A Bacillus velezensis strain isolated from oats with disease-preventing and growth-promoting properties

Endophytes have been shown to promote plant growth and health. In the present study, a Bacillus velezensis CH1 (CH1) strain was isolated and identified from high-quality oats, which was capable of producing indole-3-acetic acid (IAA) and strong biofilms, and capabilities in the nitrogen-fixing and iron carriers. CH1 has a 3920 kb chromosome with 47.3% GC content and 3776 code genes. Compared genome analysis showed that the largest proportion of the COG database was metabolism-related (44.79%), and 1135 out of 1508 genes were associated with the function "biosynthesis, transport, and catabolism of secondary metabolites." Furthermore, thirteen gene clusters had been identified in CH1, which were responsible for the synthesis of fifteen secondary metabolites that exhibit antifungal and antibacterial properties. Additionally, the strain harbors genes involved in plant growth promotion, such as seven putative genes for IAA production, spermidine and polyamine synthase genes, along with multiple membrane-associated genes. The enrichment of these functions was strong evidence of the antimicrobial properties of strain CH1, which has the potential to be a biofertilizer for promoting oat growth and disease resistance.

Root-Associated Bacteria Are Biocontrol Agents for Multiple Plant Pests

Biological control is an important process for sustainable plant production, and this trait is found in many plant-associated microbes. This study reviews microbes that could be formulated into pesticides active against various microbial plant pathogens as well as damaging insects or nematodes. The focus is on the beneficial microbes that colonize the rhizosphere where, through various mechanisms, they promote healthy plant growth. Although these microbes have adapted to cohabit root tissues without causing disease, they are pathogenic to plant pathogens, including microbes, insects, and nematodes. The cocktail of metabolites released from the beneficial strains inhibits the growth of certain bacterial and fungal plant pathogens and participates in insect and nematode toxicity. There is a reinforcement of plant health through the systemic induction of defenses against pathogen attack and abiotic stress in the plant; metabolites in the beneficial microbial cocktail function in triggering the plant defenses. The review discusses a wide range of metabolites involved in plant protection through biocontrol in the rhizosphere. The focus is on the beneficial firmicutes and pseudomonads, because of the extensive studies with these isolates. The review evaluates how culture conditions can be optimized to provide formulations containing the preformed active metabolites for rapid control, with or without viable microbial cells as plant inocula, to boost plant productivity in field situations.

Genetic transformation system for Bacillus velezensis NSZ-YBGJ001 and curing of the endogenous plasmid pBV01

OBJECTIVES

To construct a genetic transformation system for Bacillus velezensis NSZ-YBGJ001 and identify the origin element in an endogenous plasmidpBV01 for curing pBV01 by plasmid incompatibility.

RESULTS

A plasmid pUBC01 was constructed, and then an electrotransformation system for B. velezensis NSZ-YBGJ001 was developed, which reached ~ 1000 transformants per microgram of pUBC01 DNA. Additionally, a 7276-bp circular plasmid pBV01 with a G + C content of 37.5% was isolated from B. velezensis NSZ-YBGJ001 and analyzed via sequence analysis. To cure pBV01, an incompatible plasmid pBV02 harboring the replication element of pBV01 was developed and functionally replicated in both Bacillus subtilis WB600 and B. velezensis NSZ-YBGJ001. pBV01 was cured through introduction of pBV02 into B. velezensis NSZ-YBGJ001 after serial subculturing for approximately 40 generations. Finally, another plasmid, pBV03, was constructed based on pBV-ori, and exogenous genes in pBV03 could be efficiently expressed in B. subtilis.

CONCLUSIONS

The results of this study, including the genetic transformation system, plasmid-curing strategy, and exogenous gene expression, will support genetic manipulation of B. velezensis to promote its application in biocontrol and industry.

Genetically modified entomopathogenic bacteria, recent developments, benefits and impacts: A review

Entomopathogenic bacteria (EPBs), insect pathogens that produce pest-specific toxins, are environmentally-friendly alternatives to chemical insecticides. However, the most important problem with EPBs application is their limited field stability. Moreover, environmental factors such as solar radiation, leaf temperature, and vapor pressure can affect the pathogenicity of these pathogens and their toxins. Scientists have conducted intensive research to overcome such problems. Genetic engineering has great potential for the development of new engineered entomopathogens with more resistance to adverse environmental factors. Genetically modified entomopathogenic bacteria (GM-EPBs) have many advantages over wild EPBs, such as higher pathogenicity, lower spraying requirements and longer-term persistence. Genetic manipulations have been mostly applied to members of the bacterial genera Bacillus, Lysinibacillus, Pseudomonas, Serratia, Photorhabdus and Xenorhabdus. Although many researchers have found that GM-EPBs can be used safely as plant protection bioproducts, limited attention has been paid to their potential ecological impacts. The main concerns about GM-EPBs and their products are their potential unintended effects on beneficial insects (predators, parasitoids, pollinators, etc.) and rhizospheric bacteria. This review address recent update on the significant role of GM-EPBs in biological control, examining them through different perspectives in an attempt to generate critical discussion and aid in the understanding of their potential ecological impacts.

Characteristics and Application of a Novel Species of Bacillus: Bacillus velezensis

Bacillus velezensis has been investigated and applied more and more widely recently because it can inhibit fungi and bacteria and become a potential biocontrol agent. In order to provide more clear and comprehensive understanding of B. velezensis for researchers, we collected the recent relevant articles systematically and reviewed the discovery and taxonomy, secondary metabolites, characteristics and application, gene function, and molecular research of B. velezensis. This review will give some direction to the research and application of this strain for the future.

Complete Genome Sequence of Bacillus velezensis GQJK49, a Plant Growth-Promoting Rhizobacterium with Antifungal Activity

Bacillus velezensis GQJK49 is a plant growth-promoting rhizobacterium with antifungal activity, which was isolated from Lycium barbarum L. rhizosphere. Here, we report the complete genome sequence of B. velezensis GQJK49. Twelve gene clusters related to its biosynthesis of secondary metabolites, including antifungal and antibacterial antibiotics, were predicted.

Assessment of the Antimicrobial Activity and the Entomocidal Potential of Bacillus thuringiensis Isolates from Algeria

This work represents the first initiative to analyze the distribution of B. thuringiensis in Algeria and to evaluate the biological potential of the isolates. A total of 157 isolates were recovered, with at least one isolate in 94.4% of the samples. The highest Bt index was found in samples from rhizospheric soil (0.48) and from the Mediterranean area (0.44). Most isolates showed antifungal activity (98.5%), in contrast to the few that had antibacterial activity (29.9%). A high genetic diversity was made evident by the finding of many different crystal shapes and various combinations of shapes within a single isolate (in 58.4% of the isolates). Also, over 50% of the isolates harbored cry1, cry2, or cry9 genes, and 69.3% contained a vip3 gene. A good correlation between the presence of chitinase genes and antifungal activity was observed. More than half of the isolates with a broad spectrum of antifungal activity harbored both endochitinase and exochitinase genes. Interestingly, 15 isolates contained the two chitinase genes and all of the above cry family genes, with some of them harboring a vip3 gene as well. The combination of this large number of genes coding for entomopathogenic proteins suggests a putative wide range of entomotoxic activity.