جداسازي سويه‌هاي بومي باكتري Bacillus thuringiensis از خاك برخي از مهمترين مناطق استان فارس و ارزيابي اثر كشندگي آنها بر روي لارو حشره شب‌پره هندي

Extraction of local isolates of Bacillus thuringiensis from the soils of Fars province and evaluation of their toxicity on larva of Plodia interpunctella (Hubner)

باكتريBacillu thuringiensis (Bt) پروتئين‌­هايي بلوري توليد مي­كند كه براي گونه ­هاي مختلف حشرات سمي مي ­باشد. در اين مطالعه سويه ­هاي Btاز خاك ­هاي برخي از نواحي استان فارس جداسازي و اثر كشندگي آنها روي حشره شب‌پره‌هندي (Plodia interpunctella Hubner) مورد بررسي قرار گرفت. بدين منظور، 110 جدايه باكتري از خاك مناطق شيراز، مرودشت، فسا و سروستان جداسازي شد. شناسايي اوليه جدايه ­ها بر اساس رنگ آميزي گرم و بررسي بلور پروتئيني با استفاده از ميكروسكوپ فازكنتراست صورت گرفت. جدايه ها از نظر شكل بلور پروتئيني كروي و لوزي بودند. بررسي مولكولي به روش PCR نشان داد كه از 110 جدايه جمع ­آوري شده، 40 جدايه حاوي ژن Cry1 بودند. بررسي كشندگي آنها روي لارو سن سوم حشره شب­پره هندي مطالعه گرديد. بر طبق نتايج اين پژوهش، غلظت sporeml-1 108×2 بعد از گذشت 72 ساعت، به ­عنوان مؤثرترين تيمار در نظر گرفته شد و سه جدايه sh20،g44 و FA-16 به ­ترتيب با درصد تلفات 33/53، 80 و 33/73 بالاترين ميزان مرگ‌ و مير را روي لارو­هاي سن سوم حشره شب‌پره‌هندي ايجاد نمودند. جدايه­ هاي g46-29، g45-5، TA22، 35b و E8 روي لارو سن سوم حشره شب‌پره‌هندي بي‌تاثير بودند. اميد است كه بتوان با معرفي اين جدايه­ هاي بومي باكتري Bt، گامي مهم در راستاي توليد داخلي سموم بيولوژيك برداشت.

Bacillu thuringiensis (Bt) produces crystalline proteins that are toxic to various insect species. In this study, Bt strains were isolated from the soils of some areas of Fars province and their toxicity on larva of Plodia interpunctella (Hubner) was investigated. For this purpose, 110 strains were isolated from the soils of Shiraz, Marvdasht, Fasa and Sarvestan. Initial identification of the isolates was carried out on the basis of Gram staining and morphological characteristics of protein crystals using phase-contrast microscopy. The protein crystals of the isolates were spherical and rhombic. Molecular analysis by PCR showed that 40 isolates of the collection were contained Cry1 gene.The isolatestoxicity was studied on third instar larvae of P. interpunctella. According to the results of this study, 2×108 sporeml-1 concentration after 72 hours was considered as the most effective treatment and the three isolates sh20, g44 and FA-16 had the highest mortality (53.33%, 80% and 73.33%, respectively) onlarva of Indian meal moth. Isolates g46-29, g45-5, TA22, 35b, and E8 were ineffective on the third instar larvae of Indian meal moth. In general, the bioassay results showed that the strains isolated from the soils of the study area had considerable toxic effect on Indian meal moth larvae. We hope that introducing these native isolates of Bt will be an important step to produce domestic biological pesticides.