Totally 192 actinomycetes colonies were isolated from 18 marine sediment samples of Palk Strait region of Bay of Bengal, India. Among them, 68 isolates were morphologically distinct on the basis of colour of spore mass, reverse side colour, aerial and substrate mycelia formation, production of diffusible pigment and sporophore morphology. Thirty-nine isolates were assigned to the genus Streptomyces, Actinopolyspora (10), Saccharopolyspora (7), Actinomadura (4), Nocardiopsis (3), Micromonospora (2), Actinomyces (1), Actinoplanes (1) and Microbispora (1). From these, 64 isolates with aerial mycelia, 65 isolates with substrate mycelia and 61 isolates had both aerial and substrate mycelia.
Totally 25 marine soil samples were collected from the region of Palk Strait of Bay of Bengal, Tamil Nadu, and were subjected to the isolation of actinomycetes. Sixty-eight morphologically distinct isolates were obtained and 37% (25) of them had antimicrobial activity. The potential producer was named as Streptomyces sp. VPTS3-1 and the phylogenetic evaluation on the basis of 16S rDNA sequence further categorized the organism as Streptomyces afghaniensis VPTS3-1. Further, the antimicrobial compound was extracted from the isolate using various solvents and the antimicrobial efficacies were tested against bacterial and fungal pathogens. In addition, in vitro optimization of parameters for the antimicrobial compound production revealed that the suitable pH as 7-8, the period of incubation as 9 days, temperature (30°C), salinity (2%), and starch and KNO 3 as the suitable carbon and nitrogen sources respectively in starch-casein medium.
Prey preferences of large carnivores (tiger (Panthera tigris), leopard (Panthera pardus) and dhole (Cuon alpinus)) in the tropical forest of Anamalai Tiger Reserve (ATR) were evaluated. This was the first study in ATR to estimate the density of prey and the food habits of these large carnivores. The 958-km 2 intensive study area was found to have a high mammalian prey density (72.1 animals per square kilometre) with wild boar (20.61 animals per square kilometre) and chital (20.54 animals per square kilometre) being the most common species, followed by nilgiri tahr (13.6 animals per square kilometre). When the density figures were multiplied by the average weight of each prey species, a high biomass density of 14,204 kg km −2 was obtained for the intensive study area. Scat analysis and incidental kill observation were used to determine the dietary composition of these predators. During the study from the period of March 2001 to April 2004, 1,145 tiger scats, 595 leopard scats and 2,074 dhole scats were collected and analysed. Kill data were based on direct observation of 66 tiger kills and 39 leopard kills. Sambar, with a density of 6.54 kg km −2 was the preferred prey for these carnivores. Sambar constitutes 35% of the overall diet of tiger, whereas it constitutes 17% and 25% in leopard and dhole diets, respectively. Chital was utilized less than sambar in the range of about 7%, 11% and 15% by tiger, leopard and dhole, respectively. Predator diet was estimated more accurately by scat analysis, which reveals 30% of smaller prey species in leopard's diet, which was not observed by kill data. This study reveals that ATR harbours high prey density, and these large carnivores seem mostly dependent on the wild prey rather than on domestic livestock as in some other areas in the subcontinent. These factors make ATR a potential area for long-term conservation of these endangered carnivores.
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