Utilisation of response surface methodology to optimise the culture medium for<i>Bacillus thuringiensis</i>subsp.<i>israelensis</i>

Angelo, Elisangela Andrade; Vilas-Bôas, Gislayne Trindade; Castro-Gómez, Raúl Jorge Hernán; Lopes, José

doi:10.1080/09583157.2014.983457

Cited by 8 publications

(4 citation statements)

References 23 publications

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“…In addition, changes in culture conditions affect virulence. Carbon sources or oxygen supply can interfere with toxin expression, crystal synthesis, and toxicity (Fabrízio et al 2012, Elisangela et al 2015). Surface contamination and feed incorporation are commonly used to assess insecticidal protein toxicity.…”

Section: Discussionmentioning

confidence: 99%

Relative activity of 15 bacterial strains against the larvae of Helicoverpa armigera, Spodoptera exigua, and Spodoptera litura (Lepidoptera: Noctuidae)

Cao

Chen

et al. 2023

Journal of Economic Entomology

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Crystal toxins produced by different strains of entomopathogenic Bacillus thuringiensis (Bt) have been characterized and widely applied as commercial biological pesticides owing to their excellent insecticidal properties. This study aimed to identify novel bacterial strains effective in controlling Spodoptera exigua Hübner, Helicoverpa armigera Hübner, and Spodoptera litura Fabricius. Fifteen culturable bacterial strains were isolated from 60 dead larvae (H. armigera and S. exigua) collected in the field. The biochemical characteristics and 16S rRNA sequences of these strains indicated that one strain (B7) was Lysinibacillus sp., 12 strains (B1, B3, B4, B5, B6, B8, P2, P3, P4, P5, P6, and DW) were Bt kurstaki, and P2-2 and B2 were Bacillus velezensis subsp. Laboratory bioassays indicated that strains B3, P6, B6, and P4 showed high toxicity to second-instar larvae of S. exigua, with LC50 values of 5.11, 6.74, 205.82, and 595.93 µg/ml, respectively; while the strains P5, B5, B6, and P6, were the most efficient against second-instar larvae of H. armigera with LC50 values of 725.82, 11,022.72, 1,282.90, 2,005.28, respectively, and strains DW, P3, P2, and B4 had high insecticidal activity against second-instar larvae of S. litura with LC50 values of 576.69, 1,660.96, 6,309.42, and 5,486.10 µg/ml, respectively. In conclusion, several Bt kurstaki strains with good toxicity potential were isolated and identified in this study. These strains are expected to be useful for biointensive integrated pest management programs to reduce the use of synthetic insecticides.

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Section: Discussionmentioning

confidence: 99%

Relative activity of 15 bacterial strains against the larvae of Helicoverpa armigera, Spodoptera exigua, and Spodoptera litura (Lepidoptera: Noctuidae)

Cao

Chen

et al. 2023

Journal of Economic Entomology

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“…6). It has been reported that B. thuringiensis toxin production and toxicity might also be affected by the growth medium used for sporulation (46), such that reduced virulence might result in different histories for spores which, in one case, sporulate within cadavers and in the other, in nutrient broth. However, since cadaver-derived spores showed inhibited germination ( Fig.…”

Section: Discussionmentioning

confidence: 99%

Infection of Tribolium castaneum with Bacillus thuringiensis: Quantification of Bacterial Replication within Cadavers, Transmission via Cannibalism, and Inhibition of Spore Germination

Milutinović

Höfling

Futo

et al. 2015

Appl Environ Microbiol

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Reproduction within a host and transmission to the next host are crucial for the virulence and fitness of pathogens. Nevertheless, basic knowledge about such parameters is often missing from the literature, even for well-studied bacteria, such as Bacillus thuringiensis, an endospore-forming insect pathogen, which infects its hosts via the oral route. To characterize bacterial replication success, we made use of an experimental oral infection system for the red flour beetle Tribolium castaneum and developed a flow cytometric assay for the quantification of both spore ingestion by the individual beetle larvae and the resulting spore load after bacterial replication and resporulation within cadavers. On average, spore numbers increased 460-fold, showing that Bacillus thuringiensis grows and replicates successfully in insect cadavers. By inoculating cadaver-derived spores and spores from bacterial stock cultures into nutrient medium, we next investigated outgrowth characteristics of vegetative cells and found that cadaver-derived bacteria showed reduced growth compared to bacteria from the stock cultures. Interestingly, this reduced growth was a consequence of inhibited spore germination, probably originating from the host and resulting in reduced host mortality in subsequent infections by cadaver-derived spores. Nevertheless, we further showed that Bacillus thuringiensis transmission was possible via larval cannibalism when no other food was offered. These results contribute to our understanding of the ecology of Bacillus thuringiensis as an insect pathogen. S uccessful pathogens need to be able to infect the host, use the host's nutrients to reproduce successfully, form new transmission stages, and finally infect another host individual (1). Reproduction and transmission are key to a pathogen's fitness and also of prime interest for understanding the evolution of virulence (2). Still, basic knowledge about such parameters is often sparse, even for otherwise-well-studied organisms, such as the insect pathogen Bacillus thuringiensis (Bt).Bacillus thuringiensis is a Gram-positive, endospore-forming insect pathogen that naturally infects its hosts via the oral route (3). Among the major virulence factors of Bt are ␦-endotoxins (Cry proteins), which are naturally produced by bacteria during the sporulation phase (4). Cry toxins are assembled in a large crystal that dissolves upon ingestion, thereby allowing the toxins to bind specifically to the midgut epithelium (4). The toxins' mode of action has been well investigated (5), and its binding results in an osmotic imbalance and cell death as a consequence of pore formation in the cell membrane (6). Because of the ability to specifically kill insects of various insect orders (7), the majority of research has focused on the implementation of Cry toxins as biopesticides (8, 9; for a review, see reference 7).Cry toxins are the best-known virulence factors of Bt. However, this bacterium is equipped with a diverse arsenal of virulence factors and other adaptations specificall...

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“…Although some studies have aimed to optimize culture conditions for the maximum production of bioactive molecules and biological activity (Angelo et al . ), it is important to bear in mind that replicating the diverse and fluctuating environmental conditions that promote metabolite production in laboratory investigations is quite challenging (Tyc et al . ).…”

Section: Optimum Cultivation Conditions For Metabolite Productionmentioning

confidence: 99%

“…Although some studies have aimed to optimize culture conditions for the maximum production of bioactive molecules and biological activity (Angelo et al 2015), it is important to bear in mind that replicating the diverse and fluctuating environmental conditions that promote metabolite production in laboratory investigations is quite challenging (Tyc et al 2017). Since the production of biologically active metabolites is especially influenced by the amount of nutrients available for uptake and use, variation often observed in the biocontrol efficacy of field applications could likely be attributed to nutrition (Anderson and Kim 2018).…”

Section: Temperature Salinity Ph and Oxygen Availabilitymentioning

confidence: 99%

Microbial metabolomics: essential definitions and the importance of cultivation conditions for utilizing Bacillus species as bionematicides

Horak

Engelbrecht

Rensburg

et al. 2019

J of Applied Microbiology

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Root‐knot nematodes are destructive phytopathogens that damage agricultural crops globally, and there is growing interest in the use of biocontrol based on rhizobacteria such as Bacillus to combat Meloidogyne species. It is hypothesized that nematicidal activity of Bacillus can be attributed to the production of secondary metabolites and hydrolytic enzymes. Yet, few studies have characterized these metabolites and their identities remain unknown. Others are speculative or fail to elaborate on how secondary metabolites were detected or distinguished from primary metabolites. Metabolites can be classified based on their origin as either intracellular or extracellular and based on their function, as either primary or secondary. Although this classification is in general use, the boundaries are not always well defined. An understanding of the secondary metabolite and hydrolytic enzyme classification of Bacillus species will facilitate investigations aimed at bionematicide development. This review summarizes the significance of Bacillus hydrolytic enzymes and secondary metabolites in bionematicide research and provides an overview of known classifications. The importance of appropriate cultivation conditions for optimum metabolite and enzyme production is also discussed. Finally, the use of metabolomics for the detection and identification of nematicidal compounds is considered.

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Utilisation of response surface methodology to optimise the culture medium forBacillus thuringiensissubsp.israelensis

Cited by 8 publications

References 23 publications

Relative activity of 15 bacterial strains against the larvae of Helicoverpa armigera, Spodoptera exigua, and Spodoptera litura (Lepidoptera: Noctuidae)

Relative activity of 15 bacterial strains against the larvae of Helicoverpa armigera, Spodoptera exigua, and Spodoptera litura (Lepidoptera: Noctuidae)

Infection of Tribolium castaneum with Bacillus thuringiensis: Quantification of Bacterial Replication within Cadavers, Transmission via Cannibalism, and Inhibition of Spore Germination

Microbial metabolomics: essential definitions and the importance of cultivation conditions for utilizing Bacillus species as bionematicides

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