Research

Here you can read about current and recent research projects I’m working on. My major interest is soil microorganisms and how they interact with the environment around them. These interactions are important for biogeochemical cycles, soil fertility, and plant health. The enzymes produced by soil microbes can also be valuable biotechnological tools. If you’re a student interested in working on a thesis or diploma project with me, visit my professional webpage for more detail and how to get in touch. You can learn about the working culture of our labspace in this article.

Biocontrol

Biological control is the use of living organisms to control pests and pathogens, instead of using chemical pesticides. This can mean animals are used to control insect populations, or that bacteria are used to kill pathogenic fungi. Picture source.

Exploring the potential for fungal antagonism and cell wall attack by Bacillus subtilis natto. The natto bacterium is used in food production in Japan, but had not been considered for biocontrol, although it lives in the soil and produces the enzymes associated with anti-fungal properties. We investigated the biocontrol potential of natto, focussing on whether we could enhance such behaviours by changing culture conditions.

The impact of steroidal glycoalkaloids on the physiology of Phytophthora infestans, the causative agent of potato late blight. Plant breeders and farmers need to know what traits to select for in crop plants that are threatened by disease. The potato has suffered from blight for centuries. We investigated potato compounds called glycoalkaloids to see what effect they had on an especially nasty potato pathogen. Our results could guide potato breeders in selecting for useful traits.

Soil bacteria

I’m fascinated by bacteria that can sense specific carbohydrates (like in plant and fungal cell walls) and respond by producing specific enzymes. A better understanding of the complex microbe-microbe interactions in the soil will help us to better manage the soil microbial ecosystem. Picture source.

Focussed metabolism of β-glucans by the soil Bacteroidetes Chitinophaga pinensisWe showed that my favourite species, C. pinensis, has a very strict preference for using fungal biomass instead of plant biomass as a source of nutrition. This will guide our efforts to characterise enzyme activities, as it gives hints to likely enzyme substrates.

Proteomic insights into mannan degradation and protein secretion by the forest floor bacterium Chitinophaga pinensis.  We used a technique called mass spectrometry in this paper to help us identify the proteins that C. pinensis secretes when grown in different conditions. This can tell us the actual enzymes involved in different processes, and which combinations of enzymes are produced at the same time.

Enzyme discovery

I characterise enzymes with potential use in biomass deconstruction or modification, often in collaboration with the Wallenberg Wood Science Centre (WWSC). Enzymes can be useful at almost every step of a wood biorefinery, to separate wood components, add new functionalities, or combine them into novel materials. Picture source.

Lytic polysaccharide monooxygenases (LPMOs) mediated production of ultra-fine cellulose nanofibres from delignified softwood fibres. Nanocellulose is an amazing material – it has the strength of steel if you prepare it correctly, and it can be made from waste wood and paper! The conventional processes for making nanocellulose use a lot of nasty chemicals, which we should move away from. This study showed how a single enzyme can be used to make nanocellulose from softwood, in very mild, energy-efficient reaction conditions.

Production of functionalised chitins assisted by fungal lytic polysaccharide monooxygenase. Chitin is a natural polymer found in shellfish and fungi that has great material properties and even bioactive properties, like inhibiting bacterial growth. We described a new enzyme that lets us make functional chitin with nanoscale dimensions while avoiding using the nasty chemicals that are typically required.

A GH115 α-glucuronidase from Schizophyllum commune contributes to the synergistic enzymatic deconstruction of softwood glucuronoarabinoxylan. Industrial utilisation of biomass for the production of fuel, materials, or chemicals, has to begin with separation of the biomass components. With plant biomass such as waste from the forestry and agricultural sectors, this is a very tricky challenge, because the biomass is so complex. We designed an enzyme cocktail allowing full deconstruction of one of the most complex carbohydrates in softwood.

A discrete genetic locus confers xyloglucan metabolism in select human gut BacteroidetesThis was a very cool study, and my first experience of publishing in a famous journal (Nature). The work attracted quite a lot of press attention when it was published. We investigated the enzymology of a human gut symbiont bacterium, and were the first to describe a complete deconstruction pathway for one polysaccharide in the gut. We focussed on xyloglucan, which is found in lettuce, tomato, and many other fruits and veg.