Decolorization Activity Research Articles

Standardization of silver nanoparticle synthesis: Photocatalytic application (immobilized with chitosan complex) with textile dyes and antibacterial activity against Staphylococcus aureus using banana pseudo stem

The purpose of the study is to standardize the silver nanoparticle (BP-AgNPs) synthesis and its antibacterial activity and photocatalytic application with the selected dyes using the banana pseudo stem extract. “One-factor analysis (OFTA)” was carried out for the standardization of silver nanoparticle synthesis and nanoparticle-chitosan complex immobilization. The parameters were identified with plant quantity (20 g), silver nitrate concentration (1 mM), the ratio of plant extract and silver nitrate solution (2:8), pH (12), temperature (37 °C), dispersed light conditions, shaking conditions (120 rpm), and time (6 h) were analysed. The photocatalytic decolorization efficiency of the standardized BP-AgNPs (immobilized with chitosan complex) has shown 96.92% for methylene blue (10 ppm) at 3 h and 97.55% for safranin (100 ppm) at 15 h. The antibacterial activity for the synthesised BP-AgNPs was determined. MIC value of the BP-AgNPs was determined to be 15.62 μg. mL−1 for S. aureus. The synthesised BP-AgNPs treated with 0.5×, 1× and 2× MIC concentration (x = 15.62 μg. mL−1) showed decreased viable counts of S. aureus (99.6% at 2× concentration having viable count of 22.6 × 102 CFU. mL−1) at 24 h incubation when compared with the control culture. The structural characteristics of the BP-AgNPs were identified as spherical with SEM and the size was identified as 12.19 ± 1.62 nm with TEM and as 37.23 ± 17.89 nm with XRD. The parameters such as FTIR, Zeta potential, EDS further supports the nanoparticle synthesis with banana pseudostem extract. The current result suggested that, the silver nanoparticles (BP-AgNPs) synthesised using the extract of the banana pseudo stem could be used as an alternative source for dye decolorization and antibacterial activities.

Indigenous copper and dye resistant bacteria: Enterobacter cloacae Suk1 and Serratia nematodiphila Suk13 isolated from Sukolilo River, Surabaya Province, Indonesia

Bioremediation using indigenous copper-resistant bacteria has been successfully used in reducing copper concentrations. However, little information is available concerning the resistance of bacteria to copper and dyes. This study, therefore, was aimed at 1) isolating and characterizing multi-resistant bacteria, 2) measuring the copper biosorption and accumulation ability, and 3) measuring the growth and decolorization ability of various dyes. Dye-multi-resistant bacteria were isolated from Sukolilo River, Indonesia. Copper resistance was determined by measuring the Minimum Inhibitory Concentration (MIC). The biosorption and accumulation abilities were measured using an atomic absorption spectrophotometer. The twelve dyes used in the test were methylene blue, malachite green, congo red, mordant orange, reactive black, direct yellow, basic fuchsine, reactive orange, dispersion orange, remazol red, wantex yellow, and wantex red. The decolorization activity was analyzed by spectrophotometry at a wavelength of 300-900 nm. The results showed that nine isolates of copper-resistant bacteria demonstrated MIC of 3-9 mM CuSO4. Enterobacter cloacae Suk1 and Serratia nematodiphila Suk13 have been demonstrated to possess multi-resistance to CuSO4, and the twelve dyes, except Enterobacter cloacae Suk1 which did not grow on malachite green and basic fuchsine. Enterobacter cloacae Suk1 was able to decolorize 89.42% of methylene blue and 83.61% of congo red in a medium supplemented with 500 ppm of each dye. Enterobacter cloacae Suk1 and Serratia nematodiphila Suk13 also accumulated copper of up to 2.61 mg and 2.48 mg/g dry weight of cell, respectively, and removed copper of up to 94.64% and 90.52% in a medium containing 5 mM CuSO4, respectively.

Biodiversity and biotechnological potential of cultivable Halophilic bacteria from Slana voda (Oravska Polhora, Slovakia) natural salt spring

AbstractHalophilic microorganisms are of immense importance in various fields of biotechnology. There is a multitude of actual or potential applications in the research of environmentally friendly applications in biodegradation, decolorization, food biotechnology, and biopolymers production. Thirty-eight strains of halophilic bacteria were isolated from the Slana voda (Slovakia, Central Europe) natural salt spring, with a tolerance of up to 20% of NaCl. The Halomonas genus accounted for more than 35% of the cultivable microbiota, followed by Shewanella and Pseudoaltermonas genera. More than 55% of bacterial isolates were able to produce at least one of the tested hydrolases (cellulase, lipase, amylase, protease) and three of them were positive for all four enzyme activities. Bacterial isolates showed a relatively high ability to degrade synthetic dyes, namely congo red, crystal violet, malachite green, methylene blue, methyl red, and safranin (5.26, 42.11, 44.74, 63.16, 92.18, and 18.42% of isolates respectively). Interestingly only a small overlap was observed between the isolates producing extremozymes and the isolates demonstrating decolorizing activity.

A Novel Phytotherapy Application: Preparation, Characterization, Antioxidant Activities and Determination of Anti-inflammatory Effects by In vivo HET-CAM Assay of Chitosan-based DDSs Containing Endemic Helichrysum pamphylicum P.H. Davis & Kupicha Methanolic Extract.

Numerous pharmaceutical applications for chitosan, a polysaccharide made from the shells of crustaceans by deacetylating chitin that occurs naturally, are currently being researched. Chitosan, a natural polymer, is successfully used to prepare many drug-carrier systems, such as gel, film, nanoparticle, and wound dressing. Preparing chitosan gels without external crosslinkers is less toxic and environmentally friendly. Chitosan-based gels containing Helichrysum pamphylicum P.H. Davis & Kupicha methanolic extract (HP) were produced successfully. The F9-HP coded gel prepared with high molecular weight chitosan was chosen as the optimum formulation in terms of pH and rheological properties. The amount of HP was found to be 98.83% ± 0.19 in the F9-HP coded formulation. The HP release from the F9-HP coded formula was determined to be slower and 9 hours prolonged release compared to pure HP. It was determined that HP release from F9-HP coded formulation with the DDSolver program was by anomalous (non-fickian) diffusion mechanism. The F9-HP coded formulation significantly showed DPPH free radical scavenger, ABTS•+ cation decolorizing and metal chelating antioxidant activity while weakly reducing antioxidant potential. According to the HET-CAM scores, strong anti-inflammatory activity was obtained by the F9-HP coded gel at a dose of 20 μg.embryo-1 (p<0.05 compared with SDS). In conclusion, it can be said that chitosan-based gels containing HP, which can be used in both antioxidant and anti-inflammatory treatment, were successfully formulated and characterized.

A pentametallic high-entropy mixed-dimensional mesoporous heterostructure for azo-dye wastewater degradation and decolorization

The degradation and decolorization of azo-dyes wastewater require more efficient methodologies to reduce this primary water pollution source. Herein, we developed a pentametallic (Au-Ti-Mg-Al-Cu) high-entropy mixed-dimensional mesoporous heterostructure (HEMDMHs) for azo-dye wastewater degradation and decolorization. This HEMDMHs structure was constructed by irregularly growing nanoscale Mg-Al-Cu layered-double-hydroxide (LDH) onto micro-scaled 2-dimensional (2D) Ti3C2Tx MXene and then in-situ synthesizing ultrasmall (<3 nm) 0-dimensional (0D) gold nanoclusters (AuNCs) onto the LDH/MXene mesoporous support. This Au-Ti-Mg-Al-Cu HEMDMHs can efficiently degrade azo-dyes wastewater within 2 min, producing colorless and clear solutions. This exceptional performance can be achieved across a wide pH range of 2 to 12 and temperatures ranging from 0 to 60 °C under sunlight. Furthermore, this HEMDMHs can be easily recoverable through centrifugation for reuse. Mechanistic investigation revealed a synergistic mechanism in which the mesoporous LDH/MXene enhances physical absorption of azo-dyes, while the AuNCs/LDH heterostructure promotes their chemical degradation. Considering its high decolorization activity, high cycle stability, reusability and controllable economic cost, our results provide a promise HEMDMHs candidate for the treatment of azo-dye wastewater.

Fungi from mangrove forest and their potential for decolorization

Role of mangrove forests has been elucidated from different aspects including culture, economic and environments, and potential microbes from mangrove area has been interested from different viewpoints. This study is to determine the diversity of fungi from mangrove forest and their ability to degrade dye. Fungi were isolated from mangrove water of Belawan, North Sumatera, and screened for their decolorization activity in Mineral Salt Medium Agar (MSMA) containing liquid dye waste at a concentration of 25%, 50%, 75%, and 100%. Five isolates, JPM 1, JPM 10, JPM 12, JPM 14 and JPM 15, of 23 purified isolates exhibited better growth response until the highest concentration of waste (100%). All isolates showed better decolorization activity under liquid culture condition. JPM 14 85.66% exhibited the highest decolorization activity after 30 days. Molecular identification of 5 potential isolates indicted that all belong to different species, namely Aspergillus niger (JPM 1), Aspergillus citrinoterreus (JPM 10), Fusarium oxysporum (JPM 12), Montagnula chromolaenicola (JPM 14) and Trichoderma lentiforme (JPM 15).

Genome-Scale Investigation of the Regulation of azoR Expression in Escherichia coli Using Computational Analysis and Transposon Mutagenesis

Bacterial azoreductases are enzymes that catalyze the reduction of ingested or industrial azo dyes. Although azoreductase genes have been well identified and characterized, the regulation of their expression has not been systematically investigated. To determine how different factors affect the expression of azoR, we extracted and analyzed transcriptional data from the Gene Expression Omnibus (GEO) resource, then confirmed computational predictions by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Results showed that azoR expression was lower with higher glucose concentration, agitation speed, and incubation temperature, but higher at higher culture densities. Co-expression and clustering analysis indicated ten genes with similar expression patterns to azoR: melA, tpx, yhbW, yciK, fdnG, fpr, nfsA, nfsB, rutF, and chrR (yieF). In parallel, constructing a random transposon library in E. coli K-12 and screening 4320 of its colonies for altered methyl red (MR)-decolorizing activity identified another set of seven genes potentially involved in azoR regulation. Among these genes, arsC, relA, plsY, and trmM were confirmed as potential azoR regulators based on the phenotypic decolorization activity of their transposon mutants, and the expression of arsC and relA was confirmed, by qRT-PCR, to significantly increase in E. coli K-12 in response to different MR concentrations. Finally, the significant decrease in azoR transcription upon transposon insertion in arsC and relA (as compared to its expression in wild-type E. coli) suggests their probable involvement in azoR regulation. In conclusion, combining in silico analysis and random transposon mutagenesis suggested a set of potential regulators of azoR in E. coli.

Trypan blue dye decolorization by Aeromonas caviae isolated from water sewage in Jakarta, Indonesia

Abstract. Pinontoan R, Susanto TSR, Lucy J, Angelina C, Soentoro SE, Purnomo JS, Cornelia M. 2024. Trypan blue dye decolorization by Aeromonas caviae isolated from water sewage in Jakarta, Indonesia. Biodiversitas 25: 1631-1637. The textile industry generates a substantial amount of hazardous chemical waste, which requires proper treatment to mitigate negative environmental and health consequences if left untreated. Studies on the removal of Trypan Blue (TB), a widely used commercial diazo textile dye, by indigenous bacteria are limited. Therefore, this study aimed to isolate, identify, and characterize microorganisms capable of decolorizing TB in textile dye-contaminated wastewater from Jakarta. Microorganisms were initially screened for decolorization activity in solid media containing TB. Among the isolated strains, TB2 isolate exhibited the highest decolorizing potential and was selected for further analysis. The morphological, biochemical, molecular, and phylogenetic characteristics of the TB2 isolate revealed that it belonged to the species Aeromonas caviae. To examine the ability of the isolate to remove TB, various culture conditions, such as pH, temperature, and agitation, were tested. The results demonstrated that the A. caviae TB2 strain could reduce up to 77.10% of TB (0.0025% (w/v)) under static conditions, pH 7.0, and 27°C over six days. To our knowledge, this is the first study to report the ability of the Aeromonas genus to decolorize TB. These results imply the potential use of A. caviae for decolorizing dye-bearing industrial wastewater.

Potential of White Rot Fungi from Berbak-Sembilang National Park, Indonesia for Decolorization and Detoxification Commercial Direct Dyes

Commercial direct dyes are frequently employed in the dyeing of Jumputan, a traditional craft originating from South Sumatra, Indonesia. The introduction of synthetic dyes into the environment can have a detrimental impact on ecosystem stability, necessitating the implementation of remedial measures. There has been a growing interest in the utilization of White Rot Fungi (WRF) as a viable biological agent for the purpose of decolorizing and detoxifying synthetic colors. However, it is imperative to investigate the isolated WRF from Berbak-Sembilang National Park (TNBS) due to the varying capacities of decolorization and detoxification exhibited by each WRF. The study involved 5 WRF from TNBS screened in solid media, and grown in a liquid medium containing commercial direct dyes (direct turquoise, direct orange and direct yellow). WRF grown on liquid medium contains a single dye, mixture dyes and temperature characterization. It measured decolorization, biomass and enzyme activities. Toxicity is measured by the BSLT method. The findings indicated that 3 specific fungi, namely Phellinus noxius (BRB 11), Lentinus sajor-caju (BRB 12) and Leotrametes menziesii (BRB 73), exhibited a significant capacity to remove the color from both individual and mixture of direct dyes through the production of laccase and MnP enzymes. The optimal temperature for decolorization of the mixture of direct dyes was 35 °C for BRB 11 (61.4 %) and BRB 73 (60.7 %), whereas BRB 12 (47.4 %) exhibited optimal temperature at 30 °C. The toxicity assay conducted using A. salina showed a progressive rise in the LC50 value, from 15.37 mgL−1 in the control group to a range of 21.63 - 35.84 mgL−1 in the treated group, indicating a detoxification process. However, the most toxic isolate was BRB 12. This study proposes the potential of 2 isolates, Phellinus noxius (BRB 11) and Leotrametes menziesii BRB 73, from TNBS for degradation of single and mixture dye wastewater in the environment. HIGHLIGHTS The discovery of 3 White Rot Fungi from TNBS (Indonesia) has the ability to remove color and reduce the level of toxicity of commercial direct dyes, both individual and mixture of commercial direct dyes. Uncovering one of White Rot Fungi has not been widely published for decolorization and detoxification commercial direct dyes, namely Leotrametes menziesii (BRB 73). The optimal temperature was 35 °C for decolorization of commercial direct dyes by Phellinus noxius (BRB 11) and Leotrametes menziesii (BRB 73) GRAPHICAL ABSTRACT

Silver nanoparticles synthesis from Crinum moorei: Optimization, characterization, kinetics and catalytic application

Nanotechnology has been developing tremendously since the 1970s. Various types of nanoparticles such as carbon, metal, bio-originated, etc. have been synthesized by a variety of physical, chemical and biological methods. Biological methods which employ bacteria, fungi and plants for the synthesis of metal nanoparticles are found to be a sustainable and eco-friendly approach. Among biological methods, plants being a cleaner and greener source are widely accepted. The present work includes screening the synthesis of silver nanoparticles using the roots and leaves extract of 15 different Indian Crinum species, optimization, characterization and kinetic studies of silver nanoparticles. Among all the species, the highest synthesis was observed by Crinum moorei which was detected by apeak at 390 nm in UV–visible spectrophotometry. The optimization of silver nanoparticle synthesis from C. moorei roots was performed based on extract concentration (1 %), salt concentration (1.5 mM), pH (9) and temperature (30°C). The kinetics study of silver nanoparticles showed a rate constant of 0.0609 h−1. Furthermore, the characterization of synthesized silver nanoparticles was conducted using TEM, SEM, FTIR, XRD, NTA and DLS. These synthesized AgNPs exhibited catalytic activity for Congo red dye decolorization, which could serve as an initiative for the further studies to control the environmental pollution caused by dyes and colorants.

Studies on Physico-chemical Characters of Distillery Waste Water and Decolorizing Bacteria

Distillery waste water possess serious environmental hazards causing eutrophication, adversely affecting the human health and the flora and fauna of the waterbodies. The conventional treatment methods applied these days are not satisfactory. So, it is a need of the present day to find alternative methods to achieve this aim. Microbial treatment serves to be the best option for the treatment of waste waters. The present work was carried out to study the physico-chemical characters of distillery waste water and to isolate, screen, characterize and identify the micro-organisms with a potential of decolorizing distillery waste water. Two isolates were obtained during the study. Their decolorizing activity in presence of various supplements for different incubation periods was checked. Both of the isolates were found to be promising for future use.

Silver and carbon nitride-doped nickel selenide for effective dye decolorization and bactericidal activity: in silico docking study.

In this study, nickel selenide (NiSe), Ag/C3N4-NiSe, and C3N4/Ag-NiSe nanowires (NWs) were synthesized via coprecipitation. The prepared NWs were employed for the degradation of the rhodamine B (RhB) dye in the absence of light using sodium borohydride (NaBH4), bactericidal activity against pathogenic Staphylococcus aureus (S. aureus) and in silico docking study to investigate the d-alanine ligase (DDl) and deoxyribonucleic acid (DNA) gyrase of S. aureus. NWs demonstrate a catalytic degradation efficiency of 69.58% toward RhB in a basic medium. The percentage efficacy of the synthesized materials was evaluated as 19.12-42.62% at low and 36.61-49.72% at high concentrations against pathogenic S. aureus. Molecular docking results suggest that both C3N4/Ag-doped NiSe and Ag/C3N4-doped NiSe possess inhibitory activities toward DDl and DNA gyrase of S. aureus, which coincides with the in vitro bactericidal activity. Based on the research outcomes, the synthesized NWs show potential as an effective agent for water purification and resistance to microbial contaminants.

Improved application of immobilized Enterobacter cloacae into a bio-based polymer for Reactive Blue 19 removal, an eco-friendly advancement in potential decolorizing systems.

The widespread use of highly complex synthetic dyes like reactive dyes in the textile industry has some adverse environmental impacts and deserves close attention. Biological treatment of these effluents utilizing various species of bacteria with remarkable efficiency in dye removal is still considered promising. Our current study deals with immobilizing an isolated bacterial strain into calcium alginate (Ca/Alg) gel beads and using it to treat pernicious pollutants like synthetic dyes. A potential Reactive Blue 19 (RB19)-degrading Enterobacter cloacae strain A1 was isolated from the Kashan textile industry and was characterized by 16S rDNA gene sequencing. The decolorization ability of strain A1 was assessed by time-based studies using free bacterial cells/immobilized in Ca/Alg. Based on the results of the 16S rDNA gene sequencing, it appears that strain A1 belonged to E.cloacae, with a 99.74% similarity. The findings suggest that immobilized strain A1 accomplished maximum decolorization activity compared with the free cells. The immobilized strain could utterly decompose and decolorize 0.05 mg/mL of RB19 within 48 h, while the free bacterial strain decolorized RB19 within 5 days. Moreover, Ca/Alg gel beads can maintain their efficiency for over three decolorization cycles. Further infrared spectroscopy (FTIR) and gas chromatograph mass spectrometer (GC/MS) investigation declared complete RB19 decomposition on reaction products. Artemia salina was used to investigate the toxicity of dye and its degraded metabolites. The LC50 values signified the pure dye as very toxic with 0.01 mg/mL concentration, while after-treatment products showed no toxic effect on larvae. This immobilization technique increased the applicability of bacterial strain for dye removal. It was beneficial for the decolorization of RB19 from textile wastewater due to a remarkable reduction in time. Notably, strain A1-immobilized beads can maintain their activity for three consecutive decolorization cycles without a considerable decrease in efficiency. PRACTITIONER POINTS: The remarkable capacity of immobilized Enterobacter cloacae strain A1 for Reactive Blue 19 (RB19) removal Immobilized A1 strain showed two-fold higher removal than free one over 48 h A promising method for enhancing RB19 decolorization Decolorization was due to degradation based on UV-Vis, FTIR, and GC/MS analysis Non-toxic posttreatment products for Artemia.

Biodegradation of crystal violet by newly isolated bacteria.

Confronting the environmental threat posed by textile dyes, this study highlights bioremediation as a pivotal solution to mitigate the impacts of Crystal Violet, a widely-utilized triphenylmethane dye known for its mutagenic and mitotic toxicity. We isolated and identified several bacterial strains capable of degrading Crystal Violet under various environmental conditions. Newly identified strains, including Mycolicibacterium nivoides, Chryseobacterium sp., Agrobacterium rhizogenes, Pseudomonas crudilactis, and Pseudomonas koreensis demonstrated significant decolorization activity of Crystal Violet, complementing the already known capabilities of Stenotrophomonas maltophilia. Initial experiments using crude extracts confirmed their degradation potential, followed by detailed studies that investigated the impact of different pH levels and temperatures on some strains' degradation efficiency. Depending on the bacteria, the degree of activity change according to pH and temperature was different. At 37 °C, Chryseobacterium sp. and Stenotrophomonas maltophilia exhibited higher degradation activity compared to 25 °C, while Pseudomonas crudilactis and Mycolicibacterium nivoides did not exhibit a statistically significant difference between the two temperatures. Mycolicibacterium nivoides performed optimally at pH 8, while Pseudomonas crudilactis showed high activity at pH 5. Stenotrophomonas maltophilia's activity remained consistent across the pH range. These findings not only underscore the effectiveness of these bacteria as agents for Crystal Violet degradation but also pave the way for their application in large-scale bioremediation processes for the treatment of textile effluents, marking them as vital to environmental sustainability efforts.

Isolation and Characterization of Dye Decolorizing Bacteria from The Textile Dye Effluents

The most significant challenge confronted by the textile industries is the discharge of dye effluents which contains toxic chemicals posing a considerable threat to environmental pollution. Biological method of treating effluents using bacteria is one of the renewed and accepted method in effluent treatment. The present study aims to isolate and characterise the dye decolorizing bacteria from the effluent samples of a dye industry from Chinnalapatti, Tamilnadu. The dye effluents were collected from the effluent plant of a leading dye industry and the Physiochemical parameters were analysed. The samples were plated in a Nutrient Agar and bacterial isolation were performed according to the standard microbiological procedures. The bacterial isolates identified by biochemical identification were tested for its efficiency to decolorize Methyl red and crystal violet dyes. Among the three isolates S1showed 98% decolorizing efficiency in reducing Methyl red dye and 92% efficiency in decolorizing crystal violet dye. Sample S2 showed 85% activity in decolorizing methyl red dye and 86% activity in decolorising Crystal violet dye. S3 showed a low decolorizing activity compared to S1 and S2. Both of these phenotypically identified isolates are subjected to molecular identification by 16s gene amplification and gene sequencing. The obtained FASTA sequence were analysed for the phylogenetic relationship and submitted to NCBI. The potential isolate that has the capacity to decolorise the dyes were identified as Bacillus Tropicus and Pseudomonas mosselli. This study proves that these bacterial strains can be used as a potential bioremediation agent in decolorizing the dye effluents.

Enhancement of photochromic molecule decolorization by coating a thin Ti(O) layer over gold nanoparticles

Abstract Photochemical decolorization reaction of terarylenes with a hydroxy or a methoxy group is studied on the surface of gold nanoparticles (AuNPs)/TiO2 thin hybrid film. AuNPs were deposited on TiO2 film after UV irradiation with HAuCl4. The colored form of terarylenes could not be decolorized at the bare AuNPs on TiO2 under irradiation of green light (530 nm in wavelength). On the other hand, effective decolorization activity of terarylene, having a hydroxy group, was observed at the surface of AuNPs/TiO2 hybrid film with an optimized number of Ti(O) insulator layers on AuNPs. The mechanism for the enhanced decoloration is proposed based on the difference in the substituent of the terarylenes.

Optimization of Pseudomonas aeruginosa isolated for bioremediation from Ha'il region of Saudi Arabia.

Majority of dyes are toxic to all the living organisms and inherently resistant to microbial degradation. Hence, decolorization and degradation of textile dye methyl red were evaluated using isolated bacterial strain Pseudomonas aeruginosa (P. aeruginosa). Methyl red dye decolorization by P. aeruginosa with respect to various parameters was optimized. Data shows that maximum possible decolorization was seen at 50 ppm dye concentration, 1400 mg/l glucose concentration, 700 mg/l sodium chloride (NaCl) concentration, pH 9, temperature 38°C, 1000 mg/l urea concentration P. aeruginosa AM-1 strain. The highest percent (91.1%) of bioremediation was achieved at 40 ppm dye concentration in Allium cepa test. These findings suggest P. aeruginosa strain (AM-1) has the potential to be used in the biological treatment of highly toxic dye which is main constituent of dyeing mill effluents due to its high decolorization activity with simple conditions. Strain AW-1 strain also has potential to bioremediate other wastewater containing methyl red dye.

Decolorization potential of malachite green by Ralstonia mannitolilytica isolated from Indonesian cassava-based fermentedfoodtapai.

Pollution due to textile dye effluent mishandling is hazardous to ecosystems and to the living beings inhabiting them. This can cause retarded photosynthesis, disrupted fish day/night cycles, unbalanced bacterial populations, and decreased oxygen concentration in contaminated water, leading to low habitability. In this study, we aimed to isolate and characterize the microorganisms found in Indonesian cassava-based fermented food tapai starter cultures as a source of potential microbes for the biological remediation of textile dye pollutants. Microorganisms in the tapai starter culture were screened for their decolorization activity via spread-culture inoculation on a solid growth medium supplemented with textile dyes. Isolated microorganisms were selected based on their ability to secrete textile dye-decolorizing extracellular enzymes via increased light penetration after incubation of the cell-free supernatant (CFS) containing extracellular enzymes in textile dye solutions. Isolate JSP1 was the only bacterium capable of producing malachite green (MG)-decolorizing extracellular enzymes, which enabled it to survive and decolorize MG up to 375ppm. Moreover, isolate JSP1 CFS was able to optimally decolorize 75% of MG at 100ppm, but its activity was diminished at concentrations > 350ppm. Colony and cellular morphology, biochemistry, and 16S rRNA tests revealed that the isolate was of Ralstonia mannitolilytica. Therefore, R. mannitolilytica isolate JSP1 may be a potential bioremediation agent for MG.

Improving hydrogen peroxide stability of a dye-decolorising peroxidase from Irpex lacteus F17 by site-directed mutagenesis

Il-DyP4, a dye-decolorizing peroxidase (DyP) from Irpex lacteus F17, has a strong ability to oxidise harmful aromatic compounds, implying application potential in the field of environmental protection. However, the low H2O2 stability of Il-DyP4 hinders its practical application. To improve the H2O2 stability of Il-DyP4, oxidation-sensitive amino acids including three Met, one Cys and ten Tyr residues were mutated to less easily oxidizable residues such as Leu, Val and Phe by site-specific mutagenesis. Mutation of the M207 site, located on the surface of the enzyme and far away from the haem group, improved H2O2 stability by 5.3-fold or more. In addition, Y234, also on the enzyme surface, was replaced with Phe and the Y234F mutant displayed 7.3-fold increased H2O2 stability. Furthermore, mutants M207V and Y234F were selected for the decolorization of various types of synthetic dyes, revealing high decolorization activities, especially for M207V with enhanced catalytic activity. The stable DyP mutant M207V has the potential for decolorization of industrial dye wastewater.

Comparison of membrane immobilized zero-valent iron nanoparticles for RED ME4BL azodye degradation

Textile industries are hailed as one of the major environmental polluters in the world, owing to their release of undesirable dye effluents. Synthetic dyes do not adhere to fabric firmly and are released into the aquatic ecosystem as effluent. Consequently, the consistent release of wastewater from numerous textile industries without previous treatment has detrimental effects on the ecosystem and human health. Treatment methods currently being used fail to degrade the dye effluents and have their own shortcomings. Immobilized nanoparticles have been extensively studied for dye remediation because of their many advantages over conventional methods. The present study aimed to compare the efficiency of two different carrier matrices [namely Poly(vinylidene fluoride) and Polyurethane] for iron nanoparticle and their decolorization activity on an azo dye (RED ME4BL). Scanning Electron Microscopy was carried out to show the deposition of iron nanoparticles on the membrane. The reaction kinetics of the bare nanoparticles were compared with that of the immobilized nanoparticles, and all were found to follow pseudo-second-order kinetics. Polyurethane immobilized iron nanoparticles showed a significant degradation of RED ME4bl than the Poly(vinylidene fluoride) immobilized iron and bare nanoparticles. This paper also demonstrates a relatively newer method for nanoparticle immobilisation using the synthetic polyurethane form.