I really need more time to fill in a gap in my microbiology education: environmental microbiology. I run across papers all the time that are absolutely fascinating, and wish I had a free year to just take some additional coursework in this area. For instance, a paper in today’s Science magazine discusses how atmospheric bacteria result in the formation of snow; more after the jump.
The authors here were looking at ice nucleators (IN) in snowfall. Think of this like crystal experiments you did as a kid–you had to stick something into the solution to serve as a seed for the crystal to grow. Snow (and other precipitation) does the same thing in the atmosphere; as the Atlanta Journal-Constitution story on the research notes, ” under most conditions, the moisture needs something to cling to in order to condense.” According to the Science paper, those seeds are frequently bacteria, including, as the author notes in the news interview, some pathogens of plants (such as Pseudomonas syringae, pictured above). Apparently (unbeknownst to me), P. syringae is already used to make fake snow, so the fact that it can serve as a seed for precipitation isn’t new. However, the authors note just how important these biological nucleators (including P. syringae) appear to be in the atmosphere:
The samples analyzed were collected during seasons and in locations (e.g., Antarctica) devoid of deciduous plants, making it likely that the biological IN we observed were transported from long distances and maintained their ice-nucleating activity in the atmosphere…our results indicate that these particles are widely dispersed in the atmosphere, and, if present in clouds, they may have an important role in the initiation of ice formation, especially when minimum cloud temperatures are relatively warm.
Bacteria…is there anything they *can’t* do?
Christner, B.C., Morris, C.E., Foreman, C.M., Cai, R., Sands, D.C. (2008). Ubiquity of Biological Ice Nucleators in Snowfall. Science, 319(5867), 1214-1214. DOI: 10.1126/science.1149757