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bioRxiv · 10.1101/2021.05.25.445389

Bacterial CRISPR abundance jumps up at around 45°C

Lan, X.-R.·Liu, Z.-L.·Niu, D.-K.
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Abstract

Although performing adaptive immunity, CRISPR-Cas systems are present in only 40% of bacterial genomes. Here, we observed an abrupt transition of bacterial CRISPR-Cas abundance at around 45{degrees}C. Phylogenetic comparative analyses confirmed that the abundance correlates with growth temperature only at the temperature range around 45{degrees}C. Meanwhile, we noticed that the diversities of cellular predators have a precipitous decline at this temperature range. The grazing risk faced by bacteria reduces substantially at around 45{degrees}C and almost disappears above 60{degrees}C. So viral lysis would become the dominating factor of bacterial mortality, and antivirus immunity has a higher priority. In temperature ranges where the abundance of cellular predators does not change with temperature, temperatures would have negligible effects on CRISPR-Cas abundance. The hypothesis predicts that bacteria should also be rich in CRISPR-Cas systems if they live in other extreme conditions inaccessible to grazing predators.

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Lan, X.-R., Liu, Z.-L., Niu, D.-K.. 2021-05-25. Bacterial CRISPR abundance jumps up at around 45°C. https://doi.org/10.1101/2021.05.25.445389

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