Decolourisation and degradation of acid orange 7 using an acclimatised BAC-ZS mixed bacterial culture

Formation of dark coloured auto-oxidation compounds had resulted in reduced efficiency of the sequential anaerobic-aerobic treatment system to decolourise sulphonated azo dyes. In view of this, a monosulphonated azo dye, Acid Orange 7 (AO7) was selected as a model dye to study the decolourisation of AO7 and its auto-oxidation compounds by a mixed bacterial culture, BAC-ZS. It consisted of three bacteria namely Brevibacillus panacihumi strain ZB1, Lysinibacillus fusiformis strain ZB2 and Enterococcus faecalis strain ZL. The decolourisation and degradation process was performed using the sequential facultative anaerobicaerobic system. Optimisation of the co-substrate showed that the combination of glucose (5 g/L) and yeast extract (3 g/L) was the best co-substrate for decolourisation; 98% of AO7 colour was removed within 2 h of facultative anaerobic phase. When the decolourised solution was further treated under the aerobic phase, auto-oxidation reaction resulted in heavy browning effect after 24 h of agitation. The browning effect had drastically decreased the decolourisation to 72%. However, continuous agitation up to 48 h successfully decolourised the auto-oxidation compounds as indicated by the increase in decolourisation up to 90%. Consequently, the decolourisation was accompanied by 73% decrease in Chemical Oxygen Demands (COD) and an increase of 94% of bacteria concentration (absorbance at 600 nm). It was also found that the initial pH 6.6 of AO7 solution dropped to pH 4.5 during facultative anaerobic decolourisation and increased to pH 7.7 at the end of aerobic treatment. The degradation of AO7 dye was determined and confirmed using the UV-Vis spectrophotometry and FTIR analysis. In addition, the formation of autooxidation compounds, 1,2-naphtholquinone and 1,4-benzoquinone were detected and monitored using HPLC analysis. Further phytotoxicity tests using Cucumis sativus confirmed detoxification of the final treated solution by BAC-ZS. Quantification of BAC-ZS using real-time polymerase chain reaction (RT-PCR) showed E. faecalis strain ZL was the dominant bacteria in the acclimatised BAC-ZS and throughout the AO7 treatment process. The annotatation of the draft genome of each bacteria revealed presence of genes coding for the azoreductases, dioxygenases and monooxygenases which played important roles in degradation and mineralisation of AO7 dye. In conclusion, the acclimatised BAC-ZS mixed bacterial culture has good potential to be used in the biological treatment of textile effluent

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Multi-messenger Observations of a Binary Neutron Star Merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ∼ 1.7 {{s}} with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of {40}-8+8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 {M}ȯ . An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ∼ 40 {{Mpc}}) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∼10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ∼ 9 and ∼ 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.</p

Micropropagation and monitoring of genetic stability of micropagated plantlets of Hornstedtia reticulata K. SCHUM

The axenic seedlings were kept in vitro as the source axenic explants. Shoot-tip explants derived from axenic off shoots were cultured in Gamborg B5 media incorporated with 30% sucrose, 3 g/L gelrite and different concentrations of cytokinins i.e. TDZ, BAP alone or in combination with NAA in the direct regeneration pathway. The primers produced amplification products which were monomorphic across the mother plants and the micropropagated plantlets, confirming the reliability of developed micropropagation protocol to produce true-to-tpe plantlets. Both leaves and leaf sheaths were used for callus induction in the indirect regeneration pathway

Development of bio-granules using selected mixed culture of decolorizing bacteria for the treatment of textile wastewater

In this study, four dye-degrading bacteria, Bacillus pumilus strain ZK1, Bacillus cereus strain ZK2, Brevibacillus panacihumi strain ZB1, and Lysinibacillus fusiformis strain ZB2 were used for the development of granule. Sterile sludge was used as seeding agent in a sequencing batch reactor under intermittent facultative anaerobic–aerobic system followed by subsequent textile wastewater treatment. Physical and morphological characteristics of the granules were determined after 112 d of development time. The average size of the mature granules reached 3.3 ± 1 mm, with integrity coefficient of 25 ± 2, settling velocity of 56 ± 5 m h-1, and sludge volume index of 35 ± 5.5 mL g-1. Mixed liquor suspended solids and mixed liquor volatile suspended solids were 12.9 ± 0.8 and 11 ± 0.6 g L-1, respectively. The developed granules showed 61% of decolorization and 46% of COD removal at HRT of 24 h. The population distribution of the bacteria consortium in mature granules developed into subsequent ratio of 1:4:9:11 from initial inoculum ratio of 1:1:1:1 of B. pumilus strain ZK1, B. cereus strain ZK2, B. panacihumi strain ZB1, and L. fusiformis strain ZB2, respectively. The results obtained indicated that this mixed culture of bacteria has good potential application for the treatment of textile wastewater

Biosorption and biodegradation of acid orange 7 by Enterococcus faecalis strain ZL: optimization by response surface methodological approach

Reactive dyes account for one of the major sources of dye wastes in textile effluent. In this study, decolorization of the monoazo dye, Acid Orange 7 (AO7) by the Enterococcus faecalis strain ZL that isolated from a palm oil mill effluent treatment plant has been investigated. Decolorization efficiency of azo dye is greatly affected by the types of nutrients and the size of inoculum used. In this work, one-factor-at-a-time (method and response surface methodology (RSM) was applied to optimize these operational factors and also to study the combined interaction between them. Analysis of AO7 decolorization was done using Fourier transform infrared (FTIR) spectroscopy, desorption study, UV-Vis spectral analysis, field emission scanning electron microscopy (FESEM), and high performance liquid chromatography (HPLC). The optimum condition via RSM for the color removal of AO7 was found to be as follows: yeast extract, 0.1 % w/v, glycerol concentration of 0.1 % v/v, and inoculum density of 2.5 % v/v at initial dye concentration of 100 mg/L at 37 °C. Decolorization efficiency of 98 % was achieved in only 5 h. The kinetic of AO7 decolorization was found to be first order with respect to dye concentration with a k value of 0.87/h. FTIR, desorption study, UV-Vis spectral analysis, FESEM, and HPLC findings indicated that the decolorization of AO7 was mainly due to the biosorption as well as biodegradation of the bacterial cells. In addition, HPLC analyses also showed the formation of sulfanilic acid as a possible degradation product of AO7 under facultative anaerobic condition. This study explored the ability of E. faecalis strain ZL in decolorizing AO7 by biosorption as well as biodegradation process

Application of zeolite-activated carbon macrocomposite for the adsorption of Acid Orange 7: isotherm, kinetic and thermodynamic studies

In this study, the adsorption behavior of azo dye Acid Orange 7 (AO7) from aqueous solution onto macrocomposite (MC) was investigated under various experimental conditions. The adsorbent, MC, which consists of a mixture of zeolite and activated carbon, was found to be effective in removing AO7. The MC were characterized by scanning electron microscopy (SEM), energy dispersive X-ray, point of zero charge, and Brunauer-Emmett-Teller surface area analysis. A series of experiments were performed via batch adsorption technique to examine the effect of the process variables, namely, contact time, initial dye concentration, and solution pH. The dye equilibrium adsorption was investigated, and the equilibrium data were fitted to Langmuir, Freundlich, and Tempkin isotherm models. The Langmuir isotherm model fits the equilibrium data better than the Freundlich isotherm model. For the kinetic study, pseudo-first-order, pseudo-second-order, and intraparticle diffusion model were used to fit the experimental data. The adsorption kinetic was found to be well described by the pseudo-second-order model. Thermodynamic analysis indicated that the adsorption process is a spontaneous and endothermic process. The SEM, Fourier transform infrared spectroscopy, ultraviolet-visible spectral and high performance liquid chromatography analysis were carried out before and after the adsorption process. For the phytotoxicity test, treated AO7 was found to be less toxic. Thus, the study indicated that MC has good potential use as an adsorbent for the removal of azo dye from aqueous solution

Decolourisation of reactive black 5 by azoreductase produced by brevibacillus panacihumi ZBI

Azoreductases are often associated with decolourisation of non–degradable azo dyes via cleavage of azo bonds. In this study,Brevibacillus panacihumi ZBI, an azo dye–degrading bacterium which has not been reported before, was used for the decolourisation of Reactive Black 5 (RB5) dye. The highest activity of azoreductase was obtained during the end of log phase. Azoreductase produced intracellularly had the highest specific activity of 0.334 U/mg compared to the culture supernatant (extracellular), resting cell and cell debris with low enzyme activity of 0.034 U/mg, 0.010 U/mg and 0.200 U/mg respectively. The optimum assay conditions for the maximum azoreductase activity were at 37°C, pH 7, RB5 dye concentration of 100 mg/L and NADH concentration of 0.2 mM by using phosphate buffer as a medium for the enzyme reaction. Alternatively, the azoreductase assay was also carried out using ionic liquid, [emim][EtSO4] that may function to enhance the activity and stability of azoreductase. Results using phosphate buffer (pH 7) showed higher enzyme activity twice that of the ionic liquid besides enhancing the stability of enzyme. Under the optimum assay conditions up to 93 % of decolourisation was achieved after 8 h of incubation. In addition, growth of bacteria was also concurrently observed during the decolourisation of RB5

Biodecolorization of recalcitrant dye as the sole sourceof nutrition using curvularia clavata NZ2 and decolorization ability of its crude enzymes

Extensive use of recalcitrant azo dyes in textile and paper industries poses a direct threat to the environment due to the carcinogenicity of their degradation products. The aim of this study was to investigate the efficiency of Curvularia clavata NZ2 in decolorization of azo dyes. The ability of the fungus to decolorize azo dyes can be evaluated as an important outcome as existing effluent treatment is unable to remove the dyes effectively. C. clavata has the ability to decolorize Reactive Black 5 (RB5), Acid Orange 7 (AO7), and Congo Red azo dyes, utilizing these as sole sources of carbon and nitrogen. Ultraviolet-visible (UV-vis) spectroscopy and Fourier infrared spectroscopy (FTIR) analysis of the extracted RB5's metabolites along with desorption tests confirmed that the decolorization process occurred due to degradation and not merely by adsorption. Enzyme activities of extracellular enzymes such as carboxymethylcellulase (CMCase), xylanase, laccase, and manganese peroxidase (MnP) were also detected during the decolorization process. Toxicity expressed as inhibition of germination was reduced significantly in fungal-treated azo dye solution when compared with the control. The cultivation of C. clavata under sequential batch system also recorded a decolorization efficiency of above 90%. The crude enzyme secreted by C. clavata also showed excellent ability to decolorize RB5 solutions with concentrations of 100 ppm (88-92%) and 1000 ppm (70-77%) without redox mediator. This proved that extracellular enzymes produced by C. clavata played a major role in decolorization of RB5

Development and performance of BAC-ZS bacterial consortium as biofilm onto macrocomposites for raw textile wastewater treatment

One of the most abundant dyes that are used extensively in the textile manufacturing are azo dyes, which may endanger water bodies since incomplete breakdown of dyes may cause mutagenic and carcinogenic compounds to persist. In this study, BAC-ZS, bacterial mixed culture consisting of three acclimatised decolourising bacteria were grown as biofilm onto macrocomposites. Different time duration between 3 to 14 days of biofilm development was studied to determine the density of biofilm attached onto macrocomposites. Sequencing batch reactors (SBRs) were set up for raw textile wastewater treatment to investigate the effectiveness of the treatment with and without the presence of biofilm (control). The treatment was performed under facultative anaerobic-aerobic condition for 20 days continuously with 48-hour of hydraulic retention time (HRT) cycle (consisting both conditions). Colour and chemical oxygen demand (COD) were monitored throughout the treatment process. Results showed that the colour and COD removal by the developed biofilm were 78.6 ± 1.4% and 76.4 ± 1.12% from initial values of 1400 ADMI and 660 mg/L, respectively while only 47.9 ± 0.9% colour and 38.0 ± 1.5% COD removal for the control. In conclusion, the biofilm of BAC-ZS mixed culture coated onto macrocomposites showed potential applications in the treatment of raw textile wastewater