Figure: Washington State University researchers Phuc Ha and Haluk Beyenal examine a bacterial culture in the laboratory. Photo Source: Washington State University

Researchers from Washington State University have for the first time grown in the laboratory the bacteria that causes Citrus Greening Disease, the world's most harmful citrus disease. The researchers were able to grow the elusive and poorly understood bacterium, Candidatus Liberibacter asiaticus (CLas) and reported their work in the journal Biofilm. The researchers used infected citrus tissues and developed a biofilm instead of using a rich growth medium. This severely limited the growth of partner bacteria and created a medium with the specific nutrients, acidity, incubation temperatures, and oxygen levels that are optimal for CLas.

Similarly, biologists from Florida State University (FSU) were able to grow a close relative of CLas called Liberacter cresens in the laboratory. Their research helped them understand why the bacteria samples are difficult to grow in the laboratory. As they ran tests, they observed that the samples changed the environment around them and then die after doing so. They also noticed that L. cresens grows slowly and requires careful maintenance, and that alkaline conditions poisoned the bacteria.

Being able to grow CLas in the laboratory will make it easier for scientists to find treatments for the disease. Citrus greening is a serious concern in the United States. Orange production in the country has steadily dropped over the last decade, plummeting from 7.98 million tons in the 2007 season to 2.2 million tons in 2018. Most of these losses have occurred in Florida because of citrus greening.

For more details, read the news articles in the WSU Insider and FSU News.