Effective bioremoval and detoxification of textile dye mixture by Alishewanella sp. KMK6

Alishewanella sp. strain KMK6 was able to degrade mixture of textile dyes (0.5–2.0 g?l^?1) within 8 h. An initial 28 % reduction in COD was observed immediately after decolorization at static anoxic conditions which on further incubation at shaking conditions reduced by 90 %. Partially purified azoreductase was able to utilize different azo dyes as substrates. The HPLC profile of dye degradation showed formation of metabolic products. Further FTIR analysis showed significant changes in the peaks corresponding to functional groups present in dye mixture and its degradation products. The genotoxicity assessment showed that the dye degradation products were non-toxic compared to dye mixture.     

Degradation of a tannery and textile dye,Navitan Fast Blue S5R by Pseudomonas aeruginosa

The degradation of Navitan Fast Blue S5R, a very important commercial diazo dye in the tannery and textile industries was investigated. Pseudomonas aeruginosa decolourized this dye at concentrations upto 1200 mg l^–1 and the organism was also able to decolourize various other tannery dyes at different levels. The organism required ammonium salts and glucose to co-metabolize the dye. Organic nitrogen sources did not support appreciable decolourization whereas, combined with inorganic nitrogen (NH₄NO₃) there was an increased effect on both growth and decolourization. Decolourization of this dye started when the organism reached late exponential growth phase and after 24 h of incubation nearly 90% of 100 mg l^–1 of the dye was decolourized. An oxygen insensitive azoreductase was involved in the decolourization mechanism. HPLC analysis confirmed the formation of metanilic acid from the dye, which on further incubation was completely metabolized under shaken culture condition.     

Physiological and biochemical studies on Fusarium oxysporum f. sp. lycopersici race 2 for its biocontrol by nonpathogenic fungi

Abstract The self-degradation of the phytopathogenic fungus Fusarium oxysporum f. sp. lycopersici race 2 ( F. oxysporum l. 2), which reached an autolysis degree of 72% after 60 days of incubation in stationary culture, occurred principally during the first 14 days of incubation, when considerable β-(1,3)-glucanase, pectinase, xylanase and chitinase activities were detected in the culture fluids. The levels of β-(1,3)-glucanase, pectinase, cellulase, chitinase and xylanase activities increased in the culture fluids of this fungus, when the culture medium was supplemented with different inducers. The vegetable juice (V8) that contained tomato juice, was the best inducer for most of these activities. Chitosan, glucosamine oligomers and Mucor rouxii mycelium extract were found to have an inhibitory effect on F. oxysporum l. 2 growth. When incubating cell walls from young mycelia of F. oxysporum l. 2 with enzymic precipitates obtained from autolyzed cultures of Mucor rouxii, Aspergillus nidulans, Penicillin oxalicum and Penicillium purpurogenum , degradations of 45%, 22%, 21% and 12%, respectively, were detected.     

Decolorization of the textile dyes by newly isolated bacterial strains

Six bacterial strains with the capability of degrading textile dyes were isolated from sludge samples and mud lakes. Aeromonas hydrophila was selected and identified because it exhibited the greatest color removal from various dyes. Although A. hydrophila displayed good growth in aerobic or agitation culture (AGI culture), color removal was the best in anoxic or anaerobic culture (ANA culture). For color removal, the most suitable pH and temperature were pH 5.5-10.0 and 20-35 degrees C under anoxic culture (ANO culture). More than 90% of RED RBN was reduced in color within 8 days at a dye concentration of 3,000 mg l(-1). This strain could also decolorize the media containing a mixture of dyes within 2 days of incubation. Nitrogen sources such as yeast extract or peptone could enhance strongly the decolorization efficiency. In contrast to a nitrogen source, glucose inhibited decolorization activity because the consumed glucose was converted to organic acids that might decrease the pH of the culture medium, thus inhibiting the cell growth and decolorization activity. Decolorization appeared to proceed primarily by biological degradation.     

Denitrification by the mix-culturing of fungi and bacteria with shell

Denitrification by pure and mixed culture of Fusarium oxysporum and Pseudomonas stutzeri in different mineral medium and in synthetic wastewater were examined. The results obtained revealed that a rapid N2 evolution by F. oxysporum and P. stutzeri in mineral medium and synthetic wastewater was observed. In co-cultures of F. oxysporum and P. stutzeri, N2O produced by F. oxysporum was rapidly consumed by P. stutzeri. This indicated that mixed culture of F. oxysporum and P. stutzeri could be used for efficient nitrate and nitrite removal. Using synthetic wastewater, about 87% of nitrate was reduced by co-denitrification of F. oxysporum and P. stutzeri after incubation for 6 days. In the further denitrification tests, the interaction of shell and mixed culture of F. oxysporum and P. stutzeri was investigated. The dinitrogen was rapidly evolved (442.48 micromol N2 produced from 1.0 mmol of NO3(-) in 36 h). These results clearly showed that shell provide a suitable microenvironment for P. stutzeri, which is beneficial to the denitrification.     

Differentiation of Fusarium oxysporum from Fusarium solani by growth and pigmentation on media containing sugar alcohols

The growth and pigmentation of 99 strains of Fusarium , mainly of Fusarium oxysporum and F. solani , on ammonium salts agar containing either mannitol, sorbitol or xylitol as sole source of carbon is described. After 7–14 d incubation strains of F. oxysporum could be distinguished from F. solani by both their pigmentation and the size and shape of conidiogenous cells. The application of these media to routine screening of isolates is discussed.     

Pseudomonas aeruginosa (GRC1) as a strong antagonist of Macrophomina phaseolina and Fusarium oxysporum

A plant growth promotory bacterial strain, isolated from the potato rhizosphere, was characterized as Pseudomonas aeruginosa (GRC1). The isolate produced an hydroxamate type of siderophore after 48 h of incubation on tryptic soy medium under iron deficient conditions. The in vitro antifungal activity of P. aeruginosa was tested against two soil-borne plant pathogens, Macrophomina phaseolina and Fusarium oxysporum. The antagonistic behaviour of the isolate was tested by dual culture technique. The growth inhibition of M. phaseolina and F. oxysporum was 74.1% and 70.5%, respectively, after 5 days of incubation. The production of hydrocyanic acid and indole acetic acid was also recorded under normal growth conditions.     

Fungal multienzyme production on industrial by-products of the citrus-processing industry

Orange peels is the principal solid by-product of the citrus processing industry and the disposal of the fresh peels is becoming a major problem to many factories. Dry citrus peels are rich in pectin, cellulose and hemicellulose and may be used as a fermentation substrate. Production of multienzyme preparations containing pectinolytic, cellulolytic and xylanolytic enzymes by the mesophilic fungi Aspergillus niger BTL, Fusarium oxysporum F3, Neurospora crassa DSM 1129 and Penicillium decumbens under solid-state fermentation (SSF) on dry orange peels was enhanced by optimization of initial pH of the culture medium and initial moisture level. Under optimal conditions A. niger BTL was by far the most potent strain in polygalacturonase and pectate lyase, production followed by F. oxysporum F3, N. crassa DSM 1129 and P. decumbens. N. crassa DSM 1129 produced the highest endoglucanase activity and P. decumbens the lowest one. Comparison of xylanase production revealed that A. niger BTL produced the highest activity followed by N. crassa DSM 1129, P. decumbens and F. oxysporum F3. N. crassa DSM 1129 and P. decumbens did not produce any beta-xylosidase activity, while A. niger BTL produced approximately 10 times more beta-xylosidase than F. oxysporum F3. The highest invertase activity was produced by A. niger BTL while the lowest ones by F. oxysporum F3 and P. decumbens. After SSF of the four fungi, under optimal conditions, the fermented substrate was either directly exposed to autohydrolysis or new material was added, and the in situ produced multienzyme systems were successfully used for the partial degradation of orange peels polysaccharides and the liberation of fermentable sugars.     

Volatile organic compounds: a potential direct long-distance mechanism for antagonistic action of Fusarium oxysporum strain MSA 35

Fusarium oxysporum MSA 35 [wild-type (WT) strain] is an antagonistic Fusarium that lives in association with a consortium of bacteria belonging to the genera Serratia, Achromobacter , Bacillus and Stenotrophomonas in an Italian soil suppressive to Fusarium wilt. Typing experiments and virulence tests provided evidence that the F. oxysporum isolate when cured of the bacterial symbionts [the cured (CU) form], is pathogenic, causing wilt symptoms identical to those caused by F. oxysporum f. sp. lactucae . Here, we demonstrate that small volatile organic compounds (VOCs) emitted from the WT strain negatively influence the mycelial growth of different formae speciales of F. oxysporum. Furthermore, these VOCs repress gene expression of two putative virulence genes in F. oxysporum lactucae strain Fuslat10, a fungus against which the WT strain MSA 35 has antagonistic activity. The VOC profile of the WT and CU fungus shows different compositions. Sesquiterpenes, mainly caryophyllene, were present in the headspace only of WT MSA 35. No sesquiterpenes were found in the volatiles of ectosymbiotic Serratia sp. strain DM1 and Achromobacte r sp. strain MM1. Bacterial volatiles had no effects on the growth of the different ff. spp. of F. oxysporum examined. Hyphae grown with VOC from WT F. oxysporum f. sp. lactucae strain MSA 35 were hydrophobic whereas those grown without VOCs were not, suggesting a correlation between the presence of volatiles in the atmosphere and the phenotype of the mycelium. This is the first report of VOC production by antagonistic F. oxysporum MSA 35 and their effects on pathogenic F. oxysporum. The results obtained in this work led us to propose a new potential direct long-distance mechanism for antagonism by F. oxysporum MSA 35 mediated by VOCs . Antagonism could be the consequence of both reduction of pathogen mycelial growth and inhibition of pathogen virulence gene expression.     

Decolorization of textile indigo dye by ligninolytic fungi

The indigo dye is extensively used by textile industries and is considered a recalcitrant substance, which causes environmental concern. Chemical products used on textile processing, which affect the environment through effluents, can be voluminous, colored and varied. Vat textile dyes, like indigo, are often used and dye mainly cellulosic fibers of cotton. Decolorization of this dye in liquid medium was tested with ligninolytic basidiomycete fungi from Brazil. Decolorization started in a few hours and after 4 days the removal of dye by Phellinus gilvus culture was in 100%, by Pleurotus sajor-caju 94%, by Pycnoporus sanguineus 91% and by Phanerochaete chrysosporium 75%. No color decrease was observed in a sterile control. Thin layer chromatography of fungi culture extracts revealed only one unknown metabolite of Rf=0.60, as a result of dye degradation.     

Tomatinase from Fusarium oxysporum f. sp. lycopersici is required for full virulence on tomato plants

Saponin detoxification enzymes from pathogenic fungi are involved in the infection process of their host plants. Fusarium oxysporum f. sp lycopersici, a tomato pathogen, produces the tomatinase enzyme Tom1, which degrades alpha-tomatine to less toxic derivates. To study the role of the tom1 gene in the virulence of F. oxysporum, we performed targeted disruption and overexpression of the gene. The infection process of tomato plants inoculated with transformants constitutively producing Tom1 resulted in an increase of symptom development. By contrast, tomato plants infected with the knockout mutants showed a delay in the disease process, indicating that Tom1, although not essential for pathogenicity, is required for the full virulence of F. oxysporum. Total tomatinase activity in the disrupted strains was reduced only 25%, leading to beta(2)-tomatine as the main hydrolysis product of the saponin in vitro. In silico analysis of the F. oxysporum genome revealed the existence of four additional putative tomatinase genes with identities to tomatinases from family 3 of glycosyl hydrolases. These might be responsible for the remaining tomatinase activity in the Deltatom1 mutants. Our results indicate that detoxification of alpha-tomatine in F. oxysporum is carried out by several tomatinase activities, suggesting the importance of these enzymes during the infection process.     

Decolorisation, biodegradation and detoxification of benzidine based azo dye

The present study deals with the decolorisation, biodegradation and detoxification of Direct Black-38, a benzidine based azo dye, by a mixed microbial culture isolated from an aerobic bioreactor treating textile wastewater. The studies revealed a biotransformation of Direct Black-38 into benzidine and 4-aminobiphenyl followed by complete decolorisation and biodegradation of these toxic intermediates. From cytotoxicity studies, it was concluded that detoxification of the dye took place after degradation of the toxic intermediates by the culture.     

Antifungal activity and enhancement of plant growth by Bacillus cereus grown on shellfish chitin wastes

Bacillus cereus QQ308 produced antifungal hydrolytic enzymes, comprising chitinase, chitosanase and protease, when grown in a medium containing shrimp and crab shell powder (SCSP) produced from marine waste. The growth of the plant-pathogenic fungi Fusarium oxysporum, Fusarium solani, and Pythium ultimum were considerably affected by the presence of the QQ308 culture supernatant. The supernatant inhibited spore germination and germ tube elongation of F. oxysporum, F. solani, and P. ultimum. The increase in the growth time of the fungal culture was associated with a gradual decrease in inhibition. Besides antifungal activity, QQ308 enhanced growth of Chinese cabbage. These characteristics were unique among known strains of B. cereus. To our knowledge, this is the first report on the antifungal and Chinese cabbage growth enhancing compounds produced by B. cereus.     

Partially purified bitter gourd (Momordica charantia) peroxidase catalyzed decolorization of textile and other industrially important dyes

The aim of this study was to evaluate the enzymatic action of partially purified bitter gourd peroxidase for the degradation/decolorization of complex aromatic structures. Twenty-one dyes, with a wide spectrum of chemical groups, currently being used by the textile and other important industries have been selected for the study. Here, for the first time we have shown peroxidases from Momordica charantia (300 EU/gm of vegetable) to be highly effective in decolorizing industrially important dyes. Dye solutions, containing 50-200 mg dye/l, were used for the treatment with bitter gourd peroxidase (specific activity of 99.0 EU/mg protein). M. charantia peroxidases were able to decolorize most of the textile dyes by forming insoluble precipitate. When the textile dyes were treated with increasing concentration of enzyme, it was observed that greater fraction of the color was removed but four out of eight reactive dyes were recalcitrant to decolorization by bitter gourd peroxidase. Step-wise addition of enzyme to the decolorizing reaction mixture at the interval of 1h further enhanced the dye decolorization. The rate of decolorization was enhanced when the dyes were incubated with fixed quantity of enzyme for increasing times. Decolorization of non-textile dyes resulted in the degradation and removal of dyes from the solution without any precipitate formation. Decolorization rate was drastically increased when the textile and other industrially important non-textile dyes were treated with bitter gourd peroxidase in presence of 1.0 mM 1-hydroxybenzotriazole. Complex mixtures of dyes were prepared by taking three to four reactive textile and non-textile dyes in equal proportions. Each mixture was decolorized by more than 80% when treated with the enzyme in presence of 1.0 mM 1-hydroxybenzotriazole. Our data suggest that the peroxidase/mediator system is an effective biocatalyst for the treatment of effluents containing recalcitrant dyes from textile, dye manufacturing, dyeing and printing industries.     

Characterization of the gene encoding pisatin demethylase (FoPDA1) in Fusarium oxysporum

The pea pathogen Fusarium oxysporum f. sp. pisi is able to detoxify pisatin produced as a defense response by pea, and the gene encoding this detoxification mechanism, FoPDA1, was 82% identical to the cytochrome P450 pisatin demethylase PDA1 gene in Nectria haematococca. A survey of F. oxysporum f. sp. pisi isolates demonstrated that, as in N. haematococca, the PDA gene of F. oxysporum f. sp. pisi is generally located on a small chromosome. In N. haematococca, PDA1 is in a cluster of pea pathogenicity (PEP) genes. Homologs of these PEP genes also were found in the F. oxysporum f. sp. pisi isolates, and PEP1 and PEP5 were sometimes located on the same small chromosomes as the FoPDA1 homologs. Transforming FoPDA1 into a pda(?) F. oxysporum f. sp. lini isolate conferred pda activity and promoted pathogenicity on pea to some transformants. Different hybridization patterns of FoPDA1 were found in F. oxysporum f. sp. pisi but these did not correlate with the races of the fungus, suggesting that races within this forma specialis arose independently of FoPDA1. FoPDA1 also was present in the formae speciales lini, glycines, and dianthi of F. oxysporum but they had mutations resulting in nonfunctional proteins. However, an active FoPDA1 was present in F. oxysporum f. sp. phaseoli and it was virulent on pea. Despite their evolutionary distance, the amino acid sequences of FoPDA1 of F. oxysporum f. sp. pisi and F. oxysporum f. sp. phaseoli revealed only six amino acid differences, consistent with a horizontal gene transfer event accounting for the origin of these genes.     

Defense responses of Fusarium oxysporum to 2,4-diacetylphloroglucinol, a broad-spectrum antibiotic produced by Pseudomonas fluorescens

A collection of 76 plant-pathogenic and 41 saprophytic Fusarium oxysporum strains was screened for sensitivity to 2,4-diacetylphloroglucinol (2,4-DAPG), a broad-spectrum antibiotic produced by multiple strains of antagonistic Pseudomonas fluorescens. Approximately 17% of the F. oxysporum strains were relatively tolerant to high 2,4-DAPG concentrations. Tolerance to 2,4-DAPG did not correlate with the geographic origin of the strains, formae speciales, intergenic spacer (IGS) group, or fusaric acid production levels. Biochemical analysis showed that 18 of 20 tolerant F. oxysporum strains were capable of metabolizing 2,4-DAPG. For two tolerant strains, analysis by mass spectrometry indicated that deacetylation of 2,4-DAPG to the less fungitoxic derivatives monoacetylphloroglucinol and phloroglucinol is among the initial mechanisms of 2,4-DAPG degradation. Production of fusaric acid, a known inhibitor of 2,4-DAPG biosynthesis in P. fluorescens, differed considerably among both 2,4-DAPG-sensitive and -tolerant F. oxysporum strains, indicating that fusaric acid production may be as important for 2,4-DAPG-sensitive as for -tolerant F. oxysporum strains. Whether 2,4-DAPG triggers fusaric acid production was studied for six F. oxysporum strains; 2,4-DAPG had no significant effect on fusaric acid production in four strains. In two strains, however, sublethal concentrations of 2,4-DAPG either enhanced or significantly decreased fusaric acid production. The implications of 2,4-DAPG degradation, the distribution of this trait within F. oxysporum and other plant-pathogenic fungi, and the consequences for the efficacy of biological control are discussed.     

Aerobic degradation of a mixture of azo dyes in a packed bed reactor having bacteria-coated laterite pebbles

A microbial consortium capable of aerobic degradation of a mixture of azo dyes consisting of two isolated strains (RRL,TVM) and one known strain of Pseudomonas putida (MTCC 1194) was immobilized on laterite stones. The amount of bacterial biomass attached to the laterite stones was 8.64 g per 100 g of the stone on a dry weight basis. The packed bed reactor was filled with these stones and had a total capacity of 850 mL and a void volume of 210 mL. The feed consisted of an equal mixture of seven azo dyes both in water as well as in a simulated textile effluent, at a pH of 9.0 and a salinity of 900 mg/L. The dye concentrations of influent were 25, 50, and 100 microg/mL.The residence time was varied between 0.78 and 6.23 h. It was found that at the lowest residence time 23.55, 45.73, and 79.95 microg of dye was degraded per hour at an initial dye concentration of 25, 50, and 100 microg, respectively. The pH was reduced from 9.0 to 7.0. Simulated textile effluent containing 50 microg/mL dye was degraded by 61.7%. Analysis of degradation products by TLC and HPLC showed that the dye mixture was degraded to nontoxic smaller molecules. The bacteria-coated pebbles were stable, there was no washout even after 2 months, and the reactor was found to be suitable for the aerobic degradation of azo dyes.     

Decolorization of Textile Dyes and Degradation of Mono-Azo Dye Amaranth by <Emphasis Type="Italic">Acinetobacter calcoaceticus</Emphasis> NCIM 2890

Acinetobacter calcoaceticus NCIM 2890 (A. caloaceticus) was found to decolorize 20 different textile dyes of various classes. Decolorization of an azo dye amaranth was observed effectively (91%) at static anoxic condition, whereas agitated culture grew well but showed less decolorization (68%) within 48 h of incubation. Induction of intracellular and extracellular lignin peroxidase, intracellular laccase, dichlorophenol indophenol (DCIP) reductase and riboflavin reductase represented their involvement in the biodegradation of amaranth. The products obtained after degradation of Amaranth were characterized as naphthalene sulfamide, hydroxyl naphthalene diazonium and naphthalene diazonium. The germination and growth of Sorghum vulgare and Phaseolus mungo seeds, and the growth of E. coli and Bacillus substilis were not inhibited by the metabolic products of the dye.     

Detoxification of azo dyes mediated by cell-free supernatant culture with manganese-dependent peroxidase activity: effect of Mn2+ concentration and H2O2 dose

White-rot fungi (WRF) are capable of degrading complex organic compounds such as lignin, and the enzymes that enable these processes can be used for the detoxification of recalcitrant organopollutants. The aim of this study is to evaluate a system based on the use of an in vitro ligninolytic enzyme for the detoxification of recalcitrant dye pollutants. The dyes selected for investigation were the anionic and cationic commercial azo dyes, basic blue 41 (BB41), acid black 1 (AB1), and reactive black 5 (RB5). A supernatant, cell-free culture of WRF with manganese peroxidase activity was used to investigate its degradative capacity under various conditions, and concentrations of cofactors, H(2)O(2) and Mn(2+). The assays were carried out using a 2(2) experimental designs whose variables were concentration of Mn(2+) (33 and 1,000 μM) and semicontinuous dosage of the H(2)O(2) (0.02 and 0.10 μmol) added at a frequency of 0.2 min(-1). The response variables analyzed were the efficiency and the initial rate of the decolorization process. The dye concentrations considered ranged from 10 to 200 mg L(-1). AB1 and RB5 were decolorized over the entire interval of concentrations studied; reaching efficiencies between 15 and 95%. Decolorization of up to 100 mg L(-1), BB41 had less than 30% efficiency. The decay of the concentration of AB1 was interpreted by two-stage kinetics model, with the exception of the condition of 33 μM Mn(2+)-0.02 μmol of H(2)O(2) in which only one stage was observed. For all assays performed with 33 μM Mn(2+), the initial rate of the decolorization process was found to be dependent on the dosage of H(2)O(2). The results of this study can be applied to the development bioreactors for the degradation of recalcitrant pollutants from the textile industry and may be used as a model for expanding the use of extracellular enzyme supernatants in bioremediation.     

Decolorization of textile plant effluent by Citrobacter sp. strain KCTC 18061P

Citrobacter sp. strain KCTC 18061P was found to be able to decolorize textile plant effluent containing different types of reactive dyes. Effects of physico-chemical parameters, such as aeration, nitrogen source, glucose and effluent concentrations on the color removal of real dye effluent by this strain were investigated. The observed changes in the visible spectra indicated color removal by the absorption of dye to cells during incubation with the strain. This strain showed higher decolorization ability under aerobic than static culture conditions. With 1% glucose, this strain removed 70% of effluent color within 5 days. Decolorization was not significantly dependent on the nitrogen sources tested. Chemical oxygen demand (COD) and biological oxygen demand (BOD) were decreased in proportion to incubation times, and their removal rates were about 35% and 50%, respectively, at 7 days of culture.