Lactococcus lactis

Lactococcus lactis is a gram-positive bacterium primarily recognized for its role in dairy fermentation, but it also functions as an opportunistic pathogen in agricultural systems. In the context of plant health, it contributes to soft rot and the degradation of plant tissues, especially when plants are already weakened by abiotic stress or primary infection.

The causative agent triggers tissue breakdown through the secretion of enzymes and metabolic byproducts that disrupt cellular integrity. This process leads to symptoms consistent with soft bacterial rot, including the loss of turgor, a mushy consistency of tissues, and the emission of a pungent, sour odor resulting from the acidification of plant juices.

A wide range of succulent vegetable crops is susceptible to colonization by this pathogen, including tomatoes, cucumbers, cabbage, and root vegetables. The damage is most visible in fruits and stems that have high moisture content, making them ideal substrates for rapid bacterial proliferation under favorable ecological conditions.

Environmental conditions favoring the development and spread of Lactococcus lactis include temperatures between 20°C and 30°C and high humidity levels. The bacteria spread easily through irrigation water, contaminated farming equipment, and contact with infested soil debris. Insects that feed on plant tissues serve as mechanical vectors, introducing the bacteria directly into the plant's vascular or cellular systems.

The economic impact is manifested in significant post-harvest losses and reduced shelf life of vegetables. Managing this pathogen requires an integrated approach focusing on sanitation and hygiene:

• Regular sanitation of greenhouses and storage facilities.
• Implementation of crop rotation to reduce bacterial loads in the soil.
• Control of pest populations to prevent mechanical injury to plants.
• Maintenance of optimal temperature and humidity levels during crop storage.