Kinetics of dye decolorization using heterogeneous catalytic system with immobilized Achromobacter xylosoxidans DDB6

Textile effluents containing toxic dyes must be treated effectively before discharge to prevent adverse environmental impacts. Traditional physical and chemical treatment methods are costly and generate secondary pollutants. In contrast, biological treatment is a more suitable, clean, versatile, eco-friendly, and cost-effective technique for treating textile effluent. It is well established that indigenous microbial populations present in effluents can effectively degrade toxic dyes. In this regard, Achromobacter xylosoxidans DDB6 was isolated from the effluent sample to decolorize crystal violet (CV), Coomassie brilliant blue (CBB), and alizarin red (AR) by 67.20%, 28.58%, and 20.41%, respectively. The growth parameters of A. xylosoxidans DDB6 in media supplemented with 100 ppm of various dyes were determined using the modified Gompertz growth model. The immobilized cells in calcium alginate beads showed apparent decolorization rate constant of 0.27, 0.18, and 0.13 h-1 for CV, CBB, and AR, respectively. The immobilized cells in a packed bed reactor with an optimum flow rate of 0.5 mL/min were used to treat 100 ppm of CV with a percentage decolorization of 79.47% after three cycles. Based on the findings, A. xylosoxidans DDB6 could be effectively used for decolorization of various dyes.

Biosynthesis and characterization of hydroxyapatite and its composite (hydroxyapatite-gelatin-chitosan-fibrin-bone ash) for bone tissue engineering applications

Hydroxyapatite (HAp) is a bioactive and biocompatible material possessing osteoconductive properties used widely in the biomedical sector. In the present study, synthesis of hydroxyapatite (HAp) using a Klebsiella pneumoniae SM24 (phosphate solubilizing bacteria) isolated from the slaughterhouse. HAp synthesized using biological source showed efficient and positive enzymatic activity in the National Botanical Research Institute Phosphate Medium (NBRIP). Characterization of HAp using FTIR revealed the presence of phosphate group hydroxyapatite and XRD spectra showed polycrystalline nature. The morphological characterization of HAp using FESEM revealed the mesoporous structure and EDX spectrum indicated presence of Ca and P as the major components. In addition, a new bone composite was prepared using the synthesized HAp, Gelatine (G), Chitosan (C), Fibrin (F) and Bone ash (HApGCF) using Simulated Body Fluid (SBF) solution. The confirmation of chemical and structural characteristics of HApGCF bone composite was achieved using FTIR, XRD and SEM analyses. The HApGCF bone composite was tested over osteoblast MG-63 cells showing effective biocompatibility and osteoblast attachment on the composite surface. Therefore, the present report proposes the in vitro application of HApGCF bone composite as a replacement for major bone damage and injury in a biocompatible and non-toxic way.

Evaluation of bioactive potential of an Aloe vera sterol extract

We prepared a crude gel material from Aloe vera succulent leaf tissues. The ethanolic extract of lyophilized A. vera gel was used for the GC-MS analysis. Hexadecanoic acid (22.22%) was identified as major compound. Sitosterol and stigmasterol were found to be 2.89% and 2.1% in the extract. HPLC analysis was carried out to confirm the presence of stigmasterol. The concentration of sterol extract needed to scavenge DPPH free radical by 50% was calculated as 5.2 mg mL(-1). In the FRAP assay, the sterol extract showed significant hydroxyl radical scavenging in a dose-dependent manner (IC50 value 1.17 µg mL(-1)). Concentration of the sample required to reduce lipid peroxidation was found to be 4.18 µg mL(-1), and the extract also possessed acetylcholinesterase activity (IC50 - 5.26 µg mL(-1)). Catalase activity was 0.196 μM H2 O2 decomposed min(-1) µg(-1) protein, whereas the peroxidase activity was 17.01 μM of pyragallol oxidized min(-1) µg(-1) protein. The extract recorded higher activity against growth of S. greseus and C. albicans in the experiments carried out to determine antibacterial and antifungal activity, respectively.

Structural and biological studies of mononuclear palladium(II) complexes containing N-substituted thiosemicarbazones

New complexes of Pd(II) with N-substituted thiosemicarbazone (1)-(3) have been synthesised and characterised by elemental analyses, IR, electronic, (1)H NMR spectroscopies. The electrochemical behaviour of the complexes has been tested by using cyclic voltammetry. The crystal structures of the complexes have been determined by single crystal X-ray diffraction technique. In all the complexes the thiosemicarbazone ligand is coordinated to palladium through ONS mode. The complex 1 crystallises in the monoclinic space group P2(1)/c with two molecules per unit cell, has the dimensions of a=9.4390(19)A, b=10.645(2)A, c=13.668(3)A, alpha=90 degrees , beta=91.43 degrees and gamma=90 degrees . The complex 3 crystallises in the monoclinic space group P2(1)/c with four molecules per unit cell, has the dimensions of a=14.119(3)A, b=11.155(2)A, c=18.503(4)A, alpha=90 degrees , beta=112.02 degrees and gamma=90 degrees . The new complexes have been tested for their antibacterial activity against various pathogenic bacteria. From this study, it was found out that the activity of the complex 2 almost reaches the effectiveness of the conventional bacteriocide Streptomycin.

Occurrence of Aeromonas hydrophila in acute gasteroenteritis among children

BACKGROUND & OBJECTIVE

The interest on the occurrence multidrug resistance and pathogenicity of Aeromonas hydrophila is increasing worldwide since it causes gasteroenteritis to children. Though reports on the occurrence of gasteroenteritis among children due to A. hydrophila in Tamil Nadu are available from certain areas, no information is available from Coimbatore. Hence, this study was undertaken to find out the occurrence of the pathogenic A. hydrophila in diarrhoeal stool of children, particularly in Coimbatore region.

METHODS

Isolation and identification of A. hydrophila was carried out from stool samples collected from children with acute diarrhoea. Multiple antibiotic resistance was determined by disc diffusion method. The pathogenicity of A. hydrophila was confirmed by production of haemolysin, protease and slime.

RESULTS

Of the 216 samples, 21 (9.7%) were positive for A. hydrophila. Among them 20 isolates were resistant to bacitracin. Most of the isolates showed multiple antibiotic resistance. Among the 21 isolates, protease and haemolysin producers were 100 and 95 per cent respectively. About 76 per cent of the isolates produced slime.

INTERPRETATION & CONCLUSION

The results of the present study indicated the presence of pathogenic A. hydrophila in the study area causing diarrhoea among children.

Incidence of haemolysin-positive and drug-resistant Aeromonas hydrophila in freshly caught finfish and prawn collected from major commercial fishes of coastal South India

The incidence of Aeromonas hydrophila in freshly caught finfish and prawns from four major commercial fish landing sites of coastal South India was studied for a period of one year. Among 514 analysed samples of seafood (410 finfish and 104 prawn), 37% of them (37.3% of finfish and 35.6% of prawn) were contaminated with A. hydrophila. A total of 255 strains of A. hydrophila were isolated. Of the total isolates, about 78.4% of them were producers of haemolysin. All strains were resistant to bacitracin and all were sensitive to chloramphenicol. The results indicate that the strains originated from high-risk sources. The presence of A. hydrophila is an indication of marine contamination. The increasing presence of haemolysin-producing multiple drug-resistant A. hydrophila in fish and prawn may become a potential human health hazard.