Fine structure in the time of flight distribution of C2 in laser produced plasma from graphite

Time resolved optical emission spectroscopy is employed to study the expansion dynamics of C2 species in a graphite plasma produced during the Nd : YAG ablation. At low laser fluences a single peak distribution with low kinetic energy is observed. At higher fluences a twin peak distribution is found. It has been noted that these double peak time of flight distribution splits into a triple peak structure at distances >_ 17mm from the target surface. The reason for the occurrence of multiple peak is due to different formation mechanisms of C2 species

Biochemical and physiological characteristics of actinomycetes isolated from high altitude shola soils of tropical Montane forest

Actinomycetes are gram-positive, free-living, saprophytic bacteria widely distributed in soil, water and colonizing plants showing marked chemical and morphological diversity. They are potential source of many bioactive compounds, which have diverse clinical effects and important applications in human medicine. In the present work, we have studied some of the physiological and biochemical characteristics of 36 actinomycete strains isolated from the shola soils of tropical montane forest; a relatively unexplored biodiversity hotspot. Ability of actinomycetes isolates to ferment and produce acids from various carbohydrate sources such as innositol, mannose, sorbitol, galactose, mannitol, xylose, rhamnose, arabinose, lactose and fructose were studied. Almost all the carbon compounds were utilized by one or other actinomycete isolates. The most preferred carbon sources were found to be xylose (94.44%) followed by fructose and mannose (91.66%). Only 41.76% of the isolates were able to ferment lactose. The ability of actinomycetes isolates to decompose protein and amino acid differ considerably. 72.22% of the isolates were able to decompose milk protein casein and 61.11% of the isolates decompose tyrosine. Only 8.33% of the strains were able to decompose amino acid hypoxanthine and none of them were able to decompose amino acid xanthine. Potential of the actinomycetes isolates to reduce esculin, urea and hippurate and to resist lysozyme was also checked. 91.66% of the isolates showed ability to decompose esculin and 63.88% of the isolates had the capacity to produce urease and to decompose urea. Only 25% of the isolate were able to decompose hippurate and 94.44% showed lysozyme resistance

SPATIOTEMPORAL VARIATION AND ANTIBACTERIAL ACTIVITY OF ACTINOMYCETES ISOLATED FROM HIGH ALTITUDE GRASSLAND SOILS OF TROPICAL MONTANE FOREST – KERALA, INDIA

TThe invention of novel antibiotics and other bioactive microbial metabolites continues to be an important aim in new drug discovery programmes. Actinomycetes have the potential to synthesize lots of diverse biologically vigorous secondary metabolites and in the last decades actinomycetes became the most productive source for antibiotics. Therefore in the present study we analyze the antibacterial activity of the actinomycetes isolated from grassland soil samples of Tropical Montane forest. A total of 33 actinomycete strains isolated were characterized and screened for antibacterial activities using well diffusion method against six specific pathogenic organisms. Identification of the isolates revealed that the majority of them were belonging to Streptomycetes followed by Nocardia, Micromonospora, Pseudonocardia, Streptosporangium, Nocardiopsis and Saccharomonospora. Among the 33 isolates, Gr1 strain showed antagonistic activity against all checked pathogens. Nine strains showed antibacaterial activity against Listeria, Vibrio cholera, Bacillus cereus, Staphylococcus aureus and Salmonella typhi and only 2 strains (Gr1and Gr25) showed antagonism to E. coli. The overall percentage of activity of actinomycetes isolates against each pathogenic bacterium was also calculated. While 63.63% of the actinomycetes were antagoinistic against Listeria, Vibrio cholerae, and Bacillus cereus, 60.6% of them were antagonistic to Staphylococcus aureus. Very few isolates (6.06%) showed antibacterial activity against E. coli. In general most of the actinomycetes isolates were antagonistic to grampositive bacteria such as Listeria, Bacillus and Staphylococcus than Gram-negative bacteria Vibrio cholerae, E. coli and Salmonella