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Biological control of an insect pest by gut‐colonizing Enterobacter cloacae transformed with ice nucleation gene
Author(s) -
Watanabe K.,
Abe K.,
Sato M.
Publication year - 2000
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.2000.00904.x
Subject(s) - biology , enterobacter cloacae , ananas , pantoea agglomerans , botany , horticulture , microbiology and biotechnology , bacteria , escherichia coli , enterobacteriaceae , biochemistry , gene , genetics
K. WATANABE, K. ABE and M. SATO.2000. The ice nucleation (IN) gene ina A of epiphytic Erwinia ( Pantoea ) ananas IN10 was transformed into Enterobacter cloacae WBMH‐3‐CM r originated from the faeces of silkworms. The transformant designated as Ent. cloacae WBMH‐3‐CM r (pICE6S13) exhibited IN activity, unlike the parent strain. The transgenic strain was ingested by mulberry pyralid larvae, fed on detached mulberry leaves, and the supercooling capacity and cold hardiness of these larvae were examined. The mean supercooling point (SCP) of the larvae ingesting the transgenic strain was − 3·3 °C, 8 °C higher than that of larvae treated with distilled water (control) and 1·5 °C higher than an ice nucleation active (INA) strain of Erw. ananas . The SCPs of the larvae were stably maintained over the 9 d after ingestion. The maintenance of these high SCPs was due to transgenic Ent. cloacae having a more stable and efficient gut colonization than Erw. ananas , which is identified by the distribution of a narrower range of SCPs (− 2 to −5 °C) in larvae treated with the transgenic stain. Furthermore, most of the larvae ingesting the transgenic strain froze and died when they were exposed to cold conditions of − 5 °C for 18 h, 3 or 7 d after ingestion. In contrast, most of the larvae ingesting no bacterium did not die under similar conditions. On the other hand, the growth ability of Ent. cloacae WBMH‐3‐CM r on mulberry leaves tended to be lower than that of epiphytic Erw. ananas , as assayed by pot tests. These findings would expand the possibility of biological control using INA bacteria since Ent. cloacae would harbour a broader host (insect) range for gut colonization and a smaller affinity to plants to benefit from prevention of plant frost injury.