Search for Cry proteins expressed by Bacillus spp. genomes, using hidden Markov model profiles

Microorganisms Associated with the Ambrosial Beetle Xyleborus affinis with Plant Growth-Promotion Activity in Arabidopsis Seedlings and Antifungal Activity Against Phytopathogenic Fungus Fusarium sp. INECOL_BM-06

Plants interact with a great diversity of microorganisms or insects throughout their life cycle in the environment. Plant and insect interactions are common; besides, a great variety of microorganisms associated with insects can induce pathogenic damage in the host, as mutualist phytopathogenic fungus. However, there are other microorganisms present in the insect-fungal association, whose biological/ecological activities and functions during plant interaction are unknown. In the present work evaluated, the role of microorganisms associated with Xyleborus affinis, an important beetle species within the Xyleborini tribe, is characterized by attacking many plant species, some of which are of agricultural and forestry importance. We isolated six strains of microorganisms associated with X. affinis shown as plant growth-promoting activity and altered the root system architecture independent of auxin-signaling pathway in Arabidopsis seedlings and antifungal activity against the phytopathogenic fungus Fusarium sp. INECOL_BM-06. In addition, evaluating the tripartite interaction plant-microorganism-fungus, interestingly, we found that microorganisms can induce protection against the phytopathogenic fungus Fusarium sp. INECOL_BM-06 involving the jasmonic acid-signaling pathway and independent of salicylic acid-signaling pathway. Our results showed the important role of this microorganisms during the plant- and insect-microorganism interactions, and the biological potential use of these microorganisms as novel agents of biological control in the crops of agricultural and forestry is important.

Differentiation of Bacillus cereus and Bacillus thuringiensis Using Genome-Guided MALDI-TOF MS Based on Variations in Ribosomal Proteins

Bacillus cereus and B. thuringiensis are closely related species that are relevant to foodborne diseases and biopesticides, respectively. Unambiguous differentiation of these two species is crucial for bacterial taxonomy. As genome analysis offers an objective but time-consuming classification of B. cereus and B. thuringiensis, in the present study, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was used to accelerate this process. By combining in silico genome analysis and MALDI-TOF MS measurements, four species-specific peaks of B. cereus and B. thuringiensis were screened and identified. The species-specific peaks of B. cereus were m/z 3211, 6427, 9188, and 9214, and the species-specific peaks of B. thuringiensis were m/z 3218, 6441, 9160, and 9229. All the above peaks represent ribosomal proteins, which are conserved and consistent with the phylogenetic relationship between B. cereus and B. thuringiensis. The specificity of the peaks was robustly verified using common foodborne pathogens. Thus, we concluded that genome-guided MALDI-TOF MS allows high-throughput differentiation of B. cereus and B. thuringiensis and provides a framework for differentiating other closely related species.

Identification and characterization of a new cry-like gene found in a Bacillus cereus strain

Bacillus thuringiensis is the most successful microbial insecticide against different pests in agriculture and vectors of diseases. Its activity is mostly attributed to the Cry proteins expressed during its sporulation phase. However, these proteins are not exclusive to B. thuringiensis. Some cry genes have been found in other Bacillus species, or even in other genera. In this work, cry genes were searched in 223 acrystalliferous bacillaceous strains. From these strains 13 amplicons were obtained, cloned, and sequenced; however, only 6 amplicons tested positive for cry-like genes, and the 6 isolates showed to be the same strain. We report the characterization of an unusual strain of B. cereus (LBIC-004) which is unable to form protein inclusions during the sporulation phase. LBIC-004 showed a high identity to B. cereus using the sequences of 16S rRNA, gyrB and hag genes; in addition, a unique plasmid pattern of the strain was obtained. A 1953-bp cry gene was identified, coding for a 651 amino acid protein with a molecular weight of 74.9 kDa. This protein showed a predicted three-domain structure, similar to all Cry proteins. However, the amino acid sequence of the protein showed only 41% identity its highest hit: the Cry8Ca1 protein, indicating the uniqueness of this cry-like gene. It was cloned and transferred into a mutant acrystalliferous B. thuringiensis strain which was used in bioassays against Caenorhabditis elegans, Aedes aegypti, Manduca sexta and Phyllophaga sp. The recombinant strain showed no crystal formation and no toxicity to the tested species.

Phylogenetic analyses suggest centipede venom arsenals were repeatedly stocked by horizontal gene transfer

Venoms have evolved over a hundred times in animals. Venom toxins are thought to evolve mostly by recruitment of endogenous proteins with physiological functions. Here we report phylogenetic analyses of venom proteome-annotated venom gland transcriptome data, assisted by genomic analyses, to show that centipede venoms have recruited at least five gene families from bacterial and fungal donors, involving at least eight horizontal gene transfer events. These results establish centipedes as currently the only known animals with venoms used in predation and defence that contain multiple gene families derived from horizontal gene transfer. The results also provide the first evidence for the implication of horizontal gene transfer in the evolutionary origin of venom in an animal lineage. Three of the bacterial gene families encode virulence factors, suggesting that horizontal gene transfer can provide a fast track channel for the evolution of novelty by the exaptation of bacterial weapons into animal venoms.

Biocontrol Potential of a Novel Endophytic Bacterium From Mulberry (Morus) Tree

Mulberry (Morus) is an economically important woody tree that is suitable for use in sericulture as forage and in medicine. However, this broad-leaved tree is facing multiple threats ranging from phytopathogens to insect pests. Here, a Gram-positive, endospore-forming bacterium (ZJU1) was frequently isolated from healthy mulberry plants by screening for foliar endophytes showing antagonism against pathogens and pests. Whole-genome sequencing and annotation resulted in a genome size of 4.06 Mb and classified the bacterium as a novel strain of Bacillus amyloliquefaciens that has rarely been identified from tree leaves. An integrative approach combining traditional natural product chemistry, activity bioassays, and high-resolution mass spectrometry confirmed that strain ZJU1 uses a blend of antimicrobials including peptides and volatile organic compounds to oppose Botrytis cinerea, a major phytopathogenic fungus causing mulberry gray mold disease. We showed that the inoculation of endophyte-free plants with ZJU1 significantly decreased both leaf necrosis and mortality under field conditions. In addition to the direct interactions of endophytes with foliar pathogens, in planta studies suggested that the inoculation of endophytes also induced plant systemic defense, including high expression levels of mulberry disease resistance genes. Moreover, when applied to the generalist herbivore Spodoptera litura, ZJU1 was sufficient to reduce the pest survival rate below 50%. A previously undiscovered crystal toxin (Cry10Aa) could contribute to this insecticidal effect against notorious lepidopteran pests. These unique traits clearly demonstrate that B. amyloliquefaciens ZJU1 is promising for the development of successful strategies for biocontrol applications. The search for new plant-beneficial microbes and engineering microbiomes is therefore of great significance for sustainably improving plant performance.