Decolourisation and degradation of textile dyes using a sulphate reducing bacteria (SRB) – biodigester microflora co-culture

Successful decolourisation and degradation of textile dyes was achieved in a biosulphidogenic batch reactor using biodigester sludge from a local municipality waste treatment plant as a source of carbonand microflora that augmented a sulphate reducing bacteria (SRB) consortium. Orange II (O II) was decolourised by 95% within one day (24 h) producing 1-amino-2-naphthol and stoichiometric quantitiesof sulphanilic acid. The latter was degraded steadily (from 290 to 43 ìM) over 20 days while 1-amino-2-naphthol disappeared from the reactor within two days. Other azo dyes, Reactive black 5 (RB 5),Reactive red 120 (RR 120), Remazol Brilliant violet 5R (RBV 5R), an anthraquinone dye Reactive blue 2 (RB 2) and an industrial azo dye mixture (Da Gama Textiles, King Williams Town, South Africa) weresuccessfully degraded with the exception of Amido black 10B (AB 10B). The Orange II degrading cultures were freeze dried to investigate the feasibility of commercialising a powdered mixed starter culture for textile effluent bioremediation, but this decreased the dye degrading efficiency. Therefore bioremediation of textile effluent with sludge and SRB can concomitantly treat two wastes while providing a cheaper alternative of the carbon source. However, the fate of more aromatic amines needs to be investigated before full commercialisation of the process

Decolourisation and degradation of reactive blue 2 by sulphate reducing bacteria (SRB) and zero valent iron in a biosulphidogenic reactor

This work was performed to determine the influence of heat treatment on sewage sludge and addition of zero valent iron (ZVI) on the degradation and decolourisation of an anthraquinone dye, reactive blue 2 (RB 2). A consortium of sulphate reducing bacteria (SRB) in a biosulphidogenic batch reactor with biodigester sludge was used. The latter supplied carbon and augmenting microorganisms. Reactors with heat treated sludge were outperformed by those with unheated sludge for the larger part of the reactor life span. A 75% decolourisation efficiency was achieved within 24 h of inoculation when 4 g ZVI/l were added in an SRB reactor with unheated sludge as opposed to 59% colour removal after four days in the same reactor without ZVI. However, decolourisation was also noted in the presence of ZVI alone, indicating existence of chemical reaction between ZVI and RB 2.Key words: Decolourisation, degradation, reactive blue 2, zero valent iron, sulphate reducing bacteria, sulphidogenic

Adaptively evolved Escherichia coli for improved ability of formate utilization as a carbon source in sugar???free conditions

Background: Formate converted from CO2 reduction has great potential as a sustainable feedstock for biological production of biofuels and biochemicals. Nevertheless, utilization of formate for growth and chemical production by microbial species is limited due to its toxicity or the lack of a metabolic pathway. Here, we constructed a formate assimilation pathway in Escherichia coli and applied adaptive laboratory evolution to improve formate utilization as a carbon source in sugar-free conditions. Results: The genes related to the tetrahydrofolate and serine cycles from Methylobacterium extorquens AM1 were overexpressed for formate assimilation, which was proved by the 13C-labeling experiments. The amino acids detected by GC/MS showed significant carbon labeling due to biomass production from formate. Then, 150 serial subcultures were performed to screen for evolved strains with improved ability to utilize formate. The genomes of evolved mutants were sequenced and the mutations were associated with formate dehydrogenation, folate metabolism, and biofilm formation. Last, 90 mg/L of ethanol production from formate was achieved using fed-batch cultivation without addition of sugars. Conclusion: This work demonstrates the effectiveness of the introduction of a formate assimilation pathway, combined with adaptive laboratory evolution, to achieve the utilization of formate as a carbon source. This study suggests that the constructed E. coli could serve as a strain to exploit formate and captured CO2

Best practice for motor imagery: a systematic literature review on motor imagery training elements in five different disciplines

<p>Abstract</p> <p>Background</p> <p>The literature suggests a beneficial effect of motor imagery (MI) if combined with physical practice, but detailed descriptions of MI training session (MITS) elements and temporal parameters are lacking. The aim of this review was to identify the characteristics of a successful MITS and compare these for different disciplines, MI session types, task focus, age, gender and MI modification during intervention.</p> <p>Methods</p> <p>An extended systematic literature search using 24 databases was performed for five disciplines: Education, Medicine, Music, Psychology and Sports. References that described an MI intervention that focused on motor skills, performance or strength improvement were included. Information describing 17 MITS elements was extracted based on the PETTLEP (physical, environment, timing, task, learning, emotion, perspective) approach. Seven elements describing the MITS temporal parameters were calculated: study duration, intervention duration, MITS duration, total MITS count, MITS per week, MI trials per MITS and total MI training time.</p> <p>Results</p> <p>Both independent reviewers found 96% congruity, which was tested on a random sample of 20% of all references. After selection, 133 studies reporting 141 MI interventions were included. The locations of the MITS and position of the participants during MI were task-specific. Participants received acoustic detailed MI instructions, which were mostly standardised and live. During MI practice, participants kept their eyes closed. MI training was performed from an internal perspective with a kinaesthetic mode. Changes in MI content, duration and dosage were reported in 31 MI interventions. Familiarisation sessions before the start of the MI intervention were mentioned in 17 reports. MI interventions focused with decreasing relevance on motor-, cognitive- and strength-focused tasks. Average study intervention lasted 34 days, with participants practicing MI on average three times per week for 17 minutes, with 34 MI trials. Average total MI time was 178 minutes including 13 MITS. Reporting rate varied between 25.5% and 95.5%.</p> <p>Conclusions</p> <p>MITS elements of successful interventions were individual, supervised and non-directed sessions, added after physical practice. Successful design characteristics were dominant in the Psychology literature, in interventions focusing on motor and strength-related tasks, in interventions with participants aged 20 to 29 years old, and in MI interventions including participants of both genders. Systematic searching of the MI literature was constrained by the lack of a defined MeSH term.</p

Enzymatic recovery of platinum (IV) from industrial wastewater using a biosulphidogenic hydrogenase

It has been established that dissolved heavy metals escaping into the environment pose a serious health hazard. As a result, there is an urgent need for controlling metal emissions into the environment.The aims of this study were to purify and biochemically characterise hydrogenase(s) from sulphate reducing consortium (SRB) and investigate the potential of the purified enzyme(s) in the recovery ofplatinum from wastewaters. A hydrogenase from sulphate reducing consortium was purified by a combination of PEG 20000 concentration, ion exchange (Toyopearl-Super Q 650 S) and size exclusion(Sephacryl S-200) chromatographies. SDS-PAGE analysis revealed a distinct protein band with a molecular mass of 58 kDa. The investigation of enzymatic platinum (IV) reduction in vitro, showedhighest hydrogen-dependent platinum (IV) reducing activity in the presence of hydrogenase and its physiological electron carrier, cytochrome c3. When the purified hydrogenase enzyme (with and without cytochrome c3) was used with the industrial effluent, containing 7.9 mg.l-1 platinum, only 10 – 15% recovery was noted pointing to a suppression of enzyme activity due to the low pH (0.38) of the effluent.Bioremediation studies on industrial effluent using resting SRB cells showed a 34% platinum removal from the effluent while growing SRB cells, within a sulphidogenic reactor, gave a platinum removal of78%, with the pH of the system fluctuating at around 5.6. Evidence of sulphate reduction and sulphide generation were not observed during this treatment process suggesting that platinum sulphide was notformed and supporting the argument that the increased amount (78%) of platinum removal from the industrial wastewater by the growing SRB cells was due to more hydrogenase/cytochrome c3 enzymecomplex being available

Isolation and Characterisation of endoglucanases from sewage sludge under biosulphidogenic conditions of sewage hydrolysis

Proceedings of the 2004 Water Institute of Southern Africa (WISA) Biennial ConferenceEndoglucanases play a key role in cellulose degradation and catalyze the initial attack on the polymer by hydrolyzing the β-1,4 glucosidic bonds within the amorphous regions of cellulose chains. Cellulolytic bacteria have been isolated and characterized from the sewage sludge and the activation of several hydrolytic enzymes under biosulphidogenic conditions of sewage hydrolysis have been reported. The aims of this study were to isolate, perform the physico-chemical characterization of endoglucanase from sewage sludge under sulphate reduction conditions of sewage hydrolysis and to investigate its Vmax,app and Km,app values using different substrates. The membrane associated endoglucanase activities were shown to have pH optima of 6 and temperature optima of 50o C. The enzymes were thermally more stable when immobilized to the floc matrix of the sludge than when they were released into the aqueous solution via sonication. For both immobilized and released enzymes, sulphate was slightly inhibitory, activity was reduced to 84 % and 77.5 % of the initial activity at sulphate concentrations between 200 and 1000 mg.ml-1, respectively. Sulphite was stimulatory to the immobilized enzymes between 200 and 800 mg.ml-1. Sulphide stimulated the activities of the endoglucanases, but inhibited activities of the soluble enzymes above 200 mg.ml-1. These results were similar to those obtained with other enzymes (lipases, β-glucosidases and proteases) previously studied in the sewage sludge in our research group. The enzyme fraction did not hydrolyse avicel (a crystalline substrate), indicating the absence of any exocellulase activity. For CMC (carboxymethylcellulose) and HEC (hydroxyethylcellulose) the enzyme had Km, app values of 4 and 5.1 mg.ml-1 respectively and Vmax, app values of 0.297and 0.185 µmol glucose min-1ml-1 respectively. Divalent ions (Cu++, Ni++ and Zn++) proved to be inhibitory while Fe++ stimulated the enzyme at concentrations between 200 and 600 mg.ml-1. Both Mg++ and Ca++ were stimulatory at concentrations between 200 and 1000 mg.ml-1. All the volatile fatty acids (acetic acid, butyric acid, propionic acid and valeric acid) inhibited the enzymes, with acetic acid eliciting the highest degree of inhibition. Induction and purification of the enzyme from sewage sludge is currently being conducted, as the sewage sludge might provide a readily available and cheap source of the enzyme for industrial and other uses

Heat or mass transfer from a sphere in Stokes flow at low Peclet number

We consider the low Péclet number, Pe≪1, asymptotic solution for steady-state heat or mass transfer from a sphere immersed in Stokes flow with a Robin boundary condition on its surface, representing Newton cooling or a first-order chemical reaction. The application of Van Dyke's rule up to terms of O(Pe3) shows that the O(Pe3logPe) terms in the expression for the average Nusselt/Sherwood number are twice those previously derived in the literature. Inclusion of the O(Pe3) terms is shown to increase the range of validity of the expansion. © 2012 Elsevier Ltd. All rights reserved