Estimation of direct-contact fraction for phenanthrene in surfactant solutions by toxicity measurement

The toxicity of solutions containing nonionic surfactants Tween 80, Brij 35 and/or phenanthrene to Pseudomonas putida ATCC 17484 was investigated. The fraction of direct contact between micellar-phase phenanthrene and bacterial cell surface was estimated by using the toxicity data and a mathematical model. The mathematical model was used to calculate phenanthrene concentration in the micellar phase and aqueous pseudophase separately. The first-order death rate constant increased from 0.088+/-0.016 to 0.25+/-0.067 h(-1) when the phenanthrene concentration was increased from 0 to 5.17 x 10(-6)M (equals water solubility). The intrinsic toxicity of surfactant was higher in Brij 35 than in Tween 80. When phenanthrene concentration was increased to 9.7 x 10(-5)M in surfactant solutions, the death rate constant increased to 1.8 +/- 0.024 and 0.41 +/- 0.088 h(-1) for 8.4 x 10(-4)M Brij 35 and 7.6 x 10(-4)M Tween 80. The direct-contact fraction was 0.083 and 0.044 for Brij 35 and Tween 80, respectively, under these conditions using exponential model. The toxicity increased with increasing phenanthrene concentration at a fixed surfactant concentration. The toxicity decreased with increasing the surfactant concentration at a fixed phenanthrene concentration due to decreased contact of bacteria with phenanthrene present in the interior of surfactant micelles.     

Enhanced biodegradation of phenanthrene by a marine bacterium in presence of a synthetic surfactant

The biodegradation of phenanthrene by the marine strain Sphingomonas sp. 2MPII (DSMZ 11572) was enhanced by the solubilizating properties of the nonionic surfactant Tween 80. After 197 h of incubation, 85 +/- 4% of the initial amount of phenanthrene (0.4 g l-1) was biodegraded in presence of Tween 80 (0.5 g l-1) as opposed to 52 +/- 5% without this synthetic surfactant. These results confirm that the activity of the strain 2MPII is limited by the bioavailability of the polycyclic aromatic hydrocarbon (PAH) substrate in the aqueous phase. Tween 80 appears to be efficient in increasing the bioavailability of hydrophobic compounds such as PAHs.     

表面活性剂对分枝杆菌KR2菌株降解菲的影响

采用同位素示踪方法,从表面活性剂的浓度、离子类型和直链长度三方面研究了表面活性剂对分枝杆菌KR2菌株降解菲的影响。结果表明,表面活性剂的存在不能促进KR2菌对菲的降解;高浓度表面活性剂(≥20mg·L^-1)的存在,使菲的降解出现延迟期,非离子表面活性剂Tween80在低浓度时(≤10mg·L^-1)可以优先作为营养基质被分枝杆菌KR2菌株利用,表面活性剂的离子类型对菲降解的抑制作用的顺序为阳离子表面活性剂TDTMA>阴离子表面活性剂LAS>非离子表面活性剂Tween80,表面活性剂的直链长度对菲降解的影响为直链越短,对微生物的毒性越大,菲降解得越不完全。     

Effect of surfactants on ethanol fermentation using glucose and cellulosic hydrolyzates

The effect of the non-ionic surfactants on the ethanol fermentation was greatly dependent on the surfactant added. While Tween 20 and Tween 80 slightly enhanced ethanol fermentation, Triton X-100 which exhibited the inghest increase in the enzymatic saccharification had a negative effect on the ethanol fermentation. The negative effect of Triton X-100 on ethanol production was the most pronounced when the cellulosic hydrolyzates were used. Tween 80 showed the best performance for the ethanol production from steam exploded wood hydrolyzate.     

Molecular characterization of surfactant-driven microbial community changes in anaerobic phenanthrene-degrading cultures under methanogenic conditions

SDS and Triton X-100 added at their critical micelle concentrations (CMCs), increased phenanthrene solubility in the presence of sediments and inhibited phenanthrene biodegradation. Triton X-100 caused more inhibition than SDS. 16S rDNA analyses revealed that both surfactants changed the microbial communities of phenanthrene-degrading cultures. Further, after the surfactant additions, parts of the microbial populations were not detected and methane production decreased. Surfactant applications, necessary to achieve actual CMCs, alter microbial community structure and diminish methanogenic activity under anaerobic conditions. We propose that this change may be related to the inhibitory effects of SDS and Triton X-100 on phenanthrene biodegradation under methanogenic conditions.     

Investigation of extractive microbial transformation in nonionic surfactant micelle aqueous solution using response surface methodology

Extractive microbial transformation of L-phenylacetylcarbinol (L-PAC) in nonionic surfactant Triton X-100 micelle aqueous solution was investigated by response surface methodology. Based on the Box–Behnken design, a mathematical model was developed for the predication of mutual interactions between benzaldehyde, Triton X-100, and glucose on L-PAC production. It indicated that the negative or positive effect of nonionic surfactant strongly depended on the substrate concentration. The model predicted that the optimal concentration of benzaldehyde, Triton X-100, and glucose was 1.2 ml, 15 g, and 2.76 g per 100 ml, respectively. Under the optimal condition, the maximum L-PAC production was 27.6 mM, which was verified by a time course of extractive microbial transformation. A discrete fed-batch process for verification of cell activity was also presented.     

Effect of triton X-100 on compactin production from<Emphasis Type="Italic">Penicillium citrinum</Emphasis>

Glucose alone was found to be the most effective carbon source for producing compactin. An initial glucose concentration of 40 g/L gave the highest compactin concentration of 250 mg/L. Among the various nitrogen sources, when 5 g/L of pharmamedia and soybean meal as the sole nitrogen source were used, respectively, the compactin concentration was higher than 250 mg/L. Especially, in the case of the mixture of 6 g/L of pharmamedia and 8 g/L of soybean meal, the compactin concentration was 400 mg/L. To select the best surfactant for effective compactin production, various surfactants were investigated. When Triton X-100 was used, the maximum compactin concentration was 445 mg/L. With the initial concentration ranging from 1.5 to 2.0 g/L, the compactin concentration was the highest at 465–450 g/L. The cell concentration was similar to that of the control without the addition of Triton X-100. On the other hand, when the above 4.0 g/L of Triton X-100 were used, the cell concentration decreased. Using the based results the continuous fed-batch cultures by adding the Triton X-100 were carried out for 10 days in an air-lift bioreactor. When 1.5 g/L of Triton X-100 was added to the culture broth at 0, 4, and 8 days of culture, respectively, the compactin production was increased with the increase of culture time. The maximum compactin concentration after 10 days of culture was 1,200 mg/L, which was about 2.0-fold higher than that of the control without the addition of Triton X-100.     

Contrasting effects of a nonionic surfactant on the biotransformation of polycyclic aromatic hydrocarbons to cis-dihydrodiols by soil bacteria

The biotransformation of the polycyclic aromatic hydrocarbons (PAHs) naphthalene and phenanthrene was investigated by using two dioxygenase-expressing bacteria, Pseudomonas sp. strain 9816/11 and Sphingomonas yanoikuyae B8/36, under conditions which facilitate mass-transfer limited substrate oxidation. Both of these strains are mutants that accumulate cis-dihydrodiol metabolites under the reaction conditions used. The effects of the nonpolar solvent 2,2,4, 4,6,8,8-heptamethylnonane (HMN) and the nonionic surfactant Triton X-100 on the rate of accumulation of these metabolites were determined. HMN increased the rate of accumulation of metabolites for both microorganisms, with both substrates. The enhancement effect was most noticeable with phenanthrene, which has a lower aqueous solubility than naphthalene. Triton X-100 increased the rate of oxidation of the PAHs with strain 9816/11 with the effect being most noticeable when phenanthrene was used as a substrate. However, the surfactant inhibited the biotransformation of both naphthalene and phenanthrene with strain B8/36 under the same conditions. The observation that a nonionic surfactant could have such contrasting effects on PAH oxidation by different bacteria, which are known to be important for the degradation of these compounds in the environment, may explain why previous research on the application of the surfactants to PAH bioremediation has yielded inconclusive results. The surfactant inhibited growth of the wild-type strain S. yanoikuyae B1 on aromatic compounds but did not inhibit B8/36 dioxygenase enzyme activity in vitro.     

Effect of surfactants on cellulase production by Nectria catalinensis

The effect of different nonionic surfactants (Tween 80, Tween 20, Triton X-100) and polyethylene glycol (PEG 6000) was tested on cellulolytic enzyme system production. Tween 80 gave the highest yield of endoglucanase, exoglucanase, and cellobiase at the 20th day of growth, presumably by causing increased permeability of cell membranes and/or by promoting the release of cell-bound enzymes. Maximal yield of endoglucanase was achieved with 1.7 mM Tween 80, whereas exoglucanase and cellobiase were at 0.85 mM. In the same way, this compound increased fungal growth. On the other hand, Tween 20 and Triton X-100 inhibited growth and cellulolytic enzyme production. High yields of endoglucanase and exoglucanase were achieved with PEG 6000 in comparison with the control, presumably by increasing enzyme stability. Received: 22 January 1996 / Accepted: 28 March 1996     

PEG和表面活性剂对棉纤维细胞合成葡聚糖的影响

以陆地棉岱字-15号棉纤维细胞为材料,用3H-葡聚糖示踪方法测定β-1,3-葡聚糖和纤维素的合成。PEG4000促进β-1,3-葡聚糖和纤维素的合成,对刺激纤维素的合成更有效;随着非离子型表面活性剂 Trion X-100和Tween 20浓度的升高,抑制β-1,3-葡聚糖和纤维素的合成程度也增加,但抑制纤维素的合成更为强烈;而阴离子表面活性剂SDS则有所不同,在较高浓度下,又出现对β-1,3-葡聚糖合成抑制的减弱,这可能与SDS载负电荷的缘故有关。结果提示,完整的细胞膜有利于纤维素的合成,细胞膜损伤则利于β-1,3-葡聚糖的合成。     

Effect of C/N/P ratio and nonionic surfactants on polychlorinated biphenyl biodegradation

This work investigated whether polychlorinated biphenyl (PCB) removal from a highly contaminated soil (7000-p.p.m.) could be enhanced by manipulating the carbon to nitrogen to phosphorus (C/N/P) ratio, and by nonionic surfactant addition. A Box–Behnken statistical experimental design was used to evaluate the combined effect of surfactant type, surfactant concentration, and C/N/P ratio in a relatively short treatment period (35 days). The variable with the greatest effect on PCB degradation was the type of surfactant used. Higher PCB removal efficiencies (39–60%) were obtained with Tween 80 (compared to Tergitol NP 10 and Triton X-100). This was attributed to its lower critical micelle concentration. Higher C/N/P ratios (increased by biphenyl addition) significantly stimulated the soil heterotrophic activity without enhancing PCB removal. This suggests that nonionic surfactants have a greater potential to enhance bioremediation of PCB-contaminated soil than efforts to enhance the soil heterotrophic activity through nutrient and analogue substrate addition.     

Quantitation of human immunoglobulin G and albumin in electroimmunodiffusion gels containing ionic and nonionic detergents

Quantitation of human immunoglobulin G (IgG) and albumin by agarose electroimmunodiffusion is influenced by the incorporation of ionic and nonionic detergents in the gel. The highest concentrations of each detergent at which human IgG and albumin determinations could be performed without perturbing the quantitations were 4% Triton X-100, 4% Tween 80, 1% NP-40, 0.5% sodium deoxycholate (SDOC), 0.5% Zwittergent, and 0.1% sodium dodecyl sulfate (SDS), and mixtures of Triton X-100, SDOC, and SDS. These detergent combinations all resulted in greater perturbations of albumin quantitation than of IgG. Immunoprecipitation of human IgG was quantitated in the absence and presence of Triton X-100, Zwittergent, and SDS. SDS was shown to cause nonspecific precipitation, whereas below 1% Triton X-100 or 0.5% Zwittergent no effects upon the immunoprecipitations were observed.     

Inhibition of Aflatoxin Production by Surfactants

The effect of 12 surfactants on aflatoxin production, growth, and conidial germination by the fungus Aspergillus flavus is reported. Five nonionic surfactants, Triton X-100, Tergitol NP-7, Tergitol NP-10, polyoxyethylene (POE) 10 lauryl ether, and Latron AG-98, reduced aflatoxin production by 96 to 99% at 1% (wt/vol). Colony growth was restricted by the five nonionic surfactants at this concentration. Aflatoxin production was inhibited 31 to 53% by lower concentrations of Triton X-100 (0.001 to 0.0001%) at which colony growth was not affected. Triton X-301, a POE-derived anionic surfactant, had an effect on colony growth and aflatoxin production similar to that of the five POE-derived nonionic surfactants. Sodium dodecyl sulfate (SDS), an anionic surfactant, and dodecyltrimethylammonium bromide, a cationic surfactant, suppressed conidial germination at 1% (wt/vol). SDS had no effect on aflatoxin production or colony growth at 0.001%. The degree of aflatoxin inhibition by a surfactant appears to be a function of the length of the hydrophobic and hydrophilic chains of POE-derived surfactants.     

Efficient polycyclic aromatic hydrocarbons dihydroxylation in direct micellar systems

Optimization of whole-cell bioconversion of the polycyclic aromatic hydrocarbons (PAHs) anthracene, phenanthrene, and naphthalene to the enantiomerically pure corresponding cis-dihydroxydihydro derivatives by the Escherichia coli JM109 (pPS1778) recombinant strain, carrying the naphthalene dioxygenase and corresponding regulatory genes cloned from Pseudomonas fluorescens N3, in micellar systems, is presented. We show that direct microemulsion systems, where a nonionic surfactant such as 1.5% (v/v) Triton X-100 plus 0.6% to 1.0% (v/v) selected oils are able to solubilize the PAHs tested at relatively high concentrations (initial concentrations in the reaction medium > or =10 mM for naphthalene and phenanthrene and > or =2 mM for anthracene), and allow for more efficient substrate bioconversion. These media, while not affecting bacteria viability and performance, provide increased efficiency and final product yields (100% for naphthalene, >30% for anthracene, >60% for phenanthrene). The phase behavior of the direct microemulsion systems for the different substrates and oils utilized was monitored as a function of their volume fraction by light scattering experiments, and related to the bioconversion results. For anthracene and phenanthrene, the dihydroxylated products have an inhibitory effect on the conversion reactions, thus hindering complete turnover of the substrates. We ascertain that such inhibition is reversible because removal of the products formed allowed the process to start over at rates comparable to initial rates. To allow for complete conversion of the PAHs tested a stepwise or continuous separation of the product formed from the micellar reaction environment is being developed.     

Mixed micelles of sphingomyelin and phosphatidylcholine with nonionic surfactants. Effect of temperature and surfactant polydispersity.

Mixed micelle formation of the polydisperse nonionic surfactant Triton X-100 as well as its homogeneous analogue, p-(1,1,3,3-tetramethylbutyl)-phenoxynonaoxyethylene glycol (OPE-9), with bovine brain sphingomyelin or dipalmitoyl phosphatidylcholine has been characterized by column chromatography on 6% agarose. At 40 degrees C, mixtures of OPE-9 and either sphingomyelin or dipalmitoyl phosphatidylcholine give a narrow size distribution for mixed micelles. A this temperature the size distribution of Triton X-100-containing mixed micelles is complicated because of the polydispersity of the oxyethylene chains. At 20 degrees C narrow size distributions are observed for mixed micelles of sphingomyelin/Triton X-100 and sphingomyelin/OPE-9 up to at least 0.06 mol fraction of lipid. For dipalmitoyl phosphatidylcholine this is observed only with OPE-9. At intermediate mol fractions of lipid (around 0.25), two populations of mixed micelles exist for sphingomyelin/Trition X-100, sphingomyelin/OPE-9, and dipalmitoyl phosphatidylcholine/OPE-9. At high mol fractions of lipid only one population of mixed micelles again exists. At 20 degrees C, sphingoymelin forms a clear solution with Triton X-100 and OPE-9 to a lipid mol fraction of at least 0.46 and 0.67, respectively. Dipalmitoyl phosphatidylcholine forms a clear solution with OPE-9 to a lipid mol fraction of at least 0.57 at the same temperature. Triton X-100 and dipalmitoyl phosphatidylcholine do not form stable, clear solutions at 20 degrees C unless the lipid mol fraction is extremely low. These results show that surfactant polydispersity and temperature are important determinants in the solubilization of lipids by nonionic surfactants. It is also shown that pure surfactant micelles and lipid/surfactant mixed micelles do not co-exist in the same solution.     

Cellular lysis of Streptococcus faecalis induced with triton X-100.

Lysis of exponential-phase cultures of Streptococcus faecalis ATCC 9790 was induced by exposure to both anionic (sodium dodecyl sulfate) and nonionic (Triton X-100) surfactants. Lysis in response to sodium dodecyl sulfate was effective only over a limited range of concentrations, whereas Triton X-100-induced lysis occurred over a broad range of surfactant concentrations. The data presented indicate that the bacteriolytic response of growing cells to Triton X-100: (i) was related to the ratio of surfactant to cells and not the surfactant concentration per se; (ii) required the expression of the cellular autolytic enzyme system; and (iii) was most likely due to an effect of the surfactant on components of the autolytic system that are associated with the cytoplasmic membrane. The possibility that Triton X-100 may induce cellular lysis by releasing a lipid inhibitor of the cellular autolytic enzyme is discussed.     

Solubilization of thyroid peroxidase by nonionic detergents.

We have examined the ability of nonionic detergents to solubilize thyroid peroxidase from a porcine thyroid particulate fraction, as measured by the release of peroxidase activity into the supernatant fraction after centrifugation at 105,000 X g for 1 hour and the retardation of the supernatant peroxidase of Sepharose 6B. The parameters of peroxidase solubilization by Triton X-100 have been investigated in detail. Under optimum conditions, 60 to 95% of the thryoid peroxidase and about 50% of the total protein is released into the 105,000 X g, 1-hour supernatant. Under the optimum conditions established with Triton X-100, a series of Brij detergents of different chemical structure were equally effective in releasing peroxidase and protein. The protein patterns of the supernatants obtained with these detergents were similar on sodium dodecyl sulfate-polyacrylamide electrophoresis gels, suggesting that the detergents studied release similar membrane proteins. The Triton X-100 and Brij 58 supernatants were chromatographed separately on Sepharose 6B equilibrated with 0.1% Triton X-100 or Brij 58, respectively. In both cases, 75 to 80% of the peroxidase activity was retarded, thereby indicating that the nonionic detergents effect solubilization of the peroxidase rather than dispersal of nonsedimentable membrane fragments. These studies report the first successful solubilization of thyroid peroxidase by nonionic detergents. Together with previous evidence from our laboratory, these experiments indicate that thyroid peroxidase is an integral membrane protein.     

Influence of Nonionic Surfactants on Bioavailability and Biodegradation of Polycyclic Aromatic Hydrocarbons

The presence of the synthetic nonionic surfactants Triton X-100, Tergitol NPX, Brij 35, and Igepal CA-720 resulted not only in increased apparent solubilities but also in increased maximal rates of dissolution of crystalline naphthalene and phenanthrene. A model based on the assumption that surfactant micelles are formed and act as a separate phase underestimated the dissolution rates; this led to the conclusion that surfactants present at concentrations higher than the critical micelle concentration affect the dissolution process. This conclusion was confirmed by the results of batch growth experiments, which showed that the rates of biodegradation of naphthalene and phenanthrene in the dissolution-limited growth phase were increased by the addition of surfactant, indicating that the dissolution rates were higher than the rates in the absence of surfactant. In activity and growth experiments, no toxic effects of the surfactants at concentrations up to 10 g liter(sup-1) were observed. Substrate present in the micellar phase was shown to be not readily available for degradation by the microorganisms. This finding has important consequences for the application of (bio)surfactants in biological soil remediation.     

Stabilization of Crystalline Acid Carboxypeptidase from Penicillium janthinellum by Nonionic Surfactants,and Inhibition of Enzyme Activity by Anionic Compounds

The crystalline acid carboxypeptidase from Penicillium janthinellum IFO-8070 was stabilized by the addition of nonionic surfactants, such as Triton X-100, Brij 35, Span 40, and Tween 20. In the presence of these stabilizers, extremely diluted enzyme (0.3 μg/ml of 50 mm sodium acetate buffer, pH 3.7) was almost completely stable after 2 days incubation at 25°C. About 35% and 20% of the enzyme activities were activated by the addition of Triton X-100 and Brij 35, respectively. Triton X-100 completely retarded inactivation at freezing (?15°C). On the other hand, anionic surfactants of SLS and LBSA, and cationic surfactant of cetyltrimethylammonium bromide strongly inactivated the enzyme. The inhibition of the fatty acid series was roughly proportional to the molecular weight of the inhibitor. Di-, and Tri-carboxylic acids also inhibited the enzyme activity.     

Adsorption of surfactants on a <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> strain and the effect on cell surface lypohydrophilic property

The adsorption behavior of five surfactants, cetyltrimethylammonium bromide (CTAB), Triton X-100, Tween 80, sodium dodecyl sulfate (SDS), and rhamnolipid, on a Pseudomonas aeruginosa strain and the effect of temperature and ionic strength (IS) on the adsorption were studied. The change of cell surface lypohydrophilic property caused by surfactant adsorption was also investigated. The results showed that the adsorption kinetics of the surfactants on the cell followed the second-order law. CTAB adsorption was the fastest one under the experimental conditions, and it took longest for SDS adsorption to equilibrate because of electric repulsion. The adsorption of Triton X-100 and Tween 80 was characterized by short equilibration time, and rhamnolipid adsorption reached equilibrium in about 90 min. The adsorption isotherms of all the surfactants on the bacterium fitted Freundlich equation well, but the adsorption capacity and mode were variations for the surfactants as indicated by k and n parameters in the equations. The adsorption mode for all the surfactants except SDS is probably hydrophilic interaction because the adsorption totally turned the cell surface to be more hydrophobic. Neither the temperature nor the IS had significant effect on CTAB adsorption, but higher IS significantly enhanced SDS adsorption and modestly strengthened adsorption of Triton X-100, Tween 80, and rhamnolipid. Higher temperature strengthened adsorption of SDS but weakened the adsorption of Triton X-100, Tween 80, and rhamnolipid.