Biodegradation by an Arthrobacter Species of Hydrocarbons Partitioned into an Organic Solvent

An Arthrobacter strain mineralized naphthalene and n-hexadecane dissolved in 2,2,4,4,6,8,8-heptamethylnonane. The extent of mineralization increased with greater volumes of solvent. Measurements under aseptic conditions of the partitioning of naphthalene into the aqueous phase from the solid phase or from heptamethylnonane showed that the rates were rapid and did not limit mineralization. The rate of mineralization of hexadecane was rapid, although partitioning of the compound into aqueous solution was not detected. The Arthrobacter sp. grown in media with or without heptamethylnonane did not excrete products that increased the aqueous solubility of naphthalene and hexadecane. Measurements of the number of cells in the aqueous phase showed that the Arthrobacter sp. attached to the heptamethylnonane-water interface, but attachment was evident even without a substrate in the heptamethylnonane. Tests with small inocula of the Arthrobacter sp. demonstrated that at least a portion of naphthalene or hexadecane dissolved in heptamethylnonane was degraded by cells attached to the solvent-water interface. The cells did not adhere in the presence of 0.1% Triton X-100. The surfactant prevented mineralization of the hexadecane initially dissolved in heptamethylnonane, but it increased the rate and extent of mineralization of naphthalene initially dissolved in heptamethylnonane. The data show that organic solvents into which hydrophobic compounds partition affect the biodegradation of those compounds and that attachment of microorganisms to the organic solvent-water interface may be important in the transformation.     

Biodegradation of naphthalene in aqueous nonionic surfactant systems.

The principal objective of this study was to quantify the bioavailability of micelle-solubilized naphthalene to naphthalene-degrading microorganisms comprising a mixed population isolated from contaminated waste and soils. Two nonionic surfactants were used, an alkylethoxylate, Brij 30 (C12E4), and an alkylphenol ethoxylate, Triton X-100 (C8PE9.5). Batch experiments were used to evaluate the effects of aqueous, micellized nonionic surfactants on the microbial mineralization of naphthalene and salicylic acid, an intermediate compound formed in the pathway of microbial degradation of naphthalene. The extent of solubilization and biodegradation under aerobic conditions was monitored by radiotracer and spectrophotometric techniques. Experimental results showed that surfactant concentrations above the critical micelle concentration were not toxic to the naphthalene-degrading bacteria and that the presence of surfactant micelles did not inhibit mineralization of naphthalene. Naphthalene solubilized by micelles of Brij 30 or Triton X-100 in liquid media was bioavailable and degradable by the mixed culture of bacteria.     

Use of surfactants and slurrying to enhance the biodegradation in soil of compounds initially dissolved in nonaqueous-phase liquids

A study was conducted to find means of enhancing the biodegradation of hydrophobic organic compounds in nonaqueous-phase liquids (NAPLs). The effects of surfactants, identity of the NAPL and agitation was investigated. When present in NAPLs, phenanthrene, di-(2-ethylhexyl) phthalate (DEHP) and biphenyl were mineralized slowly in soil. Addition of Triton X-100 or Alfonic 810-60 did not enhance the degradation of phenanthrene initially in hexadecane or dibutyl phthalate. Slurrying the soil increased the rate and extent of mineralization of phenanthrene initially in hexadecane but not in dibutyl phthalate. Addition of either of the two surfactants to the slurries did not promote the transformation. Triton X-100, Alfonic 810-60 and Tergitol 15-S-9 below their critical micelle concentrations increased the rate and sometimes the extent of mineralization in soil slurries of phenanthrene initially in 2,2,4,4,6,8,8-heptamethylnonane, but other surfactants were not stimulatory. Slurrying the soil promoted the initial mineralization of DEHP initially in dibutyl phthalate, and Alfonic 810-60 and Triton X-100 further stimulated the rate and extent of degradation in the slurries. Alfonic 810-60 increased the extent of mineralization in slurries of biphenyl in hexadecane but not in dibutyl phthalate, cyclohexane, kerosene or two oils. Little mineralization of biphenyl or DEHP initially in dibutyl phthalate occurred in soil slurries, but Tween 80, Tergitol 15-S-40 and Tergitol 15-S-9 increased the extent of mineralization. However, vigorous agitation of the slurries of soil acclimated to DEHP or the use of small volumes of the NAPL resulted in marked enhancement of the degradation. Thus, biodegradation of constituents of NAPLs in soil can be increased by the use of some surfactants, slurrying or intense agitation, but the effect will vary with the NAPL and the constituents.     

Bacterial influence on partitioning rate during the biodegradation of styrene in a biphasic aqueous-organic system

The degradation by a consortium of slightly-halophile marine bacteria of styrene initially dissolved in silicone oil was monitored in batch reactors stirred at 75, 125 and 500 rpm, respectively. In the 75 and 125 rpm cases, the styrene biodegradation rate was higher than the rate of spontaneous partitioning of styrene from the oil to the water, determined under abiotic conditions. Abiotic transfer tests carried out after biodegradation runs revealed that bacterial activity had resulted in a significant increase in the rate of styrene partitioning between the two liquid phases. Even though bacterial adsorption was noticeable at the oil-water interface, this effect appeared to be due to the release by the bacteria of chemicals in the aqueous phase. Similarity with observations made with Triton X-100 suggested that the chemicals released may have been biosurfactants or solubilizing agents.     

Effect of calcium on the surfactant tolerance of a fluoranthene degrading bacterium

Surfactants are known to increase the apparent aqueous solubility of polycyclic aromatic hydrocarbons (PAHs) and may thus be used to enhance the bioavailability and thereby to stimulate the biodegradation of these hydrophobic compounds. However, surfactants may in some cases reduce or inhibit biodegradation because of toxicity to the bacteria. In this study, toxicity of surfactants on Sphingomonas paucimobilis strain EPA505 and the effect on fluoranthene mineralization were investigated using Triton X-100 as model surfactant. The data showed that amendment with 0.48 mM (0.3 g l-1) of Triton X-100 completely inhibited fluoranthene and glucose mineralization and reduced cell culturability by 100% in 24 h. Electron micrographs indicate that Triton X-100 adversely affects the functioning of the cytoplasmic membrane. However, in the presence of 4.13 mM Ca2+-ions, Triton X-100 more than doubled the maximum fluoranthene mineralization rate and cell culturability was reduced by only 10%. In liquid cultures divalent ions, Ca2+ in particular and Mg2+ to a lesser extent, were thus shown to be essential for the surfactant-enhanced biodegradation of fluoranthene. Most likely the Ca2+-ions stabilized the cell membrane, making the cell less sensitive to Triton X-100. This is the first report on a specific factor which is important for successful surfactant-enhanced biodegradation of PAHs.     

Effect of nonionic surfactants on naphthalene dissolution and biodegradation

The effect of six nonionic surfactants, Igepal CA-720, Tergitol NPX, Triton X-100, PLE4, PLE10, and PLE23, on the dissolution rate of solid naphthalene was studied in stirred batch reactors. Results showed increased mass-transfer rates with increased surfactant concentrations up to 10 kg m-3. Dissolution experiments were adequatly described by a mechanistic mass-transfer model. Partitioning of naphthalene into the micelles and the diffusion coefficients of the micelles affected the dissolution rate most significantly. Combined dissolution and biodegradation experiments with Triton X-100 or PLE10 with naphthalene showed that the biomass-formation rate of Pseudomonas 8909N (DSM No. 11634) increased concomitantly with the mass-transfer rate under naphthalene-dissolution limited conditions up to surfactant concentrations of 6 kg m-3.     

基于遗传算法的光合细菌过氧化物酶电泳分析方法的建立

建立光合细菌中过氧化物酶的酸性聚丙烯酰胺凝胶电泳(A-PAGE)分析方法。以电泳图谱的谱带数和灰度为指标, 运用正交试验和遗传算法对该方法的电泳条件进行优化。实验结果表明, 当凝胶中Triton X-100含量为0.31%、菌体破碎时间为19 min、样品中Triton X-100含量为0.79%时, 可获得清晰的沼泽红假单胞菌过氧化物酶图谱; 当凝胶中Triton X-100含量为0.27%、菌体破碎时间为16 min、样品中Triton X-100含量为0.76%时, 可获得清晰的球形红细菌过氧化物酶图谱。本方法为光合细菌中过氧化物酶的分析提供了一种新的、简单、快速的手段。     

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.     

Amylolytic lactic acid bacteria in fish silage

An ∝aL-amylase activity has been observed in lactic acid bacteria occurring initially in fermented fish silage. The organisms belong to the genus Leuconostoc . The main fraction of the amylolytic enzyme produced by one of the isolated bacteria is cell-bound and is released into the medium at a late stage of growth. Treating cells with ultrasound or Triton X-100 increases enzyme activity in the culture filtrate. The pH range for enzyme activity is 5.0–7.0, with an optimum at pH 6.0. The enzyme is extremely labile at pH 8.0 and is inactivated at temperatures above 50°C at pH 5.8. Two enzyme fractions were found by isoelectric focusing, the main one at pH 5.00 and another at pH 4.5. Chromatography on DEAE cellulose gave two active peaks.     

Differentiation-related changes in glycoprotein synthesis by human keratinocytes.

Human keratinocytes were cultured in media in which the Ca2+ concentration controlled the stage of differentiation. In media containing less than 0.1 mM-Ca2+ keratinocytes grew as a monolayer, but in the presence of 2mM-Ca2+ the cells differentiated and formed stratified colonies. Glycoproteins of both stratified and unstratified cells were radiolabelled by metabolic incorporation of radioactive precursors and by cell-surface labelling using galactose oxidase/NaB3H4. The radiolabelled keratinocytes were extracted with 0.5% Triton X-100, and the glycoproteins in both the Triton X-100-soluble and Triton X-100-insoluble fractions were analysed by polyacrylamide-gel electrophoresis in the presence of SDS. Two Triton X-100-soluble glycoproteins with high Mr values (greater than 200,000) were major glycoproteins in stratified keratinocytes, but were present in only trace amounts in unstratified keratinocytes. Characterization of these glycoproteins by examination of the effect of tunicamycin on their synthesis and the effect of neuraminidase on their migration characteristics showed that they were cell-surface sialoglycoproteins containing O-glycosidically linked oligosaccharides. Analysis of the adherent cytoskeletons left after Triton X-100 extraction of stratified and unstratified keratinocytes revealed that a glycoprotein of Mr 184,000 was decreased in stratified keratinocytes. Incubation of unstratified keratinocytes in high-Ca2+ medium resulted in a rapid modification of the glycoprotein of Mr 184,000, and it is suggested that this event may be related to desmosome formation and stratification.     

Kinetic analysis of the dual phospholipid model for phospholipase A2 action

A kinetic scheme is proposed for the action of cobra venom phospholipase A2 on mixed micelles of phospholipid and the nonionic detergent Triton X-100, based on the "dual phospholipid model." (formula; see text) The water-soluble enzyme binds initially to a phospholipid molecule in the micelle interface. This is followed by binding to additional phospholipid in the interface and then catalytic hydrolysis. A kinetic equation was derived for this process and tested under three experimental conditions: (i) the mole fraction of substrate held constant and the bulk substrate concentration varied; (ii) the bulk substrate concentration held constant and the Triton X-100 concentration varied (surface concentration of substrate varied); and (iii) the Triton X-100 concentration held constant and the bulk substrate concentration varied. The substrates used were chiral dithiol ester analogs of phosphatidylcholine (thio-PC) and phosphatidylethanolamine (thio-PE), and the reactions were followed by reaction of the liberated thiol with a colorimetric thiol reagent. The initial binding (Ks = k1/k-1) was apparently similar for thio-PC and thio-PE (between 0.1 and 0.2 mM) as were the apparent Michaelis constants (Km = (k-2 + k3)/k2) (about 0.1 mol fraction). The Vmax values for thio-PC and thio-PE were 440 and 89 mumol min-1 mg-1, respectively. The preference of cobra venom phospholipase A2 for PC over PE in Triton X-100 mixed micelles appears to be an effect on k3 (catalytic rate) rather than an effect on the apparent binding of phospholipid in either step of the reaction.     

Influence of associated lipid on the properties of purified bovine erythrocyte acetylcholinesterase

Acetylcholinesterase has been isolated from bovine erythrocyte membranes by affinity chromatography using a m-trimethylammonium ligand. The purified enzyme had hydrophobic properties by the criterion of phase partitioning into Triton X-114. The activity of the hydrophobic enzyme was seen as a slow-moving band in nondenaturing polyacrylamide gels. After treatment with phosphatidylinositol-specific phospholipase C, another form of active enzyme was produced that migrated more rapidly toward the anode in these gels. This form of the enzyme partitioned into the aqueous phase in Triton X-114 phase separation experiments and was therefore hydrophilic. The hydrophobic form bound to concanavalin A in the absence of Triton X-100. As this binding was partially prevented by detergent, but not by alpha-methyl mannoside, D-glucose, or myo-inositol, it is in part hydrophobic. Erythrocyte cell membranes showed acetylcholinesterase activity present as a major form, which was hydrophobic by Triton X-114 phase separation and in nondenaturing gel electrophoresis moved at the same rate as the purified enzyme. In the membrane the enzyme was more thermostable than when purified in detergent. The hydrophobic enzyme isolated, therefore, represents a native form of the acetylcholinesterase present in the bovine erythrocyte cell membrane, but in isolation its stability becomes dependent on amphiphile concentration. Its hydrophobic properties and lectin binding are attributable to the association with the protein of a lipid with the characteristics of a phosphatidylinositol.     

Response of fluoranthene-degrading bacteria to surfactants

A prerequisite for surfactant-enhanced biodegradation is that the microorganisms survive, take up substrate and degrade it in the presence of the surfactant. Two Mycobacterium and two Sphingomonas strains, degrading fluoranthene, were investigated for their sensitivity towards non-ionic chemical surfactants. The effect of Triton X-100 and Tween 80 above their critical micelle concentration on mineralization of [¹⁴C]-glucose and [¹⁴C]-fluoranthene was measured in shaker cultures. Tween 80 had no toxic effect on any of the tested strains. The surfactant inhibited fluoranthene mineralization by the hydrophobic Mycobacterium spp. slightly, but more than doubled that by the two less hydrophobic Sphingomonas strains. Triton X-100 inhibited fluoranthene mineralization by all strains, yet this was more pronounced for the Sphingomonas spp. Both surfactants caused cell wall permeabilization, as shown by transient colouring of surfactant-containing media. Inhibition of glucose mineralization, indicating non-specific toxic effects of Triton X-100, was observed only for the Sphingomonas strains and the toxicity was caused by micelle-to-cell interactions. These strains, however, appeared to recover from initial Triton X-100 toxicity within 50–500 h of exposure. The ratio of surfactant concentration to initial cell density was found to determine critically the bacterial response to surfactants. For both Sphingomonas and Mycobacterium strains, this work indicates that fluoranthene solubilized in surfactant micelles is only partially available for mineralization by the bacteria tested. However, our results suggest that optimal conditions for polycyclic aromatic hydrocarbon mineralization can be developed by selection of the proper surfactant, bacterial strains, cell density and incubation conditions. Received: 6 February 1998 / Received revision: 19 June 1998 / Accepted: 19 June 1998     

Characterization of two populations of statin and the relationship of their syntheses to the state of cell proliferation

Statin has previously been identified to be a 57-kD protein present in the nuclei of quiescent and senescent human fibroblasts, but not in their replicating counterparts (Wang, E. 1985. J. Cell Biol. 100: 545-551). In the present report we demonstrate by immunoprecipitation analysis of fractionated cellular extracts the existence of two populations of statin. The Triton X-100-soluble statin is found in replicating sparse cultures as well as in quiescent confluent cultures and quiescent serum-starved cultures of young human fibroblasts, but the Triton X-100-insoluble, nuclear envelope-localized statin is present only in the quiescent cultures. Two-dimensional gel analysis of the immunoprecipitated cellular fractions reveals that both populations of statin have an isoelectric point of 5.3. Pulse-chase experiments show that statin is synthesized as a 57-kD polypeptide and is not processed from a precursor of different molecular mass. Experiments on serum stimulation of quiescent cells show that synthesis of the Triton X-100-insoluble statin decreases rapidly during the transition from the G0 to S phase, and that this decrease is accompanied by a slower reduction in synthesis of the Triton X-100-soluble statin. These results suggest that the cellular expression of the two populations of statin may be associated with the mechanisms controlling the transition between the growing state and the quiescent state and confirm the previous finding that the Triton X-100-insoluble, nuclear envelope-localized statin could be used as a marker for cells arrested at the G0 phase of the cell cycle.     

Phospholipase A2 activity towards phosphatidylcholine in mixed micelles: surface dilution kinetics and the effect of thermotropic phase transitions

Phospholipase A₂ will act on dipalmitoyl phosphatidylcholine as substrate when the phospholipid is part of a mixed micelle with Triton X-100 at a molar ratio of Triton to phospholipid of 2:1 or greater. Kinetic studies at high molar ratios of Triton X-100 to phospholipid are reported and show that the binding of phospholipase A₂ to substrate depends on the total concentration of Triton X-100 and phospholipid, but that the rate of enzymatic catalysis decreases proportionally to the Triton X-100 concentration. These results are interpreted in terms of a model involving surface dilution kinetics. The relationship of this model to that of competitive inhibition is discussed. In addition, the activity of phospholipase A₂ towards dipalmitoyl phosphatidylcholine and dimyristoyl phosphatidylcholine at different temperatures is reported, and the results show a direct effect of the thermotropic phase transition of dipalmitoyl phosphatidylcholine on enzymatic activity.     

The solubilization and morphological change of human platelets in various detergents

The solubilization of human gel-filtered platelets by octyl glucoside, Triton X-100, dodecylsulfate, and deoxycholate was compared from the analysis of (1) cell lysis, (2) marker leakiness, and (3) component solubility. These analyses all revealed that the effect of detergent concentration on the solubilization of platelets by these detergents was exerted in three stages, i.e., the prelytic, lytic, and complete platelet-lysis stages. These analyses also indicated several differences among platelets in these detergents. (i) The ratio of the platelet-saturation concentration (PSC) to critical micellar concentration (CMC) was about 1/2 for octyl glucoside. Triton X-100 and dodecylsulfate, while it was close to 1 for deoxycholate. (ii) Platelets in octyl glucoside. Triton X-100, and dodecylsulfate all showed parallel curves in cell lysis, protein solubilization and marker leakiness, while the platelet lysis in deoxycholate was identical to the phospholipid solubilization. (iii) The solubility curves of various components in Triton X-100 and deoxycholate were parallel. However, the solubility of cholesterol in octyl glucoside was lower than that of protein and phospholipid. In dodecylsulfate, the solubility of phospholipid and cholesterol was very low in comparison with that of protein. In addition, morphological studies using scanning electron microscopy (scanning EM) revealed that the solubilization by octyl glucoside or Triton X-100 might occur via membrane area expansion. On the other hand, the solubilization by dodecylsulfate or deoxycholate showed membrane vesiculation prior to cell lysis. Moreover, in the prelytic stage, the morphological change in platelets in octyl glucoside showed only concentration dependence by swelling to an ellipsoid and then to a sphere. However, the morphological change in platelets in the other three detergents was dependent not only on the detergent concentration but also on prolonged incubation. Specifically, in Triton X-100, the cells initially changed to spiculate discs and then reached their final shape as swollen discs with surface invagination. In dodecylsulfate and deoxycholate the morphological changes were almost the same. The cell initially deformed in shape to a spiculate disc and finally to a stretched-out flat form. The results are discussed according to the bilayer couple hypothesis. Also, in the prelytic stage, these detergents caused inhibition of the response of platelets to collagen and ADP-fibrinogen.     

Low surfactant concentration increases fungal mineralization of a polychlorinated biphenyl congener but has no effect on overall metabolism

Three white rot fungi were compared for their ability to attack polychlorinated biphenyl (PCB) congeners in the presence and absence of the non-ionic Triton X-100 or the anionic Dowfax 8390 surfactants at half their critical micelle concentrations. Neither surfactant affected PCB biodegradation monitored by gas chromatography but the release of 14CO2 from 2,4',5-[U-14C]trichlorobiphenyl by Trametes versicolor was stimulated 12% by Triton X-100. Since mineralization is the complete metabolism of the congener and biodegradation was measured as substrate disappearance, Triton X-100 is proposed to aid intracellular solubilization of 2,4',5-trichlorobiphenyl for complete oxidation by T. versicolor.     

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.     

Effects of Triton X-100 and Quillaya Saponin on the ex situ bioremediation of a chronically polychlorobiphenyl-contaminated soil

The possibility of enhancing the ex situ bioremediation of a chronically polychlorinated biphenyl (PCB)-contaminated soil by using Triton X-100 or Quillaya Saponin, a synthetic and a biogenic surfactant, respectively, was studied. The soil, which contained about 350 mg/kg of PCBs and indigenous aerobic bacteria capable of growing on biphenyl or on monochlorobenzoic acids, was amended with inorganic nutrients and biphenyl, saturated with water and treated in aerobic batch slurry- and fixed-phase reactors. Triton X-100 and Quillaya Saponin were added to the reactors at a final concentration of 10 g/l at the 42nd day of treatment, and at the 43rd and 100th day, respectively. Triton X-100 was not metabolised by the soil microflora and it exerted inhibitory effects on the indigenous bacteria. Quillaya Saponin, on the contrary, was readily metabolised by the soil microflora. Under slurry-phase conditions, Triton X-100 negatively influenced the soil bioremediation process by affecting the availability of the chlorobenzoic acid degrading indigenous bacteria, whereas Quillaya Saponin slightly enhanced the biological degradation and dechlorination of the soil PCBs. In the fixed-phase reactors, where both the surfactant availability and the mixing of the soil were lower, Triton X-100 did not exert inhibitory effects on the soil biomass and enhanced significantly the soil PCB depletion, whereas Quillaya Saponin did not influence the bioremediation process. Received: 28 April 1998 / Received last revision: 15 July 1998 / Accepted: 29 July 1998     

Promoting pellet growth of Trichoderma reesei Rut C30 by surfactants for easy separation and enhanced cellulase production

It is desirable to modify the normally filamentous Trichoderma reesei Rut C-30 to a pellet form, for easy biomass separation from the fermentation medium containing soluble products (e.g., cellulase). It was found in this study that this morphological modification could be successfully achieved by addition of the biosurfactant rhamnolipid (at ≥ 0.3g/L) and the synthetic Triton X-100 (at ≥ 0.1g/L) to the fermentation broth before the cells started to grow actively. Thirteen other surfactants tested were not as effective. Furthermore, the added rhamnolipid and Triton X-100 increased the maximum cellulase activity (Filter Paper Units) produced in the fungal fermentation; the increase was 68 ± 7.8% for rhamnolipid and 73 ± 12% for Triton X-100. At the concentrations required for pellet formation, rhamnolipid had negative effect on the cell growth: with increasing rhamnolipid concentrations, the growth rate decreased and the lag-phase duration increased linearly. Triton X-100 caused no significant differences in growth rate or lag phase.