Mycodegradation of low-density polyethylene by Cladosporium sphaerospermum, isolated from platisphere.

Plastic accumulation is a severe threat to the environment due to its resistivity to thermal, mechanical and biological processes. In recent years, microbial degradation of plastic waste disposal is of interest because of its eco-friendly nature. In this study, a total of 33 fungi were isolated from the plastisphere and out of which 28 fungal species showed halo zone of clearance in agarized LDPE media. The fungus showing highest zone of clearance was further used to evaluate its degradation potential. Based on morphological and molecular technique, the fungus was identified as Cladosporium sphaerospermum. The biodegradation of LDPE by C. sphaerospermum was evaluated by various methods. The exposure of LDPE with C. sphaerospermum resulted in weight loss (15.23%) in seven days, higher reduction rate (0.0224/day) and lower half-life (30.93 days). FTIR analysis showed changes in functional group and increased carbonyl index in LDPE treated with C. sphaerospermum. SEMimages evidenced the formation of pits, surface aberrations and grooves on the LDPE film treated with the fungus whereas the untreated control LDPE film showed no change. AFM analysis confirmed the surface changes and roughness in fungus treated LDPE film. This might be due to the extracellular lignolytic enzymes secreted by C. sphaerospermum grown on LDPE. The degradation of polyethylene by Short chain alkanes such as dodecane, hexasiloxane and silane were identified in the extract of fungus incubated with LDPE film through GC-MS analysis which might be due to the degradation of LDPE film by C. sphaerospermum. This was the first report on the LDPE degradation by C. sphaerospermum in very short duration which enables green scavenging of plastic wastes.

Substituent enhanced fluorescence properties of star α-cyanostilbenes and their application in bioimaging.

A series of star α-cyanostilbenes with D-π-A structures comprising triphenylamine as the donor, the cyanovinyl group as the acceptor and different substituents on the terminal phenyl rings were synthesized and characterized. The influence of the substituents on the photophysical, electrochemical and thermal properties of the star molecules was investigated in detail. A strongly electron withdrawing nitro substituent on the phenyl ring (NTBTNPA) increased the absorption and emission maxima, the Stokes shift, and the difference between the ground and excited state dipole moments and decreased the fluorescence quantum yield, fluorescence lifetime and band gap energy between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). This molecule (i.e., NTBTNPA) also showed aggregation-induced enhanced emission; it showed emission at 608 nm in pure DMF and displayed red-shifted emission at 625 nm and new emission at 706 nm in a DMF/water (50 : 50) binary mixture. Aggregation of this molecule in different DMF/water mixtures was confirmed by the dynamic light scattering method. The HOMO, LUMO and band gap energy values of all the star molecules calculated theoretically using density functional theory (DFT) were in good agreement with the experimentally determined values. The biocompatibility of NTBTNPA was tested with two Gram positive and two Gram negative bacteria and also with a fungus. Based on the photophysical properties, NTBTNPA was used as a fluorophore for bio-imaging application of a fungus, Rhizoctonia solani, as a model and the results obtained were excellent.

Growth optimization, free radical scavenging and antibacterial potential of Chlorella sp. SRD3 extracts against clinical isolates.

AIM: The aim of present work was to explore the potential of Chlorella sp. SRD3 extracts for antioxidant and antibacterial activity along with the evaluation of minimum inhibitory concentration (MIC) and haemolytic activity to detect RBC cell damage. METHODS AND RESULTS: Screening and isolation of microalgae was performed using bold basal medium under normal illuminance (at 27°C) and microscopic observation. Growth of the microalgae was optimized using a different medium and light source. The isolated microalgae incubated under fluorescent light when cultured in F/2 medium showed a highest dry biomass yield of 3·77 ± 0·1 g l-1 , when compared to the growth under direct sunlight (2·74 ± 0·07 g dwt l-1 ). The quantitative analysis of extracts revealed higher phenols, flavonoids and proanthocyanidins in ethyl acetate and hexane extracts followed by methanol. The antioxidant activity of extracts was tested against 1-diphenyl-2-picrylhydrazyl and ABTS radical, its reducing power assay was performed. From antibacterial activity, the two extracts showed better inhibition against Gram-negative bacteria. Also, they resulted in very low MIC values with effective activity against pathogens. In haemolytic activity, no haemolysis occurred, when the concentration (µg ml-1 ) was below 64 for methanol and 32 for ethyl acetate extract. In addition, Chlorella sp. extracts were characterized by GC-MS analysis to detect the major compounds. CONCLUSION: The polar extracts revealed satisfactory results against the clinical isolates and the compounds responsible were reflected in the GC-MS spectrum. SIGNIFICANCE AND IMPACT OF THE STUDY: The present study revealed significant biological potentials of the green alga, Chlorella sp. such as antioxidant, antibacterial and hemolytic activities. Therefore, this vital source might serve as a cost-effective, alternative choice to the pharmaceutical and food industries in the near future.

Purification, crystal structure and antimicrobial activity of phenazine-1-carboxamide produced by a growth-promoting biocontrol bacterium, Pseudomonas aeruginosa MML2212.

AIM: To purify and characterize an antimicrobial compound produced by a biocontrol bacterium, Pseudomonas aeruginosa MML2212, and evaluate its activity against rice pathogens, Rhizoctonia solani and Xanthomonas oryzae pv. oryzae. METHODS AND RESULTS: Pseudomonas aeruginosa strain MML2212 isolated from the rice rhizosphere with wide-spectrum antimicrobial activity was cultured in Kings'B broth using a fermentor for 36 h. The extracellular metabolites were isolated from the fermented broth using ethyl acetate extraction and purified by two-step silica-gel column chromatography. Three fractions were separated, of which a major compound was obtained in pure state as yellow needles. It was crystallized after dissolving with chloroform followed by slow evaporation. It is odourless with a melting point of 220-222 degrees C. It was soluble in most of the organic solvents and poorly soluble in water. The molecular mass of purified compound was estimated as 223.3 by mass spectral analysis. Further, it was characterized by IR, (1)H and (13)C NMR spectral analyses. The crystal structure of the compound was elucidated for the first time by X-ray diffraction study and deposited in the Cambridge Crystallographic Data Centre (http://www.ccde.com.ac.uk) with the accession no. CCDC 617344. CONCLUSION: The crystal compound was undoubtedly identified as phenazine-1-carboxamide (PCN) with the empirical formula of C(13)H(9)N(3)O. SIGNIFICANCE AND IMPACT OF THE STUDY: As this is the first report on the crystal structure of PCN, it provides additional information to the structural chemistry. Furthermore, the present study reports the antimicrobial activity of purified PCN on major rice pathogens, R. solani and X. oryzae pv. oryzae. Therefore, the PCN can be developed as an ideal agrochemical candidate for the control of both sheath blight and bacterial leaf blight diseases of rice.

Self-fusion of protoplasts enhances chitinase production and biocontrol activity in Trichoderma harzianum.

Protoplasts were isolated from Trichoderma harzianum strain PTh18 using lysing enzymes and self-fusion of T. harzianum protoplasts was carried out using polyethylene glycol in STC buffer. The fused protoplasts of T. harzianum were regenerated and 15 self-fusants were selected to study the chitinase production and biocontrol activity. High chitinase activity was measured in the culture filtrates of most of the self-fusants (87%) than the parent. Among the fusants, the strain SFTh8 produced maximum chitinase with a two-fold increase as compared to the parent strain. All the self-fusants exhibited increased antagonistic activity against Rhizoctonia solani than the parent. The crude chitinase preparation of SFTh8 lysed the mycelia of T. harzianum, Trichoderma viride and Trichoderma reesei and released the protoplasts in higher number than the crude chitinase preparation of parent strain PTh18.

Secretion of keratinolytic enzymes and keratinolysis by Scopulariopsis brevicaulis and Trichophyton mentagrophytes: regression analysis.

A survey on keratinophilic fungi from poultry-farm soils at Namakkal and from feather dumping soils at Chennai, India, revealed the existence of 34 species of fungi. Most of the fungi exhibited variable efficiency in producing extracellular keratinase when grown in plates with chicken feathers as the sole carbon and nitrogen source. The fungi Aspergillus flavus, Aspergillus niger, Aspergillus versicolor, Chrysosporium state of Arthroderma tuberculatum, Paecilomyces carneus, Scopulariopsis brevicaulis, Trichoderma viride, and Trichophyton mentagrophytes were efficient candidates to degrade the feathers. However, when cultivating the strains in submerged conditions in a medium containing chicken feathers as the sole nutrients source, Aspergillus glaucus, Chrysosporium keratinophilum, Curvularia lunata, Fusarium solani, and Penicillium citrinum also proved to be potent. Among all species, S. brevicaulis and Trichophyton mentagrophytes produced higher amounts of keratinase in both methods. Conditions for keratinase production were optimized by statistical design and surface plots. The highest keratinase activity was estimated by S. brevicaulis (3.2 KU/mL) and Trichophyton mentagrophytes (2.7 KU/mL) in the culture medium with chicken feathers and shows (79% and 72.2% of degrading ability, respectively).

Improvement of physical stability and dissolution rate of celecoxib suspensions by complexation with beta-cyclodextrins.

Solid dispersions of celecoxib with beta-cyclodextrins were prepared by physical mixing, slugging and kneading methods at 1:1 and 1:2 molar ratios and characterized by differential scanning calorimetry. Celecoxib suspensions were formulated employing its solid dispersions with sodium carboxymethylcellulose as the suspending agent. Stability studies were conducted by subjecting all the suspensions to freeze-thaw cycling. The suspensions were evaluated for particle size, sedimentation volume, viscosity, redispersibility and dissolution rate initially and after stability testing. Celecoxib suspensions formulated employing its solid dispersions exhibited good physical stability and gave higher dissolution rates than those formulated with celecoxib alone. The suspension prepared from solid dispersions (1:2) by the kneading method gave the highest improvement in dissolution rate and efficiency. Celecoxib in the inclusion complex with beta-cyclodextrin produced suspensions of better physical stability and dissolution rate.

Nanosuspensions as the most promising approach in nanoparticulate drug delivery systems.

Over the years, controlled drug delivery as well as site-specific delivery have made considerable advances. One area that contributed significantly to this progress is the rapidly developing field of colloidal drug delivery systems. Nanoparticles, one of the colloidal drug delivery systems, may enable new possibilities for therapy that presently have not been investigated. Recent advances in nanoparticle research are discussed here. The present review highlights new and upcoming developments such as nanosuspensions and solid lipid nanoparticles.

Purification, characterization, and antifungal activity of chitinase from Fusarium chlamydosporum, a mycoparasite to groundnut rust, Puccinia arachidis.

Chitinase (EC 3.2.1.14) was isolated from the culture filtrate of Fusarium chlamydosporum and purified by ion-exchange chromatography and gel filtration. The molecular mass of purified chitinase was 40 kDa as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Chitinase was optimally active at a pH of 5 and stable from pH 4 to 6 and up to 40 degrees C. Among the metals and inhibitors tested, mercuric chloride completely inhibited the enzyme activity. The activity of chitinase was high on colloidal and pure chitin. The purified chitinase inhibited the germination of uredospores of Puccinia arachidis and also lysed the walls of uredospores and germ tubes. The results from these experiments indicated that chitinase of F. chlamydosporum plays an important role in the biocontrol of groundnut rust.