A novel Bacillus thuringiensis isolate toxic to cotton pink bollworm (Pectinophora gossypiella Saunders)

New roles for Bacillus thuringiensis in the removal of environmental pollutants

For a long time, the well-known Gram-positive bacterium Bacillus thuringiensis (Bt) has been extensively studied and developed as a biological insecticide for Lepidoptera and Coleoptera pests due to its ability to secrete a large number of specific insecticidal proteins. In recent years, studies have found that Bt strains can also potentially biodegrade residual pollutants in the environment. Many researchers have isolated Bt strains from multiple sites polluted by exogenous compounds and characterized and identified their xenobiotic-degrading potential. Furthermore, its pathway for degradation was also investigated at molecular level, and a number of major genes/enzymes responsible for degradation have been explored. At present, a variety of xenobiotics involved in degradation in Bt have been reported, including inorganic pollutants (used in the field of heavy metal biosorption and recovery and precious metal recovery and regeneration), pesticides (chlorpyrifos, cypermethrin, 2,2-dichloropropionic acid, etc.), organic tin, petroleum and polycyclic aromatic hydrocarbons, reactive dyes (congo red, methyl orange, methyl blue, etc.), and ibuprofen, among others. In this paper, the biodegrading ability of Bt is reviewed according to the categories of related pollutants, so as to emphasize that Bt is a powerful agent for removing environmental pollutants.

Genome profiling of an indigenous Bacillus thuringiensis isolate, T405 toxic against the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

In this study, we present the molecular and insecticidal characteristics of an indigenous Bt isolate T405 toxic against the maize fall armyworm (FAW), Spodoptera frugiperda. The presence of cry1, cry2 (cry2Aa & cry2Ab) and vip3A1 genes in T405 was confirmed. The SDS-PAGE gel analysis confirmed the occurrence of Cry and Vip proteins with molecular masses of 130, ∼88 and 65 kDa in T405. LC₅₀ estimates of T405 and HD1 were 161.37 and 910.73 μg ml^-1 for neonates whereas, 412.29 and 1014.95 μg ml^-1 correspondingly for 2^nd instar FAW larvae. Scanning Electron Microscopy depicted the existence of bipyramidal, spherical and cubic crystals in T405 spore suspension. The whole genome sequencing and assembly of T405 produced a total of 563 scaffolds with a genome size of 6,673,691 bp. The BLAST similarity search showed that 12 plasmids were distributed in this genome. Genome annotation revealed the presence of 6174 protein coding genes, 13 rRNA and 98 tRNA, in which 6126 genes were completely annotated for their functions through sequence similarity search, domains/motifs identification and gene ontology studies. Further analysis of these genes identified the presence of many insecticidal toxin protein coding genes viz., cry1Ac32, cry1Ab9, cry1Aa6, cry1Ac5, cry1Aa18, cry1Ab8, cry1Ab11, cry2Aa9, cry1Ia40, cry2Aa9, cry1Ia40, cry2Ab35, cyt, vip3Aa7 and tpp80Aa and several additional virulence assisted factors viz., immune inhibitor A, phospholipase C, sphingomyelinase, cell wall hydrolases, chitinase, hemolysin XhlA and seven urease subunit coding genes (ureA, ureB, ureC, ureD, ureE, ureF, ureG) in the annotated genome.

BtToxin_Digger: a comprehensive and high-throughput pipeline for mining toxin protein genes from Bacillus thuringiensis

SUMMARY

Bacillus thuringiensis (Bt) has been used as the most successful microbial pesticide for decades. Its toxin genes are used for the development of genetically modified crops against pests. We previously developed a web-based insecticidal gene mining tool BtToxin_scanner. It has been frequently used by many researchers worldwide. However, it can only handle the genome one by one online. To facilitate efficiently mining toxin genes from large-scale sequence data, we re-designed this tool with a new workflow and the novel bacterial pesticidal protein database. Here, we present BtToxin_Digger, a comprehensive and high-throughput Bt toxin mining tool. It can be used to predict Bt toxin genes from thousands of raw genome and metagenome data, and provides accurate results for downstream analysis and experiment testing. Moreover, it can also be used to mine other targeting genes from large-scale genome and metagenome data with the replacement of the database.

AVAILABILITY AND IMPLEMENTATION

The BtToxin_Digger codes and web services are freely available at https://github.com/BMBGenomics/BtToxin_Digger and https://bcam.hzau.edu.cn/BtToxin_Digger, respectively.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

ٍSome biologically active microorganisms have the potential to suppress mosquito larvae (Culex pipiens, Diptera: Culicidae)

Malaria is a disease caused by protozoan species of the genus Plasmodium. It is widespread and becoming a challenge in several African countries in the tropical and subtropical regions. In 2010, a report was published showing that over 1.2 million death cases were occurred globally due to malaria in just one year. The transmission of the disease from one person to another occurs via the bite of the Anopheles female. It is known that Plasmodium ovale, P. vivax, P. malariae, P. falciparum, and P. knowlesi are the highly infective malaria species. The problem of this disease is the absence of any effective medical treatment or vaccine, making the mosquito control is the only feasible way for disease prevention. Pesticides are currently the most widely used method for mosquito control, despite its well-known negative effects, including health hazards on human, the increasing insecticidal resistance, and the negative impact on the environment and beneficial organisms. Biological control (also called: biocontrol) of insects has been a promising method to overcome the negative effects of using chemical insecticides, as it depends on just using the natural enemies of pests to either minimize their populations or eradicate them. This article provides an overview of the recent and effective biological means to control malaria, such as bacteria, fungi, viruses, larvivorous fish, toxorhynchites larva and nematodes. In addition, the importance, advantages, and disadvantages of the biocontrol methods will be discussed in comparison with the traditionally used chemical methods of malaria control with special reference to nanotechnology as a novel method for insects’ control.