Isolation and characterization of Lepidoptera specific Bacillus thuringiensis strains predominantly from north-eastern states of India (original) (raw)
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A novel Bacillus thuringiensis strain and its pathogenicity against three important pest insects
Journal of Stored Products Research, 2012
A highly pathogenic Bacillus thuringiensis (Bt) strain was isolated from a soil sample in Turkey and characterized in terms of both its 16S-ITS rDNA region and cry gene content. This strain (SY49.1) harboured several cry genes producing crystalline inclusions known to have toxicity on lepidopteran, dipteran and coleopteran pests. The 16S-ITS sequence analysis of Bt SY49.1 showed 98% similarity to Bt serovar andalousiensis BGSC 4AW1. The larvae of Ephestia kuehniella and Plodia interpunctella were treated with a spore-crystal mixture of this strain in the dose range of 50e1000 mg g À1. Mortality rates were higher than 90% at the highest concentration for these pests. For Tribolium castaneum much higher concentrations were needed than with lepidopteran pests larvae. At the highest concentration tested of 10 mg g À1 , about 62% mortality was obtained. It was concluded that this native strain of Bt could be used as an effective biocontrol agent against various lepidopteran pests.
IOP Conference Series: Earth and Environmental Science, 2018
Bacillus thuringiensis is a gram-positive bacterium that produces crystal proteins toxic (ᴕ-endotoxin) specific to the target insect, but is not toxic to humans and non-target organisms. This study aims to explore the origin of the soil bacterium B. thuringiensis subdistrict Sekayu, Banyuasin, South Sumatra and toxicity to larvae of lepidoptera. Fifty soil samples were taken from Musi Banyuasin District, namely 15 from Kayuare strip 2, 20 from Kayuare and 15 from Lumpatan. Isolation, characterization, identification and screening test were conducted in the laboratorium of Pest and Disease, Agricultural Faculty, Sriwijaya University. Isolat codes were given based on the area origin of the samples. Results of the study showed that from 50 isolates of bacteria that had been isolated, there were 15 bacterial isolates, characterized by morphology and physiology the same as B. thuringiensis, which has round colonies, white, wrinkled edges, slippery, elevation arise, aerobic and gram-positive. Of the 15 codes that contain positive isolates of B. thuringiensis, we have obtained several isolates of the following codes:
Isolation and characterization of Lepidopteran specific Bacillus thuringiensis
Seven Bacillus thuringiensis strains were isolated and selected on the basis of primary toxicity test from 22 representative soil samples of Middle Gujarat region of India. Characterization of the strains provided useful information on its distribution with a native cry gene. SDS-PAGE analysis of these isolates shows presence of major bands of Cry1 type of pattern, which was comparable with standard check of B. thuringiensis var. kurstaki HD-73. Only one isolate gave different banding pattern. Characterization of strains was based on PCR with general and specific primers for cry genes. Use of cry primers elucidated that majority of the isolates carried cry1 gene indicating their effectiveness against Lepidopteran pests while use of gene specific primers indicated preponderance of cry1A and cry1Ac genes and some isolates confirmed the presence of cry1Ab and cry1B, cry1C, cry1D and cry9 genes. Result of SDS-PAGE of whole-cell proteins indicated that all the isolates differed from each other including the standard, showing the usefulness of diversity studies. Bioassays with Helicoverpa armigera exhibited LD 50 of 1.73 x 10 7 spores-crystal mixture/cm 3 by isolate HP-4 in comparison LD 50 of 3.14 x 10 7 spores-crystal mixture/cm 3 of B. thuringiensis var. kurstaki HD-73.
Egyptian Journal of Biological Pest Control
Background The indiscriminate use of synthetic insecticides is not affordable and poses collateral damage to humans, non-target organisms, and environmental health. Bacillus thuringiensis (Bt) is a cosmopolitan, antagonistic soil bacterium employed as an alternative to chemical insecticides in pest management. In this study, genetic diversity and insecticidal activity of 50 indigenous Bt isolates were investigated in order to find the effective Bt isolates with a broad spectrum of insecticidal activity against lepidopteran insects. Results Most of the Bt isolates investigated appeared as creamy white in colour and fried egg or mucoid-type colonies having a flat or raised elevation with entire or undulated margins. Out of 50 isolates investigated, crystal shapes varied from cuboidal (40.00%), spherical (36.00%), bipyramidal (30.00%), rectangular (10.00%), and minute crystal attached to the spores (28.00%). SDS-PAGE analysis revealed that the molecular weight of the crystal proteins o...
Plant Protection
Cotton is a cash crop of many countries as it serves as a source of fiber, edible oil, and seedcake. It is grown in a diverse range of environment. Bacillus thuringiensis (Bt) is a gram positive bacterium found in different habitats but mostly found in soil. This bacterium produces endotoxin which is harmful for various insects. Numerous crystal-forming strains of Bt exist in nature, but not all of them are efficient against insect pests. Bt cotton is prevalent internationally because of less insect attack. The key objective of this research was to analyze different Bacillus thuringiensis isolates residing in soil of different cotton fields of Multan and Bahawalpur districts and to identify them on the basis of morphology. To attain this, different soil samples were collected from Multan (Gup wala, Mosey Wala, Taloki Wala, Hafiz Wala, Choudary Wala, Basti Mangla Mari, Sharkha Wala, Lawain Wala, Ghulamo Wala) and Bahawalpur district (Basti Deewan Wali, Check No 8, Basti Tariqabad, Ba...
Isolation and Characterization of Native Isolates of Bacillus thuringiensis from Vidarbha Region
International Journal of Current Microbiology and Applied Sciences, 2017
The indiscriminate use of chemical insecticides leads considerable damage to environment and imbalance the ecology. The continuous and overuse of chemical insecticides imparts resistance in vectors of human diseases along with agricultural pests (Georghiou, 1990). Biocontrol is the better option than chemical pesticides in order to control insect pests in insect management programme (Aramideh et al., 2010). Bacillus thuringiensis is gram positive, aerobic, endospore forming and ubiquitous in nature with genome size 2.4 to 5.7 Mbp, distinguished from other bacilli by International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 1 (2017) pp. 798-806 Journal homepage: http://www.ijcmas.com
A highly pathogenic strain of Bacillus thuringiensis serovar kurstaki in lepidopteran pests
Journal of microbiology (Seoul, Korea), 2007
In order to detect and identify the most toxic Bacillus thuringiensis strains against pests, we isolated a B. thuringiensis strain (Bn1) from Balaninus nucum (Coleoptera: Curculionidae), the most damaging hazelnut pest. Bn1 was characterized via morphological, biochemical, and molecular techniques. The isolate was serotyped, and the results showed that Bn1 was the B. thuringiensis serovar, kurstaki (H3abc). The scanning electron microscopy indicated that Bn1 has crystals with cubic and bipyramidal shapes. The Polymerase Chain Reactions (PCRs) revealed the presence of the cry1 and cry2 genes. The presence of Cry1 and Cry2 proteins in the Bn1 isolate was confirmed via SDS-PAGE, at approximately 130 kDa and 65 kDa, respectively. The bioassays conducted to determine the insecticidal activity of the Bn1 isolate were conducted with four distinct insects, using spore-crystal mixtures. We noted that Bn1 has higher toxicity as compared with the standard B. thuringiensis subsp. kurstaki (HD-1...
The Journal of General and Applied Microbiology, 2012
Bacillus thuringiensis is a rod-shaped, gram-positive, endospore-forming bacterium. It is distinguished from three other closely related Bacillus spp., viz. B. cereus, B. anthracis and B. mycoides, because of its ability to synthesize delta endotoxins (Cry proteins) as protein inclusion crystals during sporulation (Hofte and Whiteley, 1989). The presence of a parasporal crystal, which is outside the exosporium of the endospore, is indicative of production of the toxin, and serves as a marker for this species. The bacterium was initially discovered as a pathogen of various insects and was fi rst used as an insecticidal agent. It is found in soil where it leads a saprophytic existence, but becomes an opportunistic pathogen of insects when ingested. The delta-endotoxin causes midgut paralysis and disruption when ingested by the insect host. The specifi c activities of the toxin towards insects and nontoxic nature toward animals have made this organism a useful biocontrol agent. The insecticidal crystal (Cry)
The occurrence and insecticidal activity of Bacillus thuringiensis in the arid environments
Abstract Pest control in Saudi Arabia is entirely relied on the application of chemical agents. Little information is known about the natural presence of Bacillus thuringiensis species that possess insecticidal activity in the environment of Saudi Arabia. It would be of interest to search for native species of toxic Bt strains that can be used in pest control management. Thus the aim of this study was to investigate the natural presence of Bacillus thuringiensis species that are toxic to pests in the environment of Makkah Province, western Saudi Arabia. A total of 100 soil samples and five dead larvae of Spodoptera littoralis (Lepidoptera) were examined for the presence of Bacillus thuringiensis. The bacterium was isolated by acetate-selective enrichment and plating. Identification of isolates was performed by microscopic examination, analysis of parasporal inclusions protein profiles by SDS-PAGE, toxicity assay, analysis of 16S rDNA genes and DNA sequencing for PCR products. The confirmed Bacillus thuringiensis isolates, eight in total, were recovered from 5% of soil samples and from 60% of dead larvae. These isolates exhibited strong activity against 1st instar larvae of S. littoralis. Although Bacillus thuringiensis was not found to be abundant in soil habitats in Makkah Province, the results suggest that the bacterium is part of the indigenous microflora of the area we have explored. This is the first report of the natural presence of lepidopteran-toxic strains of Bacillus thuringiensis in the environment of western Saudi Arabia, particularly in Makkah Province.