Mechanistic insights on enzyme mediated-metabolite cascade during decolourization of Reactive Blue 13 using novel microbial consortium.

Understanding the role of oxido-reductase enzymes followed by deciphering the functional genes and their corresponding proteins are crucial for the speculation of molecular mechanism for azo dye degradation. In the present study, decolourization efficiency of developed microbial consortium was tested using 100 mgL-1 reactive blue 13 (RB13) and the results showed ∼92.67% decolourization of RB13 at 48 h of incubation. The fourier-transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) analysis were performed to identify the metabolites formed during RB13 degradation, followed by hypothesizing the metabolic pathway. The GC-MS analysis showed formation of 1,4-dihydronaphthalen-1-ol and 1,3,5-triazin-2-amine as the final degraded compounds after enzymatic breakdown of RB13 dye. The activity of different oxido-reductase enzymes was determined, and the results showed that NADH DCIP reductase and azo reductase had higher activity than other enzymes. It clearly indicated the degradation was initiated with the enzymatic cleavage of azo bond of RB13. Further, the functional genes were annotated against the database of clusters of orthologous groups (COGs) and kyoto encyclopedia of genes and genomes (KEGG). It provided valuable information about the role of crucial functional genes and their corresponding proteins correlated with dominant bacterial species in degradation of RB13. Hence, the present research is the first systematic study that correlated the formation of degradation compounds with the functional genes/enzymes and their corresponding bacterial species responsible for RB13 degradation.

Effect of Arsenic on Fluoride Tolerance in Microbacterium paraoxydans Strain IR-1.

Fluoride (F) and arsenic (As) are two major contaminants of water and soil systems around the globe, causing potential toxicity to humans, plants, animals, and microbes. These contaminated soil systems can be restored by microorganisms that can tolerate toxic stress and provide rapid mineralization of soil, organic matter, and contaminants, using various tolerance mechanisms. Thus, the present study was undertaken with the arsenic hyper-tolerant bacterium Microbacterium paraoxydans strain IR-1 to determine its tolerance and toxicity to increasing doses of fluoride, either individually or in combination with arsenic, in terms of growth inhibition using a toxicity unit model. The minimum inhibitory concentration (MIC)and half maximal inhibitory concentration (IC50) values for fluoride increased, from 9 g/L to 11 g/L and from 5.91 ± 0.1 g/L to 6.32 ± 0.028 g/L, respectively, in the combination (F + As) group. The statistical comparison of observed and expected additive toxicities, with respect to toxicity unit (TU difference), using Student's t-test, was found to be highly significant (p < 0.001). This suggests the antagonistic effect of arsenic on fluoride toxicity to the strain IR-1. The unique stress tolerance of IR-1 ensures its survival as well as preponderance in fluoride and arsenic co-contaminated sites, thus paving the way for its possible application in the natural or artificial remediation of toxicant-exposed degraded soil systems.

Yeast assisted algal flocculation for enhancing nutraceutical potential of Chlorella pyrenoidosa.

The present research describes yeast assisted algal flocculation followed by evaluation of algae-yeast flocs for nutritional profile as potent food product. Co-flocculation of Chlorella pyrenoidosa using Saccharomyces cerevisiae showed 58.33 ± 2.37% flocculation efficiency. Nutrient composition of algae-yeast flocs (CP-Y) depicted higher protein content (35.52%) as compared to algae (23.72%) and yeast biomass (33.89). Amino acid profiles of CP-Y biomass depicted increase in essential amino acid content with higher ratio of essential to non-essential amino acid (0.68) as compared to Y (0.57) and CP (0.57) biomass. Lipid and carbohydrate content of CP-Y flocs was estimated as 26.95 ± 0.57% and 21.12 ± 0.83%, respectively. Fatty Acid Methyl Esters (FAME) analysis showed presence of omega rich polyunsaturated fatty acids (PUFAs) like α-linolenic acid (ω-3), Linoleic acid (ω-6), Palmitoleic acid (ω-7) etc in CP-Y biomass. The study provides novel insights on nutrition enriched biomass obtained after algal-yeast flocculation, which can be a better alternative to existing flocculation methods for food applications.

Potential role of N-acetyl glucosamine in Aspergillus fumigatus-assisted Chlorella pyrenoidosa harvesting.

BACKGROUND: Algal harvesting is a major cost which increases biofuel production cost. Algal biofuels are widely studied as third-generation biofuel. However, they are yet not viable because of its high production cost which is majorly contributed by energy-intensive biomass harvesting techniques. Biological harvesting method like fungal-assisted harvesting of microalgae is highly efficient but poses a challenge due to its slow kinetics and poorly understood mechanism. RESULTS: In this study, we investigate Aspergillus fumigatus-Chlorella pyrenoidosa attachment resulting in a harvesting efficiency of 90% within 4 h. To pinpoint the role of extracellular metabolite, several experiments were performed by eliminating the C. pyrenoidosa or A. fumigatus spent medium from the C. pyrenoidosa-A. fumigatus mixture. In the absence of A. fumigatus spent medium, the harvesting efficiency dropped to 20% compared to > 90% in the control, which was regained after addition of A. fumigatus spent medium. Different treatments of A. fumigatus spent medium showed drop in harvesting efficiency after periodate treatment (≤ 20%) and methanol-chloroform extraction (≤ 20%), indicating the role of sugar-like moiety. HR-LC-MS (high-resolution liquid chromatography-mass spectrometry) results confirmed the presence of N-acetyl-d-glucosamine (GlcNAc) and glucose in the spent medium. When GlcNAc was used as a replacement of A. fumigatus spent medium for harvesting studies, the harvesting process was significantly faster (p < 0.05) till 4 h compared to that with glucose. Further experiments indicated that metabolically active A. fumigatus produced GlcNAc from glucose. Concanavalin A staining and FTIR (Fourier transform infrared spectroscopy) analysis of A. fumigatus spent medium- as well as GlcNAc-incubated C. pyrenoidosa cells suggested the presence of GlcNAc on its cell surface indicated by dark red dots and GlcNAc-specific peaks, while no such characteristic dots or peaks were observed in normal C. pyrenoidosa cells. HR-TEM (High-resolution Transmission electron microscopy) showed the formation of serrated edges on the C. pyrenoidosa cell surface after treatment with A. fumigatus spent medium or GlcNAc, while Atomic force microscopy (AFM) showed an increase in roughness of the C. pyrenoidosa cells surface upon incubation with A. fumigatus spent medium. CONCLUSIONS: Results strongly suggest that GlcNAc present in A. fumigatus spent medium induces surface changes in C. pyrenoidosa cells that mediate the attachment to A. fumigatus hyphae. Thus, this study provides a better understanding of the A. fumigatus-assisted C. pyrenoidosa harvesting process.

Performance evaluation of two Aspergillus spp. for the decolourization of reactive dyes by bioaccumulation and biosorption.

A biological method was adopted to decolourize textile dyes, which is an economic and eco-friendly technology for textile wastewater remediation. Two fungal strains, i.e. Aspergillus lentulus and Aspergillus fumigatus, were used to study the removal of low to high concentrations (25 to 2000 mg L-1) of reactive remazol red, reactive blue and reactive yellow dyes by biosorption and bioaccumulation. The biosorption was successful only at the lower concentrations. A. lentulus was capable of removing 67-85% of reactive dyes during bioaccumulation mode of treatment at 500 mg L-1 dye concentration with an increased biomass uptake capacity. To cope up with the high dye concentration of 2000 mg L-1, a novel combined approach was successful in case of A. lentulus, where almost 76% removal of reactive remazol red dye was observed during bioaccumulation followed by biosorption. The scanning electron microscopy also showed the accumulation of dye on the surface of fungal mycelium. The results signify the application of such robust fungal strains for the removal of high concentration of dyes in the textile wastewaters.

Photochemical degradation of the hazardous dye Safranin-T using TiO2 catalyst.

Aqueous solutions of Safranin-T, a hazardous textile dye, are photodegraded under ultraviolet light using TiO2 as catalyst. The process has been carried out at different pHs, amounts of catalyst, concentrations of the dye, and effects of the electron acceptor H2O2. It is found that under the influence of TiO2 as catalyst the colored solution of the dye Safranin-T becomes colorless and the process follows first-order reaction kinetics. The optimum conditions for the degradation of the dye have been found as 5.0x10(-5) M dye concentration, pH 5.7, and 12 mg catalyst dose. In order to evaluate the effect of the electron acceptor, the effect of H2O2 on the degradation process is also monitored and it is found that generation of hydroxyl radicals and retardation of electron-hole recombination takes place. Measuring chemical oxygen demand also monitors the toxicity of the degraded dye solution and a significant decrease is observed, which implies that the photodegradation through TiO2 is a safer technique.

Adsorption of Safranin-T from wastewater using waste materials- activated carbon and activated rice husks.

Textile effluents are major industrial polluters because of high color content, about 15% unfixed dyes and salts. The present paper is aimed to investigate and develop cheap adsorption methods for color removal from wastewater using waste materials activated carbon and activated rice husk-as adsorbents. The method was employed for the removal of Safranin-T and the influence of various factors such as adsorbent dose, adsorbate concentration, particle size, temperature, contact time, and pH was studied. The adsorption of the dye over both the adsorbents was found to follow Langmuir and Freundlich adsorption isotherm models. Based on these models, different useful thermodynamic parameters have been evaluated for both the adsorption processes. The adsorption of Safranin-T over activated carbon and activated rice husks follows first-order kinetics and the rate constants for the adsorption processes decrease with increase in temperature.

Role of sublingual misoprostol for cervical priming in first trimester medical termination of pregnancy.

OBJECTIVE: To evaluate the efficacy and safety of sublingual misoprostol as facilitator in first trimester medical termination of pregnancy (MTP) by surgical method. MATERIALS AND METHODS: This was a prospective open label study conducted at a tertiary center. A total 150 patients at 6-12 wks gestation requesting for MTP were randomized into two groups. Patients in study group (n=75) received sublingual misoprostol three hours before surgical abortion and in control group (n=75) directly underwent surgical abortion without prior cervical priming with misoprostol. The outcomes of both groups were recorded in terms of baseline cervical dilatation, need of additional cervical dilatation, intraoperative blood loss, operative time and procedure related complications. The results were statistically analyzed using student-t test and chi-square test. p-value of <0.05 and <0.001 were considered significant and highly significant respectively. RESULTS: The mean baseline cervical dilatation was significantly more in study group compared to control group (8.6±1.3mm versus 5±2.3mm; p <0.001) and the operative time and intraoperative blood loss were also less (p<0.001). Higher incidence of side effects like nausea, vomiting and pyrexia were recorded in sublingual misoprostol group but were well tolerable to the patients. CONCLUSION: Sublingual misoprostol is an effective and safe drug for cervical priming prior to surgical evacuation and has good patient acceptability.

Arsenic Hyper-tolerance in Four Microbacterium Species Isolated from Soil Contaminated with Textile Effluent.

Arsenic-contaminated areas of Sanganer, Jaipur, Rajasthan, India were surveyed for the presence of metal resistant bacteria contaminated with textile effluent. Samples were collected from soil receiving regular effluent from the textile industries located at Sanganer area. The properties like pH, electrical conductivity, organic carbon, organic matter, exchangeable calcium, water holding capacity and metals like arsenic, iron, magnesium, lead and zinc were estimated in the contaminated soil. In total, nine bacterial strains were isolated which exhibited minimum inhibitory concentration (MIC) of arsenic ranging between 23.09 and 69.2mM. Four out of nine arsenic contaminated soil samples exhibited the presence of arsenite hyper-tolerant bacteria. Four high arsenite tolerant bacteria were characterized by 16S rDNA gene sequencing which revealed their similarity to Microbacterium paraoxydans strain 3109, Microbacterium paraoxydans strain CF36, Microbacterium sp. CQ0110Y, Microbacterium sp. GE1017. The above results were confirmed as per Bergey's Manual of Determinative Bacteriology. All the four Microbacterium strains were found to be resistant to 100µg/ml concentration of cobalt, nickel, zinc, chromium selenium and stannous and also exhibited variable sensitivity to mercury, cadmium, lead and antimony. These results indicate that the arsenic polluted soil harbors arsenite hyper-tolerant bacteria like Microbacterium which might play a role in bioremediation of the soil.

Amniotic fluid embolism: A diagnostic dilemma.

Amniotic fluid embolism (AFE) is a rare obstetric catastrophe with an incidence of 7.7 per 100 000 deliveries and mortality as high as 60% to 80%. We describe a case of perioperative cardiac arrest in a young parturient undergoing an emergent cesarean section. Just after delivery of live healthy male baby, patient developed disseminated intravascular coagulation not responding to resuscitation with fluids and blood products. Her autopsy revealed edematous lungs with amniotic fluid debris within pulmonary vessels thus establishing the diagnosis of AFE. Amniotic fluid embolism is life threatening and difficult to predict or prevent condition, which should be always be kept in mind in a parturient with sudden cardiovascular collapse, so that resuscitation commences immediately, as early intervention is essential for a positive outcome.

Removal of the hazardous dye rhodamine B through photocatalytic and adsorption treatments.

This paper reports on photocatalytic and adsorptive treatment of a hazardous xanthene dye, Rohdamine B, in wastewater. The photocatalytic degradation was carried out in the presence of the catalyst TiO(2) and the effects of pH, concentration of the dye, amount of TiO(2), temperature and electron acceptor H(2)O(2) on the degradation process were observed. It was found that photocatalytic degradation by TiO(2) is an effective, economical and faster mode of removing Rohdamine B from aqueous solutions. Attempts were also made to utilize activated carbon and rice husk as potential adsorbents to remove Rhodamine B from wastewater. The adsorption studies were carried out at 40, 50 and 60 degrees C, and the effects of pH, temperature, amount of adsorbents, concentration of adsorbate, etc., on the adsorption were measured. On the basis of adsorption data the Langmuir and Freundlich adsorption isotherm models were also confirmed. The adsorption isotherm constants thus obtained were employed to calculate thermodynamic parameters like Gibb's free energy, change in enthalpy and entropy. In order to observe the quality of wastewater COD measurements were also carried out before and after the treatments. A significant decrease in the COD values was observed, which clearly indicates that both photocatalytic and adsorption methods offer good potential to remove Rhodamine B from industrial effluents.