Efficient remediation of antibiotic pollutants from the environment by innovative biochar: current updates and prospects

The increased antibiotic consumption and their improper management led to serious antibiotic pollution and its exposure to the environment develops multidrug resistance in microbes against antibiotics. The entry rate of antibiotics to the environment is much higher than its exclusion; therefore, efficient removal is a high priority to reduce the harmful impact of antibiotics on human health and the environment. Recent developments in cost-effective and efficient biochar preparation are noticeable for their effective removal. Moreover, biochar engineering advancements enhanced biochar remediation performance several folds more than in its pristine forms. Biochar engineering provides several new interactions and bonding abilities with antibiotic pollutants to increase remediation efficiency. Especially heteroatoms-doping significantly increased catalysis of biochar. The main focus of this review is to underline the crucial role of biochar in the abatement of emerging antibiotic pollutants. A detailed analysis of both native and engineered biochar is provided in this article for antibiotic remediation. There has also been discussion of how biochar properties relate to feedstock, production conditions and manufacturing technologies, and engineering techniques. It is possible to produce biochar with different surface functionalities by varying the feedstock or by modifying the pristine biochar with different chemicals and preparing composites. Subsequently, the interaction of biochar with antibiotic pollutants was compared and reviewed. Depending on the surface functionalities of biochar, they offer different types of interactions e.g., π-π stacking, electrostatic, and H-bonding to adsorb on the biochar surface. This review demonstrates how biochar and related composites have optimized for maximum removal performance by regulating key parameters. Furthermore, future research directions and opportunities for biochar research are discussed.

An investigation of chemical and electrochemical conversion of SILAR grown Mn3O4 into MnO2 thin films

Manganese oxide is an interesting material for electrochemical properties. It is well known that Mn₃O₄ (spinel) can be electrochemically converted to MnO₂ (birnessite) via the electrochemical route during cyclic voltammetry (CV) cycling in aqueous Na₂SO₄ solution. Herein, the novel way is represented for the growth of highly adherent and compact Mn₃O₄ thin films by using successive ionic layer adsorption and reaction (SILAR) method. As grown Mn₃O₄ thin films are converted into MnO₂ after chemical treatment by hydrochloric acid (HCl) via a disproportionate reaction. Mn₃O₄ thin films are converted into MnO₂ by both chemical and electrochemical paths. During chemical conversion, at acidic pH, the crystal water insertion (H₃O⁺) in Mn₃O₄ crystal provides the necessary driving force to transform it into MnO₂ crystal. During electrochemical transformation, the specific capacitance was found to increase from 72 (1st CV cycle) to 393 F/g (1600th CV cycle). On the other hand, the specific capacitance was increased from 72 to 258 F/g through chemical transformation. Electrochemical and chemical conversion leads to ~5.5 and ~3.5 fold, respectively, improved supercapacitive performance than pristine Mn₃O₄ thin films. Both chemical and electrochemical conversion routes are extremely useful to recycle battery waste for supercapacitor applications.

α-Cellulose Fibers of Paper-Waste Origin Surface-Modified with Fe3O4 and Thiolated-Chitosan for Efficacious Immobilization of Laccase

The utilization of waste-paper-biomass for extraction of important α-cellulose biopolymer, and modification of extracted α-cellulose for application in enzyme immobilization can be extremely vital for green circular bio-economy. Thus, in this study, α-cellulose fibers were super-magnetized (Fe3O4), grafted with chitosan (CTNs), and thiol (-SH) modified for laccase immobilization. The developed material was characterized by high-resolution transmission electron microscopy (HR-TEM), HR-TEM energy dispersive X-ray spectroscopy (HR-TEM-EDS), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) analyses. Laccase immobilized on α-Cellulose-Fe3O4-CTNs (α-Cellulose-Fe3O4-CTNs-Laccase) gave significant activity recovery (99.16%) and laccase loading potential (169.36 mg/g). The α-Cellulose-Fe3O4-CTNs-Laccase displayed excellent stabilities for temperature, pH, and storage time. The α-Cellulose-Fe3O4-CTNs-Laccase applied in repeated cycles shown remarkable consistency of activity retention for 10 cycles. After the 10th cycle, α-Cellulose-Fe3O4-CTNs possessed 80.65% relative activity. Furthermore, α-Cellulose-Fe3O4-CTNs-Laccase shown excellent degradation of pharmaceutical contaminant sulfamethoxazole (SMX). The SMX degradation by α-Cellulose-Fe3O4-CTNs-Laccase was found optimum at incubation time (20 h), pH (3), temperatures (30 °C), and shaking conditions (200 rpm). Finally, α-Cellulose-Fe3O4-CTNs-Laccase gave repeated degradation of SMX. Thus, this study presents a novel, waste-derived, highly capable, and super-magnetic nanocomposite for enzyme immobilization applications.

Thiolation of Chitosan Loaded over Super-Magnetic Halloysite Nanotubes for Enhanced Laccase Immobilization

This study focuses on the development of a nanosupport based on halloysite nanotubes (HNTs), Fe3O4 nanoparticles (NPs), and thiolated chitosan (CTs) for laccase immobilization. First, HNTs were modified with Fe3O4 NPs (HNTs-Fe3O4) by the coprecipitation method. Then, the HNTs-Fe3O4 surface was tuned with the CTs (HNTs-Fe3O4-CTs) by a simple refluxing method. Finally, the HNTs- Fe3O4-CTs surface was thiolated (-SH) (denoted as; HNTs- Fe3O4-CTs-SH) by using the reactive NHS-ester reaction. The thiol-modified HNTs (HNTs- Fe3O4-CTs-SH) were characterized by FE-SEM, HR-TEM, XPS, XRD, FT-IR, and VSM analyses. The HNTs-Fe3O4-CTs-SH was applied for the laccase immobilization. It gave excellent immobilization of laccase with 100% activity recovery and 144 mg/g laccase loading capacity. The immobilized laccase on HNTs-Fe3O4-CTs-SH (HNTs-Fe3O4-CTs-S-S-Laccase) exhibited enhanced biocatalytic performance with improved thermal, storage, and pH stabilities. HNTs-Fe3O4-CTs-S-S-Laccase gave outstanding repeated cycle capability, at the end of the 15th cycle, it kept 61% of the laccase activity. Furthermore, HNTs-Fe3O4-CTs-S-S-Laccase was applied for redox-mediated removal of textile dye DR80 and pharmaceutical compound ampicillin. The obtained result marked the potential of the HNTs-Fe3O4-CTs-S-S-Laccase for the removal of hazardous pollutants. This nanosupport is based on clay mineral HNTs, made from low-cost biopolymer CTs, super-magnetic in nature, and can be applied in laccase-based decontamination of environmental pollutants. This study also gave excellent material HNTs-Fe3O4-CTs-SH for other enzyme immobilization processes.

Chitosan-Grafted Halloysite Nanotubes-Fe3O4 Composite for Laccase-Immobilization and Sulfamethoxazole-Degradation

A surface-engineered nano-support for enzyme laccase-immobilization was designed by grafting the surface of halloysite nanotubes (HNTs) with Fe3O4 nanoparticles and chitosan. Herein, HNTs were magnetized (HNTs-M) by a cost-effective reduction-precipitation method. The synthesized HNTs-M were grafted with 0.25%, 0.5%, 1%, and 2% chitosan (HNTs-M-chitosan), respectively. Synthesized HNTs-M-chitosan (0.25%), HNTs-M-chitosan (0.5%), HNTs-M-chitosan (1%) and HNTs-M-chitosan (2%) were linked with glutaraldehyde (GTA) for laccase immobilization. Among these formulations, HNTs-M-chitosan (1%) exhibited the highest laccase immobilization with 95.13% activity recovery and 100.12 mg/g of laccase loading. The optimized material was characterized thoroughly by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray powder diffraction (XRD), thermal gravimetric analysis (TGA), and vibrating sample magnetometer (VSM) analysis. The immobilized laccase (HNTs-M-chitosan (1%)-GTA-Laccase) exhibited higher pH, temperature, and storage stabilities. The HNTs-M-chitosan (1%)-GTA-Laccase possesses excellent reusability capabilities. At the end of 10 cycles of the reusability experiment, HNTs-M-chitosan (1%)-GTA-Laccase retained 59.88% of its initial activity. The immobilized laccase was utilized for redox-mediated degradation of sulfamethoxazole (SMX), resulting in 41%, 59%, and 62% degradation of SMX in the presence of 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), guaiacol (GUA), and syringaldehyde (SA), respectively. Repeated SMX degradation (57.10% after the sixth cycle) confirmed the potential of HNTs-M-chitosan (1%)-GTA-Laccase for environmental pollutant degradation. Thus, we successfully designed chitosan-based, rapidly separable super-magnetic nanotubes for efficacious enhancement of laccase biocatalysis, which can be applied as nano-supports for other enzymes.

Biodegradation of high concentration phenol using sugarcane bagasse immobilized Candida tropicalis PHB5 in a packed-bed column reactor

Biodegradation of phenolic compounds in wastewater can be effectively carried out in packed bed reactors (PBRs) employing immobilized microorganisms. A low-cost, reusable immobilization matrix in PBR can provide economic advantages in large scale removal of high concentration phenol. In this study, we evaluated the efficiency and reusability of sugarcane bagasse (SCB) as a low-cost immobilization support for high strength phenol removal in recirculating upflow PBR. An isolated yeast Candida tropicalis PHB5 was immobilized onto the SCB support and packed into the reactor to assess phenol biodegradation at various influent flow rates. Scanning electron microscopy exhibited substantial cell attachment within the pith and onto the fibrous strand surface of the SCB support. The PBR showed 97% removal efficiency at the initial phenol concentration of 2400 mg L^-1 and 4 mL min^-1 flow rate within 54 h. Biodegradation kinetic studies revealed that the phenol biodegradation rate and biodegradation rate constant were dependent on the influent flow rate. A relatively higher rate of biodegradation (64.20 mg g^-1 h^-1) was found at a flow rate of 8 mL min^-1, indicating rapid phenol removal in the PBR. Up to six successive batches (phenol removal >94%) were successfully applied in the PBR using an initial phenol concentration of 400-2400 mg L^-1 at a flow rate of 4 mL min^-1 indicating the reusability of the PBR system. The SCB-immobilized C. tropicalis could be employed as a cost-effective packing material for removal of high strength phenolic compounds in real scale PBR.

Uptake and biodegradation of emerging contaminant sulfamethoxazole from aqueous phase using Ipomoea aquatica

Plants serve as appropriate markers of worldwide pollution because they are present in almost every corner of the globe and bioaccumulate xenobiotic chemicals from their environment. The potential of a semi-aquatic plant, Ipomoea aquatica, to uptake and metabolize sulfamethoxazole (SMX) was investigated in this study. I. aquatica exhibited 100% removal of 0.05 mg L^-1 SMX from synthetic media within 30 h. The I. aquatica achieved 93, 77 and 72% removal of SMX at 0.2, 0.5 and 1 mg L^-1, respectively, after 48 h. This indicated that removal efficiency of I. aquatica was deteriorating at high concentrations of SMX. The chlorophyll and carotenoid content of I. aquatica was insignificantly influenced by SMX irrespective of its high concentration. Similarly, scanning electron microscopy (SEM) showed that exposure to SMX had an insignificant impact on morphology of the plant organelles. The mechanisms of removal by I. aquatica were explored by evaluating contributions of bioadsorption, bioaccumulation and biodegradation. There was negligible adsorption of SMX to plant roots. Accumulation of SMX within plant roots and stems was not observed; however, I. aquatica accumulated 17% of SMX in leaves. Thus, the major mechanism of elimination of SMX was biodegradation, which accounted for 82% removal of SMX. Gas chromatography-mass spectrometry (GC-MS) confirmed that I. aquatica biodegraded SMX into simpler compounds, and generated 4-aminophenol as its final product. A laboratory scale phytoreactor was used to investigate the application of I. aquatica in a simulated system, where it achieved 49% removal of SMX (0.2 mg L^-1) in 10 d.

Bio-fabrication of silver nanoparticles using the leaf extract of an ancient herbal medicine, dandelion (Taraxacum officinale), evaluation of their antioxidant, anticancer potential, and antimicrobial activity against phytopathogens

In recent years, the use of nanoparticle-based antimicrobials has been increased due to many advantages over conventional agrochemicals. This study investigates the utilization of common medicinal plant dandelion, Taraxacum officinale, for the synthesis of silver nanoparticles (TOL-AgNPs). AgNPs were evaluated for antimicrobial activity against two important phytopathogens, Xanthomonas axonopodis and Pseudomonas syringae. The morphology, size, and structure of TOL-AgNPs were characterized using UV-visible spectroscopy and X-ray diffraction (XRD). Fourier transform infrared spectroscopy (FT-IR) showed the presence of phytochemicals involved during synthesis of NPs. High-resolution transmission electron microscopy (HR-TEM) analysis shed light on the size of monodispersed spherical AgNPs ranging between 5 and 30 nm, with an average particle size of about 15 nm. The TOL-AgNPs (at 20 μg/mL concentration) showed significant antibacterial activity with significant growth inhibition of phytopathogens X. axonopodis (22.0 ± 0.84 mm) and P. syringae (19.5 ± 0.66 mm). The synthesized AgNPs had higher antibacterial activity in comparison with commercial AgNPs. Synergistic assays with standard antibiotics revealed that nanoformulations with tetracycline showed better broad-spectrum efficiency to control phytopathogens. They also possessed significant antioxidant potential in terms of ABTS (IC₅₀ = 45.6 μg/mL), DPPH (IC₅₀ = 56.1 μg/mL), and NO (IC₅₀ = 55.2 μg/mL) free radical scavenging activity. The TOL-AgNPs showed high cytotoxic effect against human liver cancer cells (HepG2). Overall, dandelion-mediated AgNPs synthesis can represent a novel approach to develop effective antimicrobial and anticancer drugs with a cheap and eco-friendly nature.

Effects of concentration and gas flow rate on the removal of gas-phase toluene and xylene mixture in a compost biofilter

The aim of this work was to study the performance of a compost/ceramic bead biofilter (6:4 v/v) for the removal of gas-phase toluene and xylene at different inlet loading rates (ILR). The inlet toluene (or) xylene concentrations were varied from 0.1 to 1.5gm^-3, at gas flow rates of 0.024, 0.048 and 0.072m³h^-1, respectively, corresponding to total ILR varying between 7 and 213gm^-3h^-1. Although there was mutual inhibition, xylene removal was severely inhibited by the presence of toluene than toluene removal by the presence of xylene. The biofilter was also exposed to transient variations such as prolonged periods of shutdown (30days) and shock loads to envisage the response and recuperating ability of the biofilter. The maximum elimination capacity (EC) for toluene and xylene were 29.2 and 16.4gm^-3h^-1, respectively, at inlet loads of 53.8 and 43.7gm^-3h^-1.

Metabolic engineering of Enterobacter aerogenes for 2,3-butanediol production from sugarcane bagasse hydrolysate

The pathway engineering of Enterobacter aerogenes was attempted to improve its production capability of 2,3-butanediol from lignocellulosic biomass. In the medium containing glucose and xylose mixture as carbon sources, the gene deletion of pflB improved 2,3-butanediol carbon yield by 40%, while the deletion of ptsG increased xylose consumption rate significantly, improving the productivity at 12 hr by 70%. The constructed strain, EMY-22-galP, overexpressing glucose transporter (galP) in the triple gene knockout E. aerogenes, ldhA, pflB, and ptsG, provided the highest 2,3-butanediol titer and yield at 12 hr flask cultivation. Sugarcane bagasse was pretreated with green liquor, a solution containing Na₂CO₃ and Na₂SO₃ and was hydrolyzed by enzymes. The resulting hydrolysate was used as a carbon source for 2,3-butanediol production. After 72 hr in fermentation, the yield of 0.395g/g sugar was achieved, suggesting an economic production of 2,3-butanediol was possible from lignocellulosic biomass with the metabolically engineered strain.

A review on the biomass pretreatment and inhibitor removal methods as key-steps towards efficient macroalgae-based biohydrogen production

(Red, green and brown) macroalgal biomass is a propitious candidate towards covenant alternative energy resources to be converted into biofuels i.e. hydrogen. The application of macroalgae for hydrogen fermentation (promising route in advancing the biohydrogen generation process) could be accomplished by the transformation of carbohydrates, which is a topic receiving broad attention in recent years. This article overviews the variety of marine algal biomass available in the coastal system, followed by the analyses of their pretreatment methods, inhibitor formation and possible detoxification, which are key-aspects to achieve subsequent H₂ fermentation in a proper way.

Bio-hythane production from microalgae biomass: Key challenges and potential opportunities for algal bio-refineries

The interest in microalgae for wastewater treatment and liquid bio-fuels production (i.e. biodiesel and bioethanol) is steadily increasing due to the energy demand of the ultra-modern technological world. The associated biomass and by-product residues generated from these processes can be utilized as a feedstock in anaerobic fermentation for the production of gaseous bio-fuels. In this context, dark fermentation coupled with anaerobic digestion can be a potential technology for the production of hydrogen and methane from these residual algal biomasses. The mixture of these gaseous bio-fuels, known as hythane, has superior characteristics and is increasingly regarded as an alternative to fossil fuels. This review provides the current developments achieved in the conversion of algal biomass to bio-hythane (H₂+CH₄).

Exploiting antidiabetic activity of silver nanoparticles synthesized using Punica granatum leaves and anticancer potential against human liver cancer cells (HepG2)

This study first time reports the novel synthesis of silver nanoparticles (AgNPs) using a Punica granatum leaf extract (PGE). The synthesized AgNPs were characterized by various analytical techniques including UV-Vis, Fourier transform infrared (FTIR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy and energy-dispersive spectra (FESEM-EDS) and high-resolution transmission electron microscopy (HRTEM). FTIR analysis revealed that the involvement of biological macromolecules of P. granatum leaf extract were distributed and involved in the synthesis and stabilization of AgNPs. A surface-sensitive technique of XPS was used to analyse the composition and oxidation state of synthesized AgNPs. The analytical results confirmed that the AgNPs were crystalline in nature with spherical shape. The zeta potential study revealed that the surface charge of synthesized AgNPs was highly negative (-26.6 mV) and particle size distribution was ranging from ∼35 to 60 nm and the average particle size was about 48 nm determined by dynamic light scattering (DLS). The PGE-AgNPs antidiabetic potential exhibited effective inhibition against α-amylase and α-glucosidase (IC₅₀; 65.2 and 53.8 μg/mL, respectively). The PGE-AgNPs showed a dose-dependent response against human liver cancer cells (HepG2) (IC₅₀; 70 μg/mL) indicating its greater efficacy in killing cancer cells. They also possessed in vitro free radical-scavenging activity in terms of ABTS (IC₅₀; 52.2 μg/mL) and DPPH (IC₅₀; 67.1 μg/mL) antioxidant activity. PGE-AgNPs displayed strong antibacterial activity and potent synergy with standard antibiotics against pathogenic bacteria. Thus, synthesized PGE-AgNPs show potential biomedical and industrial applications.

Reutilization of green liquor chemicals for pretreatment of whole rice waste biomass and its application to 2,3-butanediol production

The performance of green liquor pretreatment using Na2CO3 and Na2SO3 and its optimization for whole rice waste biomass (RWB) was investigated. Incubation of Na2CO3-Na2SO3 at a 1:1 ratio (chemical charge 10%) for 12% RWB at 100°C for 6h resulted in maximum delignification (58.2%) with significant glucan yield (88%) and total sugar recovery (545mg/g of RWB) after enzymatic hydrolysis. Recovery and reusability of the resulting chemical spent wash were evaluated to treat RWB along with its compatibility for enzymatic digestibility. Significant hydrolysis and lignin removal were observed for up to three cycles; however, further reuse of Na2CO3 and Na2SO3 lowered their performance. Significant 2,3-butanediol (BDO) was produced by Klebsiella pneumoniae KMK-05 with the RWB enzymatic hydrolysate from each pretreatment cycle. BDO yield achieved using RWB-derived sugars was similar to those using laboratory-grade sugars. This pretreatment strategy constitutes an ecofriendly, cost-effective, and practical method for utilizing lignocellulosic biomass.

Preparation of activated carbons from peach stone by H4P2O7 activation and its application for the removal of Acid Red 18 and dye containing wastewater

The present study consists of the preparation of activated carbon from peach stone (PSAC) by H₄P₂O₇ activation and its detailed characterization. The influence of different activants and various operational conditions including; soaking time, activation time, and activation temperature during PSAC preparation were systematically investigated. The chemical properties and morphology of prepared activated carbon was characterized by various analytical techniques (FTIR, SEM and EDX). TG-DTA analysis showed that the pore development of PSAC was significant at temperatures > 450°C. The prepared PSAC were utilized for the rapid removal and adsorption of Acid Red 18 (AR18) from aqueous solution that follows pseudo-second-order kinetics. The Langmuir isotherm model corresponded well with equilibrium data than the others, implying that the adsorption of AR18 onto prepared PSAC from the aqueous solutions proceeds by a monolayer formation. Thermodynamic investigations showed that the adsorption process is an exothermic and spontaneous process. During reusability studies, PSAC showed complete removal of AR18 upto seventh cycle increasing its practical applicability. Finally the prepared PSAC showed the best adsorptive capacity as compared to commercial AC for dye removal from actual industrial wastewater. This confers the possibility of applying PSAC economically viable option for the treatment of industrial wastewaters containing dye pollutants using suitable reactor.

Improving alkaline pretreatment method for preparation of whole rice waste biomass feedstock and bioethanol production

Sequential NaOH + ASC + SB as an effective pretreatment method for whole rice waste biomass hydrolysis and ethanol production.

Exploiting the efficacy of Lysinibacillus sp. RGS for decolorization and detoxification of industrial dyes, textile effluent and bioreactor studies

Complete decolorization and detoxification of Reactive Orange 4 within 5 h (pH 6.6, at 30°C) by isolated Lysinibacillus sp. RGS was observed. Significant reduction in TOC (93%) and COD (90%) was indicative of conversion of complex dye into simple products, which were identified as naphthalene moieties by various analytical techniques (HPLC, FTIR, and GC-MS). Supplementation of agricultural waste extract considered as better option to make the process cost effective. Oxido-reductive enzymes were found to be involved in the degradation mechanism. Finally Loofa immobilized Lysinibacillus sp. cells in a fixed-bed bioreactor showed significant decolorization with reduction in TOC (51 and 64%) and COD (54 and 66%) for synthetic and textile effluent at 30 and 35 mL h(-1) feeding rate, respectively. The degraded metabolites showed non-toxic nature revealed by phytotoxicity and photosynthetic pigments content study for Sorghum vulgare and Phaseolus mungo. In addition nitrogen fixing and phosphate solubilizing microbes were less affected in treated wastewater and thus the treated effluent can be used for the irrigation purpose. This work could be useful for the development of efficient and ecofriendly technologies to reduce dye content in the wastewater to permissible levels at affordable cost.

Oxidative stress response in dye degrading bacterium Lysinibacillus sp. RGS exposed to Reactive Orange 16, degradation of RO16 and evaluation of toxicity

Lysinibacillus sp. RGS degrades sulfonated azo dye Reactive Orange 16 (RO16) efficiently. Superoxide dismutase and catalase activity were tested to study the response of Lysinibacillus sp. RGS to the oxidative stress generated by RO16. The results demonstrated that oxidative stress enzymes not only protect the cell from oxidative stress but also has a probable role in decolorization along with an involvement of oxidoreductive enzymes. Formation of three different metabolites after degradation of RO16 has been confirmed by GC-MS analysis. FTIR analysis verified the degradation of functional groups of RO16, and HPTLC confirmed the removal of auxochrome group from the RO16 after degradation. Toxicity studies confirmed the genotoxic, cytotoxic, and phytotoxic nature of RO16 and the formation of less toxic products after the treatment of Lysinibacillus sp. RGS. Therefore, Lysinibacillus sp. RGS has a better perspective of bioremediation for textile wastewater treatment.

Enzymatic hydrolysis and characterization of waste lignocellulosic biomass produced after dye bioremediation under solid state fermentation

Sugarcane bagasse (SCB) adsorbes 60% Reactive Blue172 (RB172). Providensia staurti EbtSPG able to decolorize SCB adsorbed RB172 up to 99% under solid state fermentation (SSF). The enzymatic saccharification efficiency of waste biomass after bioremediation of RB172 process (ddSCB) has been evaluated. The cellulolyitc crude enzyme produced by Phanerochaete chrysosporium used for enzymatic hydrolysis of native SCB and ddSCB which produces 0.08 and 0.3 g/L of reducing sugars respectively after 48 h of incubation. The production of hexose and pentose sugars during hydrolysis was confirmed by HPTLC. The effect of enzymatic hydrolysis on SCB and ddSCB has been evaluated by FTIR, XRD and SEM analysis. Thus, during dye biodegradation under SSF causes biological pretreatment of SCB which significantly enhanced its enzymatic saccharification. Adsorption of dye on SCB, its bioremediation under SSF produces wastes biomass and which further utilized for enzymatic saccharification for biofuel production.

Decolorization and detoxification of sulfonated toxic diazo dye C.I. Direct Red 81 by Enterococcus faecalis YZ 66

Isolated Enterococcus faecalis YZ 66 strain shows ability to decolorize various industrial dyes among which, it showed complete decolorization and degradation of toxic, sulfonated recalcitrant diazo dye Direct Red 81 (50 mg/L) within 1.5 h of incubation under static anoxic condition. The optimum pH and temperature for decolorization was 7.0 and 40°C, respectively. Significant induction in the activity of intracellular oxidoreductive enzymes suggested its involvement in the decolorization of Direct Red 81. The biodegradation of Direct Red 81 was monitored by UV-Visible, FT-IR spectroscopy and HPLC. The final products were characterized by GC-MS and possible pathway of the degradation of the dye was proposed. The phytotoxicity assay (with respect to plants Sorghum vulgare and Phaseolus mungo) revealed that the degradation of Direct Red 81 produced nontoxic metabolites. Finally E. faecalis was employed to decolorize actual industrial effluent showing decolorization (in terms of ADMI value) with moderate COD and BOD reduction. Moreover the result increases the applicability of the strain for the treatment of industrial wastewaters containing dye pollutants.

Application of Co-naphthalocyanine (CoNPc) as alternative cathode catalyst and support structure for microbial fuel cells

Co-naphthalocyanine (CoNPc) was prepared by heat treatment for cathode catalysts to be used in microbial fuel cells (MFCs). Four different catalysts (Carbon black, NPc/C, CoNPc/C, Pt/C) were compared and characterized using XPS, EDAX and TEM. The electrochemical characteristics of oxygen reduction reaction (ORR) were compared by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The Co-macrocyclic complex improves the catalyst dispersion and oxygen reduction reaction of CoNPc/C. The maximum power of CoNPc/C was 64.7 mW/m(2) at 0.25 mA as compared with 81.3 mW/m(2) of Pt/C, 29.7 mW/m(2) of NPc/C and 9.3 mW/m(2) of carbon black when the cathodes were implemented in H-type MFCs. The steady state cell, cathode and anode potential of MFC with using CoNPc/C were comparable to those of Pt/C.

Multicomponent cellulase production by Cellulomonas biazotea NCIM-2550 and its applications for cellulosic biohydrogen production

Among four cellulolytic microorganisms examined, Cellulomonas biazotea NCIM-2550 can grow on various cellulosic substrates and produce reducing sugar. The activity of cellulases (endoglucanase, exoglucanase, and cellobiase), xylanase, amylase, and lignin class of enzymes produced by C. biazotea was mainly present extracellularly and the enzyme production was dependent on cellulosic substrates (carboxymethyl cellulose [CMC], sugarcane bagasse [SCB], and xylan) used for growth. Effects of physicochemical conditions on cellulolytic enzyme production were systematically investigated. Using MnCl(2) as a metal additive significantly induces the cellulase enzyme system, resulting in more reducing sugar production. The efficiency of fermentative conversion of the hydrolyzed SCB and xylan into clean H(2) energy was examined with seven H(2)-producing pure bacterial isolates. Only Clostridiumbutyricum CGS5 exhibited efficient H(2) production performance with the hydrolysate of SCB and xylan. The cumulative H(2) production and H(2) yield from using bagasse hydrolysate (initial reducing sugar concentration = 1.545 g/L) were approximately 72.61 mL/L and 2.13 mmol H(2)/g reducing sugar (or 1.91 mmol H(2)/g cellulose), respectively. Using xylan hydrolysate (initial reducing sugar concentration = 0.345 g/L) as substrate could also attain a cumulative H(2) production and H(2) yield of 87.02 mL/L and 5.03 mmol H(2)/g reducing sugar (or 4.01 mmol H(2)/g cellulose), respectively.

Decolorization and biodegradation of reactive dyes and dye wastewater by a developed bacterial consortium

A bacterial consortium (consortium GR) consisting of Proteus vulgaris NCIM-2027 and Micrococcus glutamicus NCIM-2168 could rapidly decolorize and degrade commonly-used sulfonated reactive dye Green HE4BD and many other reactive dyes. Consortium GR shows markedly higher decolorization activity than that of the individual strains. The preferable physicochemical parameters were identified to achieve higher dye degradation and decolorization efficiency. The supplementation of cheap co-substrates (e.g., extracts of agricultural wastes) could enhance the decolorization performance of consortium GR. Extent of mineralization was determined with TOC and COD measurements, showing nearly complete mineralization of Green HE4BD by consortium GR (up to 90% TOC and COD reduction) within 24 h. Oxidoreductive enzymes seemed to be involved in fast decolorization/degradation process with the evidence of enzymes induction in the bacterial consortium. Phytotoxicity and microbial toxicity studies confirm that the biodegraded products of Green HE4BD by consortium GR are non-toxic. Consortium GR also shows significant biodegradation and decolorization activities for mixture of reactive dyes as well as the effluent from actual dye manufacturing industry. This confers the possibility of applying consortium GR for the treatment of industrial wastewaters containing dye pollutants.

Ecofriendly degradation of sulfonated diazo dye C.I. Reactive Green 19A using Micrococcus glutamicus NCIM-2168

Micrococcus glutamicus NCIM-2168 exhibited complete decolorization and degradation of C.I. Reactive Green 19A (an initial concentration of 50 mg l(-1)) within 42 h at temperature 37 degrees C and pH 8, under static condition. Extent of mineralization was determined with total organic carbon (TOC) and chemical oxygen demand (COD) measurement, showing a satisfactory reduction of TOC (72%) and COD (66%) within 42 h. Enzyme studies shows involvement of oxidoreductive enzymes in decolorization/degradation process. Analytical studies of the extracted metabolites confirmed the significant degradation of Reactive Green 19A into various metabolites. The microbial toxicity and phytotoxicity assay revealed that the degradation of Reactive Green 19A produced nontoxic metabolites. In addition, the M. glutamicus strain was applied to decolorize a mixture of ten reactive dyes showing a 63% decolorization (in terms of decrease in ADMI value) within 72 h, along with 48% and 42% reduction in TOC and COD under static condition.

Decolorization and biodegradation of textile dye Navy blue HER by Trichosporon beigelii NCIM-3326

Navy blue HER was decolorized and degraded within 24h by Trichosporon beigelii NCIM-3326 under static condition. In the present study, we investigated various physicochemical parameters such as agitation, temperature, pH, cell concentration, initial dye concentration and different carbon and nitrogen sources to achieve maximum dye degradation by T. beigelii. Sequentially, decolorization and decrease in the total organic carbon (TOC) of Navy blue HER by T. beigelii were measured. Among five strains T. beigelii gave the better performance on the decolorization of Navy blue HER along with a 95% TOC reduction within 24h. A significant increase in the activities of NADH-DCIP (dichlorophenolindophenol) reductase and azoreductase in the cells obtained after complete decolorization presumably indicates involvement of these enzymes in decolorization process. UV-vis, TLC, HPLC and FTIR analysis of extracted products confirmed the biodegradation of Navy blue HER. Phytotoxicity study demonstrated no toxicity of the biodegraded products with respect to plants viz. Phaseolus mungo and Sorghum vulgare. In addition to Navy blue HER, this strain also shows ability to decolorize various industrial dyes, including Red HE7B, Golden yellow 4BD, Green HE4BD, Orange HE2R, Malachite green, Crystal violet and Methyl violet.

Enhanced decolorization and biodegradation of textile azo dye Scarlet R by using developed microbial consortium-GR

A developed consortium-GR, consisting of Proteus vulgaris NCIM-2027 (PV) and Micrococcus glutamicus NCIM-2168 (MG), completely decolorized an azo dye Scarlet R under static anoxic condition with an average decolorization rate of 16,666 microg h(-1); which is much faster than that of the pure cultures (PV, 3571 microg h(-1); MG, 2500 microg h(-1)). Consortium-GR gave best decolorization performance with nearly complete mineralization of Scarlet R (over 90% TOC and COD reduction) within 3h, much shorter relative to the individual strains. Induction in the riboflavin reductase and NADH-DCIP reductase was observed in the consortium, suggesting the involvement of these enzymes during the fast decolorization process. The FTIR and GC-MS analysis showed that 1,4-benzenediamine was formed during decolorization/degradation of Scarlet R by consortium-GR. Phytotoxicity studies revealed no toxicity of the biodegraded products of Scarlet R by consortium-GR. In addition, consortium-GR applied for mixture of industrial dyes showed 88% decolorization under static condition with significant reduction in TOC (62%) and COD (68%) within 72 h, suggesting potential application of this microbial consortium in bioremediation of dye-containing wastewater.

Simultaneous production of 2,3-butanediol, ethanol and hydrogen with a Klebsiella sp. strain isolated from sewage sludge

A Klebsiella sp. HE1 strain isolated from hydrogen-producing sewage sludge was examined for its ability to produce H2 and other valuable soluble metabolites (e.g., ethanol and 2,3-butanediol) from sucrose-based medium. The effect of pH and carbon substrate concentration on the production of soluble and gaseous products was investigated. The major soluble metabolite produced from Klebsiella sp. HE1 was 2,3-butanediol, accounting for over 42-58% of soluble microbial products (SMP) and its production efficiency enhanced after increasing the initial culture pH to 7.3 (without pH control). The HE1 strain also produced ethanol (contributing to 29-42% of total SMP) and a small amount of lactic acid and acetic acid. The gaseous products consisted of H2 (25-36%) and CO2 (64-75%). The optimal cumulative hydrogen production (2.7 l) and hydrogen yield (0.92mol H2 mol sucrose(-1)) were obtained at an initial sucrose concentration of 30g CODl(-1) (i.e., 26.7gl(-1)), which also led to the highest production rate for H2 (3.26mmol h(-1)l(-1)), ethanol (6.75mmol h(-1)l(-1)) and 2,3-butanediol (7.14mmol h(-1)l(-1)). The highest yield for H2, ethanol and 2,3-butanediol was 0.92, 0.81 and 0.59molmol-sucrose(-1), respectively. As for the overall energy production performance, the highest energy generation rate was 27.7kJ h(-1)l(-1) and the best energy yield was 2.45kJmolsucrose(-1), which was obtained at a sucrose concentration of 30 and 20g CODl(-1), respectively.

Study of mixed function oxidase system in Aspergillus ochraceus (NCIM 1146)

Aspergillus ochraceus (NCIM-1146) has shown the ability to degrade cholesterol, camphor and naphthalene, when 96 h grown mycelium incubated in medium containing these organic compounds. Presence of higher level of electron transport components and biotransformation enzyme activity were observed in Aspergillus ochraceus, when grown in potato dextrose medium for 96 h. The enzyme activity preferred NADPH as a cofactor and shows inhibition in the presence of CO, indicating cytochrome P-450 mediated reactions. A significant increase in the levels of electron transport components and biotransformation enzyme activity were observed in presence of different inducers (viz. cholesterol, camphor, naphthalene, veratrole, phenobarbital, n-hexane, kerosene and saffola oil) when compared with mycelium incubated in same way with similar conditions for 2 min incubation. Analyses of the products of cholesterol and camphor using HPLC and GCMS confirm the degradation of these compounds.