Bacillus thuringiensis (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.

Weathering processes change properties and composition of spilled oil, representing the main reason of failure of bioaugmentation strategies. Our purpose was to investigate the metabolic adaptation of hydrocarbon-degrading bacteria at harsh conditions to be considered to overcome the limitations of bioaugmentation strategies at harsh conditions. Polluted soils, exposed for prolonged periods to weathered oil in harsh soils and weather conditions, were used. Two types of enrichment cultures were employed using 5% and 10% oil or diesel as sole carbon sources with varying the mineral nitrogen sources and C/N ratios. The most effective isolates were obtained based on growth, tolerance to toxicity, and removal efficiency of diesel hydrocarbons. Activities of the newly isolated bacteria, in relation to the microenvironment from where they were isoalted and their interaction with the weathered oil, showed individual specific ability to adapt when exposed to such factors, to acquire metabolic potentialities. Among 39 isolates, ten identified ones by 16S rDNA genes similarities, including special two Pseudomonas isolates and one Citrobacter isolate, showed particularity of shifting hydrocarbon-degrading ability from short chain n-alkanes (n-C12–n-C16) to longer chain n-alkanes (n-C21–n-C25) and vice versa by alternating nitrogen source compositions and C/N ratios. This is shown for the first time.

The study of microbial communities in relation to their ecology, interaction, and genetics must be covered in Qatar with special soil, weather and water. Microorganisms of an environment never having been exposed to such factors do not have necessarily the ability to resist. However, when exposed to such factors, they are often able to adapt, that is to say the potential to acquire metabolic potentialities by recruitment vertical or horizontal specific genes, or recruitment of metabolic pathways present in the genome but not expressed. In polluted environments with oil hydrocarbons, the phenomena of horizontal/vertical transfers, mutations and adaptation to environmental stressors increase the metabolic capabilities of bacteria, including expanding their range of substrates, and allow their adaptation to new substrates. Extensive research on such fields is often focusing on genetic studies, meaning that the genes pools and expression as well as species occurrence are considered as basis. However, from the biotechnological point of view, the cell is considered, as an analogy, as factory. All its components (physical structure and the functions of the organelles and metabolic activities) are strictly regulated by regulatory machineries strictly controlled by the microenvironment. This approach will help answer the question on the different microbial communities that are available in Qatar soil and how they are unique in some biological activities. Indeed, the focus of our research is to characterize and demonstrate the diversity of biological activities within bacterial communities and strains of the same species. Here, we consider the bacterial activities related to polluting oil hydrocarbondegrading communities, including those which are biosurfactant-producers, Here, we showed that the isolation and screening strategy affected a lot, the selection of the hydrocarbon-degrading bacteria, by combining the bacterial tolerance to hydrocarbon toxicity to the hydrocarbons degradative activities. We demonstrated that several Qatari isolates are able to shift their activity from a range of hydrocarbons to another by the effect of the nitrogen source, C/N ratio and organic nitrogen source. By application of Factorial Investigation of Strains' Potentiality to Degrade Hydrocarbons, which is original in the attempt to integrate the study of the most essential nutritional elements as well as their interactions in one experimental frame, we demonstrated diversity of nutritional requirements among the same bacterial group of Pseudomonas aeruginosa strain, isolated in Qatar. Strains' response to altered growth conditions varied substantially; although they were from the same taxonomical group.