Ice-nucleation negative fluorescent pseudomonads isolated from Hebridean cloud and rain water produce biosurfactants H. E. Ahern, K. A. Walsh, T. C. J. Hill, and B. F. Moffett University of East London, Romford Road, Stratford, London, UK Environment Agency, Wallingford, UK Received: 1 September 2006 – Accepted: 15 September 2006 – Published: 4 October 2006 Correspondence to: T. C. J. Hill (t.c...

Primary biological aerosol particles (PBAPs) may play an important role in aerosol–climate interactions, in particular by affecting ice formation in mixed phase clouds. However, the role of PBAPs is poorly understood because the sources and distribution of PBAPs in the atmosphere are not well quantified. Here we include emissions of fungal spores and bacteria in a global aerosol microphysics mo...

The ice nucleation activities of five different Pseudomonas syringae, Pseudomonas viridiflava and Erwinia herbicola bacterial species and of SnomaxTM were investigated in the temperature range between −5 and −15C. Water suspensions of these bacteria were directly sprayed into the cloud chamber of the AIDA facility of Forschungszentrum Karlsruhe at a temperature of −5.7C. At this temperature, ab...

It is surprisingly difficult to freeze water. Almost all ice that forms under "mild" conditions (temperatures > -40 degrees C) requires the presence of a nucleating agent--a solid particle that facilitates the freezing process--such as clay mineral dust, soot or bacteria. In a computer simulation, the presence of such ice nucleating agents does not necessarily alleviate the difficulties associa...

The University of Toronto continuous flow diffusion chamber (UT-CFDC) was used to study heterogeneous ice nucleation at the International Workshop on Comparing Ice Nucleation Measuring Systems (ICIS 2007) which also represented the 4-th ice nucleation workshop, on 14–28 September 2007. One goal of the workshop was to intercompare different ice nucleation measurement techniques using the same ae...

The ice nucleation of bioaerosols (bacteria, pollen, spores, etc.) is a topic of growing interest, since their impact on ice cloud formation and thus on radiative forcing, an important parameter in global climate, is not yet fully understood. Here we show that pollen of different species strongly differ in their ice nucleation behaviour. The average freezing temperatures in laboratory experimen...

Instead of avoiding freezing, freeze tolerant invertebrates actively initiate controlled ice nucleation at relatively high sub-zero temperatures in extracellular compartments. Most produce proteinaceous ice-nucleators in their hemolymph, however the intertidal bivalve mollusc Geukensia demissa lacks this ability. Instead it utilizes at least one strain of ice-nucleation active (INA) bacteria, P...

The Arctic plant growth-promoting rhizobacterium Pseudomonas putida GR12-2 secretes an antifreeze protein (AFP) that promotes survival at subzero temperatures. The AFP is unusual in that it also exhibits a low level of ice nucleation activity. A DNA fragment with an open reading frame encoding 473 amino acids was cloned by PCR and inverse PCR using primers designed from partial amino acid seque...