The presence and role of bacterial quorum sensing in activated sludge.
Bottom Line: N-acylated-l-homoserine lactone and exoenzyme production were frequently observed among the isolates.N-acylated-l-homoserine lactones produced by this strain were identified and genes ahyI/R and chiA, encoding AHL production and response and chitinase activity respectively, were sequenced.These experiments provide insight into the relationship between AHL-mediated gene expression and exoenzyme activity in activated sludge and may ultimately create opportunities to improve sludge performance.
Affiliation: Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.Show MeSH
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Mentions: Cross‐streaking and reverse‐phase thin‐layer chromatography overlay assays indicated that the activated sludge isolate Aeromonas sp. strain GC1 produces four molecules with AHL‐like activity, three of which could be putatively identified based on Rf values as N‐butanoyl‐l‐homoserine lactone, N‐hexanoyl‐l‐homoserine lactone and N‐dodecanoyl‐l‐homoserine lactone. NSI‐MS analysis of the culture extract identified hydrogen and sodium adducts of N‐butanoyl‐l‐homoserine lactone with m/z ratios of 172.096 and 194.078 (Fig. 6A). LC‐ESI‐FTMS analysis identified N‐hexanoyl‐l‐homoserine lactone at a retention time of 17.85 min with m/z ratios of [M+H] 200.127 and [M+Na] 222.109 (Fig. 6B) and N‐dodecanoyl‐l‐homoserine lactone at a retention time of 31.41 min with m/z ratios of [M+H] 284.221 and [M+Na] 306.203 (Fig. 6C). A fourth AHL was identified as N‐octanoyl‐l‐homoserine lactone with a retention time of 24.62 min and m/z ratios of [M+H] 228.158 and [M+Na] 250.143 (Fig. 6D). All retention times matched relevant synthetic AHL standards applied.
Affiliation: Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.