Antifungal-activity-producing lactic acid bacteria as biocontrol agents in plants

Fungal infection represents a severe problem that decreases the yield and market value of fruit crops. The use of fungicides is a conventional method to control infections but it is associated with disadvantages, such as hazardous impact on public health, environmental contamination, resistance development among pathogens and high cost of agrochemicals. Biological control is an alternative approach for the treatment of fungal infections. The species of Bacillus, Pseudomonas, Enterobacter, Pantoea, Burkholderia, Lysobacter and Serratia have been successfully used in the control of fungal infections. The mechanisms involved in biocontrol are hyperparasitism or predation, production of antibiotics, lytic enzymes and induction of host resistance. Lactic acid bacteria have been used as biopreservative organisms in food and feed systems. They are a cluster of Gram-positive bacteria and include species of the genera Enterococcus, Lactobacillus, Leuconostoc, Lactococcus and Pediococcus. The ability to produce several antibacterial and antifungal substances confers biopreservation potential to lactic acid bacteria. Many have 'generally regarded as safe' status and are considered as safe from both human and environmental points of view. Their isolation is reported from vegetables, aerial plant surfaces, pickled cabbage, grass silage, malted cereals and also from soil. They produce antifungal substances, such as cyclic dipeptides, proteinaceous compounds, organic acids, fatty acids and reuterin. The biocontrol potential of lactic acid bacteria is demonstrated in the prevention of fungal infections of fruits, such as apples and grapes. Thus, living cells or product formulations of antifungal lactic acid bacteria may be prepared and used as an alternative biocontrol technology.