Ice-nucleating activity

Recent studies have further examined the iron stress response of pseudomonads using an iron-regulated, ice-nucleation gene reporter (inaZ) for induction of the iron stress response (17,18,84). This particular reporter system was developed by Loper and Lindow (85) for study of microbial iron stress on plant surfaces but was later employed in soil assays. In initial. studies, cells of Pseudomonas fluorescens and P. syringae that contained the pvd-inaZ fusion were shown to express iron-responsive ice-nucleation activity in the bean rhizosphere and phyllosphere. Addition of iron to leaves or soil reduced the apparent transcription of the pvd-inaZ reporter gene, as shown by a reduction in the number of ice nuclei produced. 

Duman, 2001 Duman et al., 1993 Wu and Duman, 1991). When its ice-nucleating activity is inhibited, the THP-activator protein does not jeopardize the deep supercooling that may be critical for survival of D. canadensis during periods of extreme cold. 

Lee, R.E. Jr., M.R. Lee, and J.M. Strong-Gunderson (1993a). Insect cold-hardiness and ice nucleating active microorganisms including their potential use for biological control. J. Insect. Physiol. 39 1-12. 

Certain strains of bacteria can competitively exclude other strains. Lindow (117) found that Ice (ice nucleation-active) populations of Pseudomonas syringae on corn plants Zea mays L.) were reduced by prior colonization of the leaves by Ice strains (ice nuleation-deficient). Interestingly, the total bacterial population was not affected by the prior inoculation of Ice strains (117). For these reasons, Lindow (117) concluded that the antagonism between these strains resulted from competitive exclusion of new arrivals to an occupied niche rather than competitive displacement. As the carrying capacity of leaf surfaces for bacteria is low relative to other plant habitats, particularly roots (101), preemptive colonization by one strain may be sufficient to reduce the population size of similar strains. The importance of competition for space among naturally colonizing microbes remains unknown. 

Ice-nucleation active bacteria. This was the first microbial product of biotechnology for which approval of field tests was requested. This has resulted in a long court battle with no final conclusion to date. After 241 experiments, expenditures of 750,000, and five man-years of research, Advanced Genetic Sciences has not yet convinced regulators and the public that their modified Pseudomonas... 

Cloning of the INA genes from Pseudomonas syrlngae and Pseudomonas fluorescens. A gene conferring ice nucleation activity was first... 

J Li, M Izquierdo, T Lee. Effects of ice-nucleation active bacteria on the freezing of some model food systems. International Journal of Food Science and Technology 32 41 9, 1997. 

Morris CE, Georgakopoulos DG, Sands DC (2004) Ice nucleation active bacteria and their potential role in precipitation. J Phys IV 121 87... 

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