Flagan, Suvi and Ching, Weng-Ki and Leadbetter, Jared R. (2003) Arthrobacter Strain VAI-A Utilizes Acyl-Homoserine Lactone Inactivation Products and Stimulates Quorum Signal Biodegradation by Variovorax paradoxus. Applied and Environmental Microbiology, 69 (2). pp. 909-916. ISSN 0099-2240 http://resolver.caltech.edu/CaltechAUTHORS:FLAaem03
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Many Proteobacteria produce acyl-homoserine lactones (acyl-HSLs) and employ them as dedicated cell-to-cell signals in a process known as quorum sensing. Previously, Variovorax paradoxus VAI-C was shown to utilize diverse acyl-HSLs as sole sources of energy and nitrogen. We describe here the properties of a second isolate, Arthrobacter strain VAI-A, obtained from the same enrichment culture that yielded V. paradoxus VAI-C. Although strain VAI-A grew rapidly and exponentially on a number of substrates, it grew only slowly and aberrantly (i.e., linearly) in media amended with oxohexanoyl-HSL as the sole energy source. Increasing the culture pH markedly improved the growth rate in media containing this substrate but did not abolish the aberrant kinetics. The observed growth was remarkably similar to the known kinetics of the pH-influenced half-life of acyl-HSLs, which decay chemically to yield the corresponding acyl-homoserines. Strain VAI-A grew rapidly and exponentially when provided with an acyl-homoserine as the sole energy or nitrogen source. The isolate was also able to utilize HSL as a sole source of nitrogen but not as energy for growth. V. paradoxus, known to release HSL as a product of quorum signal degradation, was examined for the ability to support the growth of Arthrobacter strain VAI-A in defined cocultures. It did. Moreover, the acyl-HSL-dependent growth rate and yield of the coculture were dramatically superior to those of the monocultures. This suggested that the original coenrichment of these two organisms from the same soil sample was not coincidental and that consortia may play a role in quorum signal turnover and mineralization. The fact that Arthrobacter strain VAI-A utilizes the two known nitrogenous degradation products of acyl-HSLs, acyl-homoserine and HSL, begins to explain why none of the three compounds are known to accumulate in the environment.
|Additional Information:||Copyright © 2003, American Society for Microbiology. Received 5 September 2002/ Accepted 19 November 2002 This research was supported by an infrastructural grant from the National Science Foundation (DBI-0107908) and research grants from the Department of Agriculture (CSREES 2001-01242) and the Schlumberger Foundation. We thank N. Dalleska and R. Becker for technical discussions and for help in performing LC-MS analyses and D. Newman for helpful comments.|
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|Deposited On:||20 Feb 2006|
|Last Modified:||26 Dec 2012 08:46|
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