Quorum sensing and the anaerobic regulator (ANR) control polyhydroxyalkanoate (PHA) production in Pseudomonas chlororaphis PA23

ABSTRACT Pseudomonas chlororaphis PA23 is a biocontrol agent that, in addition to producing antifungal compounds, synthesizes polyhydroxyalkanoate (PHA) polymers as a carbon and energy sink. Quorum sensing (QS) and the anaerobic regulator (ANR) are required for PA23-mediated fungal suppression; howe...

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Bibliographic Details
Published in:FEMS microbiology letters 2019-09, Vol.366 (18)
Main Authors: Mohanan, Nisha, Gislason, April, Sharma, Parveen K, Ghergab, Akrm, Plouffe, Jocelyn, Levin, David B, de Kievit, Teresa
Format: Article
Language:English
Subjects:
Biological control
Carbon
Carbon sources
Fungicides
Gene expression
Glucose
Microbiology
Pha gene
Polyhydroxyalkanoates
Polyhydroxyalkanoic acid
Polymers
Propagation (polymerization)
Pseudomonas
Pseudomonas chlororaphis
Quorum sensing
Reagents
Regulators
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Summary:ABSTRACT Pseudomonas chlororaphis PA23 is a biocontrol agent that, in addition to producing antifungal compounds, synthesizes polyhydroxyalkanoate (PHA) polymers as a carbon and energy sink. Quorum sensing (QS) and the anaerobic regulator (ANR) are required for PA23-mediated fungal suppression; however, the role of these regulators in PHA production is unknown. Strains lacking either QS or ANR accumulated less PHA polymers when propagated on Ramsay's minimal medium (RMM) with glucose or octanoate as the carbon source. In the acyl-homoserine lactone (AHL)-deficient background, all six of the genes in the pha locus (phaC1, phaC2, phaZ, phaD, phaF, phaI) showed reduced expression in RMM glucose, and all except phaC2 were repressed in RMM octanoate. Although changes in gene activity were observed in the anr mutant, they were less pronounced. Analysis of the promoter regions for QS- and ANR-binding consensus sequences revealed putative phzboxes upstream of phaZ and phaI, but no anr boxes were identified. Our findings indicate that altered pha gene expression likely contributes to the lower PHA accumulation in the QS- and ANR-deficient strains, which may be in part indirectly mediated. This study is the first to show that mcl-PHA production is under QS and ANR control. Polyhydroxyalkanoate synthesis is regulated by quorum sensing and ANR in Pseudomonas chlororaphis strain PA23.
ISSN:0378-1097
1574-6968
DOI:10.1093/femsle/fnz223