Acknowledgments
We would like to thank Dr. Michael Gerth for kindly providing comments on the manuscript. This work was supported by: a BBSRC Doctoral Training Partnership studentship (BB/M011186/1) awarded to JP; a Development and Promotion of Science and Technology Talents Project (DPST) of the Institute for the Promotion of Teaching Science and Technology, Thailand to PT and a Harry Smith Vacation studentship (Microbiology society) to HD.