What Is the Effect of Bacteria on Strawberries?

Bacterial Origins

Some potentially deadly germs lurk across a strawberry's ridged surface, which is difficult to clean, according to the online news site Science Daily. Berries are prone to contamination because they are grown close to soil, where they come into contact with E. coli or hepatitis A in manure-based fertilizer. Later, workers handpick fruit, making crops susceptible to human spread of these lethal microbes. In the eastern United States, many strawberries are grown on small family farms that allow consumers to pick their own berries, further encouraging the transmission of bacteria.

Angular leaf spot is a bacterial growth that causes strawberry stem caps to turn black, according to plant pathologist Annemiek Schilder of Michigan State University Extension's Integrated Pest Management (IPM) Resources. This sudden darkness ruins the overall appearance of a strawberry, making it hard to market. Spots also force leaves to fall too soon, which diminishes a plant's yield. Growers in Minnesota first detected this blight in 1960. Varieties hit the hardest include Glooscap, Redchief and Allstar.

Bacteria support the development of ice crystals on soft fruits like strawberries. Ice crystals force premature strawberry blooms, which carry huge potential for crop disasters, especially during early frosts, according to molecular biologist Trudy Wassenaar, who is curator of the online Bacteria Museum. Researchers learned that proteins inside the bacteria cause a buildup of ice that damages fruits. Scientists disabled the genetic material that codes this protein in what was the first use of genetically altered bacteria to protect produce.

Scientists accidentally stumbled upon a way to use germs to enhance the shelf life of strawberries. Purdue University researchers spritzed some experimental dosages of chlorine dioxide gas on strawberries to destroy bacteria, according to Science Daily. They noticed that treated strawberries lasted longer inside refrigerators because of this chemical wash. Some batches stayed fresh for up to six weeks. For the typical consumer, this bacterial agent gives them an average of two extra days before their berries turn fuzzy and have to be discarded.