## 1 Introduction  
_Pseudomonas chlororaphis_ strain PA23 is a soybean rhizosphere isolate that has been developed as a biocontrol agent to protect canola from stem rot caused by _Sclerotinia scleroorum_[1; 2]. Strain PA23 produces a number of compounds, including phenazines (PHZ), pyrrolnitrin (PRN), hydrogen cyanide (HCN), proteases, lipases and siderophores that contribute to its biological control potential [3; 4]. PHZs are bacterial secondary metabolites that have long been recognized for their broad-spectrum antibiotic activity and ability to antagonize a range of fungal phytopathogens [5; 6; 7]. Phenazine-1-carboxylic acid (PCA), one of the major PHZs produced by the fluorescent pseudomonads, was commercially named as Shenqinomycin. A 1% Shenqinomycin suspension was registered as a new biopesticide to prevent rice sheath blight, pepper blight and cucumber seedling damping-off [8]. Glucose and glycerol favor the production of PHZ in _P. chlororaphis_ PCL1391 [9], while mannitol and fructose favor the production of PRN in _P. protogens_ strain CHA0 [10]. PHZs are synthesized from glucose via the shikimic acid pathway [11]. A number of mutants defective in PHZ or PRN production, or both, were isolated from _P. chlororaphis_ PA23 [12]. These mutations affected _P. chlororaphis_ antibiotic production as well as biocontrol activity [13; 14]. PHZ production imparts deep orange pigmentation to _P. chlororaphis_ PA23 in glucose medium, while growth on octanoate results in colonies with a pale-yellow color, indicating reduced PHZ production. Fluorescent pseudomonads are known to produce biodegradable polyhydroxyalkanoates (PHAs) in excess carbon conditions when other nutrients such nitrogen, phosphorus, or oxygen are limiting. The PHAs are stored as granules in the cytoplasm and used as a carbon and energy source under carbon-limited conditions [15]. PHA and PHZ synthesis both appear to be important traits for root colonization and plant growth promotion in rhizosphere bacteria [16]. _P. chlororaphis_ can produce medium-chain-length (mcl-) PHAs consisting of C6 to C14 carbon chain monomers when grown on vegetable oils [17; 18; 19; 20] and fatty acids extracted from glycerol bottom [21] as sole carbon sources. In contrast, _P. putida_, which also produces mcl-PHA polymers, cannot utilize vegetable oils directly for PHA production because it does not secrete extracellular lipase [22]. The _P. chlororaphis_ PA23 genome encodes a _pha_ operon containing seven PHA genes, which are highly conserved among _Pseudomonas_ species. PHA can be synthesized from related (fatty acids) or unrelated carbon substrates (glucose and gluconate). Both de novo syntheses of fatty acids and degradation of fatty acids supply precursors for PHA biosynthesis. PHZs and PHAs are secondary metabolites that accumulate during stationary phase and compete with each other for carbon partitioning or electrons or for reducing power. Production of different secondary metabolites is tightly regulated in terms of transcription and translation of specific genes as well as for partitioning of carbon. Earlier experiments have shown higher production of PHAs in _P. chlororaphis_ PA23 mutants defective in PHZ production [23] and _rhlR_ mutants of _P. aeruginosa_ defective in rhamnipid biosynthesis [24], indicating that different secondary metabolites compete for precursors and reducing power. A number of mutations in regulatory gene systems, including the _gacA/gacS_ two-component system, the stationary phase sigma factor _rpoS_, and the stringent response (_relA/spoT_), are known to affect biocontrol activity of _P. chlororaphis_ PA23 by altering antibiotic synthesis [3; 25; 26; 27; 28]. Further positive and negative interactions among these genes regulate secondary metabolite production and fungal antagonism [25; 26; 27; 28; 29; 30]. Scattered information is available on the effect of these mutations on PHA production in different _Pseudomonas_ species. Mutations in the global regulatory system _gacA/gacS_ in _P. putida_ CA-3 and _P.