Aarhus Universitets segl

Specialeemner i Mikroorganismer i miljøet


Microbial Biotechnology:

Cold-active enzymes from Arctic microorganisms for the Green Transition.

In many industrial processes, enzymes are attractive, green alternatives to chemicals. Today, enzymes are key ingredients in many products like food, textiles, pharmaceuticals, and detergents, and the enzyme market for detergents alone has become a multibillion dollar industry worldwide.

A major goal of the green transition strategy is CO2 reduction, which requires energy savings throughout society. A significant contribution to this goal will be a reduction of washing temperatures from current levels of 30-60°C down to 5-20°C. This can save up to 25.5 billion kWh/year in Europe, which in terms of CO2 emission equals approx. 18 million tons of CO2 yearly, corresponding to the annual emissions of 4 million cars.

For decades, it has been a goal for producers of detergent enzymes to develop cold-active enzymes due to their performance at low-temperature resulting in significant reduction in energy consumption and costs. However, the so-called cold-active detergent enzymes on the market today cannot be classified as truly cold-active, as their optimal activity is at temperatures above 30°C.

So, in order to achieve this reduction, truly cold-active enzymes for detergents are urgently needed to make washing efficient at low temperatures. The use of cold, but effective washes in households across Europe will be symbolic of the transition from more wasteful technologies and practices to greener and more sustainable ways of living.

Development of cold-active enzymes is currently approached in two ways: 1) Protein engineering of well-known commercial mesophilic enzymes or 2) to search for new truly cold-active enzymes in microorganisms from permanently cold environments.

The focus of this project is discovery of novel, truly cold-active enzymes. Besides being cold-active, enzymes for detergents also need to be active at high pH due to detergent pH (most often ≥ pH 9). The combination of low temperature and high pH is rare among natural environments, which limits the search for novel enzymes with both traits. However, one such environment exists, namely the ikaite columns in the Ikka Fjord in South Greenland.

The project will be a part of an ongoing project, ColdZymes, funded by DFF. Depending on the duration of the student project and personal interests, the student will be able to take part in one or more of the projects or tasks described below. 

The aim of either project is to identify and characterize detergent-relevant enzymes, which are active at low temperatures and high pH.

Project 1: Function-based screening for novel enzymes

In project 1, several microbiological and biotechnological techniques will be used.


  • Culturing of microorganisms on substrates mimicking the ikaite-environment
  • Screening for novel enzymes using chromogenic substrates
  • Characterization of microorganisms and enzymes
  • Genomic analyses of cultured bacteria for identification of enzyme encoding genes
  • Cloning and characterization of enzyme encoding genes (sequencing, genomics, bioinformatics).
  • Heterologous expression, purification and characterization of enzymes

Project 2: Sequence-based screening for novel enzymes

Project 2 is mainly a bioinformatics project, but biotechnological techniques can be brought into play.


  • Isolation of environmental DNA from the ikaite columns
  • Preparation of libraries for sequencing
  • Genomic and metagenomic sequence analysis
  • Cloning and characterization of enzyme encoding genes
  • Heterologous expression, purification and characterization of enzymes

 Supervisors: Mariane Schmidt Thøgersen (Scientist, microbiology and biotechnology), mst@envs.au.dk and Thanassis Zervas (PostDoc, bioinformatics), az@envs.au.dk  

- April 2022

Microbial Biotechnology:

Enzymes degrading algal polysaccharide for pharmaceutical applications.

Marine polysaccharides like agar, carrageenan, fucoidan, and ulvan are extracted from a range of different species of macroalgae. As opposed to polysaccharides from land plants (e.g. cellulose, xylan, and pectin), the marine polysaccharides are sulfated, i.e. several saccharides in the chain carries a sulfate-group.

These polysaccharides have unique functional features like gelling, thickening, stabilizing, binding, and emulsifying effects of food.

However, recently it has been shown that marine polysaccharides (n>10) and in particular their corresponding oligosaccharides (n=2-9) possess pharmaceutical functionalities like anti-cancer, anti-viral, anti-microbial, and immune stimulating activities. Therefore, enzymes that are able to degrade polysaccharides to oligosaccharides are of great interest to academia as well as to the pharmaceutical industry.

The aim of this project is to isolate and characterize novel, marine microorganisms and enzymes that degrade polysaccharides from macroalgae.

Marine microorganisms will be isolated from macroalgae and screened for their ability to hydrolyze polysaccharides like fucoidan (from brown algae), agar, carrageenan, and furcellaran (from red algae) and/or ulvan (from green algae). The microorganisms will be characterized with respect to functionality, genetics, and ability to produce enzymes of interest.

Several microbiological and biotechnological techniques can be applied in the project.


  • Functional screening for novel enzymes
  • Characterization of microorganisms and enzymes
  • Genomic and metagenomic analyses for identification of enzyme encoding genes and gene clusters
  • Cloning and characterization of enzyme encoding genes (sequencing, genomics, bioinformatics).
  • Heterologous expression, purification, and characterization of enzymes

Depending on the duration of the project and personal interests, the student will be able to affect how the project is formed and which methods will be used.   

Supervisors: Peter Stougaard (Professor), pst@envs.au.dk and Mariane Schmidt Thøgersen (Scientist), mst@envs.au.dk

- April 2022