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Image by thomas heintz


Tulip Mania Leiden has started!

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Councilor Ashley North starts the Tulip Manie Leiden citizen science project by planting the first tulip bulb.

Saturday 30 October 2021, the kick-off of the Tulpenmanie Leiden project took place in the courtyard of BplusC at the Nieuwstraat in Leiden. Under the watchful eye of councilor Ashley North, children from different neighborhoods of Leiden planted the first organic Masterpeace tulip bulbs. Preparatory to that, however, the children made drawings of the tulip bulbs and sorted them by size through weighing. The difference in bulb size is expected to be reflected in the growth and blooming of the tulips in the spring. Organic tulip farmer and soil coach, John Huiberts, explained why research into the composition of soil is of great importance in tulip cultivation using no chemical pesticides. He also gave instructions on how best to plant the bulbs. Councilor Ashley North spoke enthusiastically to all those present and said that the ambition of this Tulip Mania Leiden project is to transform Leiden into one big BioScience Park.

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The bulbs are weighed and then sorted by size

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The organic tulip "Tulipa Masterpeace" is used for the Tulip Manie Leiden project.

Various activities are planned in the course of 2022, such as lectures, DNA walks, traveling exhibitions. Not only around the annual DNA day (April 25), but  during the months of March – September there will be varying exhibitions at various BplusC locations. 
Citizens can buy special Tulip Mania bags at the Hortus shop and plant tulip bulbs in their own front, facade and backyard or on the balcony. One in 25 bags is a so-called lucky bag.  In spring, not 10, but 9 red Masterpeace tulips will appear, plus one with a different color. In that case, one is the lucky winner. The Leiden Center for Applied Science/Hogeschool Leiden will use innovative DNA research to analyze the soil where this tulip grows: in this way the invisible soil life of Leiden will be mapped.

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Students Nils Ravensbergen and Frido van Rijnswou from SV Nucleus, helped make the start of Tulpenmanie a success! They offered visitors, among other things, tulip muffins.

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Organic tulip farmer and soil coach, John Huiberts, talks about the importance of growing tulips without chemical pesticides.

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The organic Masterpeace tulip bulbs.

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All children helped planting the bulbs.

Everyone will be able to follow the growth and blooming of the tulips in the spring of 2022. On April 25, 2022, World DNA Day, Arjen Speksnijder, lecturer in metagenomics (Leiden University of Applied Sciences/Naturalis), will give a lecture on biodiversity and DNA at BplusC to provide further background information on this citizen science project.
The first results of the soil analysis of the above-mentioned citizen science project are expected in July.

Photos: Esmee van de Berg, SV Nucleus

The "Jaar van de Tuin" has broadcast the opening of Tulip Mania Leiden!
The clip starts at 11:15

Citizen Science Winners

In the spring of 2022, several participants in the citizen science project presented a photo of the blossoming Masterpeace Tulipa tulips with among them a white tulip! At the end of the flowering season, samples were taken around the tulip bulbs in the winners' gardens. 

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Photo of one of the winning gardens in the citizen science project.

Sampling the soil after blooming

At the end of April 2022, samples were taken from the soil around the faded tulip bulbs from both the winners of the citizen science project (in the gardens where a white tulip grew next to the red tulips) and from all  the Tulip Mania tubs at the Hortus. All the DNA was isolated from these samples and all microorganisms were mapped using metagenomics. The analyses were carried out by the LCAB (Leiden Centre of Applied Sciences).


Arjen Speksnijder and LCAB student Isa Wormsbecher take samples from the planters  in the Hortus.

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Samples were taken in the gardens of the winning participants.


The samples are placed in bags and the tulips are measured.


Student Isa Wormbecher of the LCAB isolates all DNA from the soil samples.


The importance of life in the soil

The microorganisms in the soil are 'the factory of life', they process organic waste to sustain life above ground, from plants to animals to humans. They regulate the capture and release of carbon and water; They keep pests under control and help decontaminate polluted land. While other vital resources such as water and air are constantly recycled and regenerated, soil formation can take tens of years, even centuries.

How do you research life in the soil?

The biodiversity in the soil has a major influence on what can live above the ground. When biodiversity declines (due to the use of chemical pesticides or prolonged droughts), it is extremely difficult to restore soil life. For a long time, it was difficult to determine which microorganisms live in the soil. Recently, this has become easier with new DNA techniques, namely with the so-called MinION. With new knowledge of soil life, biological solutions can be devised and applied to solve problems related to the conservation of biodiversity.

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DNA helix

The DNA alphabet consists of 4 letters: A,C,G en T.

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Sanger sequencing

The old way to map DNA: DNA is cut up into little pieces and  separated on a gel by electrophoresis.

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New test to read DNA: MinION sequencing

The MinION technique makes it possible to read DNA in a new compact way. The DNA molecule is pulled into a super USB stick through a small pore or kind of buttonhole. The DNA letters can be read or determined by measuring the electrical resistance in the pore. This technique was developed by Oxford Nanopore Technologies and is being further developed by the University of Applied Sciences Leiden / LCAB (Leiden Centre of Applied Sciences) to make it easier to apply in analyses of soil samples.


Results Metagenomics

At the end of April 2022, samples were taken from the soil around the faded tulip bulbs from the winners of the citizen science project (in the gardens where a white tulip grew next to the red tulips). All the DNA was isolated from these samples and all microorganisms were mapped using metagenomics. The analyses were carried out by the LCAB (Leiden Centre of Applied Sciences)

Sites of the winning gardens with the flowering Tulipa Masterpeace tulips in Leiden where soil samples were taken for innovative DNA research. The gardens are spread over a large area in Leiden (plus a garden in Zoetermeer).

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The first measurements of bacteria and fungi in the soil samples show differences in the number and type of species. In a small soil sample, hundreds to more than a thousand species have been found! In most soil samples, these mainly consists of all kinds of bacteria, but the ratio of bacteria to fungi can vary. This first inventory of bacteria and fungi at various locations in Leiden can be regarded as the first 'baseline measurement'.

Resultaten Metagenomics
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