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Ice-minus bacteria is a common name given to a variant of the common bacterium ''Pseudomonas syringae'' (''P. syringae''). This strain of ''P. syringae'' lacks the ability to produce a certain surface protein, usually found on wild-type ''P. syringae''. The "ice-plus" protein (Ina protein, "Ice nucleation-active" protein) found on the outer bacterial cell wall acts as the nucleating centers for ice crystals.〔John Love and William Lesser. April 1989. The Potential Impact of Ice-Minus Bacteria as a Frost Protestant in New York Tree Fruit Production. Northeastern journal of agriculture and resource economics()〕 This facilitates ice formation, hence the designation "ice-plus." The ice-minus variant of ''P. syringae'' is a mutant, lacking the gene responsible for ice-nucleating surface protein production. This lack of surface protein provides a less favorable environment for ice formation. Both strains of ''P. syringae'' occur naturally, but recombinant DNA technology has allowed for the synthetic removal or alteration of specific genes, enabling the creation of the ice-minus strain. The ice nucleating nature of ''P. syringae'' incites frost development, freezing the buds of the plant and destroying the occurring crop. The introduction of an ice-minus strain of ''P. syringae'' to the surface of plants would reduce the amount of ice nucleate present, rendering higher crop yields. The recombinant form was developed as a commercial product known as Frostban. Field-testing of Frostban was the first release of a genetically modified organism into the environment. The testing was very controversial and drove the formation of US biotechnology policy. Frostban was never marketed. ==Production== To systematically create the ice-minus strain of ''P. syringae'', its ice-forming gene must be isolated, amplified, deactivated and reintroduced into ''P. syringae'' bacterium. The following steps are often used to isolate and generate ice-minus strains of ''P. syringae'': # Digest ''P. syringaes DNA with restriction enzymes. # Insert the individual DNA pieces into a plasmid. Pieces will insert randomly, allowing for different variations of recombinant DNA to be produced. # Transform the bacterium ''Escherichia coli'' (''E.coli'') with the recombinant plasmid. The plasmid will be taken in by the bacteria, rendering it part of the organism's DNA. # Identify the ice-gene from the numerous newly developed ''E. coli'' recombinants. Recombinant ''E. coli'' with the ice-gene will possess the ice-nucleating phenotype, these will be "ice-plus." # With the ice nucleating recombinant identified, amplify the ice gene with techniques such as polymerase chain reactions (PCR). # Create mutant clones of the ice gene through the introduction of mutagenic agents such as UV radiation to inactivate the ice gene, creating the "ice-minus" gene. # Repeat previous steps (insert gene into plasmid, transform ''E. coli'', identify recombinants) with the newly created mutant clones to identify the bacteria with the ice-minus gene. They will possess the desired ice-minus phenotype. # Insert the ice-minus gene into normal, ice-plus ''P. syringae'' bacterium. # Allow recombination to take place, rendering both ice-minus and ice-plus strains of ''P. syringae''. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ice-minus bacteria」の詳細全文を読む スポンサード リンク
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