Bacillus species as potential biocontrol agents against citrus diseases

Citrus diseases are the dominant threat to citrus production and cause substantial economic losses. At present, chemical control is highly effective and is widely applied in the control of agricultural diseases. However, the chemicals used may have a negative impact on the environment and human life. Biological control is considered a safe and sustainable strategy and has attracted great attention for its potential for disease control. Bacillus species show broad-spectrum antimicrobial activity and have been widely used as agricultural biocontrol agents. This study aims to provide an overview of the research on and application of Bacillus species as potential biocontrol agents against citrus diseases. Bacillus species mainly act through the antagonistic mechanisms of production of antimicrobial substances (lipopeptides, antibiotics, and volatile organic compounds), induced systemic resistance and competition for nutrients and space (colonization). Few Bacillus-based biocontrol products are applied in citrus, so developing and commercializing Bacillus products is a promising area of study. Combined strategies based on Bacillus spp. are more effective than individual strategies alone and should be used in the control of citrus diseases. This study will contribute to Bacillus-based biocontrol in the citrus industry.