumination and aeration, possessed a 61.5 mol% of Guanine + Cytosine content of DNA. The lipid profile showed the presence of mono-, di-glycosyl, sulphoquinovolosyl and phosphatidyl (MGDG, DGDG, SQDG and PG). The fatty acid profile was also studied, characterized by the absence of gamma-linolenic acid and the presence of saturated and monounsaturated C16 and C18. The latter was also present as a dienoic component. The fatty acid composition was affected by growth temperature by increasing the degree of desaturation at a lower temperature and the biosynthesis of shorter acyl chains. The effects of growth conditions other than temperature, physical, nutritional and chemical on lipid composition were also studied. The overall features of the cyanobacterium isolated from Pantelleria clustered it into Spirulina genus.     

Characteristics of in vivo isolation of free fatty acids by prokaryotic and eukaryotic algae under elevated and reduced temperature]

The paper describes the composition of extracellular free fatty acids (FFAs) and intracellular fatty acids (FAs) in the enrichment cultures of the prokaryotic alga Spirulina platensis and the eukaryotic alga Chlorella vulgaris grown at optimal, supraoptimal, and suboptimal growth temperatures. With increasing growth temperature, the degree of unsaturation of the intracellular FAs of both algae decreased, while that of the extracellular FFAs of S. platensis increased. The composition of the extracellular FFAs of C. vulgaris practically did not depend on the growth temperature.     

Exogenous Isoleucine and Fatty Acid Shortening Ensure the High Content of Anteiso-C15:0 Fatty Acid Required for Low-Temperature Growth of Listeria monocytogenes

Previous studies have demonstrated that the branched-chain fatty acid anteiso-C_15:0 plays a critical role in the growth of Listeria monocytogenes at low temperatures by ensuring sufficient membrane fluidity. Studies utilizing a chemically defined minimal medium revealed that the anteiso fatty acid precursor isoleucine largely determined the fatty acid profile and fatty acid response of the organism to lowered growth temperature. When isoleucine was sufficient, the fatty acid profile was very uniform, with anteiso fatty acids comprising up to 95% of total fatty acid, and the major fatty acid adjustment to low temperature was fatty acid chain shortening, which resulted in an increase of anteiso-C_15:0 solely at the expense of anteiso-C_17:0. When isoleucine was not supplied, the fatty acid profile became more complex and was readily modified by leucine, which resulted in a significant increase of corresponding iso fatty acids and an inability to grow at 10°C. Under this condition, the increase of anteiso-C_15:0 at low temperature resulted from the combined effect of increasing the anteiso:iso ratio and chain shortening. A branched-chain α-keto acid dehydrogenase-defective strain largely lost the ability to increase the anteiso:iso ratio. Cerulenin, an inhibitor of β-ketoacyl-acyl carrier protein synthase (FabF), induced a similar fatty acid chain shortening as low temperature did. We propose that the anteiso precursor preferences of enzymes in the branched-chain fatty acid biosynthesis pathway ensure a high production of anteiso fatty acids, and cold-regulated chain shortening results in a further increase of anteiso-C_15:0 at the expense of anteiso-C_17:0.     

Light,temperature and nitrogen starvation effects on the total lipid and fatty acid content and composition ofSpirulina platensis UTEX 1928

The total lipid and fatty acid content ofSpirulina platensis UTEX 1928 was 7.2 and 2.2% respectively of cellular dry weight under controlled conditions supporting high growth rates. With increases in irradiance from 170 to 870 μmol photon m^?2 s^?1, growth rate increased, total lipid decreased, and fatty acid composition was unaffected. At 1411 μmol photon m^?2 s^?1, total lipid increased slightly and percent composition of the fatty acid gamma linolenic acid increased. Growth and total lipid content ofS. platensis were affected by changes in growth temperature from 25 to 38 °C. With increased growth rate, total lipid content increased. This suggests that the storage of carbon increases at temperatures supporting high growth rates. The degree of saturation increased with temperature. Although the percent composition of gamma linolenic acid was higher at lower growth temperature, production was still primarily a function of growth rate. The effect of temperature on fatty acid content and degree of saturation was of secondary importance. Nitrogen starvation increased total lipid content but decreased fatty acid content as a percentage of dry weight; composition of the fatty acids was unaffected. N-starvation appeared to suspend synthesis of long chain fatty acids inS. platensis, suggesting that some other compound stores fixed carbon when nitrogen is limiting. It was concluded that fatty acid production inS. platensis is maximized by optimizing culture conditions for growth.     

Critical role of anteiso-C15:0 fatty acid in the growth of Listeria monocytogenes at low temperatures.

Listeria monocytogenes is a food-borne pathogen capable of growth at refrigeration temperatures. Membrane lipid fatty acids are major determinants of a sufficiently fluid membrane state to allow growth at low temperatures. L. monocytogenes was characterized by a fatty acid profile dominated to an unusual extent (> 95%) by branched-chain fatty acids, with the major fatty acids being anteiso-C15:0, anteiso-C17:0, and iso-C15:0 in cultures grown in complex or defined media at 37 degrees C. Determination of the fatty acid composition of L. monocytogenes 10403S and SLCC 53 grown over the temperature range 45 to 5 degrees C revealed two modes of adaptation of fatty acid composition to lower growth temperatures: (i) shortening of fatty acid chain length and (ii) alteration of branching from iso to anteiso. Two transposon Tn917-induced cold-sensitive mutants incapable of growth at low temperatures had dramatically altered fatty acid compositions with low levels of i-C15:0, a-C15:0, and a-C17:0 and high levels of i-C14:0, C14:0, i-C16:0, and C16:0. The levels of a-C15:0 and a-C17:0 and the ability to grow at low temperatures were restored by supplementing media with 2-methylbutyric acid, presumably because it acted as a precursor of methylbutyryl coenzyme A, the primer for synthesis of anteiso odd-numbered fatty acids. When mid-exponential-phase 10403S cells grown at 37 degrees C were temperature down-shocked to 5 degrees C they were able, for the most part, to reinitiate growth before the membrane fatty acid composition had reset to a composition more typical for low-temperature growth. No obvious evidence was found for a role for fatty acid unsaturation in adaptation of L. monocytogenes to cold temperature. The switch to a fatty acid profile dominated by a-C15:0 at low temperatures and the association of cold sensitivity with deficiency of a-C15:0 focus attention on the critical role of this fatty acid in growth of L. monocytogenes in the cold, presumably through its physical properties and their effects, in maintaining a fluid, liquid-crystalline state of the membrane lipids.     

Temperature- and growth-phase-regulated changes in lipid fatty acid structures of psychrotolerant groundwater Proteobacteria

Cellular fatty acid compositions of five psychrotolerant groundwater isolates representing alpha- and beta-Proteobacteria were studied at temperatures ranging from 8 to 25 degrees C. Unsaturation of straight-chain fatty acids was the most common response to decreasing temperature and was detected in four of the isolates. On solid media, decrease of temperature resulted in a decrease of cyclopropane fatty acids in beta-proteobacterial isolates. The formation of cyclopropane fatty acids depended, however, to a greater extent on the growth phase than the temperature and increased drastically as the cells entered stationary phase. The alpha-proteobacterial isolates contained a branched C(19:1) fatty acid. The formation of the branched C(19:1) increased during growth in the same way as the cyclopropane fatty acids in beta-proteobacterial strains, indicating possibly an analogous formation of the branched fatty acid by methylation of the 18:1 fatty acid. Sphingomonas sp. K6 possessed a novel temperature-induced modification of lipid fatty acids. As temperature decreased from 25 to 8 degrees C, the fatty acid composition shifted from predominantly even-carbon fatty acids to odd-carbon fatty acids. The results show completely different fatty acid modifications in two strains of the same genus Sphingomonas.     

Cold shock response of Bacillus subtilis: isoleucine-dependent switch in the fatty acid branching pattern for membrane adaptation to low temperatures.

Bacillus subtilis has developed sophisticated mechanisms to withstand fluctuations in temperature. Membrane fatty acids are the major determinants for a sufficiently fluid membrane state to ensure the membrane's function at all temperatures. The fatty acid profile of B. subtilis is characterized by a high content of branched fatty acids irrespective of the growth medium. Here, we report on the importance of isoleucine for B. subtilis to survive cold shock from 37 to 15 degrees C. Cold shock experiments with strain JH642 revealed a cold-protective function for all intermediates of anteiso-branched fatty acid biosynthesis. Metabolites related to iso-branched or straight-chain fatty acid biosynthesis were not protective. Fatty acid profiles of different B. subtilis wild-type strains proved the altered branching pattern by an increase in the anteiso-branched fatty acid content and a concomitant decrease of iso-branched species during cold shock. There were no significant changes in the fatty acid saturation or acyl chain length. The cold-sensitive phenotype of isoleucine-deficient strains in the absence of isoleucine correlated with their inability to synthesize more anteiso-branched fatty acids, as shown by the fatty acid profile. The switch to a fatty acid profile dominated by anteiso-C(15:0) and C(17:0) at low temperatures and the cold-sensitive phenotype of isoleucine-deficient strains in the absence of isoleucine focused our attention on the critical role of anteiso-branched fatty acids in the growth of B. subtilis in the cold.     

Comparisons of the effects of temperature on the liver fatty acid binding proteins from hibernator and nonhibernator mammals.

Hibernating mammals rely heavily on lipid metabolism to supply energy during hibernation. We wondered if the fatty acid binding protein from a hibernator responded to temperature differently than that from a nonhibernator. We found that the Kd for oleate of the liver fatty acid binding protein (1.5 microM) isolated from ground squirrel (Spermophilus richardsonii) was temperature insensitive over 5-37 degrees C, while the rat liver fatty acid binding protein was affected with the Kd at 37 degrees C being about half (0.8 microM) that found at lower temperatures. This same trend was observed when comparing the specificity of various fatty acids of differing chain length and degree of unsaturation for the two proteins at 5 and 37 degrees C. At the lower temperature, ground squirrel protein bound long-chain unsaturated fatty acids, particularly linoleate and linolenate, at least as well as at the higher temperature and matched requirements for these fatty acids in the diet. The most common long-chain fatty acid, palmitate, was a more effective ligand for ground squirrel liver fatty acid binding protein at 5 degrees C than at 37 degrees C, with the opposite occurring in the eutherm. Rat protein was clearly not adapted to function optimally at temperatures lower than the animal's body temperature.     

Effect of growth temperature on cellular fatty acids in sulphate-reducing bacteria

The effect of growth temperature on the cellular fatty acid composition of sulphate-reducing bacteria (SRB) was studied in 12 species belonging to eight genera including psychrophiles and mesophiles. Most of these species were of marine origin. The investigated SRB with the exception of four Desulfobacter species exhibited only a minor increase in the proportion of cis-unsaturated fatty acids (by < or = 5% per 10 degrees C) when the growth temperature was decreased; psychrophiles maintained their typically high content of cis-unsaturated fatty acids (around 75% of total fatty acids) nearly constant. The four Desulfobacter species, however, increased the proportion of cis-unsaturated among total fatty acids significantly (by > or =14% per 10 degrees C; measured in late growth phase) with decreasing growth temperature. The ratio between unsaturated and saturated fatty acids in Desulfobacter species changed not only with the growth temperature, but also with the growth state in batch cultures at constant temperature. Changes of cellular fatty acids were studied in detail with D. hydrogenophilus, the most psychrotolerant (growth range 0-35 degrees C) among the mesophilic SRB examined. Desulfobacter hydrogenophilus also formed cis-9,10-methylenehexadecanoic acid (a cyclopropane fatty acid) and 10-methylhexadecanoic acid. At low growth temperature (12 degrees C), the relative amount of these fatty acids was at least threefold lower; this questions the usefulness of 10-methylhexadecanoic acid as a reliable biomarker of Desulfobacter in cold sediments.     

Analysis of fatty acid composition of Candida species by gas-liquid chromatography using a polar column

The fatty acid composition of representative Candida species was examined by gas-liquid chromatography (GLC) using a polar column. The major fatty acids were C14:0, C16:0, C18:0 saturated, C16:1 and C18:1 monoenoic series, with or without C18 polyunsaturated acids (C18:2 and C18:3). In Torulopsis glabrata and Saccharomyces cerevisiae the C18:2 and C18:3 acids were not found, but the C10:0 and C12:0 acids were detected in S. cerevisiae. These results indicated that the Candida genus could be distinguished from Torulopsis and Saccharomyces genera by GLC analysis of fatty acids. Quantitative differences in the fatty acid composition between cells grown at high temperature (37 degrees C) and low temperature (25 degrees C) were found generally in Candida species, and the amounts of C18 polyunsaturated acids (C18:2 and C18:3) increased in the cells grown at 25 degrees C. Each Candida species showed a characteristic profile in fatty acid composition. Determination of the cellular fatty acid composition in Candida species is likely to be useful for the grouping or chemotaxonomy of newer isolates of Candida species.     

Secretion of Free Fatty Acids by Prokaryotic and Eukaryotic Algae at Optimal,Supraoptimal, and Suboptimal Growth Temperatures

The paper describes the composition of extracellular free fatty acids (FFAs) and intracellular fatty acids (FAs) in the enrichment cultures of the prokaryotic alga Spirulina platensisand the eukaryotic alga Chlorella vulgarisgrown at optimal, supraoptimal, and suboptimal growth temperatures. With increasing growth temperature, the degree of unsaturation of the intracellular FAs of both algae decreased, while that of the extracellular FFAs of S. platensisincreased. The composition of the extracellular FFAs of C. vulgarispractically did not depend on the growth temperature.     

Different cellular fatty acid pattern behaviours of two strains of Listeria monocytogenes Scott A and CNL 895807 under different temperature and salinity conditions

Cells of two strains of Listeria monocytogenes CNL 895807 and Scott A were grown to late exponential phase at different growth temperatures (37, 20 and 4 degrees C) with or without NaCl (7%), and their fatty acid compositions were analysed. The results showed that low thermal adaptation response of L. monocytogenes CNL was different than that of the Scott A strain, and it was based on both an increase of anteiso-branched-chain fatty acids and a significant decrease of straight-chain fatty acids. However, the main modifications observed in the Scott A strain when grown at a low temperature were a decrease of the proportion of ai17:0 and an increase of ai15:0. In hyperosmotic medium and over the entire temperature range (4 degrees C, 20 degrees C and 37 degrees C) the two L. monocytogenes strains showed a cellular fatty acid profile dominated by ai15:0. In addition, a decrease of the two major straight-chain fatty acids (14:0 and 16:0) was observed in the CNL strain. These results demonstrated that the CNL strain showed different behaviours of low thermal and salt adaptation to maintain membrane fluidity, which are based both on an increase of anteiso-branched-chain fatty acids, and a significant decrease of straight-chain fatty acids.     

Stable-isotope-based labeling of styrene-degrading microorganisms in biofilters

Deuterated styrene ([(2)H(8)]styrene) was used as a tracer in combination with phospholipid fatty acid (PLFA) analysis for characterization of styrene-degrading microbial populations of biofilters used for treatment of waste gases. Deuterated fatty acids were detected and quantified by gas chromatography-mass spectrometry. The method was evaluated with pure cultures of styrene-degrading bacteria and defined mixed cultures of styrene degraders and non-styrene-degrading organisms. Incubation of styrene degraders for 3 days with [(2)H(8)]styrene led to fatty acids consisting of up to 90% deuterated molecules. Mixed-culture experiments showed that specific labeling of styrene-degrading strains and only weak labeling of fatty acids of non-styrene-degrading organisms occurred after incubation with [(2)H(8)]styrene for up to 7 days. Analysis of actively degrading filter material from an experimental biofilter and a full-scale biofilter by this method showed that there were differences in the patterns of labeled fatty acids. For the experimental biofilter the fatty acids with largest amounts of labeled molecules were palmitic acid (16:0), 9,10-methylenehexadecanoic acid (17:0 cyclo9-10), and vaccenic acid (18:1 cis11). These lipid markers indicated that styrene was degraded by organisms with a Pseudomonas-like fatty acid profile. In contrast, the most intensively labeled fatty acids of the full-scale biofilter sample were palmitic acid and cis-11-hexadecenoic acid (16:1 cis11), indicating that an unknown styrene-degrading taxon was present. Iso-, anteiso-, and 10-methyl-branched fatty acids showed no or weak labeling. Therefore, we found no indication that styrene was degraded by organisms with methyl-branched fatty fatty acids, such as Xanthomonas, Bacillus, Streptomyces, or Gordonia spp.