Development of a process for biodetoxification of metal cyanides from waste waters

A bacterial consortium capable of utilising metal cyanides as a source of nitrogen was used to develop a microbiological process for the detoxification of metal cyanides (viz. copper cyanide and zinc cyanide) from electroplating waste water. Optimal conditions biodegradation of both the metal-cyanide compounds were pH 7.5, temperature 35°C, inoculum size 10⁹ cells per ml and glucose or sugarcane molasses requirement of 5 mM or 0.6 ml/l, respectively. Metal precipitates obtained during metal-cyanide biodegradation were identified as metal-hydroxides. When the treatment was carried out in a 27 l rotating biological contactor (RBC) in continuous mode, the system could achieve >99.9% removal of 0.5 mM metal cyanide (ca. 52 mg/l cyanide and 30–40 mg/l copper/zinc) in 15 h with sugarcane molasses as carbon source. The RBC treated effluent was found to be safe for discharge in the environment as confirmed by chemical analysis and fish bioassay studies.     

Isolation of an aboriginal bacterial community capable of utilizing cyanide, thiocyanate, and ammonia from metallurgical plant wastewater

An aboriginal bacterial community capable of degrading cyanide (10 mg/l) and thiocyanate (2 g/l) and eliminating ammonia (120 mg/l) had been isolated from recycled water samples after blast-furnace gas purification of a metallurgical plant wastewater. It was shown that the optimal conditions for this bacterial community were as follows: temperature, 34 degrees C; pH, 8.8-9.0; available organic matter concentration (glucose equivalent), 5 g/l; and dissolved O2 concentration, 8-10 mg/l. This aboriginal community was formed by the bacteria belonging to the genus Pseudomonas.     

Studies on the resistance of activated sludge bacteria to high concentrations of methanol, butanol, glycol, cyclohexanone and cyclohexylamine

The resistance of bacterial strains isolated from activated sludge purifying petrochemical wastewaters to high concentrations of methanol, butanol, glycol, cyclohexanone and cyclohexylamine was examined. The strains were found to be resistant to up to 5000 mg/l of methanol, butanol and glycol. Cyclohexylamine in concentration 1500 mg/l completely inhibited the growth of all examined strains whereas cyclohexanone even at concentration 4500 mg/l eliminated only about half of the isolated strains. The highest resistance to cyclohexane derivatives was shown by bacteria belonging to Pseudomonas III. None of the studied strains was, however, able to utilize cyclohexanone and cyclohexylamine as a source of barbon and energy.     

A stable isotope dilution assay for the quantification of the Pseudomonas quinolone signal in Pseudomonas aeruginosa cultures

A stable isotope dilution method was developed to analyse 2-heptyl-3,4-dihydroxyquinoline, also called the Pseudomonas quinolone signal (PQS), directly in Pseudomonas aeruginosa cultures by liquid chromatography coupled to mass spectrometry (LC/MS). PQS, along with the isobaric 2-heptyl-4-hydroxyquinoline N-oxide (HQNO), were quantified in various Pseudomonas liquid cultures using a deuterated PQS analog as internal standard. The kinetic of production of these quinolines in a growing culture of P. aeruginosa PA14 showed that their production starts at the end of the logarithmic growth phase and is maximal at the onset of the stationary growth phase. The concentration of PQS reached a maximum at 13 mg/l and then decreased, while the HQNO concentration reached 18 mg/l and then remained stable. Culture supernatants of P. aeruginosa strains PAO1 and PA14 produced similar concentrations of PQS whereas no PQS or HQNO could be detected in culture supernatants of the P. aeruginosa strain PAK or in the other Pseudomonas species tested, including phytopathogenic pseudomonads.     

A purification procedure for the soluble cytochrome oxidase and some other respiratory proteins from Pseudomonas aeruginosa.

The production of the soluble cytochrome oxidase/nitrite reductase in the bacterium Pseudomonas aeruginosa is favoured by anaerobic conditions and the presence of KNO3(20g/l) in the culture medium. Of three methods commonly used for the disruption of bacterial suspensions (ultrasonication, liquid-shear homogenization and glass-bead grinding), sonication proved the most efficient in releasing the Pseudomonas cytochrome oxidase. A polarographic assay of Pseudomonas cytochrome oxidase activity with sodium ascorbate as substrate and NNN'N'-tetramethyl-p-phenylenediamine dihydrochloride as electron mediator is described. A purification procedure was developed which can be used on the small scale (40-litre cultures) or the large scale (400-litre cultures) and provides high yields of three respiratory-chain proteins, Pseudomonas cytochrome oxidase, cytochrome c551 and azurin, in a pure state. A typical preparation of 250g of Ps.aeruginosa cell paste yielded 180mg of Pseudomonas cytochrome oxidase, 81 mg of Pseudomonas cytochrome c551 and 275mg of Pseudomonas azurin.     

Phenol utilisation by fungi isolated from activated sludge

The paper presents the efficiency of phenol removal (concentrations from 500 to 2000 mg/l) by fungi isolated from activated sludge purifying wastewater with high phenol concentration. Five fungal strains were isolated and identified. All isolated strains appeared to be Moniliales from the class of Fungi Imperfecti (Candida sp., Monosporium sp., Trichosporon sp.) Stationary cultures of the individual strains and their mixtures were maintained in Czapek medium containing phenol in concentration from 500 to 2000 mg/l. All isolated strains (except one) were capable of utilising phenol up to a concentration of 1500 mg/l. Depending on investigated strain, phenol in concentration of 500 mg/l was decomposed during 4-25 days, 750 mg/l during 4-14 days. After 20 days, a phenol decline of 1000 mg/l was observed. After 16 days, the phenol decline was 1500 mg/l. Higher phenol concentrations (1500 mg/l) were utilised only by a mixture of two strains. The investigated fungal strains showed good efficiency of phenol removal from high phenol concentration in wastewater and they may be proposed for use in the process of purifying wastewater of this type.     

Studies on the biodegradation of nonionic surfactants applied in the polyester fiber industry. I. Activated sludge bacteria degrading the surfactants.

The paper presents characteristics of 76 strains of bacteria capable of utilizing nonionic surfactants Cirrasol FP, Cirrasol SF 200 and Cirrasol TCS as the source of carbon. The strains were isolated from two activated sludges adapted to the purification of wastes containing the above compounds at concentration 150--200 mg/l. The isolated strains belonged to the genera: Achromobacter, Alcaligenes, Arthrobacter, Flavobacterium, Mycobacterium, Nocardia, Pseudomonas and Xanthomonas. With load 0.11 mg surfactant/mg d.w./day bacteria belonging to Alcaligenes were dominating. With load 0.18--0.31 mg surfactant/mg d.w./day microorganisms were dominated by Pseudomonas. The highest intensity of degradation of the studied surfactant was shown by species: Alcaligenes viscolactis, Nocardia blackwellii and Pseudomonas rathonis.     

Comparative study of Cd(II) and Cr(VI) biosorption on Staphylococcus xylosus and Pseudomonas sp. in single and binary mixtures

Biosorption of Cd(II) and Cr(VI) ions in single solutions using Staphylococcus xylosus and Pseudomonas sp., and their selectivity in binary mixtures was investigated. Langmuir and Freundlich models were applied to describe metal biosorption and the influence of pH, biomass concentration and contact time was determined. Maximum uptake capacity of cadmium was estimated to 250 and 278 mg g(-1), whereas that of chromium to 143 and 95 mg g(-1) for S. xylosus and Pseudomonas sp., respectively. In binary mixtures with Cd(II) ions as the dominant species, there is a profound selectivity for cadmium biosorption, reaching 96% and 89% for Pseudomonas sp. and S. xylosus, respectively, at 10 mg l(-1) Cd(II) and 5 mg l(-1) Cr(VI). Interesting, when chromium (VI) ions are the dominant species, there is selectivity towards chromium around 92% with S. xylosus only.     

Activation of the antioxidant complex in <Emphasis Type="Italic">Pseudomonas aurantiaca</Emphasis>—Producer of phenazine antibiotics

Two Pseudomonas aurantiaca mutant strains overproducing phenazine antibiotics (synthesis levels of 210 and 410 mg/l, respectively) along with wild-type bacteria (production level of 71–75 mg/l) and a phz⁻ mutant not producing phenazines were used to study the changes in the activity of the antioxidant complex components, that is, catalase, superoxide dismutase (SOD), glutathione reductase, and NADH oxidase; glutathione concentration (in both reduced and oxidized forms); and activity of acyl-CoA synthetase, the key enzyme of cell metabolism.     

Production and properties of biosurfactants from a newly isolated Pseudomonas fluorescens HW-6 growing on hexadecane

The newly isolated from industrial wastewater Pseudomonas fluorescens strain HW-6 produced glycolipid biosurfactants at high concentrations (1.4-2.0 g l(-1)) when grown on hexadecane as a sole carbon source. Biosurfactants decreased the surface tension of the air/ water interface by 35 mN m(-1) and possessed a low critical micelle concentration value of 20 mg l(-1), which indicated high surface activity. They efficiently emulsified aromatic hydrocarbons, kerosene, n-paraffins and mineral oils. Biosurfactant production contributed to a significant increase in cell hydrophobicity correlated with an increased growth of the strain on hexadecane. The results suggested that the newly isolated strain of Ps. fluorescens and produced glycolipid biosurfactants with effective surface and emulsifying properties are very promising and could find application for bioremediation of hydrocarbon-polluted sites.     

Evaluation of trichloroethylene degradation by E. coli transformed with dimethyl sulfide monooxygenase genes and/or cumene dioxygenase genes

Pseudomonas fluorescens IP01 grown on isopropylbenzene (cumene) and Acinetobacter sp. 20B grown on dimethyl sulfide (DMS) degraded up to 90% and 25% of 1.5 mg trichloroethylene (TCE)/l, respectively. Escherichia coli harboring the DMS monooxygenase genes from strain 20B, the cumene dioxygenase genes from strain IP01 and both oxygenase genes, degraded up to 50%, 75% and 88% of 75 mg TCE/l, respectively. The growth rates of the E. coli recombinants remained nearly unaffected by TCE at 15 150 mg/l. Thus, the E. coli recombinants were indicated to degrade high concentrations of TCE efficiently at least up to 150 mg l–1.     

Quantitative selection of denitrifying bacteria in continuous cultures and requirement for organic carbon. I. Starch

A mixed population of bacteria from bottom sludge of nitrogen wastewater reservoir was incubated in continuous culture in medium containing 1000 mg nitrate nitrogen/l and starch. Maximal efficiency of denitrification was 5 mg N/l/h. Marked changes in participation of denitrifying bacteria (16-76%) among total number of bacteria was observed, this being dependent on the ratio of starch concentration (CS) to nitrogen concentration (CN) in the medium. The optimal CS/CN ratio ensuring highest participation of denitrifying bacteria was 3.2. The amount of starch required for the denitrification of a defined quantity of nitrogen is negatively correlated (r = -0.98) with the frequency of the occurrence of denitrifying bacteria (XD) and is: CS = (5.53-0.028XD) CN. The denitrifying bacteria in continuous culture were dominated, depending on CS/CN ratio and flow rate of medium, by Alcaligenes faecalis, Paracoccus denitrificans or Pseudomonas mendocina, that is species unable to hydrolyse starch.     

Isolation and characterization of phenol-catabolizing bacteria from a coking plant

New phenol degrading bacteria with high biodegradation activity and high tolerance were isolated as Burkholderia cepacia PW3 and Pseudomonas aeruginosa AT2. Both isolates could grow aerobically on phenol as a sole carbon source even at 3 g/l. The whole-cell kinetic properties for phenol degradation by strains PW3 and AT2 showed a Vmax of 0.321 and 0.253 mg/l/min/(mg protein), respectively. The metabolic pathways for phenol biodegradation in both strains were assigned to the meta-cleavage activity of catechol 2,3-dioxygenase.     

Isolation and characterization of thymidylate synthetase mutants of Xanthomonas maltophilia

Thymidylate synthetase mutants of Xanthomonas maltophilia ATCC 13270 were isolated on a solid minimal medium containing 50 mg/l thymidine and a high concentration of trimethoprim (500 mg/l). It was found that a high concentration of trimethoprim was required to prevent background growth of the wild-type strain. The isolated mutants could grow on thymidine or dTMP at a concentration of 50 mg/l while they were unable to grow on 1000 mg/l thymine or 50 mg/l deoxyridine. Thymidylate synthetase activity was assayed in the wild-type cells and in the mutant cells but only the wild-type cells contained measurable enzyme activity.     

Production of plantlets from Aegle marmelos nucellar callus

Techniques have been developed for the regeneration of Aegle marmelos from nucellar explants. Slow-growing calli were induced from nucellar explants excised from 90–120 d-old developing fruits. The medium consisted of Murashige and Skoog formulation containing 40 g/l sucrose, 400 mg/l casein hydrolysate, 5 mg/l 1-naphthaleneacetic acid and 1 mg/l kinetin. The basal medium with high concentration (1–5 mg/l) of N6-benzyladenine (BA) and low concentration (0.1 mg/l) of NAA was suitable for regeneration of shoots from 3-month-old calli. Addition of 1 mg/l gibberellic acid (GA3) favoured shoot growth. Callus-derived shoots produced roots and developed into plantlets when transferred to half-strength MS medium supplemented with 0.5 mg/l indole-3-butyric acid (IBA) and 0.5 mg/l NAA. Approximately 5 months were required for the full regenerative process.     

Environmental impact of former gold mining on the Orangi river,Serengeti N.P., Tanzania

The Orangi river is an important all-year source of water for wildlife in the northern part of the Serengeti National Park. At two points along the river in the Banagi area, tributaries draining the adit and tailings of the Kilimafeza mine impact the Orangi. The former Au-Cu mine is subject to occasional wet season flooding leading to the release of iron ochres from the adit and physical as well as chemical mobilization of tailings material. The unpolluted river chemistry is essentially Na-Ca-HCO ₃ ^– and well-buffered. Drainage water; from the tailings are characterized by low pH (2.3) and high concentration of sulphate (up to 3280 mg/l), aluminium (275 mg/l), arsenic (324 mg/l), copper (125 mg/l), iron (622 mg/l), lead (21 mg/l), manganese (65 mg/l), and zinc (126 mg/l). Adit-drainage waters are typically of a lower pH (4.6) and have a lower concentration of sulphate (up to 1840 mg/l) and metals (up to 25 mg/l Al, 92 mg/l As, 42 mg/l Cu, 258 mg/l Fe, 9.6 mg/l Pb, 53 mg/l Mn, and 102 mg/l Zn). Mixing of these acidic waters with the alkaline river leads to rapid metal precipitation as Fe-ochre coatings on clastic sediment. This effect is more noticeable in the dry season. Consequently, although the tributaries draining the two sources are heavily contaminated, the effective buffering of the mine drainage waters restricts any potential pollution to within 1 km of the mine workings. Faecal coliforms show an antipathetic relationship to low pH and high metal conditions. The only mobile metals in the water outside this area are Mn and Zn and their contamination can be biologically monitored using a protozoan-based bioassay.     

Bioremediation of toxic chromium from electroplating effluent by chromate-reducing Pseudomonas aeruginosa A2Chr in two bioreactors

The chromate-reducing ability of Pseudomonas aeruginosa A2Chr was compared in batch culture, with cells entrapped in a dialysis sac, and with cells immobilized in an agarose-alginate film in conjunction with a rotating biological contactor. In all three systems, the maximum Cr(VI) reduction occurred at 10 mg Cr(VI)/l. Whereas at 50 mg Cr(VI)/l concentration, only 16% of the total Cr(VI) was reduced, five spikings with 10 mg chromate/l at 2-h intervals led to 96% reduction of the total input of 50 mg Cr(VI)/l. Thus maximum Cr(VI) reduction was achieved by avoiding Cr(VI) toxicity to the cells by respiking with lower Cr(VI) concentrations. At 10 mg Cr(VI)/l, the pattern of chromate reduction in dialysis-entrapped cells was almost similar to that of batch culture and 86% of the bacterially reduced chromium was retained inside the dialysis sac. In electroplating effluent containing 100 mg Cr(VI)/l, however, the amount of Cr(VI) reduced by the cells immobilized in agarose-alginate biofilm was twice and thrice the amount reduced by batch culture and cells entrapped in a dialysis sac, respectively.     

Modeling of growth kinetics for <Emphasis Type="Italic">Pseudomonas putida</Emphasis> during toluene degradation

Glucose has been often used as a secondary substrate to enhance the degradation of primary substrate as well as the increase of biomass, especially for the inhibitory range of substrate concentration. In this study, we investigated the effect of glucose concentration on growth kinetics of Pseudomonas putida during toluene degradation for a wide concentration range (60–250 mg/l). Batch microcosm studies were conducted in order to monitor bacterial growth for three different initial concentrations (2, 5, 10 mg/ml) of glucose for a given toluene concentration. Modeling of growth kinetics was also performed for each growth curve of glucose dose using both Monod and Haldane kinetics. Batch studies revealed that bacterial growth showed a distinct inhibitory phase above some limit (∼170 mg/l) for the lowest (2 mg/ml) glucose dose, but the degree of inhibition decreased as the glucose dose increased, leading to three different growth patterns. The bacterial growth followed each of the modified Wayman and Tseng, Wayman and Tseng, and Luong model as the glucose dose increased from 2 to 10 mg/ml. This indicates that glucose has a prominent influence on bacterial growth during toluene degradation and that different kinetics should be adopted for each broth condition.     

In vitro activities of tachyplesin III against Pseudomonas aeruginosa

The in vitro activities of tachyplesin III were investigated against 20 multidrug-resistant Pseudomonas aeruginosa clinical isolates. Methods included minimal inhibitory concentrations, minimal bactericidal concentrations, time-kill studies, checkerboard titration method, endotoxin-binding activity and cytotoxicity assay. Overall the organisms were susceptible to the peptide at concentrations of 0.50-4 mg/l. Tachyplesin III completely inhibits the endotoxin procoagulant activity at 22.36 mg/l concentration. Fractional inhibitory concentration indexes demonstrated synergy between the peptide and betalactams or colistin. In conclusion, the intrinsic antibacterial and antiendotoxin activities and the synergistic interactions demonstrated with clinically used antibiotics make tachyplesin III valuable as potential candidate for new therapeutic strategies aimed to treat P. aeruginosa infection.     

Isolation and Characterization of Biosurfactant-Producing Bacteria from Oil-Contaminated Soil

Two biosurfactant-producing Pseudomonas aeruginosa strains (KISR C1 and KISR B1) were isolated from Kuwaiti oil-contaminated soil, which resulted from the Gulf War. The optimum environmental conditions that supported the growth and surfactant production of both isolates were examined. The two isolates differed in their biosurfactant-stimu-lating carbon source, nitrogen concentration, and the pH of the medium. C-1 isolate produced two types of rhamnolipids with a final concentration of 98.4?g/l after spiking the nitrogen-limited medium with 10?mg/ml olive oil. The other isolate (B-1) produced only one type of rhamnolipid (5.9?g/l) after spiking the medium with crude oil. The biosurfactant produced by this strain was found to be very effective in the emulsifica-tion of crude oil. The result suggests that this isolate can potentially be used to enhance bioremediation of oil-contamination and enhanced oil recovery.