Clues to magic of manuka honey
Scientists think microbes may provide vital factor
Our understanding of gut health has ballooned as we’ve learned more about the communities of beneficial bugs that live within each of us. We now know this microbiome contributes to everything from immunity and obesity to mental health.
Now scientists suspect microbes might also be what gives one of New Zealand’s most lucrative exports, manuka honey, its active ingredient.
The native manuka plant acts as the substrate for the unique and valuable honey, which contains high levels of a compound called methylglyoxal.
This is better known to consumers around the world by the different systems that producers use to grade manuka honey — MGO or unique manuka factor, or UMF. Methylglyoxal is formed from nectar rich in a substance called dihydroxyacetone, or DHA.
“We do not yet understand why some flowers on some manuka plants produce high levels of DHA and wonder if the microorganisms in the flowers might contribute to this,” said Dr Hayley Ridgway, a senior scientist at Plant & Food Research.
“Our previous work has shown that manuka is a plant for which microbes significantly impact growth and chemistry. We also know that DHA can be made by micro-organisms.”
In a just-launched study, Ridgway and fellow researchers from Manaaki Whenua — Landcare Research and Lincoln University aimed to find out if their theory was correct.
Working in partnership with Nga¯i Tahu Farming and Ngati Porou Miere, the team plan to collect flowers from manuka lines known to produce high and low amounts of DHA in the nectar. “We will make a collection of microbes from flowers and study whether they are able to make DHA by themselves.”
They’ll then add selected microbes back to those low-DHA manuka lines to see if they can actually increase DHA production. “In this way we will increase the value of the nectar on the plant and the honey derived from it.”
The work will draw on state-of-the-art DNA tools to reveal just how microbes are doing the job, Ridgway said. “Manuka is a plant rich in microbes that can influence many aspects of its growth and health.
“Sorting through this diverse group of different organisms to find those responsible for augmenting DHA, if present, will be a challenge.”
But if they can solve the puzzle, they stand to unlock some of the secrets of the intriguing relationship between the native plant and the microbes it hosts.
The next step will be to seed New Zealand’s plantation with a new catalyst, or create highvalue seedlings.
“Our focus is on high value honey but we may also find other interconnections and dependencies with other microbes along the way — analogous to the frontiers in human health,” Ridgway said.
“We are at the forefront of an exciting new science area that will demonstrate the currently hidden world by which microbes support our wonderful native plants.
“We hope we will generate spill-over benefits to functional studies on microbes in other valued native flora.”
The study is being supported with a milliondollar grant from the Ministry of Business, Innovation and Employment’s Endeavour Fund.
Manuka is a plant rich in microbes that can influence many aspects of its growth and health.
Dr Hayley Ridgway, Plant & Food Research