A. Makhlouf, Amira A. El Kemany, A. Riad, Y. A. Abou-Youssef
{"title":"ISOLATION, TOXICITY AND MOLECULAR CHARACTERIZATION OF NATIVE Bacillus thuringiensis ISOLATES FROM EGYPTIAN SOIL","authors":"A. Makhlouf, Amira A. El Kemany, A. Riad, Y. A. Abou-Youssef","doi":"10.21608/EJGC.2015.9723","DOIUrl":null,"url":null,"abstract":"Thirty three local soil samples were collected from Westward till Sewa Oasis in Egypt to search novel isolates of Bacillus thuringiensis (Bt) and evaluate their toxic potentiality to overcome the serious problem of evolved resistance by insects to the pesticidal activity. The first instars larvae of cotton leaf worm (Spodoptera littoralis) were used to test their toxic potentiality in the presence of the two standard strains kurstaki (K) and neoleonensis H24a (N). The results showed that three isolates from Alexandria (AL3, AL7 and AL11) and two isolates from Kafr - el-Dawar (KD2 and KD3) were presumptively confirmed as Bt. by morphological and microscopic characters. The treated larvae with Insecticidal crystal protein (ICP) exhibited mortality percentage around 50% for all isolates except AL3 isolate. The vegetative insecticidal proteins (VIPs) of KD3, KD2 and AL11 isolates revealed mortality percentages more than 75%. While, AL3 and AL7 isolates showed differential toxicity. Crystal proteins analysis by SDS-PAGE showed KD2, KD3 and AL11 isolates gave similar profiles as those of \"K\" strain which was characterized with 135 kDa and 70 kDa bands. AL3 isolate failed to show any noticeable bands. According to their plasmids patterns, 4 kb was shown in all isolates and the reference strains except AL3 isolate. Cry1, Vip1 and Vip2 genes of the isolates was detected by polymerase chain reaction (PCR). The results indicated that one band with 550bp in size was present in all isolates except the AL3 isolate. Vip1 primer succeeds to amplify a band 400 bp in size in all isolates and “K\" strain. Vip2 primer failed to react with any genome of the studied isolates or reference strains. This study suggested that KD2, KD3 and AL11 isolates may lead to be identified as potential strains of Bt. for their use in the development of bioinsecticide to control insect pests in Egypt.","PeriodicalId":31811,"journal":{"name":"Egyptian Journal of Genetics and Cytology","volume":"44 1","pages":"405-422"},"PeriodicalIF":0.0000,"publicationDate":"2015-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"2","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Egyptian Journal of Genetics and Cytology","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.21608/EJGC.2015.9723","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 2
Abstract
Thirty three local soil samples were collected from Westward till Sewa Oasis in Egypt to search novel isolates of Bacillus thuringiensis (Bt) and evaluate their toxic potentiality to overcome the serious problem of evolved resistance by insects to the pesticidal activity. The first instars larvae of cotton leaf worm (Spodoptera littoralis) were used to test their toxic potentiality in the presence of the two standard strains kurstaki (K) and neoleonensis H24a (N). The results showed that three isolates from Alexandria (AL3, AL7 and AL11) and two isolates from Kafr - el-Dawar (KD2 and KD3) were presumptively confirmed as Bt. by morphological and microscopic characters. The treated larvae with Insecticidal crystal protein (ICP) exhibited mortality percentage around 50% for all isolates except AL3 isolate. The vegetative insecticidal proteins (VIPs) of KD3, KD2 and AL11 isolates revealed mortality percentages more than 75%. While, AL3 and AL7 isolates showed differential toxicity. Crystal proteins analysis by SDS-PAGE showed KD2, KD3 and AL11 isolates gave similar profiles as those of "K" strain which was characterized with 135 kDa and 70 kDa bands. AL3 isolate failed to show any noticeable bands. According to their plasmids patterns, 4 kb was shown in all isolates and the reference strains except AL3 isolate. Cry1, Vip1 and Vip2 genes of the isolates was detected by polymerase chain reaction (PCR). The results indicated that one band with 550bp in size was present in all isolates except the AL3 isolate. Vip1 primer succeeds to amplify a band 400 bp in size in all isolates and “K" strain. Vip2 primer failed to react with any genome of the studied isolates or reference strains. This study suggested that KD2, KD3 and AL11 isolates may lead to be identified as potential strains of Bt. for their use in the development of bioinsecticide to control insect pests in Egypt.