Bacteria with missing pieces: three papers
/Here are a few papers I've read lately:
It's Caulobacter crescentus, named for everyone's favorite shape of roll.
A particular DNA methyltransferase, CcrM, is conserved throughout most Alphaproteobacteria, including Caulobacter crescentus. The methyltransferase isn't strictly essential but mutant strains without ccrM have difficulties with cell division. Gonzales et al. put C. crescentus mutants lacking ccrM through more than 300 generations of experimental evolution and found that they compensated by modifying expression of ftsZ, a gene coding for a product critical to cell division. This suggests that, at least in C. crescentus, CcrM acts to promote cell division through its effect on FtsZ levels.
This isn't open access, unfortunately, but the general idea is that bacteria living in the mammalian gut naturally produce ammonia and it isn't usually a problem unless the liver can't handle all that ammonia, at which point ammonia builds up in the blood. Hyperammonemia can cause neurological disease, coma, or death. Using a mouse model and a pre-designed gut microbiome culture, Shen et al. show that hyperammonemia could be avoided by replacing the usual gut microbiome with one able to produce less ammonia. Conveniently, the engineered microbiome they employ has been in use since the 1970's so there's extensive evidence that it isn't harmful (in mice, at least).
Also not open access but there's a press release with some nice, clear graphics. This group is making excellent progress in exploring unculturable bacteria. Notably, most of the isolates they obtained are from an aquifer next to the Colorado River that luckily is well upstream of the recent mine wastewater spill.