R. Rangeshwaran ¹, K. Veenakumari ¹, Pritam Karmakar ¹, K. Ashwitha ¹, G. Sivakumar ¹, Satendar Kumar ¹

Affiliations
1 National Bureau of Agriculturally Important Insects, Post Bag No. 2491, H. A. Farm Post, Bellary Road, Hebbal, Bangalore 560 024, Karnataka, IN

Abstract

Two isolates of Bacillus thuringiensis isolated from dead lepidopteran larvae from a tea garden in Jorhat, Assam and one isolated from soil sample from Rajasthan, obtained in a nationwide screening program showed bipyramidal crystal morphology. These two isolates named as NBAII-BTAS and NBAII-BTG4 were characterized by their high level of toxicity against diamond back moth (Plutella xylostella). The PCR amplification of these two isolates revealed the expected size of the PCR product for cry1Aa, cry1Ab, cry1Ac, cry1E, cry1G, cry1I, and cry2 of 390 bps, 1111bps, 238 bps, 540 bps, 300 bps, 468 bps, and 1170 bps respectively. Purified cry proteins from each of these two cultures were subjected to SDS-PAGE analysis, where, two distinct bands of 130–140 Kda and 65 Kda corresponding to cry1 and cry2 proteins were observed. Toxicity studies was carried out using trypsin activated purified proteins against Helicoverpa armigera, where NBAII-BTG4 derived crystal proteins displayed more toxicity (0.93µg\ml) than NBAII-BTAS.

Keywords

Cry Genes, PCR, Specific Cry Primers, Bipyramidal, Toxicity.

Full Text

   

R. Rangeshwaran ¹, N. V. Vajid ¹, B. Ramanujam ¹, S. Sriram ¹, T. V. Bhaskaran ¹, Satendar Kumar ¹

Affiliations
1 National Bureau of Agriculturally Important Insects, Post Bag No. 2491, H. A. Farm Post, Hebbal, Bellary Road, Bangalore 560 024, Karnataka, IN

Abstract

Studies were carried out to evaluate the effect of adding nutrient additives to talc based formulations on the shelf life of bacteria stored under room temperature. Two organisms namely, Pseudomonas fluorescens (PDBCAB2) and Bacillus sp. (MTCC6534 - chickpea endophyte), a spore forming bacterium, were tested. A gradual increase in P. fluorescens population up to 90 days was observed in almost all the treatments that were amended with nutrients. At 90 days highest population of log 10.38 cfu g⁻¹ was noticed in talc amended with 2 per cent tryptone and glycerol. Decline in the population was observed from 90 days onwards and was rapid from 150 days onwards. At 240 days highest count of log 1 x 10^4.2 cfu g⁻¹ was obtained with formulations amended with 2% tryptone and 2% glycerol and the results indicated that 2% peptone or 2% tryptone supplemented with 2% glycerol helped P. fluorescens in its better survival. The spore forming Bacillus sp. survived well throughout the study period. At 240 days all talc formulations amended with nutrient sources showed a population of log 9.0 cfu g⁻¹ or above and the population declined to below log 7.0 cfu g⁻¹ only in non amended treatments. Slow decline started from 240 days but high cfu of log 9.30 to 9.38 g⁻¹ were noticed in yeast extract or tryptone treated treatments. Hence talc formulations that had yeast extract or tryptone supplemented with glycerol enhanced shelf life of Bacillus spp.

Keywords

Pseudomonas fluorescens, Bacillus sp, Powder Based Formulation, Talc, Shelf Life, Gram Positive, Gram Negative.

Full Text