Mumame – Quantifying mutations in metagenomes
Let me get straight to something somewhat besides the point here: summer students can achieve amazing things! One such student I had the pleasure to work with this summer is Shruthi Magesh, and a preprint based on work she did with me at the Wisconsin Institute for Discovery this summer just got published on bioRxiv (1). The preprint describes a software tool called Mumame, which uses database information on mutations in DNA or protein sequences to search metagenomic datasets and quantifies the relative proportion of resistance mutations over wild type sequences.
In the preprint (1), we first of all show that Mumame works on amplicon data where we already knew the true outcome (2). Second, we show that we can detect differences in mutation frequencies in controlled experiments (2,3). Lastly, we use the tool to gain some further information about resistance patterns in sediments from polluted environments in India (4,5). Together these analyses show that one of the most central aspects for Mumame to be able to find mutations is having a very high number of sequenced reads in all libraries (preferably more than 50 million per library), because these mutations are generally rare – even in polluted environments and microcosms exposed to antibiotics. We expect Mumame to be a useful addition to metagenomic studies of e.g. antibiotic resistance, and to increase the detail by which metagenomes can be screened for phenotypically important differences.
While I did write the code for the software (with a lot of input from Viktor Jonsson, who also is a coauthor on the preprint, on the statistical analysis), Shruthi did the software testing and evaluations, and the paper would not have been possible hadn’t she wanted a bioinformatic summer project related to metagenomics, aside from her laboratory work. The resulting preprint is available from bioRxiv and the Mumame software is freely available from this site.
References
- Magesh S, Jonsson V, Bengtsson-Palme J: Quantifying point-mutations in metagenomic data. bioRxiv, 438572 (2018). doi: 10.1101/438572 [Link]
- Kraupner N, Ebmeyer S, Bengtsson-Palme J, Fick J, Kristiansson E, Flach C-F, Larsson DGJ: Selective concentration for ciprofloxacin in Escherichia coli grown in complex aquatic bacterial biofilms. Environment International, 116, 255–268 (2018). doi: 10.1016/j.envint.2018.04.029 [Paper link]
- Lundström S, Östman M, Bengtsson-Palme J, Rutgersson C, Thoudal M, Sircar T, Blanck H, Eriksson KM, Tysklind M, Flach C-F, Larsson DGJ: Minimal selective concentrations of tetracycline in complex aquatic bacterial biofilms. Science of the Total Environment, 553, 587–595 (2016). doi: 10.1016/j.scitotenv.2016.02.103 [Paper link]
- Bengtsson-Palme J, Boulund F, Fick J, Kristiansson E, Larsson DGJ: Shotgun metagenomics reveals a wide array of antibiotic resistance genes and mobile elements in a polluted lake in India. Frontiers in Microbiology, 5, 648 (2014). doi: 10.3389/fmicb.2014.00648 [Paper link]
- Kristiansson E, Fick J, Janzon A, Grabic R, Rutgersson C, Weijdegård B, Söderström H, Larsson DGJ: Pyrosequencing of antibiotic-contaminated river sediments reveals high levels of resistance and gene transfer elements. PLoS ONE, Volume 6, e17038 (2011). doi:10.1371/journal.pone.0017038.
The Wisconsin Blog is on again
I’ve been having a very intense start of the year with the move to the US and getting the family accustomed to Madison (which has taken time and energy, but gone really well). I just wanted to make you aware of that I have started posting at the Wisconsin Blog again and hope to be sharing research related stuff from my year in the US there. For more personal stuff, our family has set up a blog (in Swedish) at this address: https://palmeiamerikat.blogspot.com. You are very welcome to follow our adventure there!
Leaving Madison
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Something to live up to
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Around the biochemistry building of the University of Wisconsin-Madison campus (and perhaps also elsewhere), there are a lot of these signs, highlighting discoveries that were made in Madison. And they really have a history to be proud of. This place is where both bacterial conjugation and transduction was discovered, paving the way for much of the genome editing and studies we take for granted today. And they also did the basics required to generate knock-out mice for genetics studies. I could go on, but I I think I made my point. This place has a lost of history. And I doubt that my slightly messy project will live up to these groundbreaking discoveries.
Farmers Market
The rest of the day I spent walking around by the Lake Monona and Lake Wingra, taking a break for a coffee at Colectivo Coffee. Very nice place with excellent pourovers. But now my feet hurts and I need to get some sleep!
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Students are coming back
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Back in Madison
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Madison is beautiful
Today I spent some time walking in the other direction from the University. Gabriel suggested I took the walk by Lake Mendota downtown, and that was a really nice walk through the forest, just by the lake. After dinner, I had ice cream on one of the landings on the picture. Madison is really a nice and beautiful city; I look forward to going here with my family next year.
Tomorrow, I am in for a six hours drive to Lansing and the EDAR conference. I hope to be writing a little about my thoughts on the conference as well, but we’ll see if I will have time to get around to that…
The Wisconsin Blog
I just wanted to notify anyone who might be interested in following my more personal reflections on my month in Wisconsin (and in Michigan over EDAR4) that I will be updating my Wisconsin Blog at this site (hopefully) regularly. The blog updates are not visible on the first page, so you will have to actively go to the Wisconsin Blog page by clicking in the upper right of the page.
My first day in Madison