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The ice Nucleation Activity of Pseudomonas fluorescens Migula and its Inhibition by Various Chemicals
Author(s) -
Mittelstüdt H.
Publication year - 1995
Publication title -
journal of phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 60
eISSN - 1439-0434
pISSN - 0931-1785
DOI - 10.1111/j.1439-0434.1995.tb00266.x
Subject(s) - ice nucleus , nucleation , pseudomonas fluorescens , dilution , pseudomonas , bacteria , biology , chemistry , microbiology and biotechnology , organic chemistry , thermodynamics , physics , genetics
The ice nucleation activity (INA) of three strains of Pseudomonas fluorecens , nos 553, 554 and 606, isolated by the Institute for Pathogen Diagnostics in Ascherleben, Germany, was determined. Under equal growth conditions and at given test temperatures the ice nucleation frequency spectra of the isolates differed slightly. The fraction of cells which acted as ice nuclei increased with falling temperatures. Below −5°C the nucleation frequency rose from 10 ‐8 to 10 ‐3 . Between, 0 and −10°C only a fraction of approximately 2 to 5 × 10 ‐3 cells performed ice nucleation activity. Fifteen newly synthesized chemicals showed no or only a very slight intrinsic INA at −5°C and −7°C. The compounds were used as antinucleators against INA‐exhibiting bacteria. In INA‐exhibiting suspensions of isolate 553 bacterial ice nuclei were reduced after treatment with the 15 compounds. Dependent on the compounds, a nucleation frequency of −8.32 to −5.10 was detected at −5°C. At −7°C, the frequency amounted to −7.89 to −5.05. As the temperature was lowered to −10°C in bacterial suspensions which were treated with 9 (of the 15) compounds, a remainder of 1.79 to 5.91 × 10 ‐6 cells retained ice nucleation activity. The most pronounced inhibitory effect was noted for the compounds 1989/6255, 1989/6436 and 1990/6158. In a 10‐fold dilution of isolate 553 the compound 1989/6153 inhibited ice nucleation between 0 and 10°C so strongly that it was about 100 times below the control. The ‘tube‐freezing’ method showed that on excised corn leaves treated with 1989/6259 and 1990/6155, the bacterial INA decreased while the super‐cooling was more pronounced. ‘Frostgard’, 1986/6205, 1986/6199 and 1989/6259 inhibited most INA‐exhibiting bacteria on corn seedlings. Compared to inoculated plants, a significantly higher percentage of treated plants survived at −2 and −3°C.