Comparative Study of the Volatile Organic Compounds Produced by a Mosquito Repellent Bacillus licheniformis Strain from Desert Soil Versus a Non-Repellent One

Mosquito-borne diseases constitute a major health issue and a high burden for many countries. The biocontrol of mosquitoes is vital for combatting such diseases. Bacteria exhibit huge potential biotechnological uses due to their adaptability and ubiquity. Volatile organic compounds (VOCs) are typically molecules with low molecular weight and high vapor pressure. The volatiles produced by bacteria are complex and can impact insect behavior. This study aimed to compare the volatiles produced by the repellent Bacillus licheniformis strain Ba1 with a closely related, yet non-repulsive one (B957). The strains were isolated from extreme environments in Morocco (desert dunes and hot springs) and their resistance to both high temperature and salinity was investigated. After cultivation, the VOCs were extracted and identified by GC-MS. The VOCs detected showed little difference between the two strains, however, their relative abundance varied greatly, suggesting a dose-dependent effect. Ba1 was found to produce both repulsive and attractive compounds as well as molecules with larvicidal effects mainly found in plant extracts. To the best of our knowledge, this is the first study of VOCs emitted by Bacillus sp. With a repulsive effect against mosquitoes.