How new yeast species are inspiring a revolution in brewing

by Kristoffer Krogerus

Lager beers – sometimes crisp & light pilsners, sometimes dark & malty doppelbocks, have a common denominator: They are all produced using the lager yeast Saccharomyces pastorianus, the workhorse of the lager brewing industry. This yeast is known for its tolerance to lower temperatures, and brewers take advantage of this when producing lager beers.

These beers typically have a ‘clean’ flavour profile (i.e. lack of yeast character) you see, and by fermenting the beer at colder temperatures, the yeast produces less flavour-active by-products.

Blog Image 5

Recent analysis of lager brewing yeast genomes has revealed that the many hundreds of strains used in the brewing industry are, in fact, all closely related – more like multiple variants of the same strain than individual strains. Brewers have essentially been using the same strain to brew lager beers for probably 500 years. This is in stark contrast to the other fermented beverage industries, ale, whiskey, wine, cider and so on, where a rich and diverse collection of individual yeast strains is taken for granted.

Therefore, there is huge potential for introducing diversity into the lager brewing industry by generating new strains of lager yeast.

But before one can create new lager yeast it is important to understand what exactly the lager yeast is…

It has been known for some time that lager yeast is actually a hybrid species – more like a mule than the proverbial workhorse. It was clear that one parent was the well-known ale yeast Saccharomyces cerevisiae. It wasn’t until recently that the other side of the family, Saccharomyces eubayanus, was discovered. This discovery has allowed for the improved characterization of lager yeasts, and also opened up the possibility to create new tailor-made lager yeast strains. This is possible through mating of selected strains from the two parent species. These new strains could, e.g. produce unique flavours or ferment the beer more efficiently.

This is exactly what has been the focus of our ongoing research projects at VTT.

Blog Image 3The research team. From left to right: Brian Gibson, Kristoffer Krogerus, Virve Vidgren and Frederico Magalhães in VTT’s pilot brewery.

Screening perfect parents to mate

There are four main challenges in generating new lager yeasts: To select suitable parent strains. To get the parents to mate. To separate the hybrid cells from the parents. And finally, to confirm that they actually are hybrids.

We began by screening a range of ale yeast strains, from both VTT’s Culture Collection and commercial yeast suppliers, for beneficial fermentation properties. Once suitable parent ale yeast strains had been identified, the next step was to try to mate them with a strain of S. eubayanus, the other parent of lager yeast.

Before mating, the parent strains still had to be modified with selection markers, so that any hybrid cells could be isolated from the population. We did this by selecting spontaneous auxotrophic mutants of the parent strains, i.e. cells that weren’t able to grow on media lacking certain amino acids. This meant the hybrid cells could be selected by their ability to grow on media lacking these certain amino acids. Mating was then attempted by simply mixing populations of both parent strains, and letting them grow for a couple of days.

After isolating some potential hybrid cells, their hybrid status was confirmed through various PCR tests, which showed whether DNA from both parent strains was present in them. After confirmation that we had produced our own lager yeast hybrids, we wanted to compare them to the parent strains in an actual wort fermentation.

To our pleasant surprise, all hybrid strains performed better than both parent strains, fermenting faster and reaching higher ethanol contents!

The hybrid strains also inherited beneficial properties from both parent strains, such as strong flocculation, cold tolerance and maltotriose utilization.

These first results suggest that this technique is suitable for producing new lager yeast strains with unique properties. These new strains also have the benefit of being non-GMO, which currently at least remains a necessity for brewers.

We are continuing our attempts to find and create perfect lager yeast hybrids at VTT. Our research will especially pay attention to flavour formation and determining how their genetic composition is reflected in their physiology.

Our work will show, for the first time, that such hybrids can be created and how they can be applied in the brewing industry. The results will appear shortly in the Journal of Industrial Microbiology and Biotechology: Krogerus, K., Magalhães, F., Vidgren, V. & Gibson, B. (2015) New lager yeast strains generated by interspecific hybridization. Journal of Industrial Microbiology and Biotechnology, in press. DOI:10.1007/s10295-015-1597-6.

Maybe someday also you have an opportunity to enjoy these new tasty lager beers in your local pub. Cheers!

Blog Image 2

The author Kristoffer Krogerus is first-year PhD student working at VTT Industrial Biotechnology. His supervisor Dr. Brian Gibson is Senior scientist and project manager with responsibility for projects relating to brewing yeast physiology and fermentation.

 

ext-kristoffer.krogerus@vtt.fi , brian.gibson@vtt.fi

www-pages of VTT’s brewing yest development

 

Natural beauty preserved in plant cells

by Liisa Nohynek

VTT

Although the darkest time of the year is already behind us in Finland, it is still a long way to summer. At this time of year Nature´s colour palette consists mainly of different shades of grey. However, we at VTT have preserved our Finnish natural plants as plant cell cultures, which delight us with their colours all year round.

Berry plant cell cultures originating from plants that grew under the midnight sun last summer are now glowing in our culturing rooms with bright colours: yellow and different shades of red, pink and purple. The flavour of our bilberry cell culture reminds us of fresh berries.

The colourful cultures do not exist only for our own joy, but are created to be used in a wide variety of applications, particularly cosmetics. Plants and their extracts are the source of a huge variety of chemicals, and have been used for promoting skin health and beauty since ancient times.

Some of the leading global cosmetic companies have recently launched products with biotechnologically produced plant cells for novel applications exploiting the rich variety of plant-derived chemicals. This activity ensues from general global trends followed by the beauty business, such as the demand for natural, ecological and chemically safe products while exploiting the latest technological methods and tools. The use of plant cell cultures instead of entire plants in cosmetic products follows these trends, and helps protect endangered natural plant species from overexploitation.

Arctic bramble, crowberry and cloudberry

We have joined in the front line of this research area and are maintaining a strong infrastructure and knowhow on plant cell culture technology. Our special interest is in Nordic plants, such as arctic bramble (Rubus arcticus), crowberry (Empetrum nigrum) and cloudberry (Rubus chamaemorus).

We cover the whole field of biotechnological processes, starting from establishment of plant cell cultures from pieces of natural plants and ending up in industrial scale production protocols for plant cells. Cultured plant cells are totipotent having the capacity to develop into any organ of the plant. However, when treated with plant growth regulators the cells multiply continuously, producing biomass consisting of identical, undifferentiated cells. In addition to the ecological advantages of this technology, the industry avoids the significant problem of plant raw material availability. The cell cultures can be sustainably generated all year round with consistent chemical quality, and production of chemically and microbiologically safe plant-based material can be ensured.

Specific cocktails of compounds in Nordic plants

The natural conditions in Northern Scandinavia are harsh, and therefore demand special properties of plant species in order for them to survive the long, cold winter and to grow and breed during the summer. A thousand years of adaptation to the short, fickle Nordic summers full of light has resulted in the development of plants with a specific cocktail of compounds protecting them from abundant UV-light, cold nights, insect and microbe attacks, and wet snow in the middle of the summer season. The genotypically expressed desired chemical compounds present in natural plants can be generated in their cell cultures.

Selected plant cell cultures contain nutritionally valuable compounds, such as omega-3 and omega-6 fatty acids, flavours and pigments, and may exhibit antimicrobial and antioxidant activities with special relevance for human skin health and beauty. For example the purple to dark-red coloured anthocyanins protecting bilberry skins against UV–light and harmful microbes have a potentially similar effect on human skin.

The chemical composition of plant cell cultures is still only partially explored

Novel bioactive compounds are continuously searched by cosmetic companies for skin care and make-up products. Plant cell culture technology, including the cultivation of less well-known plant species as well as modification of plant cell cultures with elicitors and precursors, also has the potential to respond to this need – even in the middle of the dark and freezing Nordic winter.

Liisa NohynekThe author Dr. Liisa Nohynek, Senior Research Scientist, PhD in microbiology, has special expertise in plant cell culture technology. She has extensive experience on plant bioactive compounds, especially in Nordic berries and berry cell cultures. She is also experienced in scaling-up processes enabling production of plant cell biomass with bioactivities for industrial applications. liisa.nohynek@vtt.fi

Welcome to read the new VTT Industrial Biotechnology Blog

 

The purpose of this blog is to give information on our R&D activities and share innovative topics in the field of industrial biotechnology.  We are welcoming all readers – especially our current and new industrial and academic collaborators.

The world is facing big challenges: By 2030 we need 50% more food, 45% more energy, and 30% more water. In addition, due to the climate change, usage of non-renewable fossil resources should be limited. Therefore, more sustainable ways for the production of energy, chemicals and materials are needed.

At VTT, we are tackling these challenges by developing sustainable technologies and processes based on biotechnology and our Cell Factory concept.

A variety of technologies makes it possible to face the future challenges

Our core competence is to develop yeast, photosynthetic microbes, fungal and plant cells for production of proteins, enzymes, biofuels, biomaterials and chemicals. We apply synthetic and systems biology, protein engineering, plant biotechnology, production physiology research and automation to achieve optimal, sustainable processes for different products.

From gene discovery to piloting

We offer our clients the whole chain from gene discovery and production strain development up to piloting the bioprocess.

Since our R&D activities cover widely the different fields of biotechnology, the scope of the blog posts will cover anything between protein discovery to optimization of e.g. beer brewing. The common theme of our posts is development of an efficient and sustainable production technologies.

We hope you enjoy our blog posts! Please, join the discussion, give us feedback and pose questions.

 

Kirsi-Marja Oksman-Caldentey                            Timo Pulli

Head of Research Area                                        Research Team Leader, Blog Editor

More information  about us can be found in VTT Industrial Biotechnology www-pages.

VTT. Kirsi-Marja Oksman-Calentey.Dr. Kirsi-Marja Oksman-Caldentey is heading VTT’s Industrial Biotechnology research area with 90+ research scientists and technicians. She is pharmacist by education, and she has worked both in industry and academia before coming to VTT 17 years ago. Her own scientific interest is in plant biotechnology understanding the complex biosynthetic pathways in plants leading to highly complex molecules, and how one can engineer their biosynthesis in cultivated plant cell systems towards biotechnological applications.

kirsi-marja.oksman@vtt.fi

 

 

IMG_0546Dr. Timo Pulli is leader of the Protein Discovery and Engineering team in VTT Industrial Biotechnology research area. He has wide experience in R&D, business development, and commercialization of life science related technologies. His team develops enzymes and other proteins for various applications.

timo.pulli@vtt.fi