The cooling water systems are used to remove heat generated in the various industries. Biofouling of the cooling water systems causes blocking of condenser pipes and the heat exchanger tubes. In many Gram-negative bacteria,
N-acylhomoserine lactone (AHL) are used as quorum-sensing signal
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The cooling water systems are used to remove heat generated in the various industries. Biofouling of the cooling water systems causes blocking of condenser pipes and the heat exchanger tubes. In many Gram-negative bacteria,
N-acylhomoserine lactone (AHL) are used as quorum-sensing signal molecule and associated with biofilm formation. To investigate the relationship between quorum sensing and biofouling in the cooling water system, we isolated a total of 192 bacterial strains from the five cooling water systems, and screened for AHL production. Seven isolates stimulated AHL-mediated purple pigment production in AHL reporter strain
Chromobacterium violaceum CV026 or VIR07. Based on their 16S rRNA gene sequences, AHL-producing isolates were assigned to
Aeromonas hydrophila,
Lysobacter sp.,
Methylobacterium oryzae, and
Bosea massiliensis. To the best of our knowledge,
B. massiliensis and
Lysobacter sp. have not been reported as AHL-producing species in the previous researches. AHLs extracted from the culture supernatants of
B. massiliensis and
Lysobacter sp. were identified by liquid chromatography-mass spectrometry. AHLs produced by
B. massiliensis were assigned as
N-hexanoyl-
l-homoserine lactone (C6-HSL),
N-(3-oxohexanoyl)-
l-homoserine lactone (3-oxo-C6-HSL), and
N-(3-oxooctanoyl)-
l-homoserine lactone (3-oxo-C8-HSL). AHLs produced by
Lysobacter sp. were assigned as
N-decanoyl-
l-homoserine lactone (C10-HSL) and
N-(3-oxodecanoyl)-
l-homoserine lactone (3-oxo-C10-HSL). This is the first report of identification of AHLs produced by
B. massiliensis and
Lysobacter sp. isolated from the cooling water system.
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