Antibacterial properties of silver nanoparticles synthesized by marine Ochrobactrum sp.

Metal nanoparticle synthesis is an interesting area in nanotechnology due to their remarkable optical, magnetic, electrical, catalytic and biomedical properties, but there needs to develop clean, non-toxic and environmental friendly methods for the synthesis and assembly of nanoparticles. Biological agents in the form of microbes have emerged up as efficient candidates for nanoparticle synthesis due to their extreme versatility to synthesize diverse nanoparticles with varying size and shape. In the present study, an eco favorable method for the biosynthesis of silver nanoparticles using marine bacterial isolate has been attempted. Very interestingly, molecular identification proved it as a strain of Ochrobactrum anhtropi. In addition, the isolate was found to have the potential to form silver nanoparticles intracellularly at room temperature within 24 h. The biosynthesized silver nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscope (TEM) and scanning electron microscope (SEM). The UV-visible spectrum of the aqueous medium containing silver nanoparticles showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. The SEM and TEM micrographs revealed that the synthesized silver nanoparticles were spherical in shape with a size range from 38 nm - 85 nm. The silver nanoparticles synthesized by the isolate were also used to explore its antibacterial potential against pathogens like Salmonella Typhi, Salmonella Paratyphi, Vibrio cholerae and Staphylococcus aureus.

Silver nanoparticle production by the fungus Fusarium oxysporum: nanoparticle characterisation and analysis of antifungal activity against pathogenic yeasts

The microbial synthesis of nanoparticles is a green chemistry approach that combines nanotechnology and microbial biotechnology. The aim of this study was to obtain silver nanoparticles (SNPs) using aqueous extract from the filamentous fungus Fusarium oxysporum as an alternative to chemical procedures and to evaluate its antifungal activity. SNPs production increased in a concentration-dependent way up to 1 mM silver nitrate until 30 days of reaction. Monodispersed and spherical SNPs were predominantly produced. After 60 days, it was possible to observe degenerated SNPs with in additional needle morphology. The SNPs showed a high antifungal activity against Candida and Cryptococcus , with minimum inhibitory concentration values ≤ 1.68 µg/mL for both genera. Morphological alterations of Cryptococcus neoformans treated with SNPs were observed such as disruption of the cell wall and cytoplasmic membrane and lost of the cytoplasm content. This work revealed that SNPs can be easily produced by F. oxysporum aqueous extracts and may be a feasible, low-cost, environmentally friendly method for generating stable and uniformly sized SNPs. Finally, we have demonstrated that these SNPs are active against pathogenic fungi, such as Candida and Cryptococcus .

Microalgae mediated synthesis of silver nanoparticles and their antibacterial activity against pathogenic bacteria.

Silver nanoparticles is known to have antimicrobial affects. Cyanobacteria isolates from muthupet mangrove includes Aphanothece sp, Oscillatoria sp, Microcoleus sp, Aphanocapsa sp, Phormidium sp, Lyngbya sp, Gleocapsa sp, Synechococcus sp, Spirulina sp with were set in compliance with their cellular mechanism of nano silver creation, and were investigated by UV-VIS spectrophotometer, Energy-dispersive X-ray (EDX) and scanning electron microscopy (SEM). Silver nanoparticles were spherical shaped well distributed without aggregation in solution with an average size of about 40- 80 nm. Synthesised nano silver had antibacterial production on various organisms that provoked various diseases in humans. The cellular metabolites of Microcoleus sp. only created nano silver and it enhanced the antibacterial activity against test pathogenic bacteria from MTCC (Proteus vulgaris, Salmonella typhi, Vibrio cholera, Streptococcus sp., Bacillus subtilis, Staphylococcus aureus, Escherichia coli.) The antimicrobial assay was performed using 0.001 M concentration of nano silver in well diffusion method with positive control of appropriate standard antibiotic discs Cephotaxime, Ampicillin, Tetracyclin, Cephalexin etc. Synthesised silver nanoparticles acted as an effective antimicrobial agent and proved as an alternative for the development of new antimicrobial agents to combat the problem of resistance.

Robertsonian rearrangements and pericentric inversions in Scaridae fish (Perciformes)

The parrotfishes (family Scaridae) are comprised of the subfamilies Sparisomatinae and Scarinae. They are important agents of marine bioerosion, which rework the substrate with their beaklike jaws. Despite their importance, there are no published cytogenetic data on this group. We made cytogenetic analyses of Sparisoma axillare (Sparisomatinae) and Scarus coelestinus (Scarinae) from the Brazilian coast. Differentiation in the diploid number in S. axillare compared to the basal karyotype of the Perciformes apparently occurred due to a Robertsonian fusion, combined with pericentric inversions. S. coelestinus presented a conserved diploid number, but showed considerable structural karyotypic changes, resulting mainly from pericentric inversions. The Ag-NOR sites were unique and located on the short arm of the 1st subtelocentric pair in both species (possibly homeologous), corresponding to the 11th pair in S. axillare and the 9th pair in S. coelestinus. The constitutive heterochromatin is reduced in these species and is distributed in centromeric and pericentromeric regions in most of the chromosomes. The low fundamental number compared to the Scarus genus suggests a more basal condition for Sparisoma. The chromosome formula in S. coelestinus was more diversified, deriving from large-scale pericentric inversions. Karyotypic evolution patterns observed for these representatives of the Sparisomatinae and Scarinae subfamilies, added to new data from a larger number of species, would allow us to determine if there is a tendency among the Sparisomatinae for centric fusion events.

Depósitos corneanos / Corneal deposits

Os autores relatam achados biomicroscópicos que podem ser notados na clínica diária. Achados estes que podem refletir-se por depósitos corneanos, devido a doença sistêmicas, uso de medicaçäo sistêmica ou mesmo local