The effect of microorganisms on phytotoxicity of herbicides. III. Interaction of Bacillus sp. 72 with Venzar.

Interactions between Venzar and some metabolites of Bacillus ps. 72 were studied. This strain was found to produce flavonoids increasing the phytotoxicity of Venzar. Venzar action was also increased by NH4+ ions released aboundantly by the bacterial strain.     

Humic-like substances of bacterial origin. I. Some aspects of the formation and nature of humic-like substances produced by Pseudomonas.

Two bacterial strains Pseudomonas acidovorans No 26 and Pseudomonas sp. No 4 grown in Conn and yeast extract-glucose media, or in the media enriched with tyrosine, were found to produce dark brown pigment. It was shown that in the bacterial cultures numerous phenolic and quinone-type compounds were formed and transformed to humic-like polymers. Formation of humic-like substances started in the bacterial cells and was accompanied by the presence of phenyloxidases in the bacterial cultures. The bacterial "humic acids" were obtained from the supernatants in amounts varing from 0.05 to 0.865 mg/1 mg of dry weight of cells and from the cells in amounts of 0.02 to 0.165 mg/1 mg of dry weight of cells, depending on the medium used and time of incubation. The IR spectra of the bacterial "humic acids" appeared to be very similar to IR spectrum of the synthetic humic acids (Fluka A.G.) and contained the same chemical groups as the soil humic acids. The culture medium after growth of the strain No 26 was fractionated into "fulvic, hymatomelanic and humic acid" fractions. The hydrolysates from the obtained fractions contained amino acids and uronic acids. The amino acid composition appeared to be very similar to that of soil humic acids.     

Response of sweet pepper to phenols accumulated in greenhouse substrate

Prolonged cucumber cultivation in the same substrates leads to accumulation of phytotoxic phenolic compounds. Introduction of sweet pepper as an aftercrop eliminates substrate phytotoxicity. The aim of the study was to examine whether in sweet pepper detoxication of substrate phenols occurs by means of the glucosylation process. The examined materials were substrates differing in phytotoxicity level, and sweet pepper plants grown on these substrates. Substrate phytotoxicity was obtained by means of either repeated cucumber cultivation or by phenolic acid addition. During the vegetative growth phase of sweet pepper, the phytotoxicity and phenolic compound levels in the substrate, and the glucosylated phenol contents in above-ground plant parts were determined. Results showed that sweet pepper responds to an increased presence of phenols in the substrate by an intensified glucosylation.     

Identification and Phytotoxicity Assessment of Phenolic Compounds in Chrysanthemoides monilifera subsp. monilifera (Boneseed)

Chrysanthemoides monilifera subsp. monilifera (boneseed), a weed of national significance in Australia, threatens indigenous species and crop production through allelopathy. We aimed to identify phenolic compounds produced by boneseed and to assess their phytotoxicity on native species. Phenolic compounds in water and methanol extracts, and in decomposed litter-mediated soil leachate were identified using HPLC, and phytotoxicity of identified phenolics was assessed (repeatedly) through a standard germination bioassay on native Isotoma axillaris. The impact of boneseed litter on native Xerochrysum bracteatum was evaluated using field soil in a greenhouse. Collectively, we found the highest quantity of phenolic compounds in boneseed litter followed by leaf, root and stem. Quantity varied with extraction media. The rank of phenolics concentration in boneseed was in the order of ferulic acid > phloridzin > catechin > p-coumaric acid and they inhibited germination of I. axillaris with the rank of ferulic acid > catechin > phloridzin > p-coumaric acid. Synergistic effects were more severe compared to individual phenolics. The litter-mediated soil leachate (collected after15 days) exhibited strong phytotoxicity to I. axillaris despite the level of phenolic compounds in the decomposed leachate being decreased significantly compared with their initial level. This suggests the presence of other unidentified allelochemicals that individually or synergistically contributed to the phytotoxicity. Further, the dose response phytotoxic impacts exhibited by the boneseed litter-mediated soil to native X. bracteatum in a more naturalistic greenhouse experiment might ensure the potential allelopathy of other chemical compounds in the boneseed invasion. The reduction of leaf relative water content and chlorophyll level in X. bracteatum suggest possible mechanisms underpinning plant growth inhibition caused by boneseed litter allelopathy. The presence of a substantial quantity of free proline in the target species also suggests that the plant was in a stressed condition due to litter allelopathy. These findings are important for better understanding the invasive potential of boneseed and in devising control strategies.     

Phenolic removal in olive oil mill wastewater by strains of Pleurotus spp. in respect to their phenol oxidase (laccase) activity

The ability of several Pleurotus spp. strains to remove phenolic compounds from an olive oil mill wastewater (OMW) was studied. All strains tested in this work were able to grow in OMW without any addition of nutrients and any pre-treatment, except sterilization. High laccase activity was measured in the growth medium, while 69-76% of the initial phenolic compounds were removed. The black color of OMW became yellow-brown and brighter as the strains grew. The lowest phenolic concentrations were reached after 12/15 days. A decrease of the phytotoxicity, as described by the parameter Germination Index, was noticed in the OMW treated with some Pleurotus spp strains, although this decrease was not proportional to the phenolic removal. A new parameter, namely Phenol-toxicity Index, was considered in the present paper. Using this parameter it was found that the remaining phenolics and/or some of the oxidation products of the laccase reaction in the treated OMW were more toxic than the original phenolic compounds.     

Phenolic substances as allelopathic agents arising during the degradation of rye (Secale cereale) tissues

Rye seedlings, tillering plants and crop residues were allowed to decompose in model incubation experiments. Young tissues gave rise to high concentrations of allelochemicals, whereas crop residues did not produce inhibitors. Seven phenolic acids were identified in the investigated materials; p-hydroxybenzoic protocatechuic, gallic, vanillic, syringic, p-coumaric, ferulic as well as benzoic acid. However, neither the level of these acids nor the total content of phenolic compounds corresponded to the level of phytotoxicity determined in bioassays. This demonstrated that, apart from phenolics, other unidentified water-soluble organic compounds were also responsible for the toxicity of rye decomposition products. The study was conducted within program CPBP 04.10.03. The study was conducted within program CPBP 04.10.03.     

Bacteria from wheat and cucurbit plant roots metabolize PAHs and aromatic root exudates: Implications for rhizodegradation

The chemical interaction between plants and bacteria in the root zone can lead to soil decontamination. Bacteria that degrade polycyclic aromatic hydrocarbons (PAHs) have been isolated from the rhizospheres of plant species with varied biological traits; however, it is not known what phytochemicals promote contaminant degradation. One monocot and two dicotyledon plants were grown in PAH-contaminated soil from a manufactured gas plant (MGP) site. A phytotoxicity assay confirmed greater soil decontamination in rhizospheres when compared to bulk soil controls. Bacteria were isolated from plant roots (rhizobacteria) and selected for growth on anthracene and chrysene on PAH-amended plates. Rhizosphere isolates metabolized 3- and 4-ring PAHs and PAH catabolic intermediates in liquid incubations. Aromatic root exudate compounds, namely flavonoids and simple phenols, were also substrates for isolated rhizobacteria. In particular, the phenolic compounds—morin, caffeic acid, and protocatechuic acid—appear to be linked to bacterial degradation of 3- and 4-ring PAHs in the rhizosphere.     

Effect of phenolic compounds on the co-metabolism of citric acid and sugars by Oenococcus oeni from wine

AIMS: The goal of this study was to examine the growth of Oenococcus oeni in the presence of phenolic compounds under wine conditions and to see how these compounds affect bacterial metabolism. METHODS AND RESULTS: Phenolic compounds have been added to a basal medium that simulates the composition of wine. Fifty milligrams per litre or more of phenolic compounds stimulated bacterial growth. Oenococcus oeni seemed to use citric acid and trehalose, if they were present, before glucose and fructose. Citrate was completely exhausted in three days and the yield of acetate was higher when phenolic compounds were present. CONCLUSIONS: Phenolic compounds reduced the rate of sugar consumption and enhanced citric acid consumption, increasing the yield of acetic acid. SIGNIFICANCE AND IMPACT OF THE STUDY: This study allows a better knowledge of co-metabolism of citric acid and sugars by O. oeni in the presence of phenolic compounds of wine.     

Influence of salts and phenolic compounds on olive mill wastewater detoxification using superabsorbent polymers

For a selection of nine commercially available superabsorbent polymers, the absorption capacity was evaluated for the principal absorption-inhibition constituent of OMW, mineral salts and for phytotoxic-components, the phenolic compounds. A double exponential model was established for electrical conductivities ranging 4.2-25,000 microS cm(-1). For solutions of phenolic compounds ranging 0-0.5 g l(-1), a distribution coefficient near unit was achieved, while for OMW, the phenolic compounds were concentrated inside the gel as the distribution coefficient was 1.4. Correction of OMW pH towards neutrality was found to increase the absorption capacity by up to 35%. The phytotoxicity was assessed by the germination of Lepidium sativum. Inhibition in plant growth occurred for all OMW dilutions without superabsorbent polymers application. For 5% of OMW (COD 5 gl(-1) and 200 ppm of phenolic compounds) immobilised in PNa2 (1 gl(-1)), plant growth was promoted being observed a 120% growth germination, thus indicating that olive mill wastewater detoxification occurred.     

Compartmentation of Phenolic Compounds and Phenylalanine Ammonia-Lyase in Leaves of Phyllanthus tenellus Roxb. and their Induction by Copper Sulphate

The compartmentation of phenolic compounds in mature leavesof Phyllanthus tenellus and their induction by copper sulphatewere analysed at histological and subcellular levels. Lightand electron microscopy studies demonstrated that the vacuolesof spongy cells were the main sites of phenolic accumulation.Spraying plants with copper sulphate induced punctated lesionsformed by groups of necrotic cells which accumulated brownishsubstances. Histochemical tests and fluorescence microscopyanalysis of the sprayed leaves indicated that the phenolic compoundsincreased in spongy cells within the lesions. Ultrastructuralanalyses showed that 3 h after elicitation, the organelles ofthe cells within the lesion started to collapse and the contentof phenolic substances increased in the vacuole of spongy cells.Antibody against phenylalanine ammonia-lyase (PAL) from parsleycross-reacted with the crude extract of P. tenellus leaves.Two isoforms, one of 65 kD and the other of 66 kD, were identified.Immunocytochemical studies showed that PAL was synthesized inthe palisade and spongy cells, mainly in the cytoplasm and chloroplasts.The phytotoxicity of Cu²⁺ions induced the accumulation of PALin sub-cellular compartments of palisade cells. PAL accumulationstarted to increase 3 h after elicitation and reached a maximumafter 6 h, decreasing 12 h post-induction. The increase of PALwas more evident in cells within the necrotic punctated regionsthan in surrounding cells. Since the vacuole of palisade cellsdid not accumulate phenolic compounds, the in situ studies suggestedthat the end products of PAL synthesis play a role in palisadecell wall reinforcement or might accumulate in other tissues.The symptoms induced by copper sulphate suggest that this abioticelicitor may be a useful tool in the understanding of the regulationof biosynthetic phenolic pathways inP. tenellus . Copyright2000 Annals of Botany Company Cell death, copper sulphate, heavy metal, immunolabelling, phenolic compounds, phenylalanine ammonia-lyase,Phyllanthus , transmission electron microscopy, ultrastructure     

The toxicity of a number of different bactericides to Clavibacter michiganense subsp. michiganense (Smith 1910) Jensen 1934 comb. nov. [basonym Corynebacterium michiganense pv. michiganense (AL)] and to the tomato plant, Lycopersicon esculentum

Twenty-seven proprietary products and pure chemicals were tested in vitro against cells of Clavibacter michiganense subsp. michiganense (Smith 1910) Jensen 1934 comb. nov. [basonym Corynebacterium michiganense pv. michiganense (AL)] (the cause of bacterial canker of tomato) and also for their phytotoxicity to tomato plants. The most bactericidal of these, with a minimum cidal concentration (MCC) range of > 10-< 100 μg/ml, were a phenolic product called Applied 3–78, two quaternary ammonium compounds (benzalkonium chloride and cetrimide), and a silver colloid compound. Of these, only Applied 3–78 was not phytotoxic at values of 10 μg/ml or less, although it was phytotoxic at 10000 μg/ml. Copper oxychloride and sodium hypochlorite were amongst the group with a middle range of bactericidal properties, their MCC range being from > 1000 to < 10000 μg/ml. They were phytotoxic at 1000 μg/ml or less. When organic matter, a dead yeast suspension, was added to Applied 3–78, Kohrsolin and Panacide, only the activity of Applied 3–78 was relatively unchanged. The MCC ranges were: Applied 3–78, >80–< 100 μg/ml; Kohrsolin, > 800-< 1000 μg/ml; and Panacide, > 1000 μg/ml. Phytotoxicity tests on 10 different tomato cultivars confirmed that Applied 3–78 was the least phytotoxic of these three products. Field trials on tomato crops showed that when Applied 3–78 was sprayed on the plants once, and Kohrsolin was either sprayed on or they were drenched with it once at 1000 μg/ml, no phytotoxicity symptoms developed.     

Interaction between heat shock proteins and antimicrobial peptides

Drosocin, pyrrhocoricin, and apidaecin, representing the short (18-20 amino acid residues) proline-rich antibacterial peptide family, originally isolated from insects, were shown to act on a target bacterial protein in a stereospecific manner. Native pyrrhocoricin and one of its analogues designed for this purpose protect mice from bacterial challenge and, therefore, may represent alternatives to existing antimicrobial drugs. Furthermore, this mode of action can be a basis for the design of a completely novel set of antibacterial compounds, peptidic or peptidomimetic, if the interacting bacterial biopolymers are known. Recently, apidaecin was shown to enter Escherichia coli and subsequently kill bacteria through sequential interactions with diverse target macromolecules. In this paper report, we used biotin- and fluorescein-labeled pyrrhocoricin, drosocin, and apidaecin analogues to identify biopolymers that bind to these peptides and are potentially involved in the above-mentioned multistep killing process. Through use of a biotin-labeled pyrrhocoricin analogue, we isolated two interacting proteins from E. coli. According to mass spectrometry, Western blot, and fluorescence polarization, the short, proline-rich peptides bound to DnaK, the 70-kDa bacterial heat shock protein, both in solution and on the solid-phase. GroEL, the 60-kDa chaperonin, also bound in solution. Control experiments with an unrelated labeled peptide showed that while binding to DnaK was specific for the antibacterial peptides, binding to GroEL was not specific for these insect sequences. The killing of bacteria and DnaK binding are related events, as an inactive pyrrhocoricin analogue made of all-D-amino acids failed to bind. The pharmaceutical potential of the insect antibacterial peptides is underscored by the fact that pyrrhocoricin did not bind to Hsp70, the human equivalent of DnaK. Competition assay with unlabeled pyrrhocoricin indicated differences in GroEL and DnaK binding and a probable two-site interaction with DnaK. In addition, all three antibacterial peptides strongly interacted with two bacterial lipopolysaccharide (LPS) preparations in solution, indicating that the initial step of the bacterial killing cascade proceeds through LPS-mediated cell entry.     

Nature of the Interference Mechanism of Sugarcane (Saccharum officinarum L.) Straw

Sugarcane (Saccharum officinarum L.) straw left in the field after harvest interferes with the growth of winter and summer weeds. In the last years, there was a progressive move away from burning sugarcane straw to retaining it on the soil surface after harvest to prevent soil degradation and environmental pollution. Water-soluble phenolics leachated from straw into soil may suppress weed growth. A study was carried out to investigate (1) the effect of biotic (unautoclaved) soil treated with burned and unburned sugarcane straw leachates on seedling growth and foliar proline content of beggarticks (Bidens subalternans L.) and wild mustard (Brassica campestris L.), (2) the modification of sugarcane straw phytotoxicity in abiotic (autoclaved) soil and biotic (unautoclaved) soil plus activated charcoal, and (3) changes of inorganic ions and phenolic contents in biotic soil after treatment with burned and unburned sugarcane straw leachate. Unburned straw leachate significantly inhibited root elongation of 7-d-old beggarticks and wild mustard seedlings. Burned straw leachate did not affect seedling growth of the assayed weeds suggesting that organic straw phytotoxins were involved. Experiments with activated charcoal, however, did not provide clear evidence supporting the involve of organic molecules in straw phytotoxicity. Unburned straw leachate incorporated in biotic soil was more inhibitory than in abiotic soil on root growth suggesting that microbial activity is involved in sugarcane straw interference. There was no evidence of nutrient microbial immobilization. Unburned sugarcane straw leachate increased total phenolic content in biotic soil more than in abiotic soil or biotic soil plus charcoal. Burned sugarcane straw leachate did not increase phenolic compounds levels in biotic soil. Linear regression analysis indicated a strong correlation between levels of soil phenolic contents and root growth inhibition. Soil characteristics evaluated in soil treated with burned and unburned sugarcane straw leachate suggest that straw phytotoxicity is related with organic molecules, such as phenolic compounds, rather than to variations in inorganic nutrients. Unburned straw leachate induced proline accumulation in seedling leaves of both beggarticks and wild mustard. Proline foliar content was higher in seedlings grown in biotic soil than in seedlings grown in biotic soil plus charcoal suggesting that straw organic constituents induced proline accumulation. Proline foliar content of seedlings grown in biotic soil treated with burned straw leachate was not significantly different from water control. The present study showed that sugarcane straw leachate interferes with seedling growth of beggarticks and wild mustard and that water-soluble phenolics can play a role in the seedling growth inhibition of the assayed weeds.     

Inhibitory effect of phenolic compounds and marine bacteria on larval settlement of the barnacle Balanus amphitrite amphitrite darwin

This study examined the inhibitory effect of 3 phenolic compounds and 12 strains of marine bacteria on the larval settlement of Balanus amphitrite amphitrite. The phenolic compounds used were phlorotannins, phloroglucinol and tannic acid. Phlorotannins are polymers of phloroglucinol (1,3,5‐trihydroxybenzene) known only from brown algae. Tannic acid, which exists in terrestrial plants, is composed of oligomers of phloroglucinol attached to a sugar molecule. The bacterial strains used were isolated from a natural biofilm. The following were investigated: 1) the toxicity of the phenolic compounds to B. a. amphirite in three different larval stages, viz. nauplius II, nauplius V and cyprid; 2) the potency of the compounds as inhibitors of larval settlement and the possible mechanism involved in settlement inhibition; and 3) the effects of the bacteria on larval settlement. The level of toxicity of the phenolic compounds varied widely for the larvae. Phlorotannins were most toxic, having LC₅₀ values ranging from 9.47 to 40.35 μg ml^‐1; phloroglucinol was least toxic, having LC₅₀ values of 235.12 to 368.28 μg ml^‐1. In general, nauplii were more sensitive to the toxicity of the phenolic compounds than cyprids. The greater sensitivity of nauplii may be due to their active feeding behavior, which exposes the interior of their bodies to the compounds by active intake. Phloroglucinol was the most potent settlement inhibitor, having an EC₅₀ value of 0.02 μg ml^‐1. Phlorotannins and tannic acid had EC₅₀ values of 1.90 μg ml^‐1 and 14.05 μg ml^‐1, respectively. Phloroglucinol appeared to inhibit larval settlement through a relatively non‐toxic mechanism as its LC₅₀ value was four orders of magnitude higher than its EC₅₀ value. The high potency of phloroglucinol indicates that a simple constituent of a complex natural compound can be more effective than the natural compound itself. Larval settlement bioassays with monospecies bacterial films indicated that some of the bacterial species were inhibitory to larval settlement while the others showed no effect. None of the bacterial strains in this study induced larval settlement.     

Simultaneous consumption and production of fluorescent dissolved organic matter by lake bacterioplankton

Recent evidence suggests a key role of bacterioplankton in shaping the composition of the dissolved organic matter (DOM) pool in aquatic systems, not only through consumption but also through production of specific compounds, but the latter process is still not well understood. We used a bioassay approach to assess the patterns in bacterial production and consumption of five fluorescent DOM pools in seven lakes and two streams in Southeastern Québec, Canada, and the links these patterns may have with key aspects of bacterial metabolism, DOM origin and nutrients availability. Total dissolved organic C declined by 3-15% during these incubations, whereas the specific DOM pools had very different dynamics: Two humic-like fractions accumulated in all incubations, with rates of production increasing as a function of bacterial growth efficiency, which itself increased with phosphorus concentrations. In contrast, two protein-like fractions and a third humic-like fraction either increased or declined over the course of the experiments. The net production or consumption of these pools appeared to be a function of the contribution of terrestrial C to bulk DOM (derived from δ(13) C of the DOM) and of total bacterial activity. Our results suggest that lake bacterioplankton play a dual role in DOM dynamics, as consumers and also producers, and that the interplay between DOM origin and nutrient availability appears to determine the net outcome of bacterial DOM processing, thus influencing the bulk DOM composition and its fate in these aquatic systems.     

Effect of microorganisms on the phytotoxicity of herbicides. VI. Modification of venzar activity by bacterial cultures

Interactions between two bacterial strains and venzar were compared. It was found that the mechanism of interactions is various and causes the modification of herbicide phytotoxicity. Metabolites of Bacillus subtilis 72 interfered with herbicide by affecting physiological processes in plant tissues and enhancing its inhibitory influence. Arthrobacter sp. 18 strain decreased the phytoinhibitory effect of herbicide due to conjugation with the carrier from venzar.     

Interaction between dialkylamines and bacterial agmatinase]

It was demonstrated that aliphatic dialkylamines are more effective inhibitors of bacterial agmatinase than monoalkylamines and differ from the latter by the type of inhibition. The dependence of the inhibition constant on the hydrophobicity of the compounds tested was studied. The type of this dependence was found to be different for long- and short-radical dialkylamines, the correlation equation appearing as 1g(1/Ki) = 0,33 1gPo + (2,3 +/- 0,2) for the former compounds and as 1g(1/Ki) = 1,0 1gPo + (2,2 +/- 0,2) for the latter. The enzyme inhibition by the inhibitors tested was dependent on pH: e. g. with an increase in pH the inhibiting effect was decreased. It was assumed that the inhibitor sorption by agmatinase is of hydrophobic-ionic type and that the active site of the enzyme contains two hydrophobic zones separated by a nucleophylic group. The length of the hydrophoblic zones was estimated.     

Interaction of olive oil phenol antioxidant components with low-density lipoprotein

Phenolic compounds have shown to inhibit LDL oxidation in vitro and ex vivo; however, they are hydrosoluble compounds while LDL is a lipoprotein. Analysis of phenolic compounds in LDLs by HPLC is necessary to demonstrate their binding capacity to lipoproteins. We developed and validated a solid phase extraction method (SPE) that allowed us the purification of LDL samples and their analysis by HPLC. This methodology allowed us to demonstrate the in vitro binding capacity of tyrosol, one of the main phenolic compounds in olive oil, to LDL. In the intervention dietary study with volunteers, food rich in phenolic compounds affected LDL composition. Changes in LDL phenolics composition are not observed after the short-term ingestion of food rich in phenolic compounds. However, after one week of olive oil consumption and Mediterranean diet there was an increase in phenolics (p=0.021). An accumulative effect seems necessary to observe significative differences in LDL phenolic composition.     

Major phenolic compounds in olive oil: metabolism and health effects

It has been postulated that the components in olive oil in the Mediterranean diet, a diet which is largely vegetarian in nature, can contribute to the lower incidence of coronary heart disease and prostate and colon cancers. The Mediterranean diet includes the consumption of large amounts of olive oil. Olive oil is a source of at least 30 phenolic compounds. The major phenolic compounds in olive oil are oleuropein, hydroxytyrosol and tyrosol. Recently there has been a surge in the number of publications that has investigated their biological properties. The phenolic compounds present in olive oil are strong antioxidants and radical scavengers. Olive "waste water" also possesses compounds which are strong antioxidant and radical scavengers. Typically, hydroxytyrosol is a superior antioxidant and radical scavenger to oleuropein and tyrosol. Hydroxytyrosol and oleuropein have antimicrobial activity against ATTC bacterial strains and clinical bacterial strains. Recent syntheses of labeled and unlabelled hydroxytyrosol coupled with superior analytical techniques have enabled its absorption and metabolism to be studied. It has recently been found that hydroxytyosol is renally excreted unchanged and as the following metabolites as its glucuronide conjugate, sulfate conjugate, homovanillic acid, homovanillic alcohol, 3,4-dihydroxyphenylacetic acid and 3,4-dihydroxyphenylacetaldehyde. Studies with tyrosol have shown that it is excreted unchanged and as its conjugates. This review summarizes the antioxidant abilities; the scavenging abilities and the biological fates of hydroxytyrosol, oleuropein and tyrosol which have been published in recent years.     

Removal of phytotoxic compounds from torrefied grass fibres by plant-beneficial microorganisms

We aimed to select microorganisms colonizing torrefied grass fibres (TGF) and simultaneously reducing the phytotoxicity which appeared after heat treatment of the fibres. Eighty-eight bacterial strains and one fungus, previously isolated from a sequential enrichment experiment on torrefied fibres and extracts, were tested separately for their capacity to decrease phytotoxicity. Eleven of the bacterial strains and the fungus significantly reduced phytotoxicity. These organisms were checked for their ability to grow on agar containing phenol, 2-methoxyphenol, 2,6-dimethoxyphenol, 2-furalaldehyde, pyrrole-2-carboxaldehyde and furan-2-methanol as sole carbon sources. The fungus F/TGF15 and the bacterial strain 66/TGF15 were able to grow on all six compounds. Strains 15/TGE5, 23/TGE5, 43/TGE20, 56/TGF10 and 95/TGF15 grew on two to four compounds, and strain 72/TGF15 only on one compound. Strains 31/TGE5, 34/TGE5, 48/TGE20 and 70/TGF15 did not grow on any of the single toxic compounds. GC analyses of torrefied grass extracts (TGE) determined which compounds were removed by the microorganisms. F/TGF15 was the only isolate depleting phenol, 2-methoxyphenol, 2-dihydrofuranone and pyrrole-2,5-dione-3-ethyl-4-methyl. Strains 15/TGE5, 23/TGE5, 31/TGE5 and 56/TGF10, and the fungus depleted 2-furalaldehyde, 2-furan-carboxaldehyde-5-methyl, pyrrole-2-carboxaldehyde, 5-acetoxymethyl-2-furaldehyde and benzaldehyde-3-hydroxy-4-methoxy. These promising candidates for colonizing and simultaneously reducing the phytotoxicity of TGF were affiliated with Pseudomonas putida, Serratia plymuthica, Pseudomonas corrugata, Methylobacterium radiotolerans and Coniochaeta ligniaria.