MOLECULAR CHARACTERIZATION AND HEMOLYTIC ACTIVITY OF BACILLUS THURINGIENSIS ISOLATES ACTIVE AGAINST WHITE GRUB, HOLOTRICHIA SERRATA (COLEOPTERA: SCARABAEIDAE)NAYIMABANU TAREDAHALLI, ARATI PANNURE AND A.R.V. KUMAR
Eighteen local Bacillus strains are used in the study, isolated from soils of different parts of Karnataka and characterized by their high toxicity against different species of white grubs. The Molecular identification of potential Bacillus isolates using 16Sr RNA primers and safety studies of Bacillus isolates on vertebrates was carried out in the present study. PCR amplification of 16Sr RNAgene revealed that twelve out of eighteen isolates were B. thuringiensis with the product size of 1500 bp and remaining six were non Bt isolates. The results of hemolytic activity suggest that the overall hemolysis ranged from 1.75 per cent to 47.5 per cent in case of spore crystal mixture and up to 43.6 per cent in cell free broth (CFB). The results presented here showed that the majority of fifteen spore crystal mixtures were safe for human and other vertebrates as they exhibited no or low hemolytic activity. Ten isolates were safe considering both spore crystal mixture and cell free broth. Therefore, the present work sheds some light on identification of local Bacillus isolates and the presence or absence of hemolytic activity in potential bacterial isolates toxic to white grubs which can be used as potential candidates in the biological management of white grub species.
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