Acinetobacter calcoaceticus

Acinetobacter calcoaceticus is a Gram-negative aerobic bacterium recognized in agricultural microbiology as an opportunistic plant pathogen. While often found in soil and water as a saprophyte, under favorable conditions for the pathogen and stress factors for the plant, it becomes an aggressive agent causing soft rot diseases. Its ability to produce extracellular enzymes allows it to degrade plant tissues effectively.

The host range for this bacterium includes various fleshy vegetables and fruits. Crops such as carrots, onions, cabbage, tomatoes, and cucumbers are particularly susceptible. The infection is especially problematic during the post-harvest period, as the bacterium exploits wounds caused during mechanical harvesting, packing, or handling to enter and consume the host's cellular tissue.

Symptoms of the infection typically include rapid tissue maceration. Initially, water-soaked lesions appear, which quickly expand and soften, turning the plant tissue into a mushy, slimy rot. A distinct, foul odor often accompanies the infection, which is a hallmark of many bacterial soft rot diseases caused by this and related species.

Development and spread are heavily dependent on environmental conditions. High humidity, poor air circulation, and temperatures between +20°C and +30°C provide the optimal environment for rapid bacterial multiplication. Contaminated water sources, infested soil, and unclean harvesting equipment act as the primary vehicles for transmission, facilitating the spread of the pathogen throughout a field or storage facility.

Integrated management is necessary to control the spread of this pathogen. Key prevention and protection strategies include:

• Maintaining dry and well-ventilated storage environments to inhibit bacterial growth.
• Sanitizing all equipment and storage crates to prevent cross-contamination.
• Careful handling during harvest to minimize wounding and bruising of produce.
• Removing diseased plant debris from the field to reduce the pathogen's overwintering reservoir.
• Implementing appropriate irrigation management to avoid waterlogging the soil.