Modified bacteria could protect crops and replace man-made pesticides, scientists say

Bacteria could help protect crops without man-made pesticides, according to a study which used vaccine manufacturing techniques to make the microbes safe to humans while retaining their anti-microbial properties.

UK researchers were able to remove the risk of lung infections from a modified form of the bacteria while still allowing it to prevent “damping off” a disease which kills off seeds and seedlings.

With further improvements and tests in humans, the Cardiff University-led researchers said they hope their discovery could make food production “safer, more sustainable, and toxin-free.”

Their work focused on a species burkholderia bacteria, a group which produce an array of compounds that can fight off fungus, amoebae and other bacteria species that can cause crop diseases.

“Beneficial bacteria such as burkholderia that have co-evolved naturally with plants, have a key role to play in a sustainable future,” said Professor Eshwar Mahenthiralingam, lead researcher of the study published in Nature Microbiology.

“We have to understand the risks, mitigate against them and seek a balance that works for all.”

Up until 1999 these species and other biopesticides were widely used, but then increasing recognition of the risks of serious infections in people with cystic fibrosis led to a moratorium on their use.

Since then fears about the impact of industrial scale pesticide use have grown, blamed for collapsing songbird numbers and for turning frogs and fish female by disrupting their hormones when they’re washed into rivers.

Leading environmental chemists recently warned humanity is producing new chemicals faster than it can predict their harms with many lasting a long time in the environment.

Professor Mahenthiralingam, has studied burkholderia bacteria in cystic fibrosis for many years and the research led to two new human antibiotics, Cepacin A and B.

But he and his team are now working to see if Cepacin would be effective in crop pests as well.

Using genomic sequencing of the bacterial DNA the researchers could identify the genes for burkholderia to manufacture Cepacin.

They then used techniques already deployed in live vaccine development to neutralise the bacteria’s infectious capabilities while retaining its Cepacin producing effects.

“Burkholderia split their genomic DNA across 3 fragments, called replicons,” said Professor Mahenthiralingam.

“We removed the smallest of these 3 replicons to create a mutant Burkholderia strain which, when tested on germinating peas, still demonstrated excellent biopesticidal properties.

Tests in mice susceptible to lung infections, intended to mimic the regular infections faced by people with cystic fibrosis found the mutant strain also did not cause them harm.

In combination with University of Warwick researchers, who helped in the discovery of Cepacin, the group are now looking at turning their mutant strain into a safe biopesticide that won’t build up to harmful levels in the environment.