Internships

General information on internships

Students can do various types of projects in our lab. We supervise bachelor and master internship projects but you can also find supervisors for your literature thesis. Practical internships can be in the wetlab (here termed experimental) , can be computational (here termed theorical) or can consist of a combination of those two.  All of them qualify as ‘research internships’ in virtually all of the study programmes.

Below is a list of projects that we thought of. If you are interested in one, just contact the person that is associated to that project. But there are options beyond this list. Check the Team page and click on the different team members to see their lines of research. If you are interested in a specific topic that we work on, but do not see an internship within that project listed below, just contact the team member and check for the possibilities. This is especially relevant if you are looking for a literature thesis project – these are usually tailor-made based on your interests.

If you have general questions about internships in our department see the contact information at the end of the page

Currently available


Project titleType of researchSupervisor(s)
Bioremediation of oil contaminated mangrove forestsExperimental (Master)Paul Iturbe Espinoza
p.iturbeespinoza@vu.nl
Shell uses land farming to clean up sites impacted by oil spills. Land farming reduces the concentration of petroleum constituents present in soils through processes associated with bioremediation. In sensitive ecosystems, such as mangroves, traditional remediation methodologies such as land farming can be particularly difficult due the soft ground conditions and sensitive nature of vegetation. In those types of environments, removal of surficial oil and gentle flushing of sediments to remove free oil can be effective in reducing oil concentrations. Any residual oil is further reduced by biodegradation to a level where mangrove vegetation can recover. The rate at which the biodegradation occurs is an important factor in the restoration of the mangrove ecosystem but relatively few data are available on this. Also, while it is widely acknowledged that microorganisms play an important role in the breakdown, linking rates to microbial community composition and other abiotic factors is very hard.

The objective of this MSc research project is to increase the understanding biodegradation processes in mangroves, both in terms of kinetics, involved micro-organisms and contributing abiotic factors. Shell can provide soil samples which will span a range of severity and type of oil contamination (fresh versus weathered) which can be used in experiments. It is envisaged that the student will develop a work plan based on a comprehensive literature study on this topic. Laboratory experiments can be used to establish laboratory estimates of the rate of biodegradation which can be combined with microbial community profiling as determined by Illumina amplicon sequencing.

The project is in collaboration with the Shell Technology Centre Amsterdam.
Fundamental insight in oil-degrading microbial communities using NGSExperimental (Master)Paul Iturbe Espinoza
p.iturbeespinoza@vu.nl
The IUCN-Niger Delta Panel (IUCN-NDP) was established at the request of Shell Petroleum Development Company of Nigeria Limited (SPDC), to provide science-based recommendations for the remediation and rehabilitation of biodiversity and habitats of oil spill sites in the Niger Delta. Land farming is widely used by SPDC to clear residual oil from spillages to soil in the Niger Delta. This approach reduces the concentration of petroleum constituents present in soils through processes associated with bioremediation. It is proposed by the IUCN that the use of bio surfactants, enzymes and sorbents can improve the effectiveness of this treatment. SPDC is planning to perform comparative pilot scale testing in Nigeria to determine the relative efficacy of the IUCN-NDP recommended remediation agents. It is anticipated that the tests will be performed in fully contained bio cells. The success of soil remediation by land farming is generally dependent on availability of nutrients and oxygen within the system plus the ability to overcome some of the mass transfer issues associated with hydrocarbon biodegradation. Consequently, the effects of oxygen, nutrients mass transfer will also be incorporated into the test plan in order to gain a better understanding of what influences efficient biodegradation in Nigeria soils. The experiment will test the effectiveness of the following factors on remediation success:

Nutrients (Agricultural Fertilizer), (Bio)surfactants, Enzyme products, Natural Sorbents, Tilling (oxygen and mass transfer)

The IUCN have commented that the success of remediation maybe dependent on the composition of the indigenous microbial community within the soil as determined by Illumina amplicon sequencing. Therefore, we would like to understand if and how microbial communities differ during treatment with various forms of remediation agent. The size and scope and specific objectives of the study can be discussed in more detail if you are interested developing a project. The project is in collaboration with the Shell Technology Centre Amsterdam.
Building a genome scale metabolic model for the fission yeast S. pombe Theoretical (Master)Johan van Heerden
j.van.heerden@vu.nl
&
Eunice van Pelt-Kleinjan
e.van.pelt-kleinjan@vu.nl
Background
The two distantly related yeast species, Saccharomyces cerevisiae and Schizosaccharomyces pombe, have been instrumental in our current understanding of the eukaryotic cell and its processes. Much of what we know about the cell cycle and its regulation was borne from pioneering studies with S. pombe, while S. cerevisiae has been a favourite workhorse in studies on eukaryotic metabolism (especially central carbon metabolism) and textbooks on this subject are therefore filled with insights derived from this organism.

While the cell-cycle field has embraced S. cerevisiae as a complementary eukaryotic model, researchers with a focus on metabolism have yet to harvest the potential insights to be gained from systematic (and comparative) studies of S. pombe metabolism. Today, the majority of research on S. pombe is still dedicated to unraveling cell cycle regulation and other cellular functions such as DNA repair, maintenance and aging, with very little fundamental research on the central metabolism of this yeast.

While there are many similarities between these two species, there are also several important differences including: cell morphology, the mode of cell division, the position of cell-size checkpoints during cell-cycle progression, the role of glucose sensors, the ability to respire ethanol, the presence of a glyoxylate cycle and differences in mitochondrial functions.

As many of the differences between these two species pertain to metabolic functions, a better understanding of the metabolic profile of S. pombe should serve to greatly expand our compendium of knowledge on eukaryotic metabolism, beyond that of S. cerevisiae and cancer cell lines.

Method
In this project you will build a new genome-scale metabolic model (GSMM) using software developed in our group, MetaDraft. This will enable the construction of a draft genome-scale model based only on a sequenced genome and a curated database of template models.

Outcome
You will use this GSMM model to predict the ability of S. pombe to produce biomass (i.e. to grow) on various carbon substrates. These predicitons can then be compared to existing and new experimental data, to improve and validate the model.

It is expected that this work will lead to a functional GSMM that will provide a valuable asset to the burgeoning field of S. pombe metabolic studies.

Duration of project: 5 months

Your CV: Ideally you will have a theoretical background and programming experience (preferably Python or Matlab).

Start date: May 2017 or later.
How does soluble adenylyl cyclase regulate the Warburg effect in liver cancer cells?Modelling (Master)Jurgen Haanstra
j.r.haanstra[at]vu.nl and Bas Teusink
It is generally established that most cancer cells have a different metabolic programming than primary tissue cells. In general, tumor cells perform “aerobic glycolysis” which means that they metabolize glucose by a high rate of glycolysis and subsequent fermentation into lactate, but with very limited further oxidative metabolism in the citric acid cycle. This phenomenon is called the Warburg effect. Although much research has been dedicated to the Warburg effect and several targets have been proposed, the overall mechanism remains poorly understood.
Colleagues at the AMC/Tijtgat institute have recently found that soluble adenylyl cyclase (sAC) plays an important regulatory role in the choice for aerobic glycolysis. Although sAC is the evolutionary most ancient adenylyl cyclase in mammals, it has been studied much less intensely than the transmembrane adenyl cyclases which are regulated by G-proteins. In contrast to these, sAC was found to be activated by HCO3- and also by its substrate ATP, which makes sAC an exquisite metabolic sensor.
Inhibition (or knockdown) of sAC in in several cancer cell lines enhances lactate formation and decreases oxidative glucose metabolism, thereby aggravating the Warburg effect. The exact target(s) of sAC in energy metabolism remain to be identified, but its activity affects glycolysis, the pentose phosphate pathway and glycogen homeostasis.
The goal of this project is to identify possible metabolic targets of sAC action in the human hepatoma cell line HepG2 cells. You will do this by using (and expanding) existing kinetic models of HepG2/ hepatocyte metabolism as well as core models of metabolism. With these models you will investigate whether and how metabolic regulation can explain the measured changes in metabolite concentrations after sAC inhibition (or knockdown).
Can CRISPR evolution be used to trace bacterial pathogens in food?
Theoretical (Master)Douwe Molenaar
d.molenaar[at]vu.nl and Indra Bergval (RIVM)
Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) genes are present in the genomes of many bacteria (~ 40%) and Archaea (~ 90%) and together form an adaptive microbial immune system. A typical CRISPR cassette consists of two or more direct repeat-spacer units, where the spacer sequences are mainly active against foreign DNA, such as bacteriophages and plasmids. If the cell is infected with foreign DNA and it is recognized by the CRISPR-Cas immune system, the foreign DNA is selectively degraded so that it can not be incorporated into the genome. Every time the cell is threatened with new foreign DNA, a new, unique direct repeat-spacer unit is built into the CRISPR cassette. The sequences of a CRISPR array in a bacterial genome are therefore subject to rapid evolution, which offers the possibility to use this system for typing purposes. For some bacteria, such as Mycobacterium tuberculosis, this happens routinely.
Typing pathogenic bacteria is important because it contributes to the determination of the origin/source in the event of an outbreak, to identification of transmission patterns in long-term epidemics and to the identification of certain characteristics such as virulence or resistance to specific genotypes of a certain pathogen.
In the case of food-related infections, it is particularly important to determine the source of the contamination as quickly as possible, so that targeted and effective measures can be taken or policy can be made if structural infections are involved. The increasing accessibility of whole genome sequencing technologies has made a significant contribution to the possibility of source attribution. To further investigate this information and to see whether we can specify the source attribution, we want to analyse the diversity and evolution of CRISPR arrays in specific food-related bacterial pathogens (Salmonella, Listeria, Shiga-toxin producing E. coli) throughout the food production chain ("farm to fork").

Activities within this project:

  • Development of a bioinformatics pipeline (in Python, for example) to automate the quantification and identification of CRISPR arrays from the main bacterial pathogens

  • Validation of the methodology to be developed

  • Analysis, using the developed scripts, of selected data collections (NGS data) that represent specific aspects of the food production chain.

  • Analysis of the spacer sequences: i.e. can they be used to determine which bacteriophage populations the bacterial strain has been in contact with, and thus what the source of a contamination is?


You will work closely together with Angela van Hoek, Michael Visser and Indra Bergval at the Centrum voor Infectieziektenbestrijding at RIVM, the dutch authority for control of infectious diseases.
Defining macrophage immunometabolism through omics data analysis
Background
Theoretical (Master)Jan vd Bossche,
Douwe Molenaar d.molenaar[at]vu.nl
Macrophages are innate immune cells that phagocytose and kill microbes. Although these are key features,
Macrophages are innate immune cell that are functionally very multifaceted and are involved in almost all aspects of life; from immunity and host defense, to homeostasis, tissue repair and development. To fulfil these distinct actions, macrophages adopt a plethora of polarization states. Understanding their regulation and phenotypic heterogeneity is crucial because macrophages are critical in many diseases and have emerged as attractive targets for therapy of cancer, atherosclerosis, asthma and many more “Western” killers.
We recently demonstrated the crucial role of metabolic reprogramming in distinct macrophage activation cues. LPS+IFNg-induced pro-inflammatory “M1” macrophages undergo metabolic rewiring, illustrated by heightened glycolysis. In contrast, IL-4-induced anti-inflammatory “M2” macrophages show and require high mitochondrial oxidative phosphorylation (OXPHOS). Thus, the way a macrophage digests its nutrients not only provides energy, but directly dictates its function.
To advance our findings to future therapeutic applications, our current knowledge now needs to be translated to the complex in vivo environment, where macrophages are exposed to a complex mixture of stimuli and don’t classify as M1 or M2. In other words, the metabolic roadmaps of non-M1/M2 macrophage subsets need to be defined in health and disease in both humans and animal models.

Method
In this project you will define the metabolic characteristics of different macrophage subsets using transcriptomics, proteomics and metabolomics data that are available online and with unique data that we generate(d) ourselves.


Outcome
Revealing the metabolic characteristics and needs of macrophages will reveal new (metabolic) targets to manipulate macrophage function and to improve disease outcome.
An optogenetic strategy to control glycolytic enzyme activityExperimental (Master)Johan van Heerden
j.van.heerden@vu.nl
Background
To make the appropriate adaptive decisions or to maintain homeostasis, cells monitor not only extracellular conditions, but also their internal metabolic state. Historically, changes in cellular physiology was considered to occur mainly in response to altered environmental conditions, but recent studies indicate that changes in metabolic fluxes can also trigger adaptations even when environmental conditions are stable. By monitoring changes in the concentrations of so called flux-sensing metabolites, cells can get information about their metabolic state, irrespective of the environmental state.

In microbes such as E. coli and S. cerevisiae, steady-state correlations between growth rate, mode of metabolism (respirations or fermentation) and certain key metabolic intermediates, have been interpreted as evidence for the existence of flux-sensing mechanisms. Particularly interesting is the possible role played by Fructose-1,6-bisphosphate (FBP).

FBP concentration correlates strongly with glycolytic flux, and several regulatory targets (allosteric and gene expression) have been described. FBP has therefore been suggested as part of the regulatory repertoire that modulates the physiological state of cells. In addition to FBP, Phosphoenolpyruvate (PEP) may be another flux-signalling metabolite. PEP mirrors the behaviour of FBP and could therefore serve to reinforce sensing of the central metabolic state.

The regulatory role played by flux-sensing metabolites have been inferred mainly from steady-state correlations, and many questions remain about the role these metabolites play in actually driving the adaptations associated with a specific physiological state and to what extent this is truly independent from the environment.

In this project we will attempt to gain further insight into the causative link between sensing of internal metabolic states and subsequent physiological adaptations to perturbations of the internal state, under constant environmental conditions. We will use an optogenetic strategy to design light-controllable variants of Phosphofructokinase (PFK) and Pyruvate kinase (PYK), which will allow for the dynamic in vivo manipulation of enzyme activities by illumination. Both these enzymes catalyse irreversible steps in glycolysis and changes in their relative activity is expected to impact the concentrations of FBP and PEP, respectively.

Using this novel strategy, we will explore the physiological adaptive responses of (single) cells to changes in their internal metabolic state, even though extracellular conditions remain unchanged.


Aims of the project
This project will have two major aims:
1) To develop light-controllable variants of Phosphofructokinase (PFK) and Pyruvate kinase (PYK), both glycolytic enzymes, using the latest optogenetic technologies
2) To assess the metabolic-adaptive responses of (single) yeast cells to PFK and PYK enzyme activity-levels modulated in real time via optogenetics

Duration
6-9 months (preferably 9 months, but the exact duration can be discussed).

Where
This project is a collaboration between the Teusink/Bruggeman group, at the Vrije Universiteit Amsterdam, and the Niopek group, at the University of Heidelberg.
The internship, therefore, offers the successful candidate the unique opportunity to spend time in both Amsterdam (The Netherlands) and Heidelberg (Germany). The first part of the project, the design and construction of light-controllable glycolytic enzymes, will be performed in Heidelberg. It is anticipated that this will take approximately 3-5 months. The second part, characterization and (single) cell experiments, will be completed in Amsterdam, and will take the remaining time 3-4 months.
Please note: The candidate will have to organize accommodation for themselves.

What we are looking for in a candidate
The ideal candidate should be motivated and up for of a challenge. Proven experience with molecular cloning techniques (PCR, digestion, ligation, transformation etc) is required and preferably some experience working with Saccharomyces cerevisiae. Experience with single cell measurement techniques, such as microscopy and flow cytometry, is a bonus, but not essential.
Microbial degradation of 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)Experimental (Master)Lan Anh Nguyen l.a.nguyenthi@vu.nl
Rob van Spanning rob.van.spanning@vu.nl
In the Vietnam War, Agent Orange was extensively used as a defoliant between 1962 and 1971. This herbicide comprises an equal mixture of 2,4-D and 2,4,5-T and also contains traces of 2,3,7,8-TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin). An estimated more than 45 million kg of 2,4-D (2,4-dichlorophenoxyacetic acid) and 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) was sprayed over South Vietnam. Containers with the herbicides were supplied to and stored in Bien Hoa, a former military airbase in southern Dong Nai province. Until today, Bien Hoa is a site with some of the highest levels of herbicides and dioxins in Vietnam. Since these compounds are hazardous to biological life, they need to be removed from the environment.
The objective of this MSc research project is to increase our understanding of natural biodegradation processes involved in 2,4-D and 2,4,5-T degradation. Laboratory experiments will be used to determine 2,4-D- and 2,4,5-T-degrading ability by bacterial communities in time. LC/ MS/ MS (liquid chromatography followed by mass spectrometric analyses) will be used to determine concentrations of the herbicides and microbial community profiling will be determined by Illumina amplicon sequencing. In addition, key genes (tfdA and catA) involved in herbicide degradation will be quantified in these succession experiments by qPCR. Results may be of importance in understanding and improvement of bioremediation processes.
Practical
- Duration approximately 6 months, starting from September 2018
- MSc Student from Biology, Biological Sciences, Environmental sciences, Molecular Ecology, preferably with some laboratory experience
- Location: Molecular Cell Biology VU Amsterdam and VAST Institute Hanoi, Vietnam
- For more information, contact Lan Anh Nguyen (l.a.nguyenthi@vu.nl) or Rob van Spanning; (rob.van.spanning@vu.nl)
The importance of efficiency and redundancy in metabolismTheoretical (Master)Daan de Groot
d.h.de.groot@vu.nl
&
Julia Lischke
j.lischke@vu.nl
Background
In static environments, the fastest growing microorganisms will be selected by evolution. Since resources are always limited, microbes should make offspring from these resources in the fastest and most efficient manner. Two papers from our group proved that this pressure will lead to the upregulation of only a small number of pathways through the metabolic network. Growth rate maximization will thus lead to a highly ordered metabolism: redundancy and complexity are minimized.

In contrast, in a series of papers, the theoretical ecologist prof. Robert Ulanowicz argued that a minimally complex (ecological) network is maximally unreliable. The professor argues that biology is inherently noisy, and that some redundancy is necessary to cope with unforeseen changes. Maximization of reliability will thus lead to a different metabolism: redundancy and complexity are maximized.

Using information theoretical concepts, Ulanowicz, quantifies the ‘order’ and the ‘redundancy’ in an ecological network, and argues that the two counteracting forces will balance natural networks in an intermediately ordered state.

Goal of the project
We would like to translate the ecological theory of Ulanowicz into a theory about metabolism. Given a metabolic network, and distribution of reaction rates through this network, we want to be able to calculate the order and redundancy. Using different theoretical approaches, we would then like to find out to what level of order the evolutionary pressure pushes cells.

What we expect
This project is very theoretical and somewhat abstract, and will therefore only fit a student with a strong theoretical background, and a seemingly unquenchable curiosity. Skills in Python or related programming languages are a plus, since code should be written to calculate the information theoretical quantities for arbitrary networks.
Do you want to study microorganisms involved in yogurt production in Copenhagen, Denmark?Theoretical (Master)Sebastian Mendoza
s.n.mendozafarias@vu.nl
&
Bas Teusink
b.teusink@vu.nl
Background
The yogurt you eat at home is usually produced from milk using batch cultures of two microorganisms: Streptococcus thermophilus and Lactobacillus bulgaricus. These microorganisms grow together in a symbiotic way, they consume the nutrients of milk and produce the compounds that make yogurt a food full of texture and flavors. The use of different strains for each of the species results in yogurts with different organoleptic properties. For example, the use of some strains produce yogurt with higher acidity

Goal of the project
The student will work in a joint project between VU Amsterdam and Chr. Hansen, an important company for the dairy industry. The project will develop at Chr Hansen which is located in Copenhagen, Denmark. In particular, the student will use the genomes of different strains as well as the organoleptic properties of the yogurt they produce to cluster the microorganisms in groups of biological and industrial relevance. The student will explore different bioinformatics techniques to cluster the strains and try to get insights about the mechanisms that govern the relationships between metabolism and organoleptic properties. It is expected that each of the clusters contains strains with similar metabolic properties. In this way, the student will be able to shed light into relevant metabolic features for yogurt production.

Duration
at least two months
Your CV
Ideally, you will have a theoretical background and programming experience (preferably Python, R or MATLAB).
Start Date
March 2019 or later
Can you predict yoghurt fermentation?
Modelling (Master)Julia Lischke
j.lischke@vu.nl
Yoghurt is an important part of nutrition and its fermentation is carried out since centuries. Though, many aspects of the microbial processes are not understood. Mainly because the fermentation needs the action of two or more microorganisms. Computational approaches to predict the influence of two microorganisms on each other are rare and yet to be developed. We use Yogurt as model process to investigate good strategies and validate our new developed computational approaches.
Yogurt fermentation is no continuous process. Once the milk is inoculated the involved Lactic Acid Bacteria can do their job undisturbed. We observed an unsynchronized growth pattern, when the two main organisms ferment the milk to Yoghurt. The aim of this master project is to use the widely accepted dynamic Flux balance analysis and adapt it to reflect and predict the behavior of yogurt producing Lactic Acid Bacteria. Challenges will be, to identify a suitable optimization function and implement a therefore suited algorithm in python to calculate the objective value.
During this project you will learn how to sophistically use linear programming, used not only in biology but also finance and sociology. You will also learn to generalize biological concepts, rephrase it in mathematical terms and implement it. Finally this should lead to an increased fundamental understanding of the cooperativity between yoghurt building microorganisms.
Back in time with Lactococcus lactisTheoretical/Computational (Master)Chrats Melkonian
c.melkonian@vu.nl
Herwig Bachmann & Douwe Molenaar
Background
Lactococcus lactis is one of the most important microorganisms used for the fermentation of cheese and buttermilk. Although L. lactis strains can be found both in dairy products and at plant material, the literature suggests that strains of dairy origin have evolved from plant isolates (van Hylckama Vlieg et al., 2006). In this project we want to find out whether humans played a role in the evolution of dairy strains.
The main metabolic activity of L. lactis is the conversion of lactose (milk sugar) to lactate and it is also involved in the formation of flavor volatiles and texture of dairy products. Such chemical changes are initiated by side products of L. Lactis metabolism and include: synthesis of volatile metabolites and exopolysaccharides, as well as proteolytic activity.
In a recent study of 43 genomes of L. lactis strains a long standing disparity about the two subspecies of Lactococus lactis was solved. (Wels, Michiel et al., 2019). The genomes also showed distinct differences between plant and dairy isolates. While suggestions that humans played a role in the evolution of dairy strains has been postulated a while ago the evidence for this hypothesis is not conclusive and needs re-evaluation.

On this project you will try to answer:
i) Did humans play a role in the evolution of L. lactis? Are the phenotypes of L. lactis dairy isolates shaped by human intervention or did dairy isolates evolve in nature and humans merely selected them for their phenotypic properties?
To achieve this, you will perform targeted phylogenetic analysis on genes of interest from a big collection of L. lactis strains. Concepts of the molecular clock will be applied and you will make comparisons with mammalian pathogens and genes specific to the relationship between mammals and microbes. Such comparisons should enable rough estimates of the time when certain strains evolved and what the possible role of humans in the evolution of L. lactis could have been.



Duration
From four months to six months
Your CV
Ideally, you have a bioinformatics background with programming experience (preferably R, Python). Experience in phylogenetics is recommended.
Start Date
September 2019 (date is flexible)

Reference
1) Johan ET van Hylckama Vlieg, et al.,Natural diversity and adaptive responses of Lactococcus lactis, Current Opinion in Biotechnology,Volume 17, Issue 2,2006,Pages 183-190,ISSN 0958-1669,https://doi.org/10.1016/j.copbio.2006.02.007
2) Wels, Michiel et al. “Comparative Genome Analysis of Lactococcus lactis Indicates Niche Adaptation and Resolves Genotype/Phenotype Disparity.” Frontiers in microbiology vol. 10 4. 31 Jan. 2019, doi:10.3389/fmicb.2019.00004
A step towards modern winemaking with Lachancea thermotoleransExperimental (Master or enthusiastic Bachelor)Chrats Melkonian
c.melkonian@vu.nl
Sebastian Mendoza & Douwe Molenaar. Lab: Marijke Wagner
Background
Archaeological evidence places the first production of wine in the Caucasus area, around 8000 years ago. From that point on, wine accompanied mankind throughout the course of history, during the rise and fall of empires and even associated with ancient gods and religions.

Although the “art” of winemaking evolved and became diverse across time, region and by what nowadays winemakers call ‘terroir’, the role of microbes on the task only recently started to unravel.
To convert grape must into wine, firstly alcoholic fermentation (AF) should be performed, a process that converts glucose and fructose mainly into ethanol and carbon dioxide. For the fulfilment of AF, Saccharomyces cerevisiae is the main candidate. Secondly, in most of the red grape varieties a malolactic fermentation is performed after the AF, where lactic acid bacteria (LAB), especially Oenococcus oeni convert malic acid into lactic acid which improves stability and flavor. Therefore, in industrial winemaking specialized strains of these microbes are used to guarantee consistency and quality of the final wines.

Because of climate-change, the sugar content in grapes could in the future reach higher levels, which may lead to undesirable high level of alcohol and lower acidity in wine. Already from the 90s, wine research explores the usage of alternative yeast strains to perform AF with Lachancea thermotolerans which has become popular among winemakers because of higher lactate and lower alcohol production rates (Mora et al., 1990). As a result of lactate production, co-inoculation cultures with S. cerevisiae produce wines with higher acidity and a higher volatile profile (Fleet, 2008; García et al., 2017; Morales et al., 2019).

On this project you will try to answer:
-What are the differences in phenotype between L. thermotolerans strains and S. cerevisiae relevant to wine making?
-How do the two species potentially interact?
-Could we use L. thermotolerans in winemaking to produce low alcohol wines and what is the best method to do so?

Duration
From four to six months
Your CV
Ideally, a master student in microbiology or food science, previous lab experience with quantification of growth dynamics and HPLC are desirable
Start Date
October 2019 (date is flexible)

References
Mora, J., Barbas, J. I., & Mulet, A. (1990). Growth of Yeast Species During the Fermentation of Musts Inoculated with Kluyveromyces thermotolerans and Saccharomyces cerevisiae. Am. J. Enol. Vitic., 41(2), 156–159. Retrieved from http://www.ajevonline.org/content/41/2/156.abstract
Fleet, G. H. (2008). Wine yeasts for the future. FEMS Yeast Research, 8(7), 979–995. https://doi.org/10.1111/j.1567-1364.2008.00427.x

García, M., Esteve-Zarzoso, B., Crespo, J., Cabellos, J. M., & Arroyo, T. (2017). Yeast Monitoring of Wine Mixed or Sequential Fermentations Made by Native Strains from D.O. "Vinos de Madrid" Using Real-Time Quantitative PCR. Frontiers in Microbiology, 8, 2520. https://doi.org/10.3389/fmicb.2017.02520

Morales, M. L., Fierro-Risco, J., Ríos-Reina, R., Ubeda, C., & Paneque, P. (2019). Influence of Saccharomyces cerevisiae and Lachancea thermotolerans co-inoculation on volatile profile in fermentations of a must with a high sugar content. Food Chemistry, 276, 427–435. https://doi.org/10.1016/J.FOODCHEM.2018.10.041
Translational toolboxTheoretical (Master)Berdien van Olst
berdien.vanolst@wur.nl
Goal
Mine bacterial genomes for obtaining various protein-coding sequence related parameters. These parameters are involved in translation efficiency. The ambition of the project is to create an automated translational toolbox to model the relationship between (publically available or generated within the project) transcriptome and proteome data for several bacterial species.

Background
Proteins are key elements in a cell. In order to produce proteins, mRNA needs to be translated. The translation process can be viewed as a semi-mechanical process in which each mRNA is processed by the same machinery. However, the correlation between mRNA and protein levels is relatively poor. Our results indicate that protein-coding sequence related parameters in combination with mRNA concentrations enable a much more accurate, multivariate model-driven prediction of the cellular proteome in Lactococcus lactis. This project aims to expand this conclusion to other bacterial species.

The project
You will create an automated genome sequence extraction toolbox. This toolbox will be linked to a translation-modelling environment that employs transcriptome (and proteome) data, which preferably will be extracted from public repository databases. However, you will also generate such combined datasets within this project. This involves growing several bacterial species, extracting RNA and proteome samples for analysis by RNA-seq and LC-MSMS pipelines, respectively. This project is a collaboration within Wageningen University between Host-Microbe Interactomics and Laboratory of Biochemistry, but also involves the Systems Bioinformatics group of Vrije Universiteit Amsterdam.

Requirements
• Background in bioinformatics
• Preferably experience in molecular microbiology
Measuring mitochondrial ATP dynamics in yeastExperimental (Master)Laura Luzia
(l.r.guilhermeluzia@vu.nl) and Dennis Botman
(d.botman@vu.nl)
Background
Adenosine 5’-triphosphate (ATP) is the universal energy currency of life. This cofactor is involved in processes such as intracellular transport, biosynthesis, growth and regulation of the central metabolism. Saccharomyces cerevisiae, a Crabtree-positive yeast, preferentially ferments glucose to ethanol and carbon dioxide, even though, in the presence of oxygen, respiration will generate a higher yield of ATP . In order to study the role of ATP in the control and regulation of yeast carbon metabolism, various methods are available that allow for intracellular quantification of this molecule. However, most methods rely on whole cell extracts, limiting the measurements to total ATP in a population of cells. In recent years, fluorescence resonance energy transfer (FRET)-based sensors have emerged as a promising technique to not only monitor metabolites such as ATP in vivo, but also in single cells. In this project, we will use a FRET-based ATP sensor to measure intracellular ATP in yeast cells. This sensor has the potential to be targeted to different cell compartments, providing a means to measure ATP levels in e.g. yeast mitochondria. This work will lay the foundation for further investigation into ATP dynamics and will contribute to a better understanding of central metabolic behaviours in the model eukaryote, S. cerevisiae.
In this project you will modify an existing cytosolic ATP sensor so that it can be targeted to the mitochondrial matrix of S. cerevisiae. In addition to the in vivo characterization of the targeted sensor, you will quantify cytosolic and mitochondrial ATP dynamics in S. cerevisiae during steady state growth and under carbon source transitions.
Ideally you will have an experimental background, with experience in molecular cloning techniques and microbial physiology.
Starting time: September 2019 or later.

Joint projects of Molecular Cell Biology and Earth Sciences for master students


For students not studying at the VU University Amsterdam

Internships are in principle open for students from other universities in the Netherlands or outside the Netherlands. We welcome for example ERASMUS students. Please note a few things:

  • We ask for a minimum stay of 4 months (3 months research, one month report writing) with a starting date outside the holiday season (July, August).
  • You have to be able to support your daily expenses (e.g. food, accommodation) and travelling to/from the Netherlands. Often, the international office at your own university can assist you in obtaining grants (e.g. ERASMUS grants). You may also check http://www.nuffic.nl/international-students/scholarships/grantfinder. Research costs will be covered by the internship project. We can help you with providing letters etc. for applications.
  • Finding accommodation in Amsterdam often takes 3 to 6 months. Erasmus students are helped via our international office in arranging accommodation in the VU hospitium in Amsterdam. Non-Erasmus students are advised to look for accommodation well in advance, in particular if you want to start in September, October or November.
  • Students from outside the EU should take into account that they may require a visa for the Netherlands, and that arranging this may also take a few months. Please check with the Dutch embassy in your country.
  • Non-Erasmus students may have to register at the faculty (this is relatively easy for students from other Dutch universities), or alternatively, require a statement of hospitability, and possibly have to pay a fee.

Contact information

If you are a non-VU student and from abroad you should contact Dr. Rob van Spanning (rob.van.spanning@vu.nl) if you want to do an internship in our group, and indicate your preferred project(s), starting date, length of internship, and how you will support yourself (costs for food, accommodation), as we are unable to support you financially.

VU students and other Dutch students can contact the putative internship supervisor directly. In case of general questions they can contact dr. Jurgen Haanstra (j.r.haanstra[at]vu.nl)