Category: Lab

Update on the PhD candidate evaluation

Thanks a lot to all of those who applied to the PhD position opening that closed a week ago. In total we received 59 applications, of which the vast majority were of high quality – I am sure that at least half the candidates would have made a great job in the position. However, we have to make a selection among these 59 candidates, so after reading and evaluating all 59 applications, we have now nailed down ten top candidates that we will initially move forward with. Those ten candidates should have received an e-mail today about how the process will move forward.

If you have not received an e-mail from us, the most likely explanation is that you were not among these top ten candidates (but remember to also check your spam!) In that case, you will get a follow-up once the position is filled.

Again, thanks a lot for your interest. I have been overwhelmed by the high quality and relevance of the applications.

Open PhD position

We are hiring a PhD student to work with interactions between the bacteria in human and environmental microbiomes that are important for community stability and resilience to being colonized by unwanted bacteria (including pathogens). The project seeks to unearth which environmental and genetic factors that are important determinants of bacterial invasiveness and community stability. You can read more at our Open Positions page.

We are looking for a candidate with experience with both bioinformatics and experimental microbiology. Previous experience with microbial communities is a plus, but not a must, as is work with human cell lines.

The project is fully funded by a grant from the Swedish Research Council and the position is planned for 4.5 years, with 4 years of research and course work and half a year of teaching.

If you feel that you are the right person for this position, you can apply hereWe look forward to your application! The deadline for applications is October 21.

Published paper: Temperature affects community interactions

I am very happy to announce that Emil Burman‘s (doctoral student in the lab) first first-author paper was published today in Frontiers in Microbiology. In this paper (1), we explored how temperature affected the interactions in the model microbial community THOR (2). Somewhat surprisingly, we found that even a small difference in temperature changed the community intrinsic properties (3) of this model community a lot. We furthermore find that changes in growth rates of the members of the community partially explains the changed interaction patterns, but only to some extent. Finally, we also found that biofilm production overall was much higher at lower temperatures (9-15°C) than at room temperature, and that at around 25°C and above the community formed virtually no biofilm.

The temperature range we tested is not unlikely to be encountered when incubating the community in a thermally unregulated environment. Thus, our results show that a high degree of temperature control is crucial between experiments, particularly when reproducing results across different laboratories, equipment, and personnel. This highlights the need for standards and transparency in research on microbial model communities (4).

Another important, related, aspect is that disruptive factors that discriminate against single members of the community are not unique to THOR. Instead, this is likely to be the case for other microbial model (as well as natural communities). Since only a few of these model communities have been elucidated for community behaviors outside of specific culturing conditions they were first contrived under, this may severely limit our view of interactions between microbes to specific laboratory settings. This casts some doubt on the validity of extrapolation from results obtained from microbial model communities. It seems to be important moving forward to establish that community-intrinsic behaviors in model communities are stable in the face of variable environmental conditions, such as temperature, pH, nutrient availability, and initial inoculum size.

A short backstory to this paper: this begun when Emil could not consistently replicate the results I had obtained during my postdoc (working on THOR) in Prof. Jo Handelsman’s lab at the University of Wisconsin-Madison. After a long time of troubleshooting, we realized that our lab did not hold a stable room temperature. We bought a cold incubator, and – boom – after that the expected community behavior came back. This made us realize the importance of temperature for the community-intrinsic properties of THOR, which then led to this more systematic investigation.

Great work Emil! It is nice to finally see this in its published form. Read the entire paper (open access) here!

References

  1. Burman E, Bengtsson-Palme J: Microbial community interactions are sensitive to small differences in temperature. Frontiers in Microbiology, 12, 672910 (2021). doi: 10.3389/fmicb.2021.672910
  2. Lozano GL, Bravo JI, Garavito Diago MF, Park HB, Hurley A, Peterson SB, Stabb EV, Crawford JM, Broderick NA, Handelsman J: Introducing THOR, a Model Microbiome for Genetic Dissection of Community Behavior. mBio, 10, 2, e02846-18 (2019). doi: 10.1128/mBio.02846-18
  3. Madsen JS, Sørensen SJ, Burmølle M: Bacterial social interactions and the emergence of community-intrinsic properties. Current Opinion in Microbiology 42, 104–109 (2018). doi: 10.1016/j.mib.2017.11.018
  4. Bengtsson-Palme J: Microbial model communities: To understand complexity, harness the power of simplicity. Computational and Structural Biotechnology Journal, 18, 3987-4001 (2020). doi: 10.1016/j.csbj.2020.11.043

Published paper: CAFE

We start the new year with a bang, or at least a new paper published. Bioinformatics put our paper (1) describing the software package CAFE online today (although it was accepted late last year). The CAFE package is a combination of Perl and R tools that can analyze data from paired transposon mutant sequencing experiments (2-4), generate fitness coefficients for each gene and condition, and perform appropriate statistical testing on these fitness coefficients. The paper is short, but shows that CAFE performs as good as the best competing tools (5-7) while being superior at controlling for false positives (you’ll have to dig into the supplement to find the data for that though).

Importantly, this is a collaborative effort by basically the entire research group from last spring: me, Haveela, Emil, Anna and our visiting student Adriana. A big thanks to all of you for working on this short but important paper! You can read the full paper here.

References

  1. Abramova A, Osińska A, Kunche H, Burman E, Bengtsson-Palme J (2021) CAFE: A software suite for analysis of paired-sample transposon insertion sequencing data. Bioinformatics, advance article doi: 10.1093/bioinformatics/btaa1086
  2. Chao,M.C. et al. (2016) The design and analysis of transposon insertion sequencing experiments. Nature reviews Microbiology, 14, 119–128.
  3. van Opijnen,T. and Camilli,A. (2013) Transposon insertion sequencing: a new tool for systems-level analysis of microorganisms. Nature reviews Microbiology, 11, 435–442.
  4. Goodman,A.L. et al. (2011) Identifying microbial fitness determinants by insertion sequencing using genome-wide transposon mutant libraries. Nature Protocols, 6, 1969–1980.
  5. McCoy,K.M. et al. (2017) MAGenTA: a Galaxy implemented tool for complete Tn- Seq analysis and data visualization. Bioinformatics, 33, 2781– 2783.
  6. Zhao,L. et al. (2017) TnseqDiff: identification of conditionally essential genes in transposon sequencing studies. BMC Bioinformatics, 18.
  7. Zomer,A. et al. (2012) ESSENTIALS: Software for Rapid Analysis of High Throughput Transposon Insertion Sequencing Data. PLoS ONE, 7, e43012.

Funding from the research council!

I am very happy to share the news that our starting grant application to the Swedish Research Council has been granted 3.3 million SEK of funding for four years! This is fantastic news, as it allows us to further explore the interactions between bacteria in the human microbiome that are important for community stability and resilience to being colonized by pathogens. In the granted project, we will investigate environmental and genetic factors that are important for bacterial invasiveness and community stability in the human gastrointestinal tract.

Within the scope of the project, we will establish model bacterial communities and experimental systems for the human stomach and intestine. We will then investigate how disturbances, such as antibiotic exposure, change the interactions in these microbial communities and their long-term stability. Finally, we aim to identify genes that contribute to successful bacterial colonization or resilience to invasion of established communities in the human microbiome.

Aside from myself, Prof. Sara Lindén and Dr. Kaisa Thorell from the University of Gothenburg as well as Prof. Ed Moore at the university’s Culture Collection will be involved in this project in different ways. We will also collaborate with my former postdoc supervisor Prof. Jo Handelsman as well as Dr. Ophelia Venturelli at the University of Wisconsin-Madison. Finally, we will also collaborate with Dr. Åsa Sjöling at the Karolinska Institute. I look forward to work with you all over the coming four years! A big thanks to the Swedish Research Council for believing in this research and investing in making it happen!

Two fun things

Fun things on a Friday! First of all, we have updated our lab member page with some beautiful photos! Thanks Marcus for brining your camera today!

Second, our review of factors important for antibiotic resistance development in the environment has been recognised by FEMS Microbiology Reviews as one of the papers which have made the most impact across their portfolio. It has been added to a new (well, this is old news, so semi-new) collection of papers – ‘Articles with Impact’ – many of which are very well worth a read!

Have a nice weekend!

Welcome Mahbuba, Sebastian and Marcus

The fall is here and with it comes the arrival of three new group members. This fall, we are joined by Mahbuba Lubna, Sebastian Wettersten and Marcus Wenne. All three are master students from the University of Gothenburg and they will work on very different things.

Mahbuba will work together with Emil Burman on genes responsible for invasion in microbial communities (primarily THOR), expanding on Emil’s work and testing new and existing candidate genes in a wider diversity of conditions.

Sebastian will work on improving Metaxa2, making its classifications better and also enabling even better automation of database creation. Hopefully this will increase the pace of the Metaxa2 development, which has been stagnating a bit over the last two years.

Marcus, finally, will work together with Anna Abramova on analysing antibiotic resistance in a huge metagenomic dataset previously generated in the lab.

This means that we are now seven people in the lab (so if it weren’t for the covid-associated work from home recommendations, it would start to get crowded…) We welcome our three new members and look forward to an exciting fall!

Emil Burman defends today

Emil Burman, master student in the lab, defends his master’s thesis today, titled “Biofilms, how cool are they? Effects of temperature and invasion on model microbial communities“. We wish him the best of luck today presenting this excellent work!

The Microbiology Lab Pod

As the regularly returning reader might already have seen, the lab has started podcasting! Two weeks ago, we started recording our journal clubs (on Zoom) along with some other science-related chatter. This is mostly an experiment this far, so we will see where it goes, but it was a fun an interesting experience, and I look forward to recording the next episode in May!

The experiment is called the “Microbiology Lab Pod” and can be heard on this website, on Apple podcasts, Google podcasts, Stitcher etc.

And like that, the world had changed

I guess it hasn’t passed anyone by that we are under a global lockdown (although to very different degrees – Sweden, where we’re based, has a pretty relaxed attitude to quarantining people (1), so it could be worse for us, I guess). In any case, the novel coronavirus has forced the lab to largely work from home and has upended essentially all my plans for this spring, expect for writing grant applications (which I have done a lot).

First of all, I want to thank my fellow lab members for holding out strongly in these trying times. They have consistently shown that they are the best co-workers I could ask for, and have kept calm even when anxiety hits. Thanks a lot for that. I also would like to thank the university for providing rather clear guidance on how to handle different issues that come up in these time of crisis.

With that said, I am also sad to say that there will not be a Microbiome & Probiotics Collaboration Forum in Rotterdam on May 18-20. Instead that meeting has been postponed to early December. Similarly, I will not be in Helsinki next week to talk about EMBARK. That workshop will instead, hopefully, take place on August 28. And the same story goes for the NordicMappingAMR organised by the Swedish Medical Products Agency, which will take place at a later date (I am not sure exactly when this is planned yet).

These are trying times for all of us. I hope that you stay healthy and take care of your loved ones – particularly the elderly, but not unnecessarily visiting them. My grandparents (aged 93 and 95) have started FaceTiming us, so I guess some good things come out of this mess as well. We will come out of this crisis stronger, eventually.

Footnotes

  1. There are many things I could say about the Swedish strategy regarding covid-19, but this is not really the forum. In very brief, though, I have quite some faith in that the Swedish Public Health Agency is doing a decent job. Mistakes have been made (particularly early in the pandemic) and I am slightly anxious whether the Swedish strategy will play out as well as in other countries in Northern Europe, but right now data suggest that we are doing reasonable fine. I might return to this issue in another post if time permits.