Asian Journal of Bio Science

Manju Kumari ¹, D. Manjulakumari ¹, A. R. V. Kumar ²

Affiliations
1 Department of Biotechnology, Bangalore University, Bengaluru, Karnataka, IN
2 Department of Entomology, University of Agricultural Sciences, G.K.V.K., Bengaluru, Karnataka, IN

Abstract

The Western Ghats of India is one of the world's "biodiversity hotspots" that runs along the western part of South India through four states including Karnataka. As a result, Western Ghats are expected to yield high diversity of any taxon. With a view to understand this aspect study on the diversity of Bacillus spp. in the soils of Western Ghats was conducted. A total of 292 Bacillus isolates were identified as Bacillus thuringiensis which were recovered from 35 soil samples collected from different habitats of Western Ghats of Karnataka. Soils of different habitats varied tremendously in the natural load of Bacillus CFUs. Lowest CFU load was observed in soil W15 (2.6 x 106 ) whereas the soils W13, W20, W24, W29 (8.1 x 106) yielded the highest number of Bacillus CFUs/g of soil, with an overall mean of 6.07 x 106 CFUs per g of soil. On an average, 8.34 ( 1.95) colonies were picked from each soil sample. These colonies were subjected to standard biochemical tests to identify the B. thuringiensis colonies. On an average, 5.6 (67.12 %) of the picked colonies per soil sample were observed to be B. thuringiensis colonies. Tests of activity of these isolates against a species of white grub, Holotrichia serrata (F.) and a fly pest, Musca domestica revealed 14 isolates to be active against H. serrata and 10 against M. domestica, with three of these against both the species. The study thus demonstrated that there is potential for the use of these isolates in pest management.

Keywords

Bacillus Thuringiensis, Endospores, Toxicity, Holotrichia Serrata, Musca Domestica

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L. S. Vanitha ¹, Manju Kumari ², J. Jayappa ³, S. C. Chandrashekar ¹

Affiliations
1 Department of Plant Pathology, University of Agricultural Sciences, G.K.V.K., Bengaluru (Karnataka), IN
2 Department of Biotechnology, Bangalore University, Bengaluru (Karnataka), IN
3 Raita Samparka Kendra Challakere, Chitradurg (Karnataka), IN

Abstract

Nematodes that kill the insects are called as Entomopathogenic nematodes (EPNs). These nematodes are in association with symbiotic bacteria (Xenorhabdus spp. and Photorhabdus spp.) which are known to secrete different bioactive compounds and exhibit broad spectrum biological activities viz., insecticidal, antifungal, antibacterial properties. Entomopathogenic nematodes, Steinernema and Heterorhabditis were isolated from soil using Galleria mellonella baited traps at fourteen locations representing different cropping agro-ecosystems in Gandhi Krishi Vignana Kendra campus, University of Agricultural Sciences, Bangalore, Karnataka, India. Bacteria isolated from nematodes were identified as Xenorhabdus spp. and designated as School of Ecology and Conservation one to fourty four. Two symbiotic bacterial cultures, School of Ecology and Conservation-6 and School of Ecology and Conservation-10 were used for in vitro evaluation against four plant pathogenic fungi. These two cultures have shown a good insecticidal activity when tested on second instar larvae of diamond black moth Plutella xylostella L. under in vitro condition, compared to other isolated bacterial cultures. Hence, these cultures were selected to know its fungistatic activity against four plant pathogenic fungi i.e., Fusarium oxysporum (Vanilla), Alternaria solani (Tomato), Sclerotium rolfsii (Brinjal) and Aspergillus niger (Groundnut). SEC 6 culture was found to be best for inhibiting the growth of Sclerotium rolfsii (82.41) followed by Aspergillus niger (51.73), Fusarium oxysporum (48.29) and Alternaria solani (45.10).

Keywords

Alternaria solani, Aspergillus niger, Fusarium oxysporum, Heterorhabditis spp, Sclerotium rolfsii, and Steinernema Spp.

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