Nair Kavita, Al-Thani Roda, Al-Thani Dhabia, Al-Yafei Fatima, Ahmed Talaat, Jaoua Samir
Department of Biological and Environmental Sciences, College of Arts and Sciences, Qatar University, Doha, Qatar.
Front Microbiol. 2018 Apr 11;9:708. doi: 10.3389/fmicb.2018.00708. eCollection 2018.
(Bt) based insecticidal formulations have been recognized as one of the most successful, environmentally safe and sustainable method of controlling insect pests. Research teams worldwide are in search of Bt diversity giving more choices of bio-insecticides and alternatives to address insect resistance. In fact, there are many unexplored ecologies that could harbor novel Bt strains. This study is the first initiative to explore Bt strain diversity in Qatar. A collection of 700 Bt isolates was constructed. Scanning electron microscopy of Bt crystals showed different crystal forms, with a high abundance of spherical crystals compared to the bipyramidal ones. Among the spherical crystals, four different morphologies were observed. The δ-endotoxin content of parasporal crystals from each Bt isolate revealed that there are 16 different protein profiles among the isolates of the collection. On the other hand, plasmid pattern analysis showed seven different plasmid profiles. Their insecticidal activity was predicted by exploring the δ-endotoxin coding genes and conducting qualitative insecticidal bioassays. 19 smooth spherical crystal producing isolates have been identified that could be possible candidates for endotoxin production targeting Dipteran insects. Another group of 259 isolates producing bipyramidal and cuboidal crystals could target Lepidopteran and Coleopteran insects. The remaining 422 isolates have novel profiles. In conclusion, Qatari soil ecology provides a good collection and diversity of Bt isolates. In addition to strains harboring genes encoding common endotoxins, the majority are different and very promising for the search of novel insecticidal endotoxins.
基于苏云金芽孢杆菌（Bt）的杀虫制剂已被公认为控制害虫最成功、环境安全且可持续的方法之一。全球的研究团队都在寻找Bt的多样性，以提供更多生物杀虫剂的选择以及应对昆虫抗性的替代方案。事实上，有许多未被探索的生态环境可能蕴藏着新型Bt菌株。本研究是探索卡塔尔Bt菌株多样性的首个举措。构建了一个包含700个Bt分离株的菌株库。Bt晶体的扫描电子显微镜观察显示出不同的晶体形态，与双金字塔形晶体相比，球形晶体的丰度较高。在球形晶体中，观察到四种不同的形态。每个Bt分离株伴胞晶体的δ-内毒素含量显示，该菌株库中的分离株有16种不同的蛋白质谱。另一方面，质粒图谱分析显示有七种不同的质粒图谱。通过探索δ-内毒素编码基因并进行定性杀虫生物测定来预测它们的杀虫活性。已鉴定出19个产生光滑球形晶体的分离株，它们可能是针对双翅目昆虫产生内毒素的候选菌株。另一组259个产生双金字塔形和立方形晶体的分离株可针对鳞翅目和鞘翅目昆虫。其余422个分离株具有新颖的图谱。总之，卡塔尔的土壤生态提供了丰富的Bt分离株及其多样性。除了含有编码常见内毒素基因的菌株外，大多数菌株都不同，并且在寻找新型杀虫内毒素方面非常有前景。
