Gut bacteria adapting to New Zealanders' love of fruit and veg
19 February 2019
The discovery of the first gut bacterium that specialises in breaking down a hard-to-digest substance found in plants
suggests that the human gut microbiome is evolving to accommodate our consumption of fibre-rich foods.
Plant & Food Research scientists, in collaboration with New Zealand and international research partners, discovered a new human
gut bacterium Monoglobus pectinilyticus the first specialist bacterium for pectin degradation and utilisation.
Pectin is a plant’s natural barrier to protect against bacterial attacks. It is also a primary source of dietary fibre
for humans. This structurally complex carbohydrate is not a palatable food source for most bacteria as it is not high in
energy. Yet, gut bacteria face the dilemma of having to break down the pectin barrier in order to access and digest
nutritious plant materials for survival. How gut bacteria get around this problem is important for human health and
increasing nutritional yields from dietary plants.
“M. pectinilyticus is a dedicated microorganism for breaking down pectin, a dietary fibre that makes up 40% of the plant
cell wall in common fruits and vegetables such as kiwifruit and tomato,” says Dr Caroline Kim, the Plant & Food Research scientist who leads the project. “The process wasn’t well-understood until now because few
pectin-degrading bacteria exist and none as specialised as M. pectinilyticus.
“This had left a large gap in our knowledge of how this abundant and important component of human diet is used inside
our bodies. The high degree of specialisation shows that the typically abundant pectin consumption in the human diet may
have placed evolutionary pressure on our gut microbiome to make room for specialist bacteria with dedicated niche and
function for pectin degradation. Since M. pectinilyticus only utilises pectin and no other types of carbohydrates, this
organism will provide valuable insights into how gut microbes interact with plant pectin and ultimately begin the
process of plant digestion in the human colon.”
The team analysed the faecal samples and dietary intakes of 44 healthy people in New Zealand over 10 weeks. They found
that the presence of M. pectinilyticus positively correlates to the participants’ pectin consumption - the more fibre
one eats, the more likely that this beneficial microorganism is present.
The study, “Genomic insights from Monoglobus pectinilyticus: a pectin-degrading specialist bacterium in the human
colon”, is published in the February 2019 issue of The ISME Journal, a top academic journal in microbial ecology (https://plantandfood.us5.list-manage.com/track/click?u=1b46d14e528ad30bae8b3663c=eb4a170696=5b367992d8