Molecular characterization of lepidopteran-specific toxin genes in Bacillus thuringiensis strains from Thailand
- 61 Downloads
A total of 511 local isolates of Bacillus thuringiensis from different geographical regions of Thailand were analyzed for the presence of the cry1A, cry1B, cry2A, cry9, and vip3A genes encoding for lepidopteran-specific toxins. PCR results revealed that 94.32% (482/511) of B. thuringiensis isolates harbored at least one of the detected genes, of which the cry1A, cry1B, cry2A, cry9, and vip3A genes were detected at frequencies of 90.61%, 89.63%, 76.32%, 40.70%, and 48.18%, respectively. Nineteen gene-combination profiles were discovered among 482 B. thuringiensis isolates, of which the most frequently detected profile contained the cry1A, cry1B, cry2A, and vip3A genes. Sixty-one isolates (12.66%), which harbored all of the detected insecticidal toxin genes, were further detected for the exochitinase (chi36) gene and chitinase activity. The results revealed that all 61 isolates contained the chi36 gene and exhibited chitinase activity. Insect bioassays showed that five isolates were highly toxic (more than 80% mortality) against second instar larvae of Spodoptera litura, of which the highest insect mortality (93%) was obtained from the B. thuringiensis isolates 225-15 and 417-1. Scanning electron microscopy revealed that the crystal morphologies of the five effective isolates were bipyramidal and cuboidal shapes. SDS-PAGE analysis of the spore–crystal mixture showed major bands of approximately 65 and 130 kDa. These five effective strains are alternative candidates for use as a microbial insecticide for the control of the S. litura pest.
KeywordsBacillus thuringiensis Bacterial toxin Entomopathogenic bacteria Microbial insecticide
This work was financially supported by the Kasetsart University Research and Development Institute (KURDI) and partially supported by the Research Promotion and Technology Transfer Center (RPTTC), and the Department of Microbiology (Grant year 2018) Faculty of Liberal Arts and Science, Kasetsart University, Nakhon Pathom, Thailand.
Conflict of interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.
- Juarez-Hernandez EO, Casados-Vazquez LE, del Rincon-Castro MC, Salcedo-Hernandez R, Bideshi DK, Barboza-Corona JE (2015) Bacillus thuringiensis subsp. israelensis producing endochitinase ChiA74Deltasp inclusions and its improved activity against Aedes aegypti. J Appl Microbiol 119:1692–1699CrossRefGoogle Scholar
- Lemes ARN, Figueiredo CS, Sebastião I, Marques da Silva L, da Costa Alves R, de Siqueira HÁA, Lemos MVF, Fernandes OA, Desidério JA (2017) Cry1Ac and Vip3Aa proteins from Bacillus thuringiensis targeting Cry toxin resistance in Diatraea flavipennella and Elasmopalpus lignosellus. from sugarcane. Peer J 5:e2866CrossRefGoogle Scholar
- Monnerat RG, Batista AC, de Medeiros PT, Martins ÉS, Melatti VM, Praça LB, Dumas VF, Morinaga C, Demo C, Gomes ACM, Falcão R, Siqueira CB, Silva-Werneck JO, Berry C (2007) Screening of Brazilian Bacillus thuringiensis isolates active against Spodoptera frugiperda. Plutella xylostella and Anticarsia gemmatalis. Biol Control 41:291–295CrossRefGoogle Scholar
- Rangeshwaran R, Gorky A, Viswakethu V, Karkera A, Sivakumar G, Mohan M (2014) Cry gene and plasmid profiling of Bacillus thuringiensis isolated from Indian soils. J Biol Control 28:185–191Google Scholar
- Tawatsin A, Usavadee T, Padet S (2015) Pesticides used in Thailand and toxic effects to human health. Med Res Arch 3:1–10Google Scholar
- Thammasittirong A, Prigyai K, Thammasittirong SNR (2017) Mosquitocidal potential of silver nanoparticles synthesized using local isolates of Bacillus thuringiensis subsp. israelensis and their synergistic effect with a commercial strain of B. thuringiensis subsp. israelensis. Acta Tropica 176:91–97CrossRefGoogle Scholar
- Wang K, Yan P, Cao L (2014) Chitinase from a novel strain of Serratia marcescens JPP1 for biocontrol of aflatoxin: molecular characterization and production optimization using response surface methodology. Biomed Res Int 2014:1–8Google Scholar
- Zorzetti J, Ricietto APS, Fazion FAP, Meneguim AM, Neves PMOJ, Vilas-Boas LA, Rodrigues RB, Vilas-Bôas GT (2017) Selection and characterization of Bacillus thuringiensis (Berliner) (Eubacteriales: Bacillaceae) strains for Ecdytolopha aurantiana (Lima) (Lepidoptera: Tortricidae) control. Neotrop Entomol 46:86–92CrossRefGoogle Scholar