Development of Bacillus thuringiensis in Galleria mellonella larvae exposed to gamma radiation

Bacillus thuringiensis is an invertebrate pathogen that produces insecticidal crystal toxins acting on the intestinal barrier. In the Galleria mellonella larvae infection model, toxins from the PlcR virulence regulon contribute to pathogenicity by the oral route. While B. thuringiensis is principally an oral pathogen, bacteria may also reach the insect haemocoel following injury of the cuticle. Here, we address the question of spore virulence as compared to vegetative cells when the wild-type Bt407cry- strain and its isogenic ∆plcR mutant are inoculated directly into G. mellonella haemocoel. Mortality dose-response curves were constructed at 25 and 37 °C using spores or vegetative cell inocula, and the 50% lethal dose (LD50) in all infection conditions was determined after 48 h of infection. Our findings show that (i) the LD50 is lower for spores than for vegetative cells for both strains, while the temperature has no significant influence, and (ii) the ∆plcR mutant is four to six times less virulent than the wild-type strain in all infection conditions. Our results suggest that the environmental resistant spores are the most infecting form in haemocoel and that the PlcR virulence regulon plays an important role in toxicity when reaching the haemocoel from the cuticle and not only following ingestion.

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THE PRODUCTION BY BACILLUS THURINGIENSIS BERLINER OF A HEAT-STABLE SUBSTANCE TOXIC FOR INSECTS

Canadian Journal of Microbiology ◽

10.1139/m59-020 ◽

1959 ◽

Vol 5 (2) ◽

pp. 161-168 ◽

Cited By ~ 65

Author(s):

Ellicott McConnell ◽

A. Glenn Richards

Keyword(s):

Bacillus Thuringiensis ◽

Inclusion Bodies ◽

Galleria Mellonella ◽

Culture Media ◽

Water Soluble ◽

Broth Culture ◽

Toxic Principle ◽

Heat Stable

Bacillus thuringiensis Berliner produces in vitro a heat-stable, dialyzable substance which is toxic for insects when injected. The same or a similar substance is produced in vivo. The toxic principle is of unknown composition. It is heat-stable, water-soluble, dialyzable, and resistant to low temperatures. It is probably neither a protein nor a lipid. Clearly it is distinct from the heat-labile inclusion bodies and from lecithinase. Growth-curve studies showed that the heat-stable toxin appeared in liver broth cultures during the active growth phase, prior to the formation of spores or inclusion bodies. An attempt to produce the toxic principle from culture media in the absence of bacteria was unsuccessful from sterile inocula both from in vivo and in vitro sources. The LD50 for larvae of Galleria mellonella injected with autoclaved supernatant from a 10-day-old liver broth culture of B. thuringiensis was determined to be 0.00036 ml per larva or 0.002 ml per gram of larvae. Approximately the same level of toxicity was found for another caterpillar, a fly larva, and cockroaches. After larvae of Galleria or Pyrausla have been dead for more than 2 days from infection with B. thuringiensis the bacillus could no longer be recovered. A sublethal amount of the heat-stable toxin injected into old larvae of Galleria delayed emergence of the adults by 30 to 40%. The non-pathogenic Bacillus cereus was found to produce a similar-acting, heat-stable toxin under the same conditions that one is produced by B. thuringiensis.

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The effect of cold shock on the immune response of the greater wax moth Galleria mellonella after infection with entomopathogenic bacteria Bacillus thuringiensis / Wpływ szoku zimna na odpowiedź immunologiczną barciaka większego Galleria mellonella po zakażeniu bakterią entomopatogenną Bacillus thuringiensis

Annales Universitatis Mariae Curie-Sklodowska sectio C – Biologia ◽

10.1515/umcsbio-2015-0001 ◽

2015 ◽

Vol 69 (2) ◽

Cited By ~ 1

Author(s):

Iwona Wojda ◽

Paulina Taszłow ◽

Teresa Jakubowicz

Keyword(s):

Immune Response ◽

Bacillus Thuringiensis ◽

Cold Shock ◽

Galleria Mellonella ◽

Multifunctional Protein ◽

Entomopathogenic Bacteria ◽

Greater Wax Moth ◽

Short Period ◽

Defence Proteins ◽

Wax Moth

AbstractInsect immune system consists of only innate mechanisms relied on cellular and humoral branches. Many defence proteins and peptides exist or appear in response to infection in insect’s hemolymph. The interaction between the infected host and the entomopathogen occurs in the conditions of external environment. In this work the greater wax moth larvae of Galleria mellonella were subjected to a temperature of 120C for a short period of time, directly before infection with entomopathogenic bacteria Bacillus thuringiensis. It appeared that the induction of the immune response was higher in cold-shocked animals than in larvae permanently reared at the optimal temperature of 28 0C. This enhanced immune response was manifested as higher antibacterial and lysozyme-type activity detected in full hemolymph, and as a higher level of peptides of molecular weight below 10 kDa having antibacterial activity. Moreover, other changes in the contents of proteins in the hemolymph were observed. These changes concerned inter alia apolipophorin III, the multifunctional protein of immune significance. Its level was higher in the hemolymph of animals pre-exposed to cold shock than in nonshocked, infected ones. Altogether our results indicate that the interdependence mechanisms occur between cold shock and the immune response.

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Effects of pyriproxyfen and Bacillus thuringiensis Berliner, 1915 on enzymatic antioxidant defense system and hemocytes of Galleria mellonella (L., 1758) (Lepidoptera: Pyralidae)

Turkish Journal of Entomology ◽

10.16970/entoted.672744 ◽

2021 ◽

Vol 45 (2) ◽

pp. 149-162

Author(s):

Benay TUNÇSOY ◽

Pınar ÖZALP

Keyword(s):

Bacillus Thuringiensis ◽

Antioxidant Defense ◽

Galleria Mellonella ◽

Antioxidant Defense System ◽

Defense System ◽

Enzymatic Antioxidant ◽

Lepidoptera Pyralidae

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Activation of MAP kinase pathways in Galleria mellonella infected with Bacillus thuringiensis.

Acta Biochimica Polonica ◽

10.18388/abp.2014_1942 ◽

2014 ◽

Vol 61 (1) ◽

Author(s):

Iwona Wojda ◽

Konrad Koperwas ◽

Teresa Jakubowicz

Keyword(s):

Heat Shock ◽

Bacillus Thuringiensis ◽

Map Kinase ◽

Map Kinases ◽

Galleria Mellonella ◽

Fat Body ◽

Greater Wax Moth ◽

Fat Bodies ◽

Map Kinase Pathways ◽

Wax Moth

We followed changes in the level of phospho-MAP kinases in the greater wax moth Galleria mellonella after infection with Bacillus thuringiensis. We observed an enhanced level of phosphorylated p38 and JNK in fat bodies of the infected larvae. In hemocytes, injection of B. thuringiensis caused the highest increase in phospho-JNK, however, all pathways were activated after aseptic injection. We report that Galleria mellonella larvae exposed to heat shock before infection showed an enhanced level of phosphorylated JNK in fat body. This finding is relevant in the light of our previous reports, which submit evidence that pre-shocked animals are more resistant to infection.

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A Bacillus thuringiensis Chitin-Binding Protein is Involved in Insect Peritrophic Matrix Adhesion and Takes Part in the Infection Process

Toxins ◽

10.3390/toxins12040252 ◽

2020 ◽

Vol 12 (4) ◽

pp. 252

Author(s):

Jiaxin Qin ◽

Zongxing Tong ◽

Yiling Zhan ◽

Christophe Buisson ◽

Fuping Song ◽

...

Keyword(s):

Bacillus Thuringiensis ◽

Galleria Mellonella ◽

Binding Protein ◽

Insect Pest ◽

Infection Process ◽

Peritrophic Matrix ◽

Limited Information ◽

Chitin Binding Protein

Bacillus thuringiensis (Bt) is used for insect pest control, and its larvicidal activity is primarily attributed to Cry toxins. Other factors participate in infection, and limited information is available regarding factors acting on the peritrophic matrix (PM). This study aimed to investigate the role of a Bt chitin-binding protein (CBPA) that had been previously shown to be expressed at pH 9 in vitro and could therefore be expressed in the alkaline gut of lepidopteron larvae. A ∆cbpA mutant was generated that was 10-fold less virulent than wild-type Bt HD73 towards Ostrinia furnacalis neonate larvae, indicating its important role in infection. Purified recombinant Escherichia coli CBPA was shown to have a chitin affinity, thus indicating a possible interaction with the chitin-rich PM. A translational GFP–CBPA fusion elucidated the localization of CBPA on the bacterial surface, and the transcriptional activity of the promoter PcbpA was immediately induced and confirmed at pH 9. Next, in order to connect surface expression and possible in vivo gut activity, last instar Galleria mellonella (Gm) larvae (not susceptible to Bt HD-73) were used as a model to follow CBPA in gut expression, bacterial transit, and PM adhesion. CBPA-GFP was quickly expressed in the Gm gut lumen, and more Bt HD73 strain bacteria adhered to the PM than those of the ∆cbpA mutant strain. Therefore, CBPA may help to retain the bacteria, via the PM binding, close to the gut surface and thus takes part in the early steps of Bt gut interactions.

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