Bio-insecticide Bacillus thuringiensis spores encapsulated with amaranth derivatized starches: studies on the propagation “in vitro”

• Published in: Bioprocess and biosystems engineering Vol. 38; no. 2; pp. 329 - 339
• Main Authors: Rodríguez, Ana Priscila García, Martínez, Marcela Gaytán, Barrera-Cortés, Josefina, Ibarra, Jorge E., Bustos, Fernando Martínez
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-02-2015; Springer Nature B.V
• Subjects: Amaranthus - chemistry; Bacillus thuringiensis; Bacillus thuringiensis - chemistry; Bacillus thuringiensis - physiology; Bacteria; Biotechnology; Capsules - chemical synthesis; Cell Proliferation - physiology; Chemistry; Chemistry and Materials Science; Drying; Environmental changes; Environmental conditions; Environmental Engineering/Biotechnology; Food Science; Industrial and Production Engineering; Industrial Chemistry/Chemical Engineering; Insecticides; Larvae; Materials Testing; Original Paper; Pest Control, Biological - methods; Propagation; Spores, Bacterial - chemistry; Spores, Bacterial - physiology; Starch; Starch - chemistry; Ultraviolet radiation; Starch; Microencapsulation; Amaranth
• ISSN: 1615-7591; 1615-7605
• DOI: 10.1007/s00449-014-1273-7

Bacillus thuringiensis
(
Bt
) is one of the bioinsecticides used worldwide due to its specific toxicity against target pests in their larval stage. Despite this advantage, its use is limited because of their short persistence in field when exposed to ultra violet light and changing environmental conditions. In this work, microencapsulation has been evaluated as a promising method to improve
Bt
activity. The objective of this study was to develop and characterize native and modified amaranth starch granules and evaluate their potential application as wall materials in the microcapsulation of
B thuringiensis
serovar
kurstaki
HD-1 (
Bt
- HD1), produced by spray drying. Native amaranth starch granules were treated by hydrolyzation, high energy milling (HEM) and were chemically modified by phosphorylation and succinylation. The size of the
Bt
microcapsules varied from 12.99 to 17.14 μm adequate to protect the spores of
Bt
from ultraviolet radiation. The aw coefficient of the microcapsules produced by the modified starches after drying was low (0.14–1.88), which prevent microbial growth. Microcapsules prepared with phosphorylated amaranth starch presented the highest bacterial count and active material yield. Different concentrations of the encapsulated
Bt
formulation in phosphorylated amaranth starch showed a high level of insecticidal activity when tested on
M. sexta
larvae and has great potential to be developed as a bioinsecticide formulation, also, the level of toxicity is much higher than that found in some of the products commercially available.