Analysis of Synergism between Extracellular Polysaccharide from Bacillus thuringensis subsp. kurstaki HD270 and Insecticidal Proteins

Bai Xue; Meiling Wang; Zeyu Wang; Changlong Shu; Lili Geng; Jie Zhang

doi:10.3390/toxins15100590

Analysis of Synergism between Extracellular Polysaccharide from Bacillus thuringensis subsp. kurstaki HD270 and Insecticidal Proteins

Toxins (Basel). 2023 Sep 28;15(10):590. doi: 10.3390/toxins15100590.

Authors

Bai Xue^{1

2}, Meiling Wang², Zeyu Wang², Changlong Shu², Lili Geng², Jie Zhang^{1

2}

Affiliations

¹ College of Life Sciences, Northeast Agricultural University, Harbin 150030, China.
² State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.

Abstract

Bacillus thuringiensis (Bt) is the most widely used biopesticide worldwide and can produce several insecticidal crystal proteins and vegetative insecticidal proteins (Vips) at different growth stages. In our previous study, extracellular polysaccharides (EPSs) of Bt strain HD270 were found to enhance the insecticidal activity of Cry1Ac protoxin against Plutella xylostella (L.) and promote the binding of Cry1Ac to the intestinal brush border membrane vesicles (BBMVs). Whether the synergistic activity of Bt EPSs is common to other Cry1-type or Vip proteins is unclear, as is the potential synergistic mechanism. In this study, crude EPS-HD270 was found to increase the toxicity of Cry1-type toxins and Vip3Aa11 against different lepidopteran pests by approximately 2-fold. The purified EPS-HD270 also possessed synergistic activity against the toxicity of Cry1Ac and Vip3Aa11 against Spodoptera frugiperda (J.E. Smith) and Helicoverpa armigera (Hübner). Furthermore, we found that EPS-HD270 had a strong binding ability with Vip3Aa11 and promoted the binding of Vip3Aa11 to the BBMVs of H. armigera and S. frugiperda. Bt EPS-HD270 also protected Vip3Aa11 from proteolytic processing in larval midgut juice. Bt EPSs had universal synergistic effects on Cry1-type or Vip toxins against S. frugiperda and H. armigera. Bt EPS-HD270 exhibited synergistic activity with Vip3Aa through promotion of binding to BBMVs and protection from digestion by midgut protease. The results indicated that synergistic activity with Bt toxins was an important function of Bt EPSs, which was very different from other Bacillus spp.

Keywords: BBMVs; Bacillus thuringiensis; extracellular polysaccharides; microbial pesticides; midgut juice; synergistic effects.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Bacillus thuringiensis* / metabolism
Bacillus* / metabolism
Bacterial Proteins / pharmacology
Bacterial Proteins / toxicity
Endotoxins / metabolism
Endotoxins / toxicity
Hemolysin Proteins / pharmacology
Hemolysin Proteins / toxicity
Insecticides* / metabolism
Insecticides* / toxicity
Larva / metabolism
Moths*

Substances

Insecticides
Endotoxins
Bacterial Proteins
Hemolysin Proteins

Grants and funding

This study was funded by the National Key Research and Development Program of China (2022YFE0116500), and the Agricultural Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences (CAAS-ZDRW202108).